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TAGERT.
10-05-2005, 01:17 PM
I know this has been a hot topic, but please, for the sake of realism, let€s try and keep it civil.

As most of you know I have been using Device Link data to confirm or deny statements made in this forum with regards to aircraft performance for some time now.

I have recently added roll rate analysis to my utility. I wanted to make it easy for people (sim test pilots) to fly a mission that resembles the real life conditions and methods. The method is to start at an altitude well above the 10kft altitude so you can dive down to 10kft to obtain the initial higher speeds. Once you get to 10kft all you have to do is roll the plane at least one complete 360? per each indicated speed (IAS). All the while recording a track file (*.trk). You can repeat any roll at any speed as many times as you want. All you have to do is insure that you stop and fly level for at least a few seconds in-between each roll. The analysis tool will scan through the Device Link data and pick out the peak roll rate per each roll you do and plot them on a graph.

Note I picked 10kft and IAS because most of the data we have to date is based on that setup (NACA 868). My next goal is to digitize the NACA 868 data points so we can overlay the in-game data points to see how they compare.

I don€t know what the simulation stick force is limited to, but, most seem to be under the impression that it is 50lb. With that said, you have to make sure your joystick is setup correctly. Go to Hardware Setup -> Input and make sure your joystick profile for ROLL ends in 100. Otherwise you will not be getting the full force applied.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RA...JOYSTICK_PROFILE.JPG (http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/JOYSTICK_PROFILE.JPG)


With that said, my first test was in a 109K, in that was what all the fuss was about. Kurfurst (Izzy) provided us with some roll rate numbers.

160mph = 61
170mph = 68
195mph = 72
220mph = 75
240mph = 78
280mph = 82
300mph = 73
350mph = 50

I have not gone to the trouble of converting the LW data charts yet, I have been too busy getting the utility working. I will digitize and convert them when I do the NACA 868 document. So, for now I€m taking Kurfurst word for it ( I know, I know! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif ) on the numbers that I will compare the in-game results too.

The following table contains the results of the in-game testing. As you can see, one of the hardest parts of the test is holding the 10kft altitude during the roll. The nose dips while rolling, so correcting for that will result in some variation of the altitude during the roll.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/RR_IAS_ALT_109K_10K_75FUEL.JPG


The following figure plots the in-game values from the table vs. Kurfurst€s values.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/IZZY_DATA_VS_GAME_DATA.JPG


From the graph we can see that the in-game 109K rolls much faster than expected (Kurfurst numbers) at speeds below ~235mph. From ~235mph to ~350mph the in-game 109K rolls much slower than expected (Kurfurs€s numbers). Also note, that from ~350mph and above the in-game 109K is starting to roll faster again, this was unexpected in that I have not seen any data of a plane doing that. If we were to extrapolate Kurfurst€s numbers on the slope they left off at ~350mph the in-game 109K is rolling much better than expected.

So, in summary, out of the 3 areas..

1) 160mph to 235mph
2) 235mph to 350mph
3) 350mph to 400mph

The 109K is rolling better than expected in 2 of the 3 areas.

TnB AREA (160mph to 235mph): The slow twisting attacks (wrestling) the in-game 109K has an unrealistic advantage.
BnZ AREA (235mph to 350mph): The fast slashing attacks (boxing) the in-game 109K has a unrealistic disadvantage until it reaches 350mph+, where it appears to gain an unrealistic advantage aagin.

All this is assuming Kurfurst€s numbers are correct!

So, lets try and keep cool heads here. If you have a problem with Kururst€s numbers, that is fine, please indicate your exceptions in a civil manor and have some supporting evidence. If you can convince me otherwise I will gladly update the graph with the corrected numbers.

PS If you have some real world data you want to test, send it along with the in-game track file of yoru test to naca_testing@yahoo.com and Ill process it for you. But, remember, don€t shoot the messenger, I just report the numbers, I don€t make them up! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

TAGERT.
10-05-2005, 01:17 PM
I know this has been a hot topic, but please, for the sake of realism, let€s try and keep it civil.

As most of you know I have been using Device Link data to confirm or deny statements made in this forum with regards to aircraft performance for some time now.

I have recently added roll rate analysis to my utility. I wanted to make it easy for people (sim test pilots) to fly a mission that resembles the real life conditions and methods. The method is to start at an altitude well above the 10kft altitude so you can dive down to 10kft to obtain the initial higher speeds. Once you get to 10kft all you have to do is roll the plane at least one complete 360? per each indicated speed (IAS). All the while recording a track file (*.trk). You can repeat any roll at any speed as many times as you want. All you have to do is insure that you stop and fly level for at least a few seconds in-between each roll. The analysis tool will scan through the Device Link data and pick out the peak roll rate per each roll you do and plot them on a graph.

Note I picked 10kft and IAS because most of the data we have to date is based on that setup (NACA 868). My next goal is to digitize the NACA 868 data points so we can overlay the in-game data points to see how they compare.

I don€t know what the simulation stick force is limited to, but, most seem to be under the impression that it is 50lb. With that said, you have to make sure your joystick is setup correctly. Go to Hardware Setup -> Input and make sure your joystick profile for ROLL ends in 100. Otherwise you will not be getting the full force applied.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RA...JOYSTICK_PROFILE.JPG (http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/JOYSTICK_PROFILE.JPG)


With that said, my first test was in a 109K, in that was what all the fuss was about. Kurfurst (Izzy) provided us with some roll rate numbers.

160mph = 61
170mph = 68
195mph = 72
220mph = 75
240mph = 78
280mph = 82
300mph = 73
350mph = 50

I have not gone to the trouble of converting the LW data charts yet, I have been too busy getting the utility working. I will digitize and convert them when I do the NACA 868 document. So, for now I€m taking Kurfurst word for it ( I know, I know! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif ) on the numbers that I will compare the in-game results too.

The following table contains the results of the in-game testing. As you can see, one of the hardest parts of the test is holding the 10kft altitude during the roll. The nose dips while rolling, so correcting for that will result in some variation of the altitude during the roll.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/RR_IAS_ALT_109K_10K_75FUEL.JPG


The following figure plots the in-game values from the table vs. Kurfurst€s values.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/IZZY_DATA_VS_GAME_DATA.JPG


From the graph we can see that the in-game 109K rolls much faster than expected (Kurfurst numbers) at speeds below ~235mph. From ~235mph to ~350mph the in-game 109K rolls much slower than expected (Kurfurs€s numbers). Also note, that from ~350mph and above the in-game 109K is starting to roll faster again, this was unexpected in that I have not seen any data of a plane doing that. If we were to extrapolate Kurfurst€s numbers on the slope they left off at ~350mph the in-game 109K is rolling much better than expected.

So, in summary, out of the 3 areas..

1) 160mph to 235mph
2) 235mph to 350mph
3) 350mph to 400mph

The 109K is rolling better than expected in 2 of the 3 areas.

TnB AREA (160mph to 235mph): The slow twisting attacks (wrestling) the in-game 109K has an unrealistic advantage.
BnZ AREA (235mph to 350mph): The fast slashing attacks (boxing) the in-game 109K has a unrealistic disadvantage until it reaches 350mph+, where it appears to gain an unrealistic advantage aagin.

All this is assuming Kurfurst€s numbers are correct!

So, lets try and keep cool heads here. If you have a problem with Kururst€s numbers, that is fine, please indicate your exceptions in a civil manor and have some supporting evidence. If you can convince me otherwise I will gladly update the graph with the corrected numbers.

PS If you have some real world data you want to test, send it along with the in-game track file of yoru test to naca_testing@yahoo.com and Ill process it for you. But, remember, don€t shoot the messenger, I just report the numbers, I don€t make them up! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

LEXX_Luthor
10-05-2005, 02:23 PM
Awsum.

And thanks TAGERT for making the joystick setting jpg a click link and for not making the direct linked pics oversize which can make reading threads impossible. Reading these threads is important, and you can't read them if they are corrupted by oversize pics (or gamers fighting).

I always said, the best way to compare grafs is to open each *click link* in a New Window and switch immediatley between them, instead of scrolling up and down a thread overpopulated with oversize direct linked graf pics.

Gibbage1
10-05-2005, 03:08 PM
Question. Why is there no RL data above 350?

Also the old Zero FM picked up roll rate at high speeds. The only aircraft thats in the game that should be able to do this is the P-38L with its boosted ailerons.

TAGERT.
10-05-2005, 03:23 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
Question. Why is there no RL data above 350? </div></BLOCKQUOTE>Not sure, will have to ask Kurfurts abuot that one. But, in RL you could extend that slope out to where it would hit 25?/sec at 400mph. In that *typically* (99%+) once a plane hit's it's force limit, it will decline from that point onward. Which is what is so odd about the in-game data, the in-game 109K hits it's limit at about ~195mph, then at ~255mph it is still declining, but at a slower rate.. but at ~ 305mph it defies the law of physics and starts to increase again.. very starnge.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
Also the old Zero FM picked up roll rate at high speeds. </div></BLOCKQUOTE>Not sure which zero your refering to, but the one in the NACA 868 declines over the entire range, just at different rates. That is to say, pick any mph point to the right of another mph ponit and the rollrate is less.. Which is true for all the planes in the NACA 868 chart. Only the in-game 109K can you pick a mph point to the right of another and see that it has a faster rollrte.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
The only aircraft thats in the game that should be able to do this is the P-38L with its boosted ailerons. </div></BLOCKQUOTE>Not unless the boost is uneven or does not kick in until a certain point. Which would be odd imho.. Would be like having your power stearing in your car enable itself at some point and not others.. Which would make it very hard to drive and cause loss of control imho. But, Im new to all these roll rate charts, if you have something showing the rollrate increasing like the in-game 109 does I would love to see it.

p1ngu666
10-05-2005, 03:37 PM
i think the boosted alirons just let it keep the alirons deflected at higher speeds http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif and therefor the peak roll rate will be at a higher speed, and probably faster?

crazyivan1970
10-05-2005, 03:43 PM
Keep it civil please... you know me http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

faustnik
10-05-2005, 03:46 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TAGERT.:
But, Im new to all these roll rate charts, if you have something showing the rollrate increasing like the in-game 109 does I would love to see it. </div></BLOCKQUOTE>

As far as I know, they all increase somewhat as roll speed increases as wind forces act on the control surface and then fall off as deflection becomes impossible to maintain, right? The Bf109 increasing, then decreasing, and then increasing again is really wierd.

I would expect the P-38L's aelerons to act exactly like power steering. You turn the wheel and you get a percentage of deflection. It would probably just take a little getting used to. It's not like you can't cause a car to loose control by over-controlling with power steering. ????

luftluuver
10-05-2005, 03:49 PM
Gibbage1.
Why would the testing continue when it could be seen that the rate was decreasing, unless they were experimenting with different aileron designs and configurations? They would just extrapolate the graph curve from the data already obtained.

ps Thanks Tag. http://forums.ubi.com/images/smilies/25.gif

TAGERT.
10-05-2005, 03:55 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by p1ngu666:
i think the boosted alirons just let it keep the alirons deflected at higher speeds http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif and therefor the peak roll rate will be at a higher speed, and probably faster? </div></BLOCKQUOTE>Roger, that is my impression too

TAGERT.
10-05-2005, 04:03 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by faustnik:
As far as I know, they all increase somewhat as roll speed increases as wind forces act on the control surface and then fall off as deflection becomes impossible to maintain, right? </div></BLOCKQUOTE>Looking at the NACA 868 data, and my gutt tells me that is the way it is.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by faustnik:
The Bf109 increasing, then decreasing, and then increasing again is really wierd. </div></BLOCKQUOTE>Agreed 100%! Is one of he reasons it tookd me so long to get this util done.. I saw that and figured I must have made a mistake, so I went back through all my equations and code step by step.. But.. no mistakes, that is what the in-game 109K does.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by faustnik:
I would expect the P-38L's aelerons to act exactly like power steering. You turn the wheel and you get a percentage of deflection. </div></BLOCKQUOTE>Makes since to me

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by faustnik:
It would probably just take a little getting used to. It's not like you can't cause a car to loose control by over-controlling with power steering. ???? </div></BLOCKQUOTE>No, what I was saying was with regards to Gibbages comment that there would be a point where the boosted alierons would cause your rollrate to start increasing, after your rollrate was decreasing.. like the in-game 109K does. The only way that would/could happen is if the boosted alierons didnt kick in until some point, or were none linear. Imagine driving a car and your going at a certain speed around a corner, say 54mph. Now you arms are applying 50lbs.. now at 55mph the power stearing kicks in unexpected.. now what use to take 50lb of force by you and your arms only takes 30lbs to hold the wheel where it is at.. That sudden extra boost you may not expect and causes you to jerk the wheel causing you to fly off of cliff. On the bight side.. YOUR FLYING.. but on the down side.. your going down! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

TAGERT.
10-05-2005, 04:37 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by luftluuver:
Gibbage1.
Why would the testing continue when it could be seen that the rate was decreasing, unless they were experimenting with different aileron designs and configurations? They would just extrapolate the graph curve from the data already obtained. </div></BLOCKQUOTE>You jest, but, at first glance that is what those LW graphs appear to be doing. Problem with doing that is it assumes you have an unlimited amount of force to apply. So, if you extrapolate that out using the slope before the force limit it would give you a very unrealistic curve.

For example say you didnt know where the Fw190 roll force limit was and you used the slope between 180mph(125?/sec) and 220mph(147?/sec). It would make you

m = (y2-y1)/(x2-x1)
m = (147?-125?)/(220mph-180mph)
m = 20?/40mph
m = 1?/2mph

Now use that to find the roll rate at say 320mph

m = (y2-y1)/(x2-x1)
m*(x2-x1) = (y2-y1)
y2 = m*(x2-x1)+y1
y2 = (1?/2mph)*(320mph-220mph)+147?
y2 = (1?/2mph)*(100mph)+147?
y2 = 50?+147?
y2 = 197?

Which gives us 197? instead of the actul 114?, and error of about 82?. So, extrapolating prior to the force limit is a WAG imho! But, that is what they seem to be doing, maybe the LW was trying to sugest something? i.e.

If we only had a few pilots that could bench press 500lbs we might win this war!

Prob is most guys back then, though tough, were small and not body builders.. and some were down right FEM! As can be seen in the following poster

http://www.geocities.com/grantsenn/STFU/luftlovers.jpg

There seems to be a plenty of arm-wrestling going on in that picture.. just minus the table between them! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by luftluuver:
ps Thanks Tag. http://forums.ubi.com/images/smilies/25.gif </div></BLOCKQUOTE>No prob! My pleasure! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

ImpStarDuece
10-05-2005, 05:09 PM
TAGERT, the graphs posted by Kurfurst were for a 109F-2, not for a 109K-4.

Kurfursts assertion is that the 109K-4 should have a better rate of roll than the 109F-2, if only because of redesgined wing structures reducing wing flex.

Could you possibly post a comparison between the in game data and the German test data for a 109F?

TAGERT.
10-05-2005, 05:18 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ImpStarDuece:
TAGERT, the graphs posted by Kurfurst were for a 109F-2, not for a 109K-4. </div></BLOCKQUOTE>Roger!

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ImpStarDuece:
Kurfursts assertion is that the 109K-4 should have a better rate of roll than the 109F-2, if only because of redesgined wing structures reducing wing flex. </div></BLOCKQUOTE>Wing flex does effect such things at high speeds, and the 109 was know to be pretty twisting wing wize even after the redesign. I have some pictures of the wing structers, the F and the K were not that different, they added an extra cross memeber out near the wing tip, but at the same time force a bigger tire compartment. All is all, that is a fine theroy by Kurfurst, but, it I have yet to see any real proof to support it.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ImpStarDuece:
Could you possibly post a comparison between the in game data and the German test data for a 109F? </div></BLOCKQUOTE>Im digitizing the NACA 868 data and once that is done Ill give that German data a look see. Problem is it is in TAS, so, It will take a little more time to convert.

Gibbage1
10-05-2005, 05:49 PM
NASA is currently doing a large scale study on wing flex and roll rate on modern aircraft. They took an early production F-18 and reduced the stiffness in the wings to enduce wing flex. The ailerons now only flex the wings, and the wing causes the roll, helping the aircraft roll better with less deflection. I dont know how this translates, but wing flex should not hinder roll rate that much if it helps roll rate on the F-18. The flex helps move more air in the proper direction to support the roll, not hinder it. Correct me if I am wrong.

TAGERT.
10-05-2005, 06:10 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
NASA is currently doing a large scale study on wing flex and roll rate on modern aircraft. They took an early production F-18 and reduced the stiffness in the wings to enduce wing flex. The ailerons now only flex the wings, and the wing causes the roll, helping the aircraft roll better with less deflection. I dont know how this translates, but wing flex should not hinder roll rate that much if it helps roll rate on the F-18. The flex helps move more air in the proper direction to support the roll, not hinder it. Correct me if I am wrong. </div></BLOCKQUOTE>Your right, if the flex moves in the dirction to help the air flow, but in the 109 case, with the single spar, the flex was in the oposite direction, which hindered the roll rate. A few books I have hint at that weak wing, aka flex, is why they gave up on the flettner tabs, in that it did defect the aleirons more, but, the wing flex cancled the effects, thus, moot point. But, that is just my take on it from the few books that talk about flettner tabs.

WWMaxGunz
10-05-2005, 06:45 PM
Tagert, are you also monitoring other elements than aileron and roll rate?

Like, you know; rudder, elevator, pitch and alt changes?

I get a feeling that losing alt could put in energy to speed a roll slightly.
There is also how losing alt puts the plane in less than 1G, how that would affect roll.

Rudder and elevator, especially rudder can really affect the roll rate. And the use of
those controls... if the plane doesn't roll perfectly how else to keep it in line?
But snap rolls with the rudder or just rudder assist in a roll? Is that cheating or is
it part of how they did it with one plane or another? Robert S Johnson wrote about P-47
rolls and using the rudder was part of the text.

I remember when people sent in tracks on the P-47 rolls back in AEP and Oleg did not
accept how the did them. The old "Learn to Fly!"... so I do wonder, I've never flown a
plane that was allowed aerobatics. It might be good to get what is right and not.

TAGERT.
10-05-2005, 06:57 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Tagert, are you also monitoring other elements than aileron and roll rate?

Like, you know; rudder, elevator, pitch and alt changes? </div></BLOCKQUOTE>Yes, every DeviceLink variable is collected. For example, in the table I provided it shows the altitude.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
I get a feeling that losing alt could put in energy to speed a roll slightly. </div></BLOCKQUOTE>As can be seen in the table, the fluxuation in alt was small, typical less than 50ft, worst was 150ft off of 10ft.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
There is also how losing alt puts the plane in less than 1G, how that would affect roll. </div></BLOCKQUOTE>I calcuate the "g" foce too, but, it currently does not take into accuont the roll angle effect. So, I need to add that. But know this, there was no big changes in altitude during the roll leading up to it or after it. Each roll was started from level flight at, your going to loose/gain some altitude during thes manvers, that is a given, even in real life.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Rudder and elevator, especially rudder can really affect the roll rate. And the use of those controls... if the plane doesn't roll perfectly how else to keep it in line? But snap rolls with the rudder or just rudder assist in a roll? </div></BLOCKQUOTE>No rudder was used during these tests, they were purly roll and pitch. I can detect if someone is using rudder to help or hurt the roll rates.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Is that cheating or is it part of how they did it with one plane or another? </div></BLOCKQUOTE>Not sure, but from reading a few NACA documents the purpose of roll rate testing was to see how well the alierons rolled the plane, thus I dont think they used rudder. Which is not to say you could not use rudder in combat, just, NACA testing is smart like that.. they want to watch the effect of one variable, not multi variables.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Robert S Johnson wrote about P-47 rolls and using the rudder was part of the text. </div></BLOCKQUOTE>combat fling tends to have other purposes than flight testing! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
I remember when people sent in tracks on the P-47 rolls back in AEP and Oleg did not accept how the did them. The old "Learn to Fly!"... so I do wonder, I've never flown a plane that was allowed aerobatics. It might be good to get what is right and not. </div></BLOCKQUOTE>Agreed 100% but until provin otherwise I will assume that no rudder assist was used, just makes since to me. But, if you got something that says otherwise, I will be glad to use it. Keep in mind, not talking about combat pilots tatics.. anything goes there.. talking abuot flight testing.. the kind of test done relitive to the data we are comparing to.

Grey_Mouser67
10-05-2005, 07:58 PM
If it is possible, could you compare roll rates in both directions? Torque modelling should mean that the plane rolls signficantly faster in one direction than in the other...except for Lightning.

In addition, some planes like the P-38 had an acceleration factor...moving the weight of the engine meant the plane ramped up to roll rate speed...I don't think either effect are modelled strongly but I'm wondering if this will be reflected by device link since it will only pick up "peak" roll rate. In real life, peak roll rate would be different than actual roll rate through the first revolution due to this acclelaration...I'd think that planes that have good roll rates like the Fw and clipped Spit would see less of this...I'm thinking too, that it is this dynamic that creates some of the contradictions in performance vs. pilot accounts like the good P-47 roll rate but the average numbers...and vice versa, the Hellcat's pedestrian roll rate but it feels pretty good in game to me....just thinking again. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

TAGERT.
10-05-2005, 08:19 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grey_Mouser67:
If it is possible, could you compare roll rates in both directions? </div></BLOCKQUOTE>Yes, the analysis tool works in either direction. For the 109K testing I did all my rolls clockwise.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grey_Mouser67:
Torque modelling should mean that the plane rolls signficantly faster in one direction than in the other...except for Lightning. </div></BLOCKQUOTE>Roger.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grey_Mouser67:
In addition, some planes like the P-38 had an acceleration factor... moving the weight of the engine meant the plane ramped up to roll rate speed... </div></BLOCKQUOTE>Momentum, a body at rest.. yadah yadah yadah.. All planes have to ramp up (accelerate), some are just faster than others. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grey_Mouser67:
I don't think either effect are modelled strongly but I'm wondering if this will be reflected by device link since it will only pick up "peak" roll rate. </div></BLOCKQUOTE>The ramping could be detected, in that I pick up more than the peaks, I just filter out the rest except for the peaks. But, to measure roll acc, I would probally have to up my sample rate a bit.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grey_Mouser67:
In real life, peak roll rate would be different than actual roll rate through the first revolution due to this acclelaration. </div></BLOCKQUOTE>Well, maybe peak is a bad name.. I should call them max roll rates.. Or sustained roll rates.. It is the roll rate you obtain once acc goes to zero, ie a constant rate.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grey_Mouser67:
I'd think that planes that have good roll rates like the Fw and clipped Spit would see less of this... I'm thinking too, that it is this dynamic that creates some of the contradictions in performance vs. pilot accounts like the good P-47 roll rate but the average numbers... and vice versa, the Hellcat's pedestrian roll rate but it feels pretty good in game to me....just thinking again. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif </div></BLOCKQUOTE>Roger, pilots accounts are cool and all.. but they say more about the pilot and the pilots he faced than the planes themselfs.

TAGERT.
10-05-2005, 08:23 PM
Step One

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/NACA_868.JPG

Gibbage1
10-05-2005, 09:55 PM
Step 2. Add the P-38 J and L with boost. Cant leave out the 38 http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif I know its on that chart!

TAGERT.
10-05-2005, 10:21 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
Step 2. Add the P-38 J and L with boost. Cant leave out the 38 http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif I know its on that chart! </div></BLOCKQUOTE>Errr.. which chart? I dont see it on the NACA 868 chart. But, as soon as I find it I will add it, count on it! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Anyway, here is the NACA 868 data vs. Kurfurst's numbers

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/IZZY_DATA_VS_NACA868.JPG

LEXX_Luthor
10-05-2005, 10:33 PM
Gibbage:: <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">They took an early production F-18 and reduced the stiffness in the wings to enduce wing flex. The ailerons now only flex the wings, and the wing causes the roll, helping the aircraft roll better with less deflection. </div></BLOCKQUOTE>
Would that cause roll control reversal? The wings flex opposite to ailerons? Something like this happened when Yak (http://forums.ubi.com/images/smilies/53.gif) reduced Yak-25 wing thickness without consulting his own structural engineers, and so Yak-27/28 were forever plagued with problems of ailerons flexing the wings too much and causing roll control reversal at higher speeds; never perfectly solved.

Daiichidoku
10-05-2005, 11:20 PM
just wondering, tagert...any chance that there is clipped wing zero roll data?

besides that its my fav zero in FB, it would be interesting to see how much better it is than the other zeros, and against the other types already on the list


btw, great work you've been doing for EVERYONE here, it must take a fair bit of time, nice to see objective testing, so that prehaps evryone can eventually knwo just wot de heck is going on with whatever type in question at the time, roll rates, climb, et al

http://forums.ubi.com/images/smilies/25.gif

Gibbage1
10-05-2005, 11:29 PM
http://home.att.net/~ww2aviation/P-38rollchart.JPG

TAGERT.
10-05-2005, 11:33 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
http://home.att.net/~ww2aviation/P-38rollchart.JPG </div></BLOCKQUOTE>COOL! Thanks Gibb, Ill add that in sometime this week!

TAGERT.
10-05-2005, 11:33 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Daiichidoku:
just wondering, tagert...any chance that there is clipped wing zero roll data?

besides that its my fav zero in FB, it would be interesting to see how much better it is than the other zeros, and against the other types already on the list


btw, great work you've been doing for EVERYONE here, it must take a fair bit of time, nice to see objective testing, so that prehaps evryone can eventually knwo just wot de heck is going on with whatever type in question at the time, roll rates, climb, et al

http://forums.ubi.com/images/smilies/25.gif </div></BLOCKQUOTE>Thanks! I have not see any real world data on it, but, maybe folks can send me the data and I can add it to the chart?

lrrp22
10-06-2005, 10:17 AM
Gibbage and Tagert,

That chart shows IAS roll rates, not TAS as labeled. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TAGERT.:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
http://home.att.net/~ww2aviation/P-38rollchart.JPG </div></BLOCKQUOTE>COOL! Thanks Gibb, Ill add that in sometime this week! </div></BLOCKQUOTE>

Gibbage1
10-06-2005, 01:28 PM
Its simple to find out if its TAS or IAS b matching the P-51 and FW-190 figures to other charts.

Loki-PF
10-06-2005, 03:47 PM
Hey, where is Knockwurst?



.

luftluuver
10-06-2005, 09:35 PM
Some 109Ks were fitted with Flettner tabs on their ailerons. Any real life data of the roll rate with the tabs?

Gibbage1
10-06-2005, 10:06 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by luftluuver:
Some 109Ks were fitted with Flettner tabs on their ailerons. Any real life data of the roll rate with the tabs? </div></BLOCKQUOTE>

Any proof they existed? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Kurfurst__
10-07-2005, 02:03 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TAGERT.:
Wing flex does effect such things at high speeds, and the 109 was know to be pretty twisting wing wize even after the redesign. </div></BLOCKQUOTE>

Accordng to whom, you? Sorry I don`t believe you. "It was known". Yeah, that`s the first thing I hear about. We all know who are the people participating in this thread, we all know what they would do to oppose FM corrections in the Bf 109, and if these people claim things that they cannot support with anything, I think we can safely ignore it.

I hope you will pardon me if I`d rather believe butch2k, the true 109 expert here who had never shown any kind of bias. To qoute him :

"109 wing torsion is similar to what could be found in US fighter planes. No aileron reversal at high speed, which came as a surprise to US engineers in charge of evaluation the 109 aerodynamical properties."

-Butch2k

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I have some pictures of the wing structers, the F and the K were not that different, they added an extra cross memeber out near the wing tip, but at the same time force a bigger tire compartment. All is all, that is a fine theroy by Kurfurst, but, it I have yet to see any real proof to support it. </div></BLOCKQUOTE>

It`s a fact that the wing structure was strenghtened on the 109G, I have a very document on the Bf 109G-1 that explicitely states it. The 109K had different wings but I am not sure if those were further strengtened.


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Im digitizing the NACA 868 data and once that is done Ill give that German data a look see. Problem is it is in TAS, so, It will take a little more time to convert. </div></BLOCKQUOTE>

I don`t see the problem. The in-game data doesn`t took


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Gibbage: "Question. Why is there no RL data above 350?"
TAGERT : "Not sure, will have to ask Kurfurts abuot that one. "
</div></BLOCKQUOTE>

Answer : there is, just Tagert ommitted it from his own chart.
In fact, the DVL doc goes as high as 800-900 kph, and the 400mph values can be easily read from my chart as well for both 50 and 66lbs stickforce :

http://www.onpoi.net/ah/pics/users/715_1128415529_dvlrollcurve109f-2.jpg

http://www.onpoi.net/ah/pics/users/715_1128252798_bf109roll-50lbs.gif


Parts I don`t understand :

1, Talk, talk talk about this 'increased roll rate of the 109K above 300mph. Yep, technically correct, and great smokescreen to talk about, rather than the actual issue. Did anyone notice that the 'completely unnatural increase' is actually a whole FIVE degrees/secondat 300/390mph, ie. well within and most likely measurement error of the test?

2, I don`t get why the IAS and mph has to be used for the test. The game gives kph and TAS. The original test is in the same measurements, kph and TAS. All this conversion to mph and especially to IAS just makes room for conversion error that can s*w up the whole test. I don`t think that the NACA chart, say the Crimea Map and 1944 German testing stations had the same atmospheric conditions, IAS will be different all over the place.
Besides it`s unneccesary again to convert to mph/IAS, unless we want to compare to the NACA chart, which a, we don`t want here b, was already done.


Other :

This page shows the the DVL tests were done with clockwise-rolls, ie. to the right as Tagert did, ie. left ailerons being down :

http://www.onpoi.net/ah/pics/users/852_1128025032_r4.jpg

Dave Southwood notes the following about flying the 109G:

"Roll performance is similar to a Hurricane or elliptical wing tipped Spitfire. A full stick roll through 360 degrees at 460kph takes 4 to 4.5 seconds without using rudder, and needs a force of around 20 lbf. One interesting characteristic is that rolls at lower speeds entered at less than 1g, such as a roll-off-the-top or half Cuban, have a markedly lower roll rate to the right than to the left. Therefore, I always roll left in such manoeuvres."

luftluuver
10-07-2005, 03:39 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:

Accordng to whom, you? Sorry I don`t believe you. "It was known". Yeah, that`s the first thing I hear about. We all know who are the people participating in this thread, we all know what they would do to oppose FM corrections in the Bf 109, and if these people claim things that they cannot support with anything, I think we can safely ignore it.


Answer : there is, just Tagert ommitted it from his own chart.
In fact, the DVL doc goes as high as 800-900 kph, and the 400mph values can be easily read from my chart as well for both 50 and 66lbs stickforce :

http://www.onpoi.net/ah/pics/users/715_1128415529_dvlrollcurve109f-2.jpg
</div></BLOCKQUOTE>

Kurfurst, do you oppose corrections to other a/c or do you only just want corrections for the 109?

Can you color the real test data on the graph?

The bottom curve goes to 700kph and shows a rate of between 23and 34 deg/sec. This curve only shows flight data for 20kg.

The next curve up goes into the high 700kph and maxs out between 45 and 57deg/sec at ~650kph(400mph). Only this curve shows flight data for 30kg.

The third curve up from the bottom maxs out at ~70deg/sec at a speed just over 500kph (310mph). This curve shows only flight data for 20kg.

These 3 curves are the only flight test data plotted on the graph.

Are you saying the Crimea map cannot be used for any testing of the Il-2 sim's a/c? I undestood this map should be the one used for a/c testing?

tomtheyak
10-07-2005, 03:42 AM
Kurfie,

You can make an arguement against a point without getting personal. I suggest you lighten the hell up - and don't give me that 'Gibbage did it 1st' cr@p, if Gibb did say that to/about you, then rise the he1l above it and don't respond. You certainly don't help your credibility in this forum with a response like that.

And as for bias, I believe Tagerts making some of the least subjective, honestly produced sets of data that have ever come to light - he's actually going out there and testing the game with regards to most a/c rather than fixating on one - and the fact he's doing it at all shows despite your ranting and generally unpleasant behaviour he's taken on board that you're unhappy with the 109 roll rate and respects your opinion enough to test it.

You should be grateful you have much say in these boards at all.

And as for the comment regarding TAS, Crimea map and differing atmospheric conditions over the world - Kurfie what the he1l do you want? There has to be some standard yardstick for comparison, and although you are correct, if atmospheric conditions differ for all data then thats just something we have to deal with - I personally don't own flying, full scale, gunned up stock examples of any of these planes to take up on any given day to test em, I sincerely doubt you do too - if you follow this line of arguement then theres no point testing anything at all, because it will all be wrong - including data that you present. You can't have it both ways.

And to everyone else,

I think i speak for everybody here, and speak to everybody when i say I realise how passionate you are about this game, and I share that passion, but there seems to be a serious lack of tact and manners amongst some of you; there are ways and means of presenting counter-points without resorting to insults, bad language and put-downs. I suggest some of you learn how.

p1ngu666
10-07-2005, 08:38 AM
nice post tom http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

crimea is the standard for tests, i dont think there is actully much difference between the various maps

DaimonSyrius
10-07-2005, 08:57 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by tomtheyak:
And to everyone else,

I think i speak for everybody here, and speak to everybody when i say I realise how passionate you are about this game, and I share that passion, but there seems to be a serious lack of tact and manners amongst some of you; there are ways and means of presenting counter-points without resorting to insults, bad language and put-downs. I suggest some of you learn how. </div></BLOCKQUOTE>

Speaking for me (at least) here, absolutely. Great post, Tom http://forums.ubi.com/images/smilies/25.gif

S.

Blottogg
10-07-2005, 09:39 AM
Tagert, excellent work! Thanks for taking the (significant) time to assemble this data. I envy your dedication.

Gib, the F-18 you're thinking of is the AAW (Active Aeroelastic Wing), link here:

http://www.nasa.gov/centers/dryden/news/FactSheets/FS-061-DFRC.html

Lexx, you're right, it looks like NASA is essentially using the aileron and LE flaps as trim tabs to twist the wing. I've only skimmed the site, but the big thing I'd worry about with this approach is changing the flexibility of the wing to the point that it's natural frequency shifts down enough to become a player at low speeds (i.e. below the airframe's qmax), which would shake things apart rather quickly. I'll have to read to see how they're avoiding that.

Tagert, it looks like your 190 curve in the other thread matches the slope of the flight test data at high speed, just at a consistantly lower roll rate. A simple fix for this half of the envelope might be to just buff up the virtual pilot, though I don't know what's causing it to curve up again at 400 mph. That could be a tougher fix. I was surprised to see the unrealistically high rates for both the 109 and the 190. I had thought 4.01 had significantly reduced the max roll rate across the board. FritzGryphon's data suggests otherwise. Another example of anecdote not matching the data. Perhaps the partial stick deflection has been toned down in 4.01. Reducing maximum deflection might be a way to adjust the sim's low speed rate, but I don't know if the sim engine would easily allow any of these tweaks.

The AAW reminded me of a point that came up in previous threads. The point of roll reversal is (usually) well above these WWII fighters' Vne (q max), but that doesn't mean the numbers aren't useful. They are a good indication of wing torsional stiffness, a higher control reversal speed corresponding to higher stiffness, all other things being equal.

Concerning IAS versus TAS for testing, use IAS. NASA (and NACA) and DVL use it for a reason. The airplane doesn't care how fast the molecules are hitting it, it cares about the dynamic pressure q = 1/2(rho)V^2, where rho is the air density. In other words, not just how fast molecules are hitting it, but how many. TAS isn't affected by rho, temperature or humidity, IAS is. TAS is useful mostly for navigation (along with wind info) and bragging rights.

edit - spelling, additional comments

WWMaxGunz
10-07-2005, 12:28 PM
In fact, the DVL doc extrapolates as high as 800-900 kph.......

http://www.onpoi.net/ah/pics/users/715_1128415529_dvlrollcurve109f-2.jpg

Also please note that over 30kg stickforce data does exist on this chart for 6 degrees
stick displacement while elsewhere it does not.

I think the real question is why. Looking at all areas where the curves are dashed
I see them in areas patently unflyable with such deflections at least for the low speeds.

And I suggest that at the higher speeds it is also true that either the deflection
could not be obtained or for another reason they were unable to obtain such data.

It was *certainly not* that they did not try more than 20kg force since the 6 degree
curve goes even beyond 30 kg -- unless that is an error of the chart and should not
be a solid line which I find hard to believe. Alternative is that where the actual
data is not, it could not be flown for whatever reasons, like and please Blottog
could you comment on this:

When a plane rolls the wings undergo different AOA each. One increased, one decreased.
If the increased AOA wing hits stall then it is not good, may result in spin. At high
speed for that wing, does the speed affect the differential?

With slats that are not and then are deployed (and one wing out while the other in)
you have time to deploy and effects of that which at highspeed I think it would take
expert pilots and tests to determine. Oh, wait... we DO have those tests and no data
for parts of curves and whole curves.

Is this unreasonable? I think not given such an excellent and =complete= chart.
Really, I think that the data portion gives a good description of the roll envelope
for that plane.

Good chart and really a very good plane! Isn't the 109F-2 described by most LW 109
Aces as the most maneuverable of the series?

Blottogg
10-07-2005, 02:02 PM
Neal, you're right that at low speed 1 "g" flight, the additional AoA imparted by roll to the wing moving up could be enough to stall the wing. For that reason, 1 "g" low speed roll rates should "dish out" a bit, instead of being a straight line down to zero. I believe the roll data was collected in unloaded or zero "g" rolls for that reason, at least at low speed, so the rate remains linear until wing torsion starts flattening out the curves. Unloading for the roll also avoids roll coupling, and minimizes asymmetric slat deployment and adverse yaw effects.

In a related note, folks were asking earlier whether or not rudder was used for roll tests in general. I can't find the reference, but in one of the other roll tests surfacing in these threads a while back I remember reference to using fixed (zero) rudder during the test, which I would expect was standard. In addition, as has been pointed out previously, the 109's ailerons displaced asymmetrically, no doubt to reduce adverse yaw. The flight test of the captured 109E bears this out (I think ailerons were asymmetric for both the E and F, but I'm not sure):

"...Abrupt displacement of the ailerons gives bank with no appreciable opposite yaw." (from "Messerschmitt Bf109 at War" p. 139)

Something else that others had mentioned, but just dawned on me is the top of the curves. For the 109 (and all other aircraft to some degree or another) at some point pushing harder on the stick doesn't do anything but twist the wings more. Imagine the 20 kg line going a bit further up to intersect the lower 15 deg line (I'm still wondering why there are two 15 deg displacement lines on this graph BTW) and you see that 20 kg gets you 80 deg/sec, just like 20 kg does. Another reason (besides physical limits) that 50 lb was probably picked as a practical test limit for aircraft of the period. For other aircraft, this point might be well beyond the force any pilot could generate. An airplane with big ailerons, moved through large throws, with mechanical disadvantage, and attached to very stiff wings, would behave like this (which is how I'm explaining the P-39D line in NACA 868, at least for the moment.)

My last hypothetical exercise was to extrapolate the various 109 roll curves for various deflection angles back to zero. Holtzauge had pegged it at ~1000 kph, but it should vary with deflection angle. Higher angles (were they physically possible) would bend the wing more at high speed than low angles. So 15 deg displacement would reach control reversal at a lower speed than 3 or 6 degrees. Which is just another way of demonstrating the tradeoffs between low speed and high speed roll optimization. The Spitfire (broadly speaking) had better low speed roll, but worse high speed, with more flexible wings and more aileron/deg of stick travel, while the P-51 had worse slow speed roll, but maintained its roll performance better due to its aileron design, and a stiffer wing that provided the platform for them.

As far as the one curve that does have data past 30 kg, I don't know if it was a graphics oops or the pilot was just feeling his Wheaties for that data point. He wasn't doing anything but exercising anerobically at that point though... the best roll rate was back at about (surprise, surprise) 23 kg (50 lb.)

edit - grammar

WWMaxGunz
10-07-2005, 03:19 PM
UBI just killed my first try at a reply Blotto.

1) Losing alt during the tests? Is that normal? So then we should do the same?
What effect would staying flying level have on the roll rates?

2) 1940's... would they have conducted such tests by pulling the stick with a
spring scale? If so then past some amount of deflection the scale hitting the
side of the cockpit might limit any results obtainable. That would be some
reason why there are none.
If it was me, I'd rig a push-scale with two-point pivot based on the floor.
But then, I'd be wanting complete data. Add a lever and force is NP.

3) The extra 15 degree curve with the unreadable (by me at least) label and
long-short dashed line just may be extrapolated with consideration of wing flex.

That's the short version there.

Gibbage1
10-07-2005, 03:38 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:

1, Talk, talk talk about this 'increased roll rate of the 109K above 300mph. Yep, technically correct, and great smokescreen to talk about, rather than the actual issue. Did anyone notice that the 'completely unnatural increase' is actually a whole FIVE degrees/secondat 300/390mph, ie. well within and most likely measurement error of the test?
</div></BLOCKQUOTE>

So what your saying here is something that is physically impossible to do is "OK" since its "a whole five degrees/second"?

Well 5 degrees a second above a flat line drawn from the 300MPH mark, but as we all know roll rates contenue to decline after peak, not flatten out or increase.

If you fallow the graph Tagert posted using real life data, and fallowed its downward curv, the 109 is "extrapolated" to doing about 20-30 degrees a second at 400MPH IAS. Even your own numbers state at 800KPH = 23 deg/sec. In game, its doing over 50 degrees a second. Thats a huge margin of error!

I can see why you consider this a small error. Since its in your favor. Unfortunatly 20-30 degrees of error is not "well within" any acceptable margin for error. Another fine example of you trying to fraud the community by slanting the numbers.

Gib

Grey_Mouser67
10-07-2005, 05:27 PM
Not only should roll rates decrease, but most aught to decrease at a decreasing rate down to zero or plane break up whichever occurs first at some point as speed increases.

Stick forces increase and on some planes I imagine they go past the pilot's ability to move the stick...or the plane breaks up from compressibility. I also suspect that some aircraft allow for more stick force to be applied due to the room in the cockpit, the disign of stick/yoke helping for two handed use, and the length of the stick in terms of leverage....I doubt any of this is modelled and I'm not sure that it should be.

Roll rate testing is verifying something I always knew...as did everyone else...all FM's are off...only to varying degrees.

No need to get riteously indignent about the mention of a FM or DM being incorrect...just assume it is and work towards a better FM and all will be well.

Gibbage1
10-07-2005, 05:42 PM
The ability to move the controle surface at high speed also depends greatly on the aileron design also. Or other factors such as power boosting like on the P-38. There are many many factors, but I think the biggest one is aileron design for standard WWII aircraft.

WWMaxGunz
10-07-2005, 08:11 PM
You are not suggesting ailerons were standardized, country to country
let alone plane to plane? AFAIK there was all kinds of variation.

Was the 109 uneveness of up angle to down angle used on most other planes
or was that in itself exceptional?

Gibbage1
10-07-2005, 09:57 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Was the 109 uneveness of up angle to down angle used on most other planes
or was that in itself exceptional? </div></BLOCKQUOTE>

Can you re-word that? I dont understand the question. But it seems many aircraft have the same pattern. High low speed roll rate, low mid speed roll rate, and a very strange and impossible increase of roll rate above 350MPH. This seems to be a problem with how the FM handles roll rates, not a problem with aircraft.

Also out of the 3 aircraft Tagert tested, NONE were even close to the lines on the roll charts. I did a very big roll rate test before 4.01 and they at least resembled the charts before.

p1ngu666
10-07-2005, 10:10 PM
the alirons when moved, dont move the same amount up and down, normaly more down?

F series was the poilts fav. all interviews say aswell.

109 has friese type alirons iirec, same as hurri, lanc (which does actully have a good roll rate), there are others aswell, just cant remmber em.

lanc had a divelimit of 400mph or so i think.

highspeed aliron design was a black art in ww2, ie u might just luck into having good alirons at high speed...

Gibbage1
10-07-2005, 10:39 PM
Most ailerons have more up montion then down. Like 25 degrees up, and 15 down. Spitfire is like that. I dont think its animated like that in the game.

tomtheyak
10-08-2005, 05:12 AM
Hmmm... this consistent error with roll rates seems to be for most a/c tested, and didn't Oleg introduce more inertia effects in the new FM? - perhaps a miscalculation there is whats effecting these planes so uniformly....

Hey look on the bright side, at least it seems that all planes probably suffer from this, so no-single a/c has an advantage it shouldn't have! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Blottogg
10-08-2005, 05:49 AM
What Gibbage said. Looking at the roll report here:

http://mitglied.lycos.de/luftwaffe1/aircraft/usaaf/rollrate.pdf

Shows all four aircraft included have ailerons that travel farther up than down. It also shows that the P-36 had more aileron travel, and less stick travel, than the P-40, while retaining the same wing planform. This reinforces what Holtzauge had pointed out in a prior thread, that the engineers can change the control rigging to optimize roll performance for low or high speed. In the case of the P-40, they knew they'd be going faster, so they shifted the peak roll to a higher speed, with a corresponding reduction of low speed roll.

And I've got to correct myself (again), during low speed, high AoA aileron rolls, the wing moving down will be at higher relative AoA, while the wing moving up will have its relative wind reduced by the velocity component contributed by the roll. These relative wind changes during a loaded roll are minor compared to the effect of increased camber on the wing going up though, at least initially. Its camber increases with the aileron deflection, causing the flow to separate (stall) during high AoA (loaded) rolls. Its leading edge slats will help the 109, but because of RL intertial effects (not sure if roll coupling is modeled in the FM, but I doubt it), it would still be a better idea to roll unloaded. Unloaded, the plane will still roll, even if portions of both wings stall (at very low speeds), since the amount of force needed to roll the aircraft is a lot less than that needed to hold it up in 1 "g" flight. So its the up wing stalling, but not for the reason I first gave. FWIW, what limits roll rate is the balance between the effect of increased camber on the up wing and increased AoA on the down wing:

"...the downgoing wing therefore experiences an increase in lift while the upgoing wing has a lift reduction. The resulting rolling moment opposes the rolling motion, and a steady-state rolling motion occurs when the damping moment equals the control-induced moment." - Ray Whitford "Design for Air Combat" p. 97

He also has a graph on that page showing that rudder fixed roll rate will be lower than when rudder is used to eliminate sideslip from adverse yaw, and that this reduction in roll rate is directly proportional to dihedral effect, and inversely proportional to yaw stability. Given the poor yaw stability in the current FM (this is quite probably historically correct... none of these things were designed to Cessna levels of stability), rudder fixed could be reducing roll rate by quite a bit. The alternative is to use rudder to eliminate sideslip, but that opens up a bigger can of worms (about how much rudder is too much) than I'd care to open.

As far as loosing altitude during the roll test, the small altitude change wouldn't have much effect, but to minimize it further, the test could be started in a slight climb before unloading and rolling. The flat ballistic parabola would still have minor velocity changes, being slightly slower at the top, but those minor errors would be lost in the noise compared to control surface drag, pilot technique, etc.

I don't know how they instrumented the aircraft for flight test in WWII. If anybody's on speaking or e-mail terms with Rudi Opitz or Corky Meyer, they'd be able to answer. I don't remember them mentioning much about test equipment in their articles however. They may have relied on the pilot's own "calibration", given that the force lines on the graphs (with the exeception of limiting force on the right of the graph) may have been calculated after the fact. Alternatively, perhaps they instrumented the stick as well. These days we'd just use a force transducer mounted to the stick (like the F-16 uses to send control inputs to the flight control computer). A WWII solution could have been as simple as a V shaped spring of known resistance held between the palm and stick. Push until it makes contact and you have applied "X" pounds of force. This is speculation on my part (I have NO evidence such a device was used), but it isn't hard to imagine using something like this being used. This is along the lines of what you suggested Neal, but I don't know if the pilots would have agreed to something actually fixed in place beside the stick.

Most of this dicussion is no doubt way beyond the scope of what's in our current FM, or the upcoming BoB for that matter. Where data is available, I'd like to see the FM match RL a little closer, whether replicating a RL solution (changing aileron deflection or stick force) is possible in the model, or some more esoteric changes to the code that have no real world counterpart.

Tagert, I don't know if you've already mentioned it, but did you roll to the left, right, or both during your tests? Engine torque is the only other FM explaination I can think of to explain the high roll rates at low speed.

p1ngu666
10-08-2005, 09:43 AM
oops, i was wrong http://forums.ubi.com/images/smilies/1072.gif

Viper2005_
10-08-2005, 03:03 PM
Hi everybody. I've been lurking for some time...

Hold on to your hats, cos here comes post #1!

Test flying is an extremely interesting topic and I thought I'd give you my tuppence worth...

Firstly, differential aileron movement is generally used to prevent/reduce adverse yaw. Ailerons work by modulating the camber of the wing, thereby translating the wing's polar.

If the aircraft is in 1 g flight, the result of this camber modulation is to increase the lift on one side and decrease the lift on the other. As there's no such thing as a free lunch in aviation this increase in lift causes an increase in induced drag, whilst the decrease in lift on the other side results in a decrease in induced drag.

This creates a yawing moment towards the up-going wing which must be corrected with rudder if coordinated flight is to be maintained.

Of course translation of the polar of the part of the wing associated with the aileron has some other rather "interesting" consequences.

Ailerons don't generally have much effect on the stalling Cl of the wing, and so by increasing the camber to increase lift they generally reduce the stalling alpha somewhat. Therefore, applying aileron close to the stall can easily result in departure.

Which is why one must never correct wing drop at the stall with aileron.

Adverse yaw therefore not only adds to pilot workload (try flying gliders!) but also represents a safety issue.

Various solutions have been put forward over the years.

Frize ailerons are effective, but obviously result in a drag penalty.

Differential aileron gearing is somewhat less draggy, but it also has issues as it only really works at the design Cl, and so handling may be somewhat less desirable off-design.

Possibly the most aerodynamically elegant approach is to adopt a sin^x lift distribution where x&gt;2.5. This approach was used by the horten brothers in constructing their flying wings and at x=2.5 results in neutral yaw, which becomes proverse as x is increased.

Of course this approach tends to result in large wingspans and forces a low span loading.

However, it is worth pointing out that the washout as used by the Spitfire goes some way towards approaching this condition, and is at least partially responsible for that type's good manners at the stall.

Secondly, AFAIK (says he making a massive generalisation) in WWII test flying was conducted using at least the following basic kit:

i) stopwatch - probably the single most important bit of kit in test flying, as everything important is a function of time.
Traditionally, stability was measured by measuring phugoids with a stopwatch.

ii) spring balance - just like the sort of thing you'd find at the grocer's. Used to measure stick forces, important for doing all the phugoid stuff, and also useful for stick force per g type measurements.

iii) kneeboard - no point taking measurements if you don't record them!

Later, test flying became somewhat more advanced, one of the great innovations being setting up a secondary instrument panel behind the pilot, and a camera with which to record readings as a function of time. Essentially a photographic version of a modern black box. Extra space behind the pilot (the camera not needing to see past the panel) allowed extra instrumentation to be added, often in the form of outputs from pressure tapping, strain guages etc...

Obviously the spring balance approach to stick force measurement has limitations associated with it - the bigger the force you want to measure the bigger the spring required (deflection being limited by the geometry of cockpit and pilot!). As such, the higher the stick force the lower the accuracy (error might be considered a function of stick force^n where n is slightly greater than 1).

It must be remembered that stick force measurements had to be noted down manually by the pilot on his kneepad, and obviously this is a somewhat problematic task when pulling high g loads...

Thirdly with regard to roll rates in general, it is perhaps worthwhile to examine the variation in roll rate with airspeed of an imaginary "typical" aircraft.

To make things really simple I'll start off by simply modulating Q in 0 g flight with constant atmospheric properties (thus removing the possibility of stalling the ailerons).

At low Q, maximum aileron deflection is attained with very little stick force, and roll rate is low for 2 reasons:

i) with low Q the lifting force associated with any given Cl is low and therefore inertia forces dominate, so it takes a relatively long time to reach maximum roll rate.

ii) as the aircraft is flying slowly the change in alpha at the wing tip associated with any given angular velocity is high and therefore aerodynamic damping is high.

As Q increases, aerodynamic forces get larger (reducing the impact of [i]) and because I've set the scenario up to have constant atmospheric properties, TAS must have increased, therefore reducing the impact of [ii].

Therefore roll rate initially increases with increasing Q.

However, ailerons must be designed to have a stable hinge moment (otherwise you get into all sorts of trouble!) and therefore as Q increases, the stick force required to attain a given aileron deflection will also increase. At some point the stick force will reach and exceed the capacity of the pilot, and so aileron deflection will start to decrease.

This will generally result in a gradual reduction in roll rate.

Depending upon the hinge moment (which controls the stick force/ per unit aileron deflection per unit Q) there comes a point at which the rolling force supplied by the aileron starts to bend the wing.

At this point the aileron starts to act as a tab, and will twist the wing in the opposite sense to its own deflection, resulting in "aileron reversal".

In the case of the Spitfire, the original wing had an aileron reversal speed of 580 mph, which was one of the main factors limiting the aircraft's growth.

The new wing used from the Mk 20 onwards had increased torsional rigidity, increasing aileron reversal speed to 850 mph(!), which conferred an adequate safety margin over the maximum operating speed of the aircraft (520mph IAS).

However, this analysis is somewhat simplistic as it neglects Mach number effects.

The formation of a normal shock over the wing obviously prevents the aileron from affecting the flow field forward of said shock.

Therefore, above the critical Mach number, a considerable reduction in control effectiveness may be expected. Generally this was most important in pitch, as the formation of a shock over the wing tends to shift the centre of pressure aft, whilst shock formation over the horizontal stabiliser tends to reduce elevator effectiveness, resulting in a nose down pitching moment and associated "grave yard dive" (to borrow Eric Brown's most descriptive turn of phrase).

However, the same forces are at work in roll as in pitch, and WWII fighter aircraft, most of which were effectively 1930s designs, tended to suffer at high Mach numbers, mainly due to the selection of rather thick wing sections for structural reasons...

(though aerodynamic performance at low speed was considered important as pilots were not generally thought capable of landing aircaft at speeds greater than about 100 mph, an assumption which seems quite reasonable for a grass airfield in my experience!)

In this respect the Spitfire was exceptional, with a tactically usable Mach number of around 0.82 compared with the Mustang which had a tactical Mach number of around 0.74.

Generally speaking, flight at Mach numbers greater than about 0.7 is somewhat problematic for most WWII fighters.

The highest Mach number attained by the Spitfire was 0.89, by a PR aircraft (XI if memory serves) operated by the high speed flight of the RAe at which point the propeller reduction gear failed , causing the prop to depart the aircraft. The change in CoG resulted in a rather "abrupt" pullup (11 g+). A deadstick landing was executed and the pilot walked away. The aircraft was scrapped (considerable deflection of the horizontal surfaces being noted).

I must say that I have not noticed any Mach number effects in roll in this sim.

At the end of the day this is a computer game. Errors are to be expected.

However, overall, I am impressed by the fact that this game appears to favour the same kind of tactics suggested by WWII combat reports. Therefore it must be on the right track at least...

I can't think of any "guns only" competition...

I just wish that oleg & co would give weekly or even monthly updates on what's going on. I suspect that this would put most of the patch vineyards out of business...

That's my tuppence.

WWMaxGunz
10-08-2005, 09:19 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Was the 109 uneveness of up angle to down angle used on most other planes
or was that in itself exceptional? </div></BLOCKQUOTE>

Can you re-word that? I dont understand the question. But it seems many aircraft have the same pattern. High low speed roll rate, low mid speed roll rate, and a very strange and impossible increase of roll rate above 350MPH. This seems to be a problem with how the FM handles roll rates, not a problem with aircraft.

Also out of the 3 aircraft Tagert tested, NONE were even close to the lines on the roll charts. I did a very big roll rate test before 4.01 and they at least resembled the charts before. </div></BLOCKQUOTE>

Well for one, I don't think that the FM changes due in 4.02 are just for kicks.

Two, the rise in final highspeed roll may not be exactly an FM problem but instead MAY BE
a controls problem that has the pilot always able to make a minimal deflection. You see
the difference? _FM_ is reaction to wings, control surfaces and speed and flight while
_controls_ is ability to position and move those surfaces. Seperate things, the stick
does not affect flight directly, it controls parts that do. So if there is something
that lets surfaces move always at least a minimal amount then faster speed with that will
always result in more force, more roll in this case.

OTOH, if the rolls only do this in one direction then it may be entirely due to twist in
the wings and tail to offset torque at cruise speed which becomes stronger as speed goes
above cruise and weaker at under.

WWMaxGunz
10-08-2005, 09:53 PM
Okay Viper, I'll bite. Q would be speed?

Kurfurst__
10-09-2005, 01:43 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Was the 109 uneveness of up angle to down angle used on most other planes
or was that in itself exceptional? </div></BLOCKQUOTE>

It's quite standard way for aircraft to have assymetric aileron deflection, the main reason being that they are positioned on the wing. You know, the stuff that makes the lift by faster airflow over, and slower aiflow under the wing. The forces acting on the aileron are bigger at the same deflection on the top, so less deflection is enough if you want to have balanced roll vector on both wings.

WWMaxGunz
10-09-2005, 02:51 AM
Actually the explanation of changing camber, drag differential and minimizing adverse
yaw put forth recently on this forum make even more sense.

Willy M. was sharp and had some very smart cookies working for him.

Blottogg
10-09-2005, 05:30 AM
Neal, Q is dynamic pressure, and is directly proportional to velocity squared:

q = 1/2(rho)V^2

where rho is the air density.

Viper, welcome to the forums, and excellent post! Please tell me you're an Aero Engineer, and I can put my old textbooks away. The dust is aggrevating my headcold.

You're right, there are no Mach effects in the FM, so we don't have to deal with things like Mach tuck or aileron buzz.

As far as using the spring scale for force measurements, they wouldn't have to write down the test data during the maneuver necessarily, but rather could do it between maneuvers (I used to do the same thing between BFM engagements and intercepts.) If they used a spring scale, the biggest problem would be holding the required force precisely, as you mentioned. Looking down at the spring guage while maneuvering wouldn't have been easy, so perhaps they used an adjustable pointer or stop on the scale, something along the lines of a torque wrench.

Blottogg
10-09-2005, 06:02 AM
The reason ailerons deflected asymmetrically was not to equalize the roll moments on both sides of the aircraft, but rather to minimize the affect of adverse yaw, as Viper correctly explained. Asymmetrical aileron motions would be just as effective combating adverse yaw with a symmetrical airfoil as with a cambered one. Unequal roll moments on the up and down wings are not, in and of themselves, a problem. If they were, spoilers wouldn't be used for roll control, since they don't do anything to increase lift on the up wing, only serving to decrease lift on the wing rolling down. Asymmetrical drag, leading to adverse yaw, sideslip, and the opposing rolling moment created by that, is why the up aileron moves more than the down aileron.

As a side note, spoilers can also be used symmetrically as speed brakes (as you may have noticed in an airliner on decent), or in the case of the Boeing X-32, to move the center of lift rearward for carrier landings with the original tailless configuration. Mounting them with their hingeline parallel to the swept leading edge meant that they shed vortices when they deployed, energizing the airflow enough to help keep it attached further back down the wing. This avoided a nasty potential pitch-up during slow speed flight, as airflow would otherwise separate from the rear of the wing, while the front of the delta kept flying. It was an elegent, if draggy, solution, which they may have gotten rid of when they put a horizontal tail on it. A moot point since it lost to the X-35 I guess, but still kind of neat.

Viper2005_
10-09-2005, 06:56 AM
Thanks Blotto. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Viper2005_
10-09-2005, 07:07 AM
If you consider adverse yaw as a function of wing secion design, some rather interesting conclusions come to light.

Firstly let's consider a symmetrical section in zero g flight.

Clearly there is no need for aileron gearing as equal deflections will result in equal lift and drag changes, therefore adverse yaw will be zero.

OTOH, if we place the same section in 1 g flight so that it's actually lifting, then the symmetry of the situation is lost, and the downgoing wing sees a lift reduction (rather than the production of negative lift) which results in a drag reduction which leads to adverse yaw.

Thus, adverse yaw is a function of the modulus of the lift coefficient.

Sorry for the double post. I can't seem to do the whole edit thing (it crashes firefox!).

Blottogg
10-09-2005, 07:30 AM
Thanks for the clarification, Viper. That was the point I was going for (though my previous comments on low speed roll testing while unloaded wouldn't have lead you to it.)

Viper2005_
10-09-2005, 08:55 AM
Of course this means that roll performance will vary with load factor, and therefore when conducting these tests it is important to ensure that the test profile flown accurately matches the NACA profile if the intention is to replicate NACA data.

In addition to altitude and airspeed, load factor, power setting, pitch attitude, mach number and sideslip will all impact roll rate.

And of course, roll rate will vary considerably from aircraft to aircraft for a variety of reasons, such as aileron matching, general rigging and CoG.

Whilst it is generally possible to "reverse engineer" a scientific paper like a NACA report, it is quite difficult to work out exactly what's going on in the sim, as various important details are missing. The most obvious of these is weight and balance, but there are others such as mod state.

In the case of the Spitfire, various different aileron designs were used, which had a considerable effect on roll rate and feel, but the sim doesn't mention which is modelled.

[Things are even worse in pitch. Again using the Spitfire as an example, bob weights were used to improve stick free stability as a mandatory mod ~ 1943. Meanwhile the elevator went through several design changes, changing its section and the area of its horn balance.]

As such one cannot simply say

"That's a Spitfire IX so it'll handle exactly like that other Spitfire IX I flew last week."

The same sort of thing doubtless applies to most of the other aircraft modelled in the game.

The Devil as they say is in the details...

p1ngu666
10-09-2005, 10:06 AM
there will be differences in "indentical" planes aswell.

trim tabs seem to have been really effective from what ive read aswell, stuff like bombers would really haveto wrestle them if u lost trim..

TAGERT.
10-09-2005, 10:30 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
The Devil as they say is in the details... </div></BLOCKQUOTE>And Deviclink provides most if not all of the details, i.e. the power setting, pitch attitude, and sideslip. Granted, we don€t know what those were set to during the NACA testing, but I think it is safe to say there should be some setting we can apply in-game that should thus match the NACA charts. I have not gone through all the different combinations, I decided to use common since and..

1) not use any rudder to assist the roll.
2) allow the power setting and speed to settle before rolling

For example.. In that if you were coming from 200mph to 300mph and on your way to 400mph in a dive to your test alt and rolled at 300mph you have allot of *changing* kinetic energy mixing in with your test, that and using rudder would be changing two variables and not isolating the one you were trying to test. All in all, applying common since to this and your probably get what they did back then. It was such a DUH that they didn€t even bother to mention it.

Viper2005_
10-09-2005, 05:32 PM
Will device link tell you the weight of the aircraft and its CoG position?

Here is a link to NACA Report 868 if anybody wants to read it in full...

http://naca.larc.nasa.gov/reports/1947/naca-report-868/

The comparison chart may be found on page 42.

That's my bedtime reading taken care of!

TAGERT.
10-09-2005, 06:37 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Will device link tell you the weight of the aircraft </div></BLOCKQUOTE>Given the dry weight you could calculate it.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
and its CoG position? </div></BLOCKQUOTE>Maybe, but in light of the fact that Oleg allready alluded to the fact that they dont take fule into account for CoG it probly wouldnt mater. For example, the instability of the P51 due to the added tank behind the pilot seat does not appear in the sim, because the fuel weight is distributed evenly instead of at certain points.

WWMaxGunz
10-09-2005, 08:56 PM
Either that or it's always there in some proportion.

Kurfurst__
10-10-2005, 07:26 AM
I think we miss the point here, while the usual Blottog or Max'Extrapolated'Glunz ego-show is truely interesting, I think the title was "ROLLRATE TESTING: Bf109K".

I think we missed the subject and errors in Tager's tests are still not corrected, we still lack testing results from gibbage, mglunz, or blottog who seem to be highly excited by the subject.

The major problem with Tagert's test results are that they are not compatible with the original. The original is in TAS, while Tagert did his tests with IAS readings.
Further the original is with a 109F-2, tagert did it with a 109K, though I don't think the results would be much different, it would be nice to compare like with the like, as it was noted that apart from weight issues, the 109K wing was a reinforced one over the 109F (which at the time of testing was some 3-4 years old airframe).

So to get comperable results with the original DVL tests, the in-game testing must follow the following :

- 109F-2, please.
- Full fuel load
- throttle at Dauerleistung, ie. cruising power - torque effects the test greatly!
- right hand rolls - torque again, esp. at lower speeds
- 3000m altitude
- max aileron deflection (=15degrees)
- no rudder/elevator input
- and use TAS, TAS, TAS, TAS !!!

Ie. the problem is that while TAS, absolute speed would be the same ingame and in RL, IAS conversions vary with atmoshperic conditions and could be incompatible. Besides, why do extra work. This is about bug fixing, not fixation about relative performance to other aircraft.

WWMaxGunz
10-10-2005, 07:39 AM
Hey Kranky, there is no DVL DATA for 15 deg aileron deflection.

Why don't you fly the test yourself and post track if you're so keen on it?

I just Googled 'Glunz' and there's a very large family that goes by that name? In fact, there are Glunz' in Germany and the US, maybe Scandanavia. You are not by any chance trying to use someone's family name as any kind of insult, are you?

Viper2005_
10-10-2005, 11:40 AM
NACA 868 says:

"FLIGHT INVESTIGATIONS
PROCEDURE FOR DETERMINING ROLLING PERFORMANCE

Description of maneuver. - The rolling performance of an airplane usually is determined during abrupt aileron rolls made from laterally level, trimmed, straight flight at different indicated airspeeds. Power for level flight ordinarily is used at speeds below the level-flgith speed obtainable with maximum continuous power; above this speed rolls are made during steady level flight with maximum continuous power. The test altitude is not particularly important unless compressibility effects are involved. In a given series of tests, however, the altitude should be maintained approximately constant.

At each selected speed five rolls in each direction, with a different control deflection for each roll, usually are sufficient. A greater number of control deflections may be necessary for airplanes having very nonlinear lateral-control characteristics. At high speeds the maximum control deflection may have to be restricted in order to ensure that the aerodynamic forces on the ailerons and on other parts of the airplane do not exceed the structural design limits.

Each test roll is made by moving the control (stick or wheel) abruptly to some predetermined deflection and by holding the control at that deflection until the maximum rolling velocity occurs. Until maximum rolling velocity occurs, the rudder is held in its original trim position. Recovery from the maneuver is made by any method the pilot desires. The control should be deflected as rapidly as possible. When control forces permit, full deflection can be reached in about 0.1 to 0.2 second. The desired control deflection usually can be obtained by means of a variable stop device attached to the stick or control wheel; however with such an arrangement care must be exercised to ensure that the proper control forces are measured.

Variables measured. - The following variables are measured during the most general investigations for determining the rolling performance of an airplane:

(1)Rolling velocity
(2) Free-streem impact pressure or indicated airspeed
(3) Rudder position
(4) Aileron position
(5) Stick or control-wheel deflection
(6) Stick or control-wheel force
(7) Aileron hinge moments
(8) Pressure altitude
(9) Free-air temperature
(10) Aileron distortion

Presentation of data. - The test results may be plotted in the form of a time history, as illustrated in figure 9, for a roll with ailerons partly deflected. The maximum helix angle pb/2V is computed from the maximum rolling velocity, the wing span, and the true airspeed. The values of aileron force and deflection which occur at the time of maximum rolling velocity shold be used since the steady force that the pilot will be able to hold is of primary interest. When there is a large negative value of Cha or when there is a spring-tab system with a weak spring, the maximum force and deflection as well as the force and deflection at maximum rolling velocity may have to be considered. Pilots usually are made to show the variable of control force and pb/2V with total aileron deflection for each of the test indicated airspeeds. Another very useful plot is one in whcih the total aileron deflection, the rolling velocity at some standard altitude, and pb/2V are plotted against indicated airpseed for a fixed value of the control force.

When aileron hinge-moment coefficients are to be plotted, the tests should be made with the trim tab locked in one position (preferably neutral) because the variation of hinge-moment coefficient with speed may be somewhat obscured if the control fore is trimmed to zero at each speed tested."

Gibbage1
10-10-2005, 12:00 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:

I think we missed the subject and errors in Tager's tests are still not corrected, we still lack testing results from gibbage, mglunz, or blottog who seem to be highly excited by the subject.
</div></BLOCKQUOTE>

Were is your test's?

If you look at SimHQ, other people have done the test' and every single one looks about the same, with the same high roll at low speed, drop, then the same pickup in roll at high speed.

TAGERT.
10-10-2005, 10:16 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
NACA 868 says:

"FLIGHT INVESTIGATIONS
PROCEDURE FOR DETERMINING ROLLING PERFORMANCE

Description of maneuver. - The rolling performance of an airplane usually is determined during abrupt aileron rolls made from laterally level, trimmed, straight flight at different indicated airspeeds. Power for level flight ordinarily is used at speeds below the level-flgith speed obtainable with maximum continuous power; above this speed rolls are made during steady level flight with maximum continuous power. The test altitude is not particularly important unless compressibility effects are involved. In a given series of tests, however, the altitude should be maintained approximately constant.

At each selected speed five rolls in each direction, with a different control deflection for each roll, usually are sufficient. A greater number of control deflections may be necessary for airplanes having very nonlinear lateral-control characteristics. At high speeds the maximum control deflection may have to be restricted in order to ensure that the aerodynamic forces on the ailerons and on other parts of the airplane do not exceed the structural design limits.

Each test roll is made by moving the control (stick or wheel) abruptly to some predetermined deflection and by holding the control at that deflection until the maximum rolling velocity occurs. Until maximum rolling velocity occurs, the rudder is held in its original trim position. Recovery from the maneuver is made by any method the pilot desires. The control should be deflected as rapidly as possible. When control forces permit, full deflection can be reached in about 0.1 to 0.2 second. The desired control deflection usually can be obtained by means of a variable stop device attached to the stick or control wheel; however with such an arrangement care must be exercised to ensure that the proper control forces are measured.

Variables measured. - The following variables are measured during the most general investigations for determining the rolling performance of an airplane:

(1)Rolling velocity
(2) Free-streem impact pressure or indicated airspeed
(3) Rudder position
(4) Aileron position
(5) Stick or control-wheel deflection
(6) Stick or control-wheel force
(7) Aileron hinge moments
(8) Pressure altitude
(9) Free-air temperature
(10) Aileron distortion

Presentation of data. - The test results may be plotted in the form of a time history, as illustrated in figure 9, for a roll with ailerons partly deflected. The maximum helix angle pb/2V is computed from the maximum rolling velocity, the wing span, and the true airspeed. The values of aileron force and deflection which occur at the time of maximum rolling velocity shold be used since the steady force that the pilot will be able to hold is of primary interest. When there is a large negative value of Cha or when there is a spring-tab system with a weak spring, the maximum force and deflection as well as the force and deflection at maximum rolling velocity may have to be considered. Pilots usually are made to show the variable of control force and pb/2V with total aileron deflection for each of the test indicated airspeeds. Another very useful plot is one in whcih the total aileron deflection, the rolling velocity at some standard altitude, and pb/2V are plotted against indicated airpseed for a fixed value of the control force.

When aileron hinge-moment coefficients are to be plotted, the tests should be made with the trim tab locked in one position (preferably neutral) because the variation of hinge-moment coefficient with speed may be somewhat obscured if the control fore is trimmed to zero at each speed tested." </div></BLOCKQUOTE>That is exactally the method I used.. except that I didnt roll it left and right, just right. What is not clear is did they take the average of those two, the max of those two, or the min of those two per speed?

Funny, how my comon since matched the NACA methods to a "T" except for the right and left thing. I just figured the roll with the torq would produce the best roll rates, thus the ones that would be advertised.

TAGERT.
10-10-2005, 10:20 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
I think we miss the point here, while the usual Blottog or Max'Extrapolated'Glunz ego-show is truely interesting, I think the title was "ROLLRATE TESTING: Bf109K".

I think we missed the subject and errors in Tager's tests are still not corrected, we still lack testing results from gibbage, mglunz, or blottog who seem to be highly excited by the subject.

The major problem with Tagert's test results are that they are not compatible with the original. The original is in TAS, while Tagert did his tests with IAS readings.
Further the original is with a 109F-2, tagert did it with a 109K, though I don't think the results would be much different, it would be nice to compare like with the like, as it was noted that apart from weight issues, the 109K wing was a reinforced one over the 109F (which at the time of testing was some 3-4 years old airframe).

So to get comperable results with the original DVL tests, the in-game testing must follow the following :

- 109F-2, please.
- Full fuel load
- throttle at Dauerleistung, ie. cruising power - torque effects the test greatly!
- right hand rolls - torque again, esp. at lower speeds
- 3000m altitude
- max aileron deflection (=15degrees)
- no rudder/elevator input
- and use TAS, TAS, TAS, TAS !!!

Ie. the problem is that while TAS, absolute speed would be the same ingame and in RL, IAS conversions vary with atmoshperic conditions and could be incompatible. Besides, why do extra work. This is about bug fixing, not fixation about relative performance to other aircraft. </div></BLOCKQUOTE>Actully we allready tested the 109F over at SimHQ

http://www.simhq.com/simhq3/sims/boards/bbs/ultimatebb....topic;f=144;t=001073 (http://www.simhq.com/simhq3/sims/boards/bbs/ultimatebb.php?ubb=get_topic;f=144;t=001073)

As for TAS.. aint going to happen! When I get around to converting the 109 charts I will convert the TAS to IAS. In that the bulk of my data is in IAS.

Kurfurst__
10-11-2005, 03:19 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWMaxGunz:
Hey Kranky, there is no DVL DATA for 15 deg aileron deflection. </div></BLOCKQUOTE>

Kranky ? Is that your mothers name?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I just Googled 'Glunz' and there's a very large family that goes by that name? In fact, there are Glunz' in Germany and the US, maybe Scandanavia. You are not by any chance trying to use someone's family name as any kind of insult, are you? </div></BLOCKQUOTE>

Why dont you just go and see a shrink ? You need one, with these paranoid symptoms.. I am sure they can give you some pill to chill you down a bit.

Kurfurst__
10-11-2005, 03:24 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TAGERT.:
Actully we allready tested the 109F over at SimHQ

http://www.simhq.com/simhq3/sims/boards/bbs/ultimatebb....topic;f=144;t=001073 (http://www.simhq.com/simhq3/sims/boards/bbs/ultimatebb.php?ubb=get_topic;f=144;t=001073) </div></BLOCKQUOTE>


Great. It appears that none of these tests included data points for 400 mph. Gibbage claims though the tests show an abnormal increase... they go 360 at best. Is gibbage a lying then, again...?



<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">As for TAS.. aint going to happen! When I get around to converting the 109 charts I will convert the TAS to IAS. In that the bulk of my data is in IAS. </div></BLOCKQUOTE>

OK, so you admit none of your tests is compatible with the historical data, and you are manipulating the figures with conversions of your own taste. That's EXACTLY what I suspected. Now you confirmed. Thank you.

I guess we can ignore all of your so called "tests" as you were manipulating the test results, then.

One interesting point is visible even on your retouched tests however, is the fact that the 109E and F/G/K have exactly the same roll behaviour, despite the fact that their wing and aileron structure was very different.It`s an obvious bug, given the changes, I except the squared tipped 109E to roll better at roll speeds, but worser at high speeds than the later versions with improved ailerons and wings.

JuHa-
10-11-2005, 05:57 AM
Some points to consider about the ingame testing:

Throttle settings and speed:

If the throttle is kept at a constant point, then obtaining desired speed and altitude will be tricky. And, the speed will not keep constant during the roll, as the plane will
either deaccelerate/accelerate due to speed/power combination.

If the throttle is adjusted to keep specific speed at an altitude, the torque from the engine will be different for each speed/measurement. The speed will be closer to constant than with the alternative method.

In game the rapid changes of throttle induces sudden rolls due to changes in torque and these should be avoided, IMHO.
IF there's a necessity to get results without the torque effect, then the roll due torque alone has to be measured
and removed from the results. If the torque is about constant for the whole roll, the removal is a simple procedure.

The real question is, which method resembles more the test method in RL ?
I'd try to follow that in the first place.


Altitude&elevator:

The thing here is, that unless some corrective elevator is used, the plane will drop upto ~200m of altitude during the roll _when_ flying slow (under 300km/h).
Which is worse? Drop of altitude or use of elevator?
Use of rudder should be avoided, I agree on that.

Fuel amount:

If I remember correctly, the usual testing should be conducted with Crimea map, noon .... and with 50% fuel? I'd like to
add that I prefer to test with unlimited 50% fuel, as then the weight of the plane will not change during the flight.

Plane type:

What I've tested, the E4, F2 and K4 all shared the same roll performance. Had a look upon the results of other planes, and this seems to be some very generic limitation of the FM.
Results so far show that all (tested) planes have their peak roll somewhere between 200..250s and then just taper off.


IAS/TAS.

Would be simpler to use TAS, I agree. But I'm just too used (and spoiled) to work with SI-units... http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif


Stick deflection:

Only thing we can control is that our joysticks will have the full travel programmed in the profile and that we use it during the roll.
If this induces only a fixed amount of force to the ingame stick,
then the roll rate has to be compared against values achieved with specified force.


Direction of roll:

While setting up the plane for rolls, I had to apply some pressure to the right (of the stick) to counter the torque induced roll to
the left. So clockwise rolling for Bfs is the slower diretion IMO.
If the rolls are made to both directions and averaged, this would eliminate the torque component out of it. Which sounds nice.

Good thing is, that all results are obtained with the same method, so they are comparable.
And as the results show, roll rates are generally so off from the mark that some
+/- 10degree/s error just doesn't matter...

Kurfurst__
10-11-2005, 10:19 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JuHa-:
Some points to consider about the ingame testing:

Throttle settings and speed:

If the throttle is kept at a constant point, then obtaining desired speed and altitude will be tricky. And, the speed will not keep constant during the roll, as the plane will either deaccelerate/accelerate due to speed/power combination. </div></BLOCKQUOTE>

Altitude keeping is not very important for test results, if within a few hundred meters, thats good enough. Obtaining the specific speed should be easy with some practice, by finding out the neccesary dive angle vs. throttle.



<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">If the throttle is adjusted to keep specific speed at an altitude, the torque from the engine will be different for each speed/measurement. The speed will be closer to constant than with the alternative method.

In game the rapid changes of throttle induces sudden rolls due to changes in torque and these should be avoided, IMHO.
IF there's a necessity to get results without the torque effect, then the roll due torque alone has to be measured
and removed from the results. If the torque is about constant for the whole roll, the removal is a simple procedure.

The real question is, which method resembles more the test method in RL ?
I'd try to follow that in the first place. </div></BLOCKQUOTE>



Did you consider switching TORQUE MODEL = OFF...? I wonder if that would help the problem without creating a new one...


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Altitude&elevator:

The thing here is, that unless some corrective elevator is used, the plane will drop upto ~200m of altitude during the roll _when_ flying slow (under 300km/h).
Which is worse? Drop of altitude or use of elevator?
Use of rudder should be avoided, I agree on that. </div></BLOCKQUOTE>

I think the loss of a few hundred meters of altitude is quite irrelevelant - the original tests also had some variation of altitude, it's unavoidable since some of the measured speeds would be hard to reach with the early 109F with 601N engine, at max CONTINOUS power! See at the end. The NACA 868 report notes the diffos with altitude change, but they are only visible with big changes, ie. 5-10 000 feet altitude differences. A +- few hundred can be safely ignored.

However the Dauerleistung throttle would make sense, since 109/190s had their rudder tabs set to give neutral rudder during cruise, or to be exact, a given power output, since torque is dependant on the engine power, not airspeed! This way they did not need to worry about the rudder.


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Fuel amount:

If I remember correctly, the usual testing should be conducted with Crimea map, noon .... and with 50% fuel? I'd like to add that I prefer to test with unlimited 50% fuel, as then the weight of the plane will not change during the flight. </div></BLOCKQUOTE>

It would be interesting to test at 25% and 100% fuel, but imho it would not much difference (real tests had fully tanked plane btw), either in RL (Bf 109 did not have wing tanks, just a single one), or in game since the engine doesn't model mulitple fuel tank CoG afaik.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Plane type:

What I've tested, the E4, F2 and K4 all shared the same roll performance. Had a look upon the results of other planes, and this seems to be some very generic limitation of the FM.
Results so far show that all (tested) planes have their peak roll somewhere between 200..250s and then just taper off. </div></BLOCKQUOTE>

If it's true, that quite bad news. That means fixing would be hard, I dont know how the FM is built up to give final values, but basically roll rate is = aileron effectiveness (deg of roll generated by deg of ail. deflection) x (aileron deflection, limited by stickforce at given speed).

The problem is that if one looks at the NACA curve, it's quite clear some planes have good aileron effectiveness and limited by deflection and stickforce (ie. Spit, 190, 109, P-39), and others like the P-51, P-47 etc. have light controls, so they don't fell off sharply (what is there is a result of wing twist), but even with the full deflection available at all speeds, it's basically dictated by the comperatively low aileron deflection angles and/or aileron effectivness.

Which in short means there's no general FM cure. Ie. fixing the 109/190 etc. would be easy, as we only need to downtune the low-speed roll (by decreasing aileron effectiveness, as max deflection is possible, whole curve gets 'lower' on Y axis), and uprate the high speed roll (=decreasing stick forces, shifting the curve right on the X axis), and voila!

However as the game doesn't seem to take into account wing twist, doing the same on planes like P-47 would not work, they would get a constantly increasing roll rate with speed, unless they would be too modelled as 'heavy stick, high aileron effectiveness' planes...



<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">IAS/TAS.

Would be simpler to use TAS, I agree. But I'm just too used (and spoiled) to work with SI-units... http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif </div></BLOCKQUOTE>


IMHO it's a major factor. We can easily get totally incompatible data if the conversions are not the same all the way - IAS conversions are largely dependant on atmospheric pressures, and we have no idea of these conditions of either
a, 1944 DVL roll test on Bf 109
b, Crimea map
c, (NACA report 868, which was itself was compliled of various tests from UK, USA etc.)



<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Direction of roll:

While setting up the plane for rolls, I had to apply some pressure to the right (of the stick) to counter the torque induced roll to
the left. So clockwise rolling for Bfs is the slower diretion IMO. </div></BLOCKQUOTE>

Correct. But since the original tests were also done clockwise (right rolls, appearent from the graphs), we must do the same. Dave Southwood notes the clockwise rolling is slower, as noted.


If the rolls are made to both directions and averaged, this would eliminate the torque component out of it. Which sounds nice.

Good thing is, that all results are obtained with the same method, so they are comparable.
And as the results show, roll rates are generally so off from the mark that some
+/- 10degree/s error just doesn't matter...[/QUOTE]


TO SUMMERIZE THE CORRECT TEST METHODS TO GET 100% COMPATIBLE RESULTS WITH THE REAL LIFE TESTING OF THE 109 BY DVL :

- Bf 109 F-2 (if the 109E and 109F and 109G/K roll the same in the game, that's quite bad... especially with the E/F being similiar).
- 100% fuel
- (ammo? - empty?)
- Throttle setting : RL was Dauerleistung during the test. So this must be used.
Dauerleistung was defined for the 109F-2's DB601N engine as 2300 rpm, 1.15 ata. This could be read from MAP and RPM gauges of the cocpit. Note that this has (should be) a major factor in torque, and thus roll rate
- no rudder input
- clockwise, ie. right-hand rolls
- 3000m altitude. Some margin of error is allowed however, see the RL tests themselves, it has no noticable effect.
- TAS, TAS, TAS. IAS/TAS conversions can completely invalidate testing result, due to the great margin of error between conversions. The original test is in TAS, so this HAS to be followed. A little mistake of conversion can easily mean 20 deg/sec difference compared to comparable value - ie. completely useless.

Blottogg
10-11-2005, 02:53 PM
Viper, thanks for pulling the relevent text from the NACA document. I'm a little surprised at the loaded roll for low speeds, but as you pointed out, unloaded would affect the rate. I'd just worry about departing while measuring roll at speeds near the stall speed.

Another good point is the use of TAS for calculating helix angle. One more use of TAS it hadn't dawned on me to include. The test pilots would of course be recording IAS, and for roll rate (not helix angle) IAS is the speed to use, since it intrinsically reflects atmospheric conditions, as well as roll rate at any combination of temp/altitude/humidity that produce the same IAS (which is all the pilot sees or cares about anyway.) The slide-rule jockeys on the ground will need altitude, temperature and humidity data to convert to TAS and calculate pb/2V... the test pilots were hardly doing this conversion in the cockpit.

Is anyone able to see any units for the airspeed scale on the 109F-2 chart, or have these been omitted? Every other document we've got uses IAS, and unless the Germans backed roll rate out of pb/2V, I can't see them graphing this in TAS. Graphing roll rate in TAS without including the temp/humidity data at which the test was run would have made the data uselessly unrepeatable. An IAS run would be valid across the spectrum of temperature and humidity, which is one of the big reasons the NACA report specifies it be used.

WWMaxGunz
10-11-2005, 03:33 PM
Blotto, Viper, regarding the NACA procedures to test roll rates loaded, can you
explain below "The NACA 868 report notes the diffos with altitude change,"?

I might interpret the document wrong, unlike the authority below.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:

Altitude keeping is not very important for test results, if within a few hundred meters, thats good enough. Obtaining the specific speed should be easy with some practice, by finding out the neccesary dive angle vs. throttle.


I think the loss of a few hundred meters of altitude is quite irrelevelant - the original tests also had some variation of altitude, it's unavoidable since some of the measured speeds would be hard to reach with the early 109F with 601N engine, at max CONTINOUS power! See at the end. The NACA 868 report notes the diffos with altitude change, but they are only visible with big changes, ie. 5-10 000 feet altitude differences. A +- few hundred can be safely ignored.

</div></BLOCKQUOTE>

Viper2005_
10-11-2005, 04:07 PM
Changes in altitude change the properties of the atmosphere in 2 important ways

i) air density

ii) air temperature

Air density is at the root of the whole IAS/TAS debate.

In an isothermal atmosphere, maximum roll rate is a function of TAS because the maximum helix angle attainable by the wingtip will remain constant. (Of course in a high TAS/low Q situation, it may take a long time to build up to that maximum roll rate...)

Temperature variations meanwhile change the Mach number assocaited with any given TAS.

Mach number effects, such as shock formation above the critical Mach number, can have a pretty dramatic effect upon aircraft stability and control.

As such, if you're going to use test data to predict flight performance (which is generally the object of the exercise) then it isn't enough to simply specify TAS; you need to specify the Mach number too if Mach number effects are significant.

The worst case is flight at high altitude, where large TAS may be obtained, and the atmosphere is cold so the speed of sound is low.

Thankfully, the rate of change of air temperature is pretty low with respect to altitude, at only a couple of K per 1000 feet.

As the speed of sound varies as the square root of the absolute temperature, changes in Mach number associated with altitude excursions of under 1000 feet tend to be pretty small. I would expect that errors associated with the altitude lost in a single 1 g roll from level flight would be small enough to neglect.

As for the process of test flying, generally speaking IAS won't be used because it's so prone to error. One of the first things done with a new aircraft is a measurement of the ASI errors. Correction tables can then be produced.

On the day of the test, another aircraft can be sent to measure the atmospheric properties at the desired altitude, and it's then pretty simple for the test pilot or engineers to calculate what speed must be shown on the ASI to attain the desired test TAS conditions.

Preparation is key.

Having carried out the tests, the next stage is to reduce the data to something useful. This is the hard bit.

Generally a first step is to correct the data back to standard atmosphere conditions in order that all test data remains compatible - otherwise tests carried out on different days are not directly comparable.

http://www.ae.su.oz.au/aero/atmos/atmos.html

Note that this relates to the modern (1976 if memory serves) standard atmosphere.

When using German data it is important to remember that there's no particular reason to assume that they used the same standard atmosphere. It is therefore important when comparing German data with NACA data to first discover what standard atmosphere the Germans used in their tests and then convert all the data to the same standard atmosphere. Otherwise you're comparing apples and oranges, especially if IAS is used...

Blottogg
10-11-2005, 04:54 PM
Viper, maybe I had my pilot hat on instead of my engineering hat, but aside from calibration errors and compressibility effects, shouldn't basic aircraft performance speeds (stall, takeoff, landing as well as speed for maximum roll rate) be at the same IAS regardless of density altitude variations? If my Bf-109 stalls at 150 kph IAS at sea level standard day, it will still stall at 150 kph IAS at 1000 meters pressure altitude, won't it? Indicated stall speed is stall speed for a given weight and configuration. It won't vary on the ASI as the temperature or humidity changes. There will no doubt be instrument errors, so perhaps CAS would be more correct for duplicating numbers from aircraft to aircraft. But won't the IAS be consistent no matter who's standard atmosphere is used to convert the data to TAS after collection? Or is the problem that raw IAS data is converted to TAS, then converted back to graph the IAS for the pilots? If two different standards are used for the two conversions, that would obviously be a problem. I was assuming that with IAS we were seeing the data recorded by the test pilot. Some or all of these assumptions being wrong wouldn't be a first for me.

WWMaxGunz
10-11-2005, 07:52 PM
And about alt loss and loading in tests?

Viper2005_
10-11-2005, 08:02 PM
This is a difficult question to answer without writing a rather long essay!

Stall speed (as in IAS) is a horrible concept. Stall alpha is a lot more useful.

if we get rid of all of the errors then we can just say that IAS = Q.

If we then assume a constant lift requirement then the Q at which the stall alpha produces this amount of lift will remain pretty constant,

(neglecting compressibility and reynolds number effects)

Note the rather large number of assumptions between stall alpha and stall IAS.

Roll rates are a different matter.

The highest roll rate will be attained pretty close to "coffin corner".

In general one might expect maximum roll rate at higher IAS at low altitudes than at high altitudes.

Low down, TAS is low, so you hit the helix angle limit at a fairly low roll rate. Go faster and you become force limited.

High up TAS is high, so higher roll rates are attained before the helix angle limit is reached.

As such the battle now is to avoid Mach number effects, which will therefore limit IAS, so you'll tend towards coffin corner as you climb.

Stall IAS may well increase at high altitudes due to mach number effects, and there is also a tendency for pilots to confuse the stall with simply running out of excess power.

Of course in a fast jet at low level, vast quantities of excess power can disguise the stall most effectively... Of course FBW helps too.

As for the standard atmosphere thing, different standard atmospheres would assume different air densities and temperatures at any give altitude and therefore a slightly different IAS/TAS conversion.

As such, speeds and helix angles won't "line up" properly and an artificial picture will be generated.

This all gets especially nasty because nobody ever flew an aeroplane on a standard day, and therefore various corrections will have been made to turn raw data into standardised data.

You can think of it as representing a built-in altitude error.

ECV56_Rolf
10-11-2005, 08:53 PM
Assuming that the relation in between IAS and TAS at the same altitude will be the same in different places with different barometrical conditions, and different ground altitude, is correct?

TAGERT.
10-11-2005, 09:25 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
Great. </div></BLOCKQUOTE>Your welcome.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
It appears that none of these tests included data points for 400 mph. Gibbage claims though the tests show an abnormal increase... they go 360 at best. Is gibbage a lying then, again...? </div></BLOCKQUOTE>No, Gibbage is not lying, Gibbage is just more informed that you are. My early graphs showed the abnormal increase more in that I didnt limit them to the same range as the NACA graph. In that I thought it would be less confusing to people if I used the same range, but, clearly it confused you, so, I guess Ill open up the limits to focus more on that abnormal increase. Thanks for the feedback, I guess I gave you too much credit to figure that one out on your own.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
OK, so you admit none of your tests is compatible with the historical data, and you are manipulating the figures with conversions of your own taste. That's EXACTLY what I suspected. Now you confirmed. Thank you. </div></BLOCKQUOTE>That kind of spin might work in the court room, but not here in the real world. The fact is I have not manipulated any figures, they are exactaly as they appeared in the NACA document, same units, same range, same everyting. Guess that was just a little too complicated for you to figure out? Take another look and maybe you will notice this time that I have not ploted the 109 data yet, thus no TAS to IAS conversion has been done! Guess that was a little too complicated for you to figure out? As for when I get around to converting the 109 roll rate charts I will have to.. how did you say it? manipulate the data? Hmmm, no, that is not the right way to say it.. It would be the way some lawyer would say it if tring to mislead people, but not how a engineer would say it. The words and engineer would use are "convert to differnet units". Happens all the time in the real world, which is probally why you missed it. I guess that was just a little too complicated for you to realise that some CONVERSION would have to be done, I would either have to convert 10 IAS charts to TAS or just "1" TAS chart to IAS. Simple math would tell a first grader that doing "1" is easier than doing "10", but I guess that was a little too complicated for you to figure out? Or did you realise all that and are just trying to spin it? I hope the later, for your sake! Otherwise you have bigger problems in life than this simulation being off a bit.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
I guess we can ignore all of your so called "tests" as you were manipulating the test results, then. </div></BLOCKQUOTE>Promise?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
One interesting point is visible even on your retouched tests however, is the fact that the 109E and F/G/K have exactly the same roll behaviour, despite the fact that their wing and aileron structure was very different.It`s an obvious bug, given the changes, I except the squared tipped 109E to roll better at roll speeds, but worser at high speeds than the later versions with improved ailerons and wings. </div></BLOCKQUOTE>LOL! What a typical lawyer move.. Discredit the data in one breath, and then use the data as proof in the next breath. You cant have it both ways.. Unless your talking to real stupid people that wouldnt pick up on it.. Which does shead some light as to how OJ got off the hook. But most people here are not that thick! Thank god they can see right thorough your smoke screen.

Kurfurst__
10-12-2005, 07:09 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TAGERT.:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
Great. </div></BLOCKQUOTE>Your welcome.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
It appears that none of these tests included data points for 400 mph. Gibbage claims though the tests show an abnormal increase... they go 360 at best. Is gibbage a lying then, again...? </div></BLOCKQUOTE>No, Gibbage is not lying, Gibbage is just more informed that you are. My early graphs showed the abnormal increase more in that I didnt limit them to the same range as the NACA graph. In that I thought it would be less confusing to people if I used the same range, but, clearly it confused you, so, I guess Ill open up the limits to focus more on that abnormal increase. Thanks for the feedback, I guess I gave you too much credit to figure that one out on your own.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
OK, so you admit none of your tests is compatible with the historical data, and you are manipulating the figures with conversions of your own taste. That's EXACTLY what I suspected. Now you confirmed. Thank you. </div></BLOCKQUOTE>That kind of spin might work in the court room, but not here in the real world. The fact is I have not manipulated any figures, they are exactaly as they appeared in the NACA document, same units, same range, same everyting. Guess that was just a little too complicated for you to figure out? Take another look and maybe you will notice this time that I have not ploted the 109 data yet, thus no TAS to IAS conversion has been done! Guess that was a little too complicated for you to figure out? As for when I get around to converting the 109 roll rate charts I will have to.. how did you say it? manipulate the data? Hmmm, no, that is not the right way to say it.. It would be the way some lawyer would say it if tring to mislead people, but not how a engineer would say it. The words and engineer would use are "convert to differnet units". Happens all the time in the real world, which is probally why you missed it. I guess that was just a little too complicated for you to realise that some CONVERSION would have to be done, I would either have to convert 10 IAS charts to TAS or just "1" TAS chart to IAS. Simple math would tell a first grader that doing "1" is easier than doing "10", but I guess that was a little too complicated for you to figure out? Or did you realise all that and are just trying to spin it? I hope the later, for your sake! Otherwise you have bigger problems in life than this simulation being off a bit.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
I guess we can ignore all of your so called "tests" as you were manipulating the test results, then. </div></BLOCKQUOTE>Promise?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
One interesting point is visible even on your retouched tests however, is the fact that the 109E and F/G/K have exactly the same roll behaviour, despite the fact that their wing and aileron structure was very different.It`s an obvious bug, given the changes, I except the squared tipped 109E to roll better at roll speeds, but worser at high speeds than the later versions with improved ailerons and wings. </div></BLOCKQUOTE>LOL! What a typical lawyer move.. Discredit the data in one breath, and then use the data as proof in the next breath. You cant have it both ways.. Unless your talking to real stupid people that wouldnt pick up on it.. Which does shead some light as to how OJ got off the hook. But most people here are not that thick! Thank god they can see right thorough your smoke screen. </div></BLOCKQUOTE>



So much talk, so little to tell.

Kurfurst__
10-12-2005, 07:16 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
When using German data it is important to remember that there's no particular reason to assume that they used the same standard atmosphere. It is therefore important when comparing German data with NACA data to first discover what standard atmosphere the Germans used in their tests and then convert all the data to the same standard atmosphere. Otherwise you're comparing apples and oranges, especially if IAS is used... </div></BLOCKQUOTE>

Exactly, that's what I was talking all the time. Hence why I used another German tests table with a 109G, that lists both Vw and Va at 3km, so we might get some idea what would be the German standard at this altitude. It happened to be an 1 - .861 relation between TAS, and IAS at 3km.


But take note, IAS conversion is only important if you want to compare the DVL 109 data (in TAS) against the NACA 868 roll chart (obtained from several countries, in both EAS and IAS).

But as long we only want to test how the Il2 sim relates the the real life DVL data, we don't have to (we shouldn't, as it would most likely lead to incompatible data) convert the data at all.

Simple. We've got a RL data curve in TAS.
Just do the testing in the sim, and record the roll rate measured at given TAS number - 100% compatible, no room for error, I don't see why do in another, more complicated and error-prone way at all...

Viper2005_
10-12-2005, 02:35 PM
Well the problem is that there is no particular reason to assume that IL2 uses the same standard atmosphere as the German tests or indeed as the NACA tests.

Logically I would expect it to use the 1976 International Standard Atmosphere.

As such some conversion may be required.

Hoarmurath
10-12-2005, 03:20 PM
NACA did the report, not the testing. report 868 is not a testing report.

TAGERT.
10-12-2005, 10:10 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
Well the problem is that there is no particular reason to assume that IL2 uses the same standard atmosphere as the German tests or indeed as the NACA tests.

Logically I would expect it to use the 1976 International Standard Atmosphere.

As such some conversion may be required. </div></BLOCKQUOTE>Roger that, the so called standard atmospher did not become a standard until the mid to late 50s. Prior to that, eveyone had a little different standard.. espically for high alt stuff, (40kft+) but not so much for low alt stuff.

Blottogg
10-13-2005, 09:38 AM
Okay, so IAS is useful from a pilot's perspective as an approximation of AoA (with apologies for the imprecision of this from an engineering perspective), allowing an IAS reference to AoA dependent performance such as turn, stall and climb. Given that most of these airspeeds are down in the noise level for compressibility (unless we start looking at the upper and right edges of the envelope for climb and turn, or cruise performance for a U-2R recce jet), I'm not too disturbed by this approximation. Even if the sim replicated performance completely accurately for incompressible flow, performance would start to diverge from RL as Mach became significant, since Mach effects aren't currently simulated AFAIK.

WRT roll performance however, IAS is not directly applicable, because roll performance is dependent on the geometry of pb/2V, not AoA. As such the distance data contained within TAS is required. My bad. I also wonder why roll data on the 109 chart is extrapolated down to 0 kph, which is part of what lead me down the primrose path of unloaded roll. If roll performance is measured at 1 g, then roll should drop to 0 at 1 g stall speed (or at the TAS corresponding to 1 g level fight Clmax), since any roll attempt at that Cl will likely stall at least one wing. Or am I smoking dope again?

Viper, any idea why the NACA roll data is plotted versus IAS, and whether that IAS data is raw, or an idealized IAS derived from TAS, itself calculated from raw IAS data using temperature and humidity data recorded by a chase plane as you mentioned? That seems awfully convoluted, but may have been done to benefit line pilots, who wouldn't have TAS or AoA references in the cockpit from which to reference roll performance.

I don't know what atmospheric data is incorporated into Il-2, nor how it compares to the 1976 ISA, or whatever standard atmosphere the DVL and NACA used in the 40's. I do know that several aircraft in the game (the 110 comes to mind) have OAT gauges. Devicelink may also pull temperature information, though Tagert could answer that, not I. There's no wet bulb thermometer available, so unless Devicelink can pull humidity data, that's a loss. And we're still minus the atmospheric data the guys used in the '40's. In order to convert all available roll data to a common atmosphere TAS, we'd need either more data, or more assumptions. Either way, this is becoming more than a casual inquiry.

While using the wrong standard atmosphere conversions will introduce error, I'm not so sure it would always be a significant error. From Viper's link, the full spread of humidity variation amounts to a less than 3% variable, for example (unless I'm reading the graph for Kh humidity correction factor wrong, which is distictly possible.) Any error would make engineers cringe, but from a pilot point of view, if the errors are small by themselves, or are small in aggregate (such as some IAS-TAS-IAS conversion cycles), they may not be worth worrying about.

TAGERT.
10-13-2005, 09:57 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blottogg:
Viper, any idea why the NACA roll data is plotted versus IAS, and whether that IAS data is raw, or an idealized IAS derived from TAS, itself calculated from raw IAS data using temperature and humidity data recorded by a chase plane as you mentioned? That seems awfully convoluted, but may have been done to benefit line pilots, who wouldn't have TAS or AoA references in the cockpit from which to reference roll performance. </div></BLOCKQUOTE>My *guess* is that the IAS speeds were adj to the standard atmosphere. Which is what the NACA did for climb rate testing.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blottogg:
While using the wrong standard atmosphere conversions will introduce error, I'm not so sure it would always be a significant error. </div></BLOCKQUOTE>That is my take on it, espically at lower altitudes. It wasnt until after the war that they really started looking at the upper atmospher (40kft+) with great interest (ie rockets and X15 stuff) and that is where most of the standadizing was done because everyone had a different theory as to what it was.

Viper2005_
10-13-2005, 01:24 PM
Well the page before the roll rate graph there is a graph of the same data re-arranged to give helix angle instead of rate.

As such the TAS thing is taken care of.

IAS is a convenient shorthand for Q and at constant hinge moment coefficent, stick force will be proportional to Q. Of course Mach number effects can then start playing about with the hinge moment coefficient...

The big problem with the standard atmosphere thing is that it will result in systematic errors between data sets, opening a whole can of red vs blue worms.

It's rather difficult to get to the bottom of the situation because both sides used slightly different test conditions and often broke the placard limits when flying captured aircraft.

As such you can't just add a simple fudge factor to make the performance plots line up.

I would expect the worst case error at 10,000 feet to be ~ 10%...

WWMaxGunz
10-13-2005, 05:42 PM
Places where Oleg has to make a complex call between data, AE knowledge and code.
And then a bunch of players with their favorite charts argue about which is right.

Blottogg
10-13-2005, 05:46 PM
Thanks Viper, I kept going back to roll rate instead of the helix angle graph. I'm assuming you mean this one:

http://www.onpoi.net/ah/pics/users/852_1128017315_r3.jpg

With q clearly marked on the X-axis. For those who don't read technical German (like me), AltaVista translates the text of Abb.11 as:

"middle aileron deflection over the stagnation pressure with stick deflection and stick force"

Though I'm assuming AltaVista is having some problems with technical German too, and the "middle aileron deflection" is actually helix angle. Stagnation pressure is just another way of saying q, or dynamic pressure. Now all I have to do is take a sample helix angle, convert the corresponding q to TAS using the 1976 std atm data, solve for p, and compare with the roll rate graph to get an idea how far off that standard atmosphere data is from whatever the DVL used, at least for that one data point.

While I'm asking questions I should have learned in my performance course, I'll ask this one as well. In a test report on the Fw-190 roll rate (posted in another thread), it refers to Kb2 as being constant, and = -0.11. The portion of the test report is here:

http://www.onpoi.net/ah/pics/users/282_1128078793_roll2m.jpg

Hop2002 thinks it's an aileron efficiency coeffecient, or a correction factor for aileron control linkage friction and distortion, which I think is correct. But truth be told I don't remember seeing the Kb2 coefficient during my undergraduate level coursework oh so many years ago. Thanks again for patience and input.

More later, gotta go rescue my wife. The Miata is misbehaving. Probably has something to do with all the extra plumbing I shoveled under the hood.

TAGERT.
10-13-2005, 10:11 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
I would expect the worst case error at 10,000 feet to be ~ 10%... </div></BLOCKQUOTE>I have not done enough testing to say for sure yet, but, there appears to be about 10% error just between runs, thus, the difference in std atm would fall within that noise.

Skalgrim
10-16-2005, 08:22 AM
109 rollrate is until 480km/h ias better as p51 rollrate

make 109 rollrate weaker than too p51 rollrate weaker

and why not p39 rollrate, she roll much better as american data say, and and

only why you has problem to defeats 109, than work at you skill perhaps

almost all rollrate seem not correct, when you will change 109 rollrate than for all plane and especially p39.

p51 rollrate at great altitude is overmodel, because rollrate depent from ias and not tas

but at 7000m can a p51 with 400km/h ias easy
out roll 109g, although p51 can not match rollrate from 109g until 480km/h ias

because ias and tas are mixup




<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TAGERT.:
I know this has been a hot topic, but please, for the sake of realism, let€s try and keep it civil.

As most of you know I have been using Device Link data to confirm or deny statements made in this forum with regards to aircraft performance for some time now.

I have recently added roll rate analysis to my utility. I wanted to make it easy for people (sim test pilots) to fly a mission that resembles the real life conditions and methods. The method is to start at an altitude well above the 10kft altitude so you can dive down to 10kft to obtain the initial higher speeds. Once you get to 10kft all you have to do is roll the plane at least one complete 360? per each indicated speed (IAS). All the while recording a track file (*.trk). You can repeat any roll at any speed as many times as you want. All you have to do is insure that you stop and fly level for at least a few seconds in-between each roll. The analysis tool will scan through the Device Link data and pick out the peak roll rate per each roll you do and plot them on a graph.

Note I picked 10kft and IAS because most of the data we have to date is based on that setup (NACA 868). My next goal is to digitize the NACA 868 data points so we can overlay the in-game data points to see how they compare.

I don€t know what the simulation stick force is limited to, but, most seem to be under the impression that it is 50lb. With that said, you have to make sure your joystick is setup correctly. Go to Hardware Setup -&gt; Input and make sure your joystick profile for ROLL ends in 100. Otherwise you will not be getting the full force applied.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RA...JOYSTICK_PROFILE.JPG (http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/JOYSTICK_PROFILE.JPG)


With that said, my first test was in a 109K, in that was what all the fuss was about. Kurfurst (Izzy) provided us with some roll rate numbers.

160mph = 61
170mph = 68
195mph = 72
220mph = 75
240mph = 78
280mph = 82
300mph = 73
350mph = 50

I have not gone to the trouble of converting the LW data charts yet, I have been too busy getting the utility working. I will digitize and convert them when I do the NACA 868 document. So, for now I€m taking Kurfurst word for it ( I know, I know! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif ) on the numbers that I will compare the in-game results too.

The following table contains the results of the in-game testing. As you can see, one of the hardest parts of the test is holding the 10kft altitude during the roll. The nose dips while rolling, so correcting for that will result in some variation of the altitude during the roll.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/RR_IAS_ALT_109K_10K_75FUEL.JPG


The following figure plots the in-game values from the table vs. Kurfurst€s values.

http://www.geocities.com/grantsenn/NACA_RESULTS/ROLL_RATES/109K/IZZYDATA/IZZY_DATA_VS_GAME_DATA.JPG


From the graph we can see that the in-game 109K rolls much faster than expected (Kurfurst numbers) at speeds below ~235mph. From ~235mph to ~350mph the in-game 109K rolls much slower than expected (Kurfurs€s numbers). Also note, that from ~350mph and above the in-game 109K is starting to roll faster again, this was unexpected in that I have not seen any data of a plane doing that. If we were to extrapolate Kurfurst€s numbers on the slope they left off at ~350mph the in-game 109K is rolling much better than expected.

So, in summary, out of the 3 areas..

1) 160mph to 235mph
2) 235mph to 350mph
3) 350mph to 400mph

The 109K is rolling better than expected in 2 of the 3 areas.

TnB AREA (160mph to 235mph): The slow twisting attacks (wrestling) the in-game 109K has an unrealistic advantage.
BnZ AREA (235mph to 350mph): The fast slashing attacks (boxing) the in-game 109K has a unrealistic disadvantage until it reaches 350mph+, where it appears to gain an unrealistic advantage aagin.

All this is assuming Kurfurst€s numbers are correct!

So, lets try and keep cool heads here. If you have a problem with Kururst€s numbers, that is fine, please indicate your exceptions in a civil manor and have some supporting evidence. If you can convince me otherwise I will gladly update the graph with the corrected numbers.

PS If you have some real world data you want to test, send it along with the in-game track file of yoru test to naca_testing@yahoo.com and Ill process it for you. But, remember, don€t shoot the messenger, I just report the numbers, I don€t make them up! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif </div></BLOCKQUOTE>

WWMaxGunz
10-16-2005, 08:38 AM
Would that be the P-39D, Skalgrim?

Kurfurst__
10-17-2005, 05:32 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blottogg:
http://www.onpoi.net/ah/pics/users/852_1128017315_r3.jpg

With q clearly marked on the X-axis. For those who don't read technical German (like me), AltaVista translates the text of Abb.11 as:

"middle aileron deflection over the stagnation pressure with stick deflection and stick force" </div></BLOCKQUOTE>

It translates to :

"Middle-values of aileron deflection angle plotted against dynamic pressure, with Stick deflection angle yK and stickforce Pk being the parameters."

Basically it shows how much avarage aileron (ie. up/down) would one get with maximum (15 degree) stick deflection at a given dynamic pressure, with a given stickforce.

There isn't anything surprising in that they give middle values(?eng term), ie. the Bf 109 had assymetric deflection of the ailerons up and down as noted, +12 and -22 if I recall correctly, which is indeed something like 15 degrees of 'middle value', or so - I dont have the tests handy.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I would expect the worst case error at 10,000 feet to be ~ 10%... </div></BLOCKQUOTE>

Ie. if one looks at tagert's curve, this could mean the data at 350 mph IAS is not 50 deg/sec, but 65 deg/sec... that's quite a difference imho.

Again, WHY bother with IAS if we can measure in TAS, and we have data in TAS in the first place ?

luftluuver
10-17-2005, 06:42 AM
quote: I would expect the worst case error at 10,000 feet to be ~ 10%...

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Ie. if one looks at tagert's curve, this could mean the data at 350 mph IAS is not 50 deg/sec, but 65 deg/sec... that's quite a difference imho. </div></BLOCKQUOTE>

How do you arrive at an increase of 15deg/sec (50 &gt; 65)? 10% of 50 is only 5.

If your math is used, that could mean the roll rate is as low 35deg/sec, or 10.3 sec for a complete 360 roll.

Is this 10% the overall variance, +5 &gt; -5 = 10, or a +10/-10 variance?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Again, WHY bother with IAS if we can measure in TAS, and we have data in TAS in the first place? </div></BLOCKQUOTE>

Why use IAS? Well so that the 109's performance can be compared to the other a/c on the NACA graph.


BTW, is not sig text restricted to 3 lines.
Do you have special priviledges that allow 20 lines?

I am curious on how you get away with contravening the Ubi rules?

Viper2005_
10-17-2005, 07:29 AM
Blotto, actually I meant this graph

http://naca.larc.nasa.gov/reports/1947/naca-report-868/index.cgi?page41.gif

As for the German graph, I agree with Kurfurst - they've plotted an average. If you think about the geometry, the term "middle aileron" is a pretty accurate description in the circumstances...

Kb2 is a balance coefficient

http://www.bf109.com/flying.html

A small negative value is desirable. if Kb2&gt;0 then you're into overbalance country, which will obviously do horrible things to stick free stability...

Viper2005_
10-17-2005, 07:38 AM
http://www.bf109.com/manuals.html

translations anybody?

Blottogg
10-18-2005, 11:28 PM
Sorry for being away, but I've spent my free time over the last few days beating my head against the wall that is BoB II WoV.

Thanks for the translation Kurfurst. The average aileron deflection angle would explain why using that value as the helix angle wasn't making the math work out (and not my poor algerbra skills for a change.) In my defense, the shape of the two graphs is similar. It's also interesting to note the reduction in aileron deflection with increasing q. Even with control rods, there is quite a bit of deformation in the aileron controls at speed, though how much is in the control rods, bellcranks and bearings, and how much is bending of the wing structure around those components I don't know. I'm sure this deformation isn't unique to the 109 however, as the helix angle for most of the aircraft in the NACA 868 graph show the same trend prior to stick force limits being reached.

Thanks (again) for the definition Viper. I should have taken a control systems course instead of "aerospace decelerators" (aka parachutes.) Moving the aileron hinge point aft, or adding spades, would then tend to increase Kb2, which as you said would be a bad thing if the value becomes positive. In that case, the ailerons would tend to move towards full deflection unless actively restrained by the pilot. Making those modifications to an aircraft with a Kb2&lt;&lt;0 would be useful in reducing stick forces in roll though (like my old Decathalon.)

Well, 4.02 finished downloading, so off to mess with that for a bit. With all the FM tweaking, I'm afraid 4.02 may have made Tagert's hard work with 4.01 a moot point, at least until the 4.02 FM observation threads start popping up.