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SkyChimp
11-07-2004, 04:17 PM
There was a recent post on the "innaccurate" climb rate of the F4U-1D. There was a Navy document posted to support the claim the climb rate was overmodelled.

The Bureau Or Aeronautics data sheet that was posted has some sustained climb times listed on it. In order to achieve these times, the tests MUST be conducted properly and in the SAME MANNER that produced the numbers.

The best climb speed for the F4U-1D was 144mph IAS. That's 125 knots or 231 km/h IAS. In order to conduct a time-to-climb test, you must enter the blimb at sea-level at no more and no less than 144mph IAS. Combat power must be applied and pitched into a climb. During the climb, the plane must be held at such an angle that 144 mph IAS is maintained (no more, no less).

I've conducted a climb test on the F4U-1D on no less than 5 occassions and on average I am getting to 10,000 feet in 3 minutes 20 seconds, 20,000 feet in 7 minutes 3 seconds. That is remarkebly close to the climb rate in the BuAer spec sheet.

Kwiatos
11-07-2004, 04:38 PM
is still such thing like best climb speed for planes in PF?

XyZspineZyX
11-07-2004, 04:42 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
I've conducted a climb test on the F4U-1D on no less than 5 occassions and on average I am getting to 10,000 feet in 3 minutes 20 seconds, 20,000 feet in 7 minutes 3 seconds. That is remarkebly close to the climb rate in the BuAer spec sheet. <HR></BLOCKQUOTE>

But if he's getting _superior_ climb at some speed other than the "best climb speed", then of course there is a problem with the model http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

The "climb rate" stat is not just some inane curiosity to see how fast the plane can get altitude when flown at some arbitrary speed... rather it is supposed to be the fastest possible rate at which the aircraft can sustain a long climb. If the game plane can exceed best climb rate of the real plane then there is a problem, no matter what speed is used for the test.

SkyChimp
11-07-2004, 04:50 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AgentBif:
But if he's getting _superior_ climb at some speed other than the "best climb speed", then of course there is a problem with the model http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

The "climb rate" stat is not just some inane curiosity to see how fast the plane can get altitude when flown at some arbitrary speed... rather it is supposed to be the fastest possible rate at which the aircraft can sustain a long climb. If the game plane can exceed best climb rate of the real plane then there is a problem, no matter what speed is used for the test. <HR></BLOCKQUOTE>

Not necessarily. If you haul-*** along at top speed at sea level then haul back on the stick you will get significantly better climb times than you should. There's a big difference in entering a climb at 144mph and entering it at 350mph. Theres a difference between a zoom-climb and a sustained climb.

I'd suggest anyone perform the test, in the manner I described, and see what you get.

Col.Kurtz
11-07-2004, 04:53 PM
well
climbchart of Corsair from Manual gives 135 Knots for Climb that is 250km/h IAS
My test where done with start from Airport with timecount at liftoff with 220km/h then acceleration to 260km/H while Climbing then substained climb to alt:

Results:

F4U-1a 2135HP

In game:
3050m in 2:42min =54sec too fast
6100m in 5:10min =2:32min too fast

M/sec-ft/min
0-1k--18,9--3720 (2890ft/min real)
1-2k--18,5--3640
2-3k--18,2--3580
3-4k--21,3--4192
4-5k--20,4--4015
5-6k--19,2--3779
6-7k€"18,9--3720

Corsair MK.I has identical performance

-----
F4U-1D 2250HP

In game:
3050m in 2:31min = 47sec too fast
6100m in 4:56min = 2:10min too fast


M/sec--ft/min
0-1k€"20,8 -- 4094
1-2k€"18,5 -- 3641
2-3k€"20,4 -- 4015
3-4k€"20,4 -- 4015
4-5k€"21,7 -- 4278
5-6k---20 --- 3937
6-7k-- 18,9 €" 3713

---------------
F6F5 Hellcat

In game:
3040m in 2:48min too fast
6140m in 5:28min 2:14min too fast

M/sec.---ft/min
0-1k=18,9--3713
1-2k=17,2--3392
2-3k=17,5--3451
3-4k=19,6--3858
4-5k=18,9--3714
5-6k=17,2--3392
6-7k=18,2--3576

----------------

To make you happy i did rightnow a test with your recommed 250km/h(235knots)
and got this:
F4U-1D
3100m---2:29min
6100m---4:51min http://forums.ubi.com/images/smilies/88.gif


Here a report: (see climbspeed and compare with FW190...)
There is no way that corsair climbs faster at higher speeds if it would do in PF it would be even worser overmodelling.. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif
http://home.arcor.de/sebastianleitiger/190A5vsF4U-1DvsF6F-3/corsair1.jpg

Enjoy your UFO till Patch http://forums.ubi.com/images/smilies/cry.gif

XyZspineZyX
11-07-2004, 05:09 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
If you haul-*** along at top speed at sea level then haul back on the stick you will get significantly better climb times than you should. There's a big difference in entering a climb at 144mph and entering it at 350mph. Theres a difference between a zoom-climb and a sustained climb.

I'd suggest anyone perform the test, in the manner I described, and see what you get. <HR></BLOCKQUOTE>

Ok, yeah, the test is for sustained climb, not a zoom climb. So the speed in question should be held for the entire test... by adjusting your climb angle accordingly.

But if one can show a superior climb rate at some sustained speed other than what some official test found was the best climb speed of the real aircraft, then that's a very interesting data point!

SkyChimp
11-07-2004, 05:13 PM
135 knots is for the F4U-1 with the R-2800-8 engine. The F4U-1D had the R-2800-8W engine.

Not only do you have to perform the test properly, you have to compare it to the same aircraft.

Best climb speeds varied between models, even is by only a few knots.

SkyChimp
11-07-2004, 05:16 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AgentBif:

Ok, yeah, the test is for sustained climb, not a zoom climb. So the speed in question should be held for the entire test... by adjusting your climb angle accordingly.

But if one can show a superior climb rate at some sustained speed other than what some official test found was the best climb speed of the real aircraft, then that's a very interesting data point! <HR></BLOCKQUOTE>

If you don't start the test at the proper speed, then NO portion of the test will be correct - becasue you will always be higher than you would have been had you started at the right speed. If you start the climb at 350mph and let your speed bleed to 144 mph, you get to every altitude too soon.

Takata_
11-07-2004, 05:30 PM
Skychimp,
Take it easy; they need to load the plane exactly like it was in RL for test, with the same atmospheric conditions they had this day : we need to ask to Oleg to make this place for the climb test.

By the way, the test is off something like 2 mn out of 7, that mean the plane climb ~1.4 his RL performance. http://forums.ubi.com/images/smilies/88.gif

SkyChimp
11-07-2004, 06:05 PM
I'm easy, I always am. I just find it interesting when someone proclaims the performance of a plane in the game to be wrong when they aren't conducting the test in the same manner as the real-life test they are comparing it to. Case-in-point is Col. Kurtz.

Kurtz wrote that he was "correctly" shifting the blower at certain altitudes and his numbers weren't what they were supposed to be. Well, if he wants to achieve the numbers on Buzzsaw's chart, then he needs to perform the test that was performed in Buzzsaw's chart.

Kurtz was shifting as follows:
1) Climb to 1000m with neutral Gear
2) @1000m change in low Blower (2stage in Game)
3) @6000m set high blower

To be consistent with Buzzsaw's BuAer report, it should have been as follows:
1) Don't use neutral blower at all, start out with aux blower in low.
2) Start Climb from sea-level at 144mph IAS, not lower, not higher.
3) Maintain combat power
4) Continue climb at 144 mph IAS, not lower, not higher
5) shift from low to high somewhere between 12,500 feet and 14,500 feet

VF-29_Sandman
11-07-2004, 06:11 PM
so there's a 3 stage supercharger to be set?

SkyChimp
11-07-2004, 06:24 PM
Sort of. The F4U has a 2 stage supercharger, with three modes.

The engine stage supercharger ran whever the engine ran. However, the auxillery supercharger (blower) was a 2 speed unit (3 if you count neutral).

So the Corsair usually operated down low with the engine stage supercharger running, but the aux blower in neutral. At medium altitudes it would run with the aux blower in low. At high altitude it would run in high. 3 different modes.

WWMaxGunz
11-07-2004, 07:28 PM
You could state for a certainty here what is combat power settings, for those
of us who are not sure what was used?

Also loading, how much fuel and ammo?

SkyChimp
11-07-2004, 07:37 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
You could state for a certainty here what is combat power settings, for those
of us who are not sure what was used?

Also loading, how much fuel and ammo? <HR></BLOCKQUOTE>

Max, here is the chart Buzzsaw posted. Refer to column labeled #1. The climb chart that goes with it follows. Again, refer to the climb line labeled #1:

http://web.cetlink.net/~howardds/27328170.gif
http://members.cox.net/us.fighters/1DClimb.jpg

WWMaxGunz
11-07-2004, 08:01 PM
TY Chimp, just so we're all on the same page, same chart.

Now to wait for Kurtz and why best climb should be 10 kph higher.

Still, if you exceed best climb with the same power and loading
but another speed, what does that say?

VW-IceFire
11-07-2004, 08:18 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Kwiatos:
is still such thing like best climb speed for planes in PF? <HR></BLOCKQUOTE>
Yep...I don't know them all..essentially I know really know the FW190A's climb speed well. Its somewhere between 370 and 400 kph IAS. Oleg also mentioned that its best climb is in this range so that validates things enough for me.

Part of being an expert in one plane or another is when you come to know these things. Can get out out of nasty situtations and allow you to outclimb or out manuver another who may not know his plane as well.

SkyChimp
11-07-2004, 08:19 PM
In real life, to get best SUSTAINED climb in the F4U-1D, it has to be done at Combat Power from Sea Level at about 144 mph IAS. Maintaining 144 mph IAS is done by pitching the aircraft, not using the throttle, which is alreay set to combat power.

If the plane was pitched up too far, climb angle increased too much, the speed falls below 144 mph IAS and the climb-rate would fall. Likewise, if it was pitched too low, climb angle decreased, the speed will rise and climb-rate would fall. Best sustained climb rate was achieved at a combination of combat power, 144 mph IAS, and whatever climb angle it took to maintain 144 mph.

The optimal climb speed does not stay constant. I does for about the first 15,000 feet, then it falls off by about 5mph, remain constant from there up to about 25,000 feet, where it drops off again. Again, the throttle is always set to combat power throughout the climb and speed is maintained by adjusting climb angle. Essentially what happens is that as the plane gets higher, the climb angle will flatten, even if the optimal climb speed remains stay the same. This happens because the engine is losing power as altitude increases.

The key word here is SUSTAINED climb. It's possible to achieve better climb rates and faster time-to-climb numbers, but they can't be sustained. But even though they can't be sustained, entering into a SUSTAINED climb (test) at a speed higher than the optimal climb speed will screw up the whole test because it will reduce all your time-to-climb numbers.

XyZspineZyX
11-07-2004, 08:47 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
2) Start Climb from sea-level at 144mph IAS, not lower, not higher.
...
4) Continue climb at 144 mph IAS, not lower, not higher
<HR></BLOCKQUOTE>

2 and 4... No.

We just got through discussing this point Chimp! All he has to do is pick some speed and sustain it all the way through the test. If the game plane then underclimbs, then the test speed was less than the aircraft's optimal climb speed. If the game plane overclimbs the real plane, then something is wrong with the game.

XyZspineZyX
11-07-2004, 08:53 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
You could state for a certainty here what is combat power settings, for those
of us who are not sure what was used? <HR></BLOCKQUOTE>

I'm pretty sure "combat power" is 100% (no WEP or whatever). From the chart, fuel and oil are partial loads. Ammo, I'm not sure, but I suspect that that is full load.

RAF74_Buzzsaw
11-07-2004, 09:29 PM
Salute

First of all, I am surprised to hear such a specious argument from SkyChimp. He is usually interested only in the facts. This is the type of argument which was previously used to justify some of the ridiculously overmodelled 109 climbrates.

The issue here is MAXIMUM RATE OF CLIMB. The speed at which that maximum rate of climb is achieved is irrelevant.

The speed which SkyChimp mentions, ie. 144 mph, or 230 kph is the speed at which the Corsair achieved its maximum rate of climb HISTORICALLY.

Since this is a game, not real life, it just so happens that the maximum rate of climb for the virtual Corsair F4U-1D is achieved at a slightly different speed.

HOWEVER... I am prepared to indulge such ridiculous arguements because whether the climb is done at 230 kph or 280 kph, the Corsair still climbs too fast.

I re-did the tests using the following criteria:

Starting speed: 230 KILOMETERS (not knots) per hour. (144 mph)

Starting height: Sea level.

Climb Speed: 230 kph.

Following climb times were achieved:

5000 ft (1524 Meters): 1 minute 12 seconds, for an average climbrate between sea level and 5000 ft of 4166 feet per minute, or clearly too high.

10,000 ft (3048 meters): 2 minutes 45 seconds, for and average climbrate between sea level and 10,000 ft of 3636 feet per minute.

20,000 ft (6096 meters): 6 minutes 2 seconds, for an average climbrate of 3314 feet per minute between sea level and 20,000 ft.

Climb times to 10,000 ft are 33 seconds too fast.

Climb times to 20,000 ft are 1 minute 1 second too fast.

So the fact remains, whether we choose to cripple the climbrate test of the Corsair or not, it climbs too fast.

Records of my tests are available for anyone who PM's me.

LEXX_Luthor
11-07-2004, 09:56 PM
ewwhh two heavyweight anti~LuftWhiners in the ring. http://www.lexxfans.com/phpBB2/images/smiles/023.gif

I say no more than 10 to 20 pages, depending on the breaks.

Fehler
11-08-2004, 02:37 AM
A couple of questions:

1.) If these sustained climb tests are optimal, in other words and slower or faster you wont get up to altitude as quickly, then why are almost all these tests done with "combat power?"

I am assuming that "Combat power" would equate to 100%, rads on auto or some similar configuration in the game (Correct?) I assume this because a test wouldnt be very valid if you could not actually attain a certain altitude because of overheating issues. Is this correct in assumption?

2.) What sort of climb speeds should be expected in the F4U or any other plane for that matter if Emergency power, boost, etc are employed?

I have seen data for some of the german planes that include boosts as part of climb tests. I was just wondering what sort of data there is for planes like the Corsair.

One of the reasons I dont actually do much testing is because a lack of understanding what all the data really means. In other words, numbers are only numbers until you can understand why you are attaining certain results.

For the average pilot in WWII, things like, My plane can outclimb the enemy's plane after I reach 15000 ft. were obviously important. But all that is obviously given that both aircraft are equal in energy when entering their best sustained climb rates, correct?

Oh well, Ill let you guys hash out the Corsair. It is a great looking plane, and fun to fly, but it's not my favorite PT aircraft.

Nubarus
11-08-2004, 03:45 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Col.Kurtz:
well
climbchart of Corsair from Manual gives 135 Knots for Climb that is 250km/h IAS
My test where done with start from Airport with timecount at liftoff with 220km/h then acceleration to 260km/H while Climbing then substained climb to alt:

Results:

F4U-1a 2135HP

In game:
3050m in 2:42min =54sec too fast
6100m in 5:10min =2:32min too fast

M/sec-ft/min
0-1k--18,9--3720 (2890ft/min real)
1-2k--18,5--3640
2-3k--18,2--3580
3-4k--21,3--4192
4-5k--20,4--4015
5-6k--19,2--3779
6-7k€"18,9--3720

Corsair MK.I has identical performance

-----
F4U-1D 2250HP

In game:
3050m in 2:31min = 47sec too fast
6100m in 4:56min = 2:10min too fast


M/sec--ft/min
0-1k€"20,8 -- 4094
1-2k€"18,5 -- 3641
2-3k€"20,4 -- 4015
3-4k€"20,4 -- 4015
4-5k€"21,7 -- 4278
5-6k---20 --- 3937
6-7k-- 18,9 €" 3713

---------------
F6F5 Hellcat

In game:
3040m in 2:48min too fast
6140m in 5:28min 2:14min too fast

M/sec.---ft/min
0-1k=18,9--3713
1-2k=17,2--3392
2-3k=17,5--3451
3-4k=19,6--3858
4-5k=18,9--3714
5-6k=17,2--3392
6-7k=18,2--3576

----------------

To make you happy i did rightnow a test with your recommed 250km/h(235knots)
and got this:
F4U-1D
3100m---2:29min
6100m---4:51min http://forums.ubi.com/images/smilies/88.gif


Here a report: (see climbspeed and compare with FW190...)
There is no way that corsair climbs faster at higher speeds if it would do in PF it would be even worser overmodelling.. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif
http://home.arcor.de/sebastianleitiger/190A5vsF4U-1DvsF6F-3/corsair1.jpg

Enjoy your UFO till Patch http://forums.ubi.com/images/smilies/cry.gif <HR></BLOCKQUOTE>

Last time I heard nearly all planes (Axis or Allied) have overmodelled climb rates.

Why do you (like a few others) always pick on a few planes (obviously from the side you fly against) and not all of them (Axis and Allied alike)?

This trend has been going on for al long as I can remember. http://forums.ubi.com/images/smilies/51.gif

WWMaxGunz
11-08-2004, 05:02 AM
Fehler, overheat and fuel consumption? When you're not staying over friendly ground
or in the Pacific it's a long swim home then running WEP all the way up is nuts.
Also in a fight, who flys climbs at 144 mph?? Well, yeah there is the climbing
spiral tactic. Wanna bet the pilots knew what WEP would get them?

JG77Von_Hess
11-08-2004, 07:46 AM
Hello Skychimp!
Very interresting charts. do you know if its 3 or 4 bladed propeller used on F4U? is it a special test engine to dump for scrap after one test run? How long for continous overboost? *1minute? Are climb charts calculated or timed real flying?

Just to cut out things a bit for those interrested:

Normal Climb: The normal climb is the best rate of climb with out overworking the engine. The manufactor recommends a certain airspeed and power settings for normal climb.

Maximum angle climb. This climb usually is not an extended one and seldom contineous for more than a couple thausand feets. The Max angle of climb is found at speed wich the maximunm exess thrust is found. It will be found at the speed at wich the greatest amount of thrust componenet is availeble to move the airplane upward as compared to its forward motion.

Also important to note Interferrence drag:
Interference drag is caused by the interfernce of the airflow between parts of the airplane such as would be found at intersection of the wings or empennage with fuselage. This drga is lessened by filleting theses areas so airflow is more gradual. This drag increases as the angle between the fuselage and tail decreas for 90 deg. This drag increses radicllly for the low wing at higher AoA, this also means that corsair is not too well off in prolonged corcsksrew and spiral climbs More bad for a low-winged plane.

So looking at many aspects even the little choppy I16 you will see that this plane is a way better design the corsir.

Testing in IL2 also is difficult, what propeller efficiency do wo have 1.0 for all planes? This will make a difference to real life if that would only be 0.85 as its normal figure for a high efficiency propller today.

Regards.

VH.

JG77Von_Hess
11-08-2004, 09:07 AM
A Freindly Bump from me to Skychimp.

since u have posted a few charts i thought u might have a few more!

what about a chart that shows Bhp/Thp availeble and required versus true airspeed for the corsair at (sealevel gros weight)

And one that shows Excess horsepower too! that would be very interresting. for both R-2800-8(B) and (W) as u already know both used in pacific.

Regards.

VH.

JtD
11-08-2004, 09:44 AM
Combat power is the all out maximum available power on a plane. 110% plus WEP.

JG77Von_Hess
11-08-2004, 10:39 AM
Ugh!! I hope that my wicked spelling aint causing too much trouble in understand what i am talking about in the 2 posts just above, (Dang this english spelling http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif)

Regards.

VH.

WWMaxGunz
11-08-2004, 10:53 AM
Oleg had stated before about people's tables with Spitfires and FW's that FB
models even the propeller type and efficiency so make sure those match what
is in the sim. But I have not seen what the sim uses! Perhaps buried in some
place I didn't yet look, PF comes with extra data in the readme (Specific
Plane Features) and in the manual it states Combat Power as 100%, WEP is
Emergency Power, not for all combat situations.

Wish I knew all what Oleg has posted, a collection of info on the sim from
those all in one piece would be valuable.

clint-ruin
11-08-2004, 10:58 AM
Unfortunately around the time of the first upgrade the boards search function was simply unusable. Would have liked to have added some more into Adorantes Ask Oleg thing otherwise. Everything from early 2003 is pretty much gone. Otherwise you might want to try looking for Olegs posts over on the SimHQ boards, there's a note on how to find his posts in the AO topic here.

JG77Von_Hess
11-08-2004, 11:23 AM
http://forums.ubi.com/groupee_common/emoticons/icon_cool.gifThx fellas!

But it still does not anwser the questions, u see skychimps postin that if u want to do comment on climb u have to do them poperly, and when people do that in IL2 Universe he shows a chart from real life, with so many variables not mentioned that the whole thing runs loose.
So for once just to do it all as right as possible vital pizes of the puzzel is missing.

So if Skychimp can anwser or any other, what i ask in them 2 post just above i would a happy camper.

And Skyc. This is absolute no attemp to make u look bad.

Regards.

VH.

JtD
11-08-2004, 11:40 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
Combat Power as 100%
<HR></BLOCKQUOTE>

100% is supposed to be military power.

clint-ruin
11-08-2004, 11:42 AM
What's kind of funny is that this exact climb power/climb angle thing has been gone through before by both Buzz and Chimp, Buzz with the 1.11 109 and Skychimp over the p-39 [here: http://www.simhq.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=98;t=004181;p=5#000 199 ].

JG77Von_Hess
11-08-2004, 12:04 PM
Yeah i remember the beginning of that one, so much hate in it, i was just looking for loose ends with the corsair just as of interrest.

(Correection, it actually only contains a moderate flak exchange http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif)

I wont really like to get invovled in plane vs plane shoot out thx.

Regards.

VH.

clint-ruin
11-08-2004, 12:49 PM
Yeah Oleg turned up in one of those threads and mentioned the way airfoil shape plays into things and other final tune stuff. But I think Chimp has it right - if you are going to match a chart, match the conditions too. Seen a lot of angst over La7 climbs with people comparing Forsazh climbs with unboosted climb charts..

JG77Von_Hess
11-08-2004, 12:56 PM
http://forums.ubi.com/groupee_common/emoticons/icon_smile.gifThats right.
This is why im looking for things like this:

***
Very interresting charts. do you know if its 3 or 4 bladed propeller used on F4U? is it a special test engine to dump for scrap after one test run? How long for continous overboost? *1minute? Are climb charts calculated or timed real flying?
***

And lots more in my first 2 posts.

Regadrs.

VH.

Col.Kurtz
11-08-2004, 01:29 PM
Here:
http://img79.exs.cx/img79/6838/F4U-1a.jpg

Game results:

F4U-1a 2135HP

In game:
3050m in 2:42min =54sec too fast
6100m in 5:10min =2:32min too fast

Height--meter/sec--ft/min
0-1k--18,9--3720 (2890ft/min real)
1-2k--18,5--3640
2-3k--18,2--3580
3-4k--21,3--4192
4-5k--20,4--4015
5-6k--19,2--3779
6-7k€"18,9--3720
1k=1000m

Powerload of
F4U-1a @5460KG (12039lb) with 2135HP is 2,55kg/HP
FW190A5 @4100kg (9038lb) with 1720PS is 2,38kg/PS
That is both max Power

The programmers just made a mistake and used a F4U-4 climb chart and did it very well.
F4U-4 reaches 6100m in 4:54min (real)
The F4U-1D has exactly this performance in PF!!(6100m in 4:56min)
It is just that simple!

JG77Von_Hess
11-08-2004, 02:34 PM
Thx Col. Kurtz.

Regards.

VH.

SkyChimp
11-08-2004, 08:52 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AgentBif:
2 and 4... No.

We just got through discussing this point Chimp! All he has to do is pick some speed and sustain it all the way through the test. If the game plane then underclimbs, then the test speed was less than the aircraft's optimal climb speed. If the game plane overclimbs the real plane, then something is wrong with the game. <HR></BLOCKQUOTE>

Not necessarily. If the PF planes climbs faster than what the BuAer chart says it should, then it could simply be a result of performing the test improperly.

If I zoom from sea-level to 10,000 feet, I'll get a better time-to-climb number than the one listed in the BuAer document posted by Buzzsaw - because the BuAer document doesn't present data from a zoom-climb test. Does that mean the plane in PF climbs too fast? Not at all, it simply means I didn't conduct my test in the same manner that produced the BuAer numbers.

It's easy to reduce Time-To-Climb numbers. And by reducing them, you inflate climb rates. You can do it by zooming into a climb and by starting your timing at an improper moment. It doesn't mean something is wrong, but it may mean you didn't conduct your test properly.

XyZspineZyX
11-08-2004, 09:06 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AgentBif:
We just got through discussing this point Chimp! All he has to do is pick some speed and sustain it all the way through the test. <HR></BLOCKQUOTE>

Not necessarily.

If I zoom from sea-level to 10,000 feet, I'll get a better time-to-climb number than the one listed in the BuAer document posted by Buzzsaw - because the BuAer document doesn't present data from a zoom-climb test. <HR></BLOCKQUOTE>

Sigh!

Which is why I said "pick a speed and sustain it all the way through the test". A sustained speed in a long climb test is NOT a zoom climb. This is the 2nd time now that I've clarified this point (after having made it initially) and at least one other person pointed this out as well.

You keep insisting that the user employ the same speed as the real plane's best climb speed but that's a bogus requirement if the game aircraft has a _different_ optimal climb speed. A game test that reveals superior sustained climb rate indicates a flaw in the game, regardless of what speed the test used.

SkyChimp
11-08-2004, 09:08 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG77Von_Hess:
Hello Skychimp!
Very interresting charts. do you know if its 3 or 4 bladed propeller used on F4U?
<HR></BLOCKQUOTE>

All Corsairs in PF have 3 blade props, as they did in real life. The first production Corsair with a 4-blade prop was the F4U-4, which isn't represented in PF.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
is it a special test engine to dump for scrap after one test run? How long for continous overboost? *1minute? Are climb charts calculated or timed real flying?
<HR></BLOCKQUOTE>

Test were normally conducted with stock, service grade aircraft, unless otherwise noted.

Time limitations for Combat Power were simply guidelines. Exceeding the time limitations didn't necessarily mean something would happen. Limitiations were set to keep the pilot aware of his engine condition.

Climb RATE charts are usually extrapolated from Time-To-Climb charts. Climb Rates can be determined by how long is took t get from one altitude to a higher altitude.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
Just to cut out things a bit for those interrested:

Normal Climb: The normal climb is the best rate of climb with out overworking the engine. The manufactor recommends a certain airspeed and power settings for normal climb.
<HR></BLOCKQUOTE>

Normal Climb as in that BuAer document mean Normal Power - an engine power setting.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
Maximum angle climb. This climb usually is not an extended one and seldom contineous for more than a couple thausand feets. The Max angle of climb is found at speed wich the maximunm exess thrust is found. It will be found at the speed at wich the greatest amount of thrust componenet is availeble to move the airplane upward as compared to its forward motion.
<HR></BLOCKQUOTE>

Climb angle is incidental to the climb speed and power setting. When a plane climbs at combat power, it's throttle can't be increased to keep speed up. As a plane climbs at combnat power, it will have to continually pitch down to maintain speed - due to the ever decreasing power.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
Also important to note Interferrence drag:
Interference drag is caused by the interfernce of the airflow between parts of the airplane such as would be found at intersection of the wings or empennage with fuselage. This drga is lessened by filleting theses areas so airflow is more gradual. This drag increases as the angle between the fuselage and tail decreas for 90 deg. This drag increses radicllly for the low wing at higher AoA, this also means that corsair is not too well off in prolonged corcsksrew and spiral climbs More bad for a low-winged plane.

So looking at many aspects even the little choppy I16 you will see that this plane is a way better design the corsir.

Testing in IL2 also is difficult, what propeller efficiency do wo have 1.0 for all planes? This will make a difference to real life if that would only be 0.85 as its normal figure for a high efficiency propller today.

Regards.

VH. <HR></BLOCKQUOTE>

I'm not getting into this one. Simply because its outside of the scope of this thread and it's getting late.

SkyChimp
11-08-2004, 09:11 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AgentBif:
Sigh!

Which is why I said "pick a speed and _sustain it all the way through the test_". A _sustained_ speed in a long climb test is NOT a zoom climb. This is the 2nd time now that I've clarified this point (after having made it initially) and at least one other person pointed this out as well.

You keep insisting that the user employ the same speed as the real plane's best climb speed but that's a bogus requirement if the game aircraft has a _different_ optimal climb speed. A game test that reveals superior sustained climb rate indicates a flaw in the game, regardless of what speed the test used. <HR></BLOCKQUOTE>

Then Bif, conduct your onw test and post your results. Don't just nitpick mine.

SkyChimp
11-08-2004, 09:23 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Col.Kurtz:
Here:
http://img79.exs.cx/img79/6838/F4U-1a.jpg

Game results:

F4U-1a 2135HP

In game:
3050m in 2:42min =54sec too fast
6100m in 5:10min =2:32min too fast

Height--meter/sec--ft/min
0-1k--18,9--3720 (2890ft/min real)
1-2k--18,5--3640
2-3k--18,2--3580
3-4k--21,3--4192
4-5k--20,4--4015
5-6k--19,2--3779
6-7k€"18,9--3720
1k=1000m

Powerload of
F4U-1a @5460KG (12039lb) with 2135HP is 2,55kg/HP
FW190A5 @4100kg (9038lb) with 1720PS is 2,38kg/PS
That is both max Power

The programmers just made a mistake and used a F4U-4 climb chart and did it very well.
F4U-4 reaches 6100m in 4:54min (real)
The F4U-1D has exactly this performance in PF!!(6100m in 4:56min)
It is just that simple! <HR></BLOCKQUOTE>

You make very bold statements here. You CAN NOT conduct the test of the F4U-1A using that chart ALONE. It doesn't give critical information that is required to conduct the test. This is what I'm getting at. People throwing up charts and failing to understand what they say, then declaring their tests prove that the PF planes are modelled wrong.

That chart, just like Buzzsaw's, has a climb chart that goes with it, which clearly shows the mode of the supercharger during the climb. Additionally, you will need the climb speed from the pilot's manual. Once you have these, you can begin.

Your results are too vague to be taken seriously. Where did you start? When did you start timing? What was your supercharger mode when you began to climb? Etc, etc, etc.

You posted in another thread that you tested your plane in this manner:
Cooler open
Mixtur to 120%(auto Rich)
Fullpower
Climb to 1000m with neutral Gear
@1000m change in low Blower (2stage in Game)
@6000m set high blower

That's not the way either the F4U-1 or the F4U-1D were flown in those BuAer data sheets, yet you are perfectly content to compare your results to them.

XyZspineZyX
11-08-2004, 09:33 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
Additionally, you will need the climb speed from the pilot's manual. Once you have these, you can begin. <HR></BLOCKQUOTE>

Gah!

He will NOT need the climb speed from the real plane!

I just got done explaining this to you a FOURTH time. If you cannot refute that point with some kind of reasoning, then it is disingenuous of you to persist with this fallacy.

SkyChimp
11-08-2004, 09:57 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AgentBif:
Gah!

He will NOT need the climb speed from the real plane!

I just got done explaining this to you a FOURTH time. If you cannot refute that point with some kind of reasoning, then it is disingenuous of you to persist with this fallacy. <HR></BLOCKQUOTE>

I'm not sure what you don't understand about LIKE tests. It's not like it's a difficult concept.

If he is not performing his test that way it was performed to produced the BuAer numbers, then the comparison is invalid. Get it? It's really not that hard.

How about if I just haul *** along at some unspecified speed then haul back into a climb then declare my results aren't consitent with the BuAer results. Makes a helluva lot of sense.

All that **** on planes like superchargers and throttles, in reallife as in the game, are there for a reason - because they make a difference.

RAF74_Buzzsaw
11-08-2004, 11:12 PM
Salute SkyChimp

Please do not continue to suggest that other testers starting speed was excessive.

In my revised test, I started my climb from a speed of 230 kph or 144 mph.

And I still got faster times to altitude.

33 seconds faster to 10,000 ft and 1:01 faster to 20,000 ft.

I maintained a climbspeed of 230 kph throughout.

>>>>>

The fact is, I am interested in having aircraft perform as they did historically, WITHIN the limitations of the game engine. The crucial issue here is how fast an aircraft can climb, not the exact means by which they achieve the particular climbrate.

Because someone flying on the servers is not going to maintain a speed of 230 kph, if he can get a better climb at 270 kph.

I will also clearly state, that unlike others such as Isegrim/Kurfurst, I have no axe to grind. I am not a Luftwhiner, neither do I champion solely U.S. or British Aircraft.

I pushed hard for the P-47 to be improved, and I also have pointed out past problems with the 190 modelling.

If people want a Corsair which is an extraordinarily good performer, then they should ask Oleg to model the F4U-4A, which saw service historically, and would certainly dominate. It graphically is almost identical to the existing F4U-1D.

It would not be unrealistic for players to expect it to be done, it saw combat in much larger numbers than either the TA-152, He-162 or some of the speculative models which have been produced for the series.

XyZspineZyX
11-09-2004, 12:18 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
If he is not performing his test that way it was performed to produced the BuAer numbers, then the comparison is invalid. Get it? It's really not that hard.
<HR></BLOCKQUOTE>

Yes, my objection is simple too, yet you keep misunderstanding it!

1) The real test is to demonstrate the aircraft's best sustained climb rate.

2) If a gamer can demonstrate a far superior sustained climb rate, then the game model is flawed.

The only hard constraints that I think are necessary are:

a) same throttle setting as the official test
b) same load of expendables (fuel, ammo, etc)
b) climb for the same vertical distance
c) sustain airspeed through entire climb

All other parameters that I can think of at the moment are variable without invalidating the test.... Whatever the gamer can do to eek out better climb performance within the above constraints are legitimate means.

The point is to see if the game plane has dramatically superior capability compared to what the real plane was able to do.

Gatt59
11-09-2004, 12:34 AM
Well, I'm not a chart/test *****, however I cant really understand how an F4U-1A, able to sustain an 80-85deg bank turn *forever* (with full stick deflection) or a loop *forever*, can climb the right way. Same thing for the Wildcat.

The arenas will be a furballers heaven, indeed. No need to learn E management at all. Great.

Tipo_Man
11-09-2004, 01:45 AM
Well concerning the realtive climb performance, since some think that all planes climb faster than they should...
I'd be very interested how can a F4U-1 outclimb a FW-190A9, which is the current situaton in the game... really interested since both planes had similar power, but the Corsair weights 2000lbs more...

LeOs.K-Ande
11-09-2004, 04:00 AM
I think buzz is right. why was the test done if not for to have data of the best sustained climb? If the test was done with xxx mph then that must have been the maximun sustained climb speed.

What would have been the point to do a test with half power/speed anyway.

It clearly is the case that it climbs a bit too fast but now we just have to figure out how much. ( wep/no wep radiators etc )

I do see the point that chimp is trying to make. Also real pilots had to be careful not to break their engine because of too much strain but in the game you really cant break your engine ( unless you start to play with manual prop pich in 109 http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif )

WWMaxGunz
11-09-2004, 06:31 AM
The chart Kurtz posted give BHP and RPM for all the climb regimes.
Match that if possible.

I agree that best constant speed should be a matter of what it is in the sim.
IRL it says 144mph and that I don't believe was because faster was better.
I do expect some difference, not to would be stupid.

JG77Von_Hess
11-09-2004, 07:24 AM
Hello again!

Skychimp, look at the 2 posts again, i know its a bit cryptic. perhaps take them to someone who studies aronautics or a pilot school, that might help in understanding.

First: My climb test in PF(GAME) matches some of those mentioned here and its not yours. They do have have some remarkebly resmblence to the F4U-4 (Stonger Engine 4 Bladed prop) Climb figures given in real life. And u rush out and saying they are righ for for corsair we have in PF(Game).

Posting a chart wich is dated august 1945, with some things missing (4 bladed props was tested in real life) im not a clown i can see that the graphics in PF(Game) shows 3 blades. look here and understand:

***
But it still does not anwser the questions, u see skychimps postin that if u want to do comment on climb u have to do them poperly, and when people do that in IL2 Universe he shows a chart from real life, with so many variables not mentioned that the whole thing runs loose.
***

Thats was whats goin to happen!!!

Then start to calculate a bit on things thats all theres needed, posting charts with some smart convincing words are fine, but really understanding them charts skychimp can be difficult, and for some it might be just enough, but for me its not.. you c i know the anwser to my own questions in this post and the 2 charts i mention in lower of my 2 post u can make them ur self if u have all the variables availebel.

only thing i dont have the anwser for my self:
***
Testing in IL2 also is difficult, what propeller efficiency do wo have 1.0 for all planes? This will make a difference to real life if that would only be 0.85 as its normal figure for a high efficiency propller today.
***

All wahts mentioned in them post have a valid for being asked!!!

I will be away untill 15th but i will gladely do a discuss on this matter with anyone who will not try to make others look like idiots!!

PS.. And for those who might think im trying to poo the Corsair.. No its not about a spicific plane.

Regards.

VH.

Col.Kurtz
11-09-2004, 12:40 PM
My Tests are reliable.

Climbspeed for F4U Corsair was 135Knots that is 250KM/H. (250km/h Climbspeed even gives some second faster climb in PF as 260km/h)
It is documented in Manual and Comparsion report of F4U-1D vs FW190A5
They where flown at max Power,that auxlailiary stage was used from sealevel is just a claim from SkyChimp
There would be no sense in doing so because it would lower enginepower when engaging the auxlailiary stage to low and also Manual clearly say that Neutral/Lowblower has do be used until mainfold pressure drops below desired power.
The Power only drops more as higher the Mainfold pressure is.
But this is absolutely unimportant to our testing...
The real ship was flown in a way so that desired Power rating could be hold and so do we in Game.
Il2 PF does not simulate this in great detail,the supercharger changing height is static---> no ram effect so it has to get changed at the same height,at all airspeeds and Power ratings!
So in the F4U Corsair and Hellcat you have to set supercharger to lowblower at 1000m(~3000ft) regardless of speed(ingame)

Even if i would play SkyChimp game and use 2stage at SL from start it would not make the result much diffrent.
If the Test is done with 2stage frome start i´m only 16sec slower in climb at first 1000m..


F4U-1a 2135HP

In game:
3050m (10000ft) in 2:42min =54sec too fast(38sec with SkyChimp thought of "ideal" Test)
6100m(20000ft) in 5:10min =2:32min too fast(2:16min too fast with SkyChimp thought of "ideal" Test)

-----
F4U-1D 2250HP

In game:
3050m(10000ft) in 2:31min = 47sec too fast (31sec too fast with SkyChimp thought of "ideal" Test)
6100m(20000ft) in 4:56min = 2:10min too fast(1:54min too fast with SkyChimp thought of "ideal" Test)

-----
F6F5 Hellcat

In game:
6100m(20000ft) in 5:28min 2:14min too fast

Think of a normal 1943 Bf109G6 that reaches 6000m in less than 4min and you know how realistic the Hellcat and Corsair is at the moment...

And again for all people that dont read my posts..
Condition for the tests are 100% Fuel,Start from GROUND begin to count time at liftoff with 220km/h at 0m height constand climb at 260km/h IAS (140knots,160mph) cooler open.

This picture maybe better fit as SkyChimps sign http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif
http://www.kprkpr.de/Info/Hunde/3-affen.jpg

Stiglr
11-09-2004, 01:22 PM
The classic fanboi graphic there, isn't it?

Just replace "evil" with "criticism" and it fits perfectly.
http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Korolov
11-09-2004, 01:29 PM
Don't forget to mention Targetware, Stiglr!

Heater1962
11-09-2004, 03:48 PM
I am not saying anyone is right or wrong here, I just wonder how many of the "aeronautical engineers" here have ever heard of "standard day" and if so how are you doing it in your testing? If you have to ask what "standard day" is then you should not be "testing"

JG77Von_Hess
11-09-2004, 04:26 PM
Well ok i dont c where any claims to be aeronautical engineers here. I do constrution engeneering and static calculation, but i can give u a hint how to cunduct it in IL2
Pick crimia map at noon sellect an airfield as low as possible to sealevel check temp gauge in plane on parking slot engine off, if it raises to around 15deg c we are pretty close.

VH.

GR142_Astro
11-09-2004, 04:51 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Nubarus:

Last time I heard nearly all planes (Axis or Allied) have overmodelled climb rates.

Why do you (like a few others) always pick on a few planes (obviously from the side you fly against) and not all of them (Axis and Allied alike)?

This trend has been going on for al long as I can remember. http://forums.ubi.com/images/smilies/51.gif <HR></BLOCKQUOTE>

http://forums.ubi.com/images/smilies/25.gif A-MEN! This post is buried amongst the chart wars, but is probably more spot-on that some are willing to admit. Many planes' climbrates are overdone in IL2. Hasn't everyone noticed?

The 109, P51, Ki84, Spit, La7 and other popular aircraft are some of the biggest offenders. The 190 series and P47s are some of the only planes that seem to have "honest" climbrates and FMs.

But yes, by all means single out the Corsair and Hellcat. Let's also continue to use ahistorical US-grade fuel to overspeed the Ki84 though.

SkyChimp
11-09-2004, 07:40 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AgentBif:

Yes, my objection is simple too, yet you keep misunderstanding it!

1) The real test is to demonstrate the aircraft's best sustained climb rate.

2) If a gamer can demonstrate a far superior sustained climb rate, then the game model is flawed.

The only hard constraints that I think are necessary are:

a) same throttle setting as the official test
b) same load of expendables (fuel, ammo, etc)
b) climb for the same vertical distance
c) sustain airspeed through entire climb

All other parameters that I can think of at the moment are variable without invalidating the test.... Whatever the gamer can do to eek out better climb performance within the above constraints are legitimate means.

The point is to see if the game plane has dramatically superior capability compared to what the real plane was able to do. <HR></BLOCKQUOTE>


"Sustained climb rate." There is no such thing as a "sustained climb 'RATE'" in a combat power climb test for the F4U-1D. If you perform the test in the manner that generated the BuAer numbers, then the rate at any given altitude IS NOT sustained. The climb RATE drops throughout the entire climb. Look at the chart I posted and tell me where in the combat power climb line the rate is sustained from one altitude to the next. It isn't. If it never stays the same - if it's always dropping - then it's NOT sustained, is it?

The test is one of a SUSTAINED CLIMB at a SUSTAINED SPEED. A sustained climb at a sustained speed WILL NOT produce a sustained climb rate. It can't.

It useless and completely academic to conduct a "sustained climb 'rate'" test. The only climb rate that can be sustained is the lowest climb rate achievable, and sooner or later that can't even be sustained. It's easy to sustain a climb rate of 100 feet per minute up to the altitude where the plane won't even climb that fast. But it's impossible to sustain a climb rate of 3,370 feet per minute above the altitude (in this case SL) where it can be achieved.

Hoarmurath
11-09-2004, 08:09 PM
Well, skychimp is right, you have to conduct the tests the same way that was done for obtaining the RL data, or you can't compare them...

I made the test, i was curious about all of these, and i'm quite used to climb test testing according to naca standard procedures.

For F4U-1D i found

climb at military power (100%)

3 min 20 sec to 10000 feet
6 min 55 sec to 20000 feet

i think these nombers are on the low end, i messed with the supercharger. If i have the time to make better tests with supercharger better used, i will post them...

i entered the climb at 100m, near the best sustained climb speed of 144 mph, plane fully loaded with fuel and ammo, trim neutral. The tests were done on crimea map, over water, at 12:00, clear weather.

SkyChimp
11-09-2004, 08:17 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Col.Kurtz:
My Tests are reliable.

Climbspeed for F4U Corsair was 135Knots that is 250KM/H. (250km/h Climbspeed even gives some second faster climb in PF as 260km/h)

It is documented in Manual and Comparsion report of F4U-1D vs FW190A5
<HR></BLOCKQUOTE>

Yes. It's 135 knots.



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
They where flown at max Power,that auxlailiary stage was used from sealevel is just a claim from SkyChimp
<HR></BLOCKQUOTE>

It's not a "claim" from me, it's fact. And it's readily apparent in the climb chart that goes with that page you posted.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
There would be no sense in doing so because it would lower enginepower when engaging the auxlailiary stage to low and also Manual clearly say that Neutral/Lowblower has do be used until mainfold pressure drops below desired power.
<HR></BLOCKQUOTE>

It doesn't matter what the manual says in this regard. It matters how the test was conducted you want to compare to, because you need to stay consistent with it. It's easy to figure out if you look at the chart that came with that BuAer page you posted. Here it is clearly showing that neutral blower was not used in the combat power climb, or for combat power speed for that matter:

http://members.cox.net/us.fighters/f4u1blowermode.jpg



<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
F4U-1a 2135HP

In game:
3050m (10000ft) in 2:42min =54sec too fast(38sec with SkyChimp thought of "ideal" Test)
6100m(20000ft) in 5:10min =2:32min too fast(2:16min too fast with SkyChimp thought of "ideal" Test)

-----
F4U-1D 2250HP

In game:
3050m(10000ft) in 2:31min = 47sec too fast (31sec too fast with SkyChimp thought of "ideal" Test)
6100m(20000ft) in 4:56min = 2:10min too fast(1:54min too fast with SkyChimp thought of "ideal" Test)

-----
F6F5 Hellcat

In game:
6100m(20000ft) in 5:28min 2:14min too fast

Think of a normal 1943 Bf109G6 that reaches 6000m in less than 4min and you know how realistic the Hellcat and Corsair is at the moment...

And again for all people that dont read my posts..
Condition for the tests are 100% Fuel,Start from GROUND begin to count time at liftoff with 220km/h at 0m height constand climb at 260km/h IAS (140knots,160mph) cooler open.

This picture maybe better fit as SkyChimps sign http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif
http://www.kprkpr.de/Info/Hunde/3-affen.jpg <HR></BLOCKQUOTE>

Actually, I conducted my own "ideal test" and got numbers only seconds off what they were according the BuAer report. So what are you doing differently?

SkyChimp
11-09-2004, 08:21 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Hoarmurath:
Well, skychimp is right, you have to conduct the tests the same way that was done for obtaining the RL data, or you can't compare them...

I made the test, i was curious about all of these, and i'm quite used to climb test testing according to naca standard procedures.

For F4U-1D i found

climb at military power (100%)

3 min 20 sec to 10000 feet
6 min 55 sec to 20000 feet

i think these nombers are on the low end, i messed with the supercharger. If i have the time to make better tests with supercharger better used, i will post them...

i entered the climb at 100m, near the best sustained climb speed of 144 mph, plane fully loaded with fuel and ammo, trim neutral. The tests were done on crimea map, over water, at 12:00, clear weather. <HR></BLOCKQUOTE>

Those numbers are extremely close to mine and extremely close to the numbers on the BuAer report. And they're certainly well within any margin of error due to fumbling with a watch or keyboard.

Hoarmurath
11-09-2004, 09:02 PM
ok, i made the test while using the supercharger at 2500m like the readme say....

i obtain these numbers :

3 min 15 sec to 10000 feet
6 min 38 sec to 20000 feet

quite close to what i had before... Remember these numbers are obtained at 100% power, so without water injection.

What annoy me is that i had the curiosity to check the object viewer, and was surprised to see that the F4U-1D was given for more than 10 minutes to reach 6000m (slightly less than 20000 feet)... Not what i obtain in game...

XyZspineZyX
11-09-2004, 10:09 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
"Sustained climb rate." There is no such thing as a "sustained climb 'RATE'" in a combat power climb test for the F4U-1D.
<HR></BLOCKQUOTE>

Sorry Chimp, you misunderstood me. Of COURSE the aircraft doesn't hold a particular climb rate through 20k feet!

The term "sustained climb" refers to a climb that is not a zoom climb... something which you kept harping on for like 5 posts even when I repeatedly acknowledged that zooming invalidates a climb rate test. So I started using the term "sustained climb" to distinguish the climb test in question from one that involves zooming... all just so you would stop trying to object by bringing up that (sigh) zooming makes such a test invalid.

SO, clearly "sustained climb rate" is the instantaneous climb at any point in a sustained climb. It is the same as "climb rate" but it clarifies the nature of the climb as one that does not involve zooming.

Is that clear?

Oy!

Hoarmurath
11-09-2004, 10:23 PM
Just had the patience to wait for my 56k to finish download all these charts.

Well, sorry Chimp, but i think they are right, i didn't test the combat power climb, but the military power climb. While the data indicate that the object viewer is wrong (at least for F4U-1D), the in game testing show a noticeable difference of 20% even according to human mistakes in the course of the test, this is a lot...

Either we are not refering to the good data, or the plane performance is somewhat wrong.

All we have to do is find out if we are reading the charts correctly http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

uhoh7
11-10-2004, 01:45 AM
So, skychimp where do you stand on the FM debate?

The current debate swirls around energy bleed, rather than combat power climbs, though i asume the climb test should show some affects of the light drag/low energy bleed issue.

uhoh7

Nubarus
11-10-2004, 02:16 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by GR142_Astro:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Nubarus:

Last time I heard nearly all planes (Axis or Allied) have overmodelled climb rates.

Why do you (like a few others) always pick on a few planes (obviously from the side you fly against) and not all of them (Axis and Allied alike)?

This trend has been going on for al long as I can remember. http://forums.ubi.com/images/smilies/51.gif <HR></BLOCKQUOTE>

http://forums.ubi.com/images/smilies/25.gif A-MEN! This post is buried amongst the chart wars, but is probably more spot-on that some are willing to admit. Many planes' climbrates are overdone in IL2. Hasn't everyone noticed?

The 109, P51, Ki84, Spit, La7 and other popular aircraft are some of the biggest offenders. The 190 series and P47s are some of the only planes that seem to have "honest" climbrates and FMs.

But yes, by all means single out the Corsair and Hellcat. Let's also continue to use ahistorical US-grade fuel to overspeed the Ki84 though. <HR></BLOCKQUOTE>

That's because they don't want to hear about that.
All they want is for a particular plane that they encounter online to get fixed and keep the overmodelled climb on their favorate rides intact.

I would say test ALL planes (Correctly according to the test data provided) and then send in a bug report to Oleg.

But my guess is they don't do that and rather keep on bickering here about one or two plane types from the side they fly against.

clint-ruin
11-10-2004, 02:30 AM
I can say that when I was just trying to do simple sea level tests for overheating on Crimea before 2.04 - it is a lot of work going through everything flyable. I only got about 50% in through major types before I got completely pissed off with doing it, and that's one of the simplest FM tests you can do.

I don't think there's any issue with just looking at one plane and trying to get it right. I do think that it's bad to take one plane and then use that as some kind of smoking gun OMFG OLEG BIAS HUGHAHALGA thing.

Nubarus
11-10-2004, 02:45 AM
I ask you Clint, really, what's the use of targetting one plane when only 2 plane models (P47 and FW190) have a correct climb rate in the extremely large flyable plane list in this game?

It's pretty obvious what's on some people's agenda here with remarks like "Enjoy your UFO until patch" and happely fly a Bf109 or Ki84 or any other Axis fighter other then the FW190 and don't mention anything about it's excessive climb rate.

I call that hypocricy since (according to their own standards) they fly a UFO themselves as well.

clint-ruin
11-10-2004, 03:35 AM
What's the use ?

Um.

Because then it would be .. correct? Or at least looked at to see if it's correct. Noone's coming around to chop off your fingers to prevent you from running your own tests, or not yet anyhow.

Which ones other than the P-47 and FW190 do you think exceed their real climb rates -when tested with the same parameters as the original tests- ? I am sure that if you mention it someone will go and take a look.

WWMaxGunz
11-10-2004, 03:44 AM
The PF manual clearly states Combat Power as 100% throttle in the sim.

I AM NOT SAYING THAT IS CORRECT!

Just that if 1C used 100% power to achieve the results of the report then that may be
why somebody can fly the test at 100% power and say the FM is good while another can
fly it at 110% and say the FM is not.

Hello... Oleg? Please, what one is right by the way PF works?

Edit:Add
Funny, but if the speeds and climbs were made for wrong power, then maybe other things
being questioned or related values/formula had to adjusted to make performance fit.

Nubarus
11-10-2004, 03:51 AM
The Spits, the P51's, the LA's, most of the Bf109's to name a few so pretty much every plane has an excessive climb rate then the original planes.

As for not getting my fingers chopped off, well I see that differently since I posted this a long time ago as well and the same "Get it correct" cruisaders in this thread stepped in and turned the thread into a flamewar.

All they want is for the Allied planes to get fixed and leave their own planes alone.

clint-ruin
11-10-2004, 03:57 AM
The easiest way to avoid that is just to mail to pf@1c.ru directly. You might get no response whatsoever rather than flamed though :>

When I last looked Il2compare at least was giving very very close climbs for the P-51d, at least as far as SL climb was concerned. What specifically is wrong with it? Which model, which alt range, what settings?

Kwiatos
11-10-2004, 05:11 AM
Il2 Compare is not accurate in climb rate and turn rate. Only best climb speed and max speed of planes. So dont use Il2 Compare to check climb rate of planes.

clint-ruin
11-10-2004, 05:14 AM
If you look at what it is actually measuring [0m instance only] rather than what you would like to think it is measuring then it ain't too bad. Yes it's always off by a little, sometimes by a lot, but as I said - I don't see anything there that is grossly out for the P51s climb. It was about 100m/s out last I looked, and given that Il2c can be that much out on its own ..

And another thing - top speeds I've noticed can be off as much as about 30kmh in il2c. Tends to be within about 5% of what the game gets though.

JtD
11-10-2004, 06:27 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by clint-ruin:
... It was about 100m/s out last I looked... <HR></BLOCKQUOTE>

You know, 100m/s is quite a lot. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

clint-ruin
11-10-2004, 07:05 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JtD:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by clint-ruin:
... It was about 100m/s out last I looked... <HR></BLOCKQUOTE>

You know, 100m/s is quite a lot. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif <HR></BLOCKQUOTE>

Yeah, but it's ROC at constant TAS at 0m in Il2c. Correct me if I'm wrong, but given the performance curves of engines, if you are measuring to any point beyond its critical alt you are going to get less than that as you go. I don't believe everything Il2c spits out but it's usually not -that- far out [patches tend to be the main thing that throws it - Ta152 for one has gone up and down], certainly not as far as people make out. I see so, so many people comparing Il2c to the wrong chart in real life, comparing sustained turns at 0m to other alts and even to instantaneous turns, etc.

It's an OK utility, it's how people use it that tends to be the problem! :>

k5054
11-10-2004, 08:22 AM
Clint, he means 100m/s is 328 ft/s is 19680 ft/min. You made a typo.

clint-ruin
11-10-2004, 08:42 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by k5054:
Clint, he means 100m/s is 328 ft/s is 19680 ft/min. You made a typo. <HR></BLOCKQUOTE>

Ah betweeen cones and viva la bam I wasn't paying attention :>

Sorry jtd :>

lbhskier37
11-10-2004, 11:15 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by GR142_Astro:
Let's also continue to use ahistorical US-grade fuel to overspeed the Ki84 though. <HR></BLOCKQUOTE>

OT, but unless the US testers modded the engine to use a higher boost pressure or advanced the spark timing using higher grade fuel doesn't give you a performance boost if the engine was designed to function properly with the lower grade fuel. The only thing higher grade fuel does is let you higher cylinder pressures/temperatures before you get detonation. Running these higher pressures/temperatures requires a physical mod to the engine.

And BTW to all those "picking on one plane" whiners, I wouldn't be caught dead in a Ki84, fly the Corsair and want it and all aircraft with uber climb fixed. Quit whining about people testing one plane, do you know how long it takes to test one? Go test whatever planes you want fixed or shut up about it.

effte
11-12-2004, 02:42 PM
Countering things as I find them, as there€s really too much inaccurate information in this thread to just leave it alone.

Your speed should be stabilized before reaching the lower limit to the altitude test block. This is an obvious given. The exact value it is stabilized at is one of the independent variables of performance testing. This testing will give a maximum climb rate at a certain speed for each altitude, with interpolation, which is then Vy for that setting.

The Bureau of Aeronautics data sheet specified different times to altitude for three different power settings, only one of which was combat power If you are going to complain about test procedures, do it properly...

If an aircraft can achieve a climb rate above that of a given specification at one airspeed, there is also another airspeed at which it can achieve exactly the climb rate of that specification.

It can also achieve a climb rate superior to that fixed speed climb rate by varying the air speed throughout the test block! Finding exactly what speed schedule to use takes extensive flight testing.

Getting solid aircraft performance data is more akin to squeezing water out of a rock than to blowing your nose. The latter method seems to be what most people involved in the €œaircraft x doesn€t have the performance of reference y€ are doing.

As for the Fw190 testing document, it explicitly specifies that it focused on qualitative rather than quantitative data. In plain English, this means: Don€t get fixated on the numbers, they are likely to be off.

One of the main shortcomings of IL-2 climb performance testing goes is the lack of OAT, which is required to calculate the correct atmospheric parameters. As we have indications that temperatures vary between maps, this means that tests made in one map does not automatically compare to tests made in another. Hm, do some planes actually have (working) OAT gauges? Interesting if so!

Neutral blower was used in all the 1945 tests with the F4U-1D, but in the one with a clean aircraft and combat power only up to 2000 feet. Neutral blower will no longer provide the overboost MAP of combat power above this altitude. Thus, low blower had to be used. For the 1944 F4U-1 report conveniently referred to later when the data therein fit better with the posters theory, without comment on the switch of report used, low blower was used already from SL. You see a similar increase in the shift-over altitude between tests 2 and 3, due to test 3 and 4 being at normal power while test 2 was at military. To get accurate results, we will of course have to change blower gears when appropriate to the aircraft modelled in the game, not when historic data suggests.

The shift point between blower gears is on the left side of the flatter sections, where the power loss due to the MAP dropping off, as the blower can€t fully compensate for the lower ambient pressure, equals the power loss associated with going to a higher blower gear.

Does anyone happen to have a link to a POH for the aircraft?

I repeat: You do NOT need the historical climb speed from the POH. They are very unlikely to be the same in the game!

A heavier aircraft can outclimb a lighter aircraft with the same amount of power if the heavier aircraft has less drag.

And nobody is prepared to claim to be an aero engineer? OK, I€ll do it then... *sigh* http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Now, we have two different reports on two models of the F4U floating around in the debate as well. The F4U-1D-1C report from August 1945 (NAVAER 1335-D) and the F4U-1 report from March 1944. True to the performance figure debating standard, people seem to quote both reports depending on which one supports the point they are currently trying to make. Very convenient, but also bloody stupid. For the record, I€m mainly basing my argument on the August 1945 one, as it was the first to surface. It is also slightly more interesting as far as illustrating the effects of blower settings go.

Sustained climb would be a climb where kinetic energy is not exchanged for positional energy (altitude). In other words, basically a constant speed climb.

In my world (which is not the US Navy in the 1940s), combat power means all out maximum power. Yes, you are likely to fry your engine if you do this to 10,000 feet. However, nothing prevents you from deriving the time to 10,000€ analytically from several tests of shorter duration.
Military power is maximum without overboosting or using water injection. Normal would be a setting which is selected considering fuel consumption, engine wear etc etc, generally good for your everyday climb out.

Radiator settings are not specified, but they would probably be adjusted to give the desired cylinder head temperatures. One can assume auto rich mixture for additional cooling and detonation prevention at these high power settings.


My opinion on the endless performance bickering: I don€t care whether the aircraft perform as they did historically in tests, as long as they€re in the same ballpark as the historic data, and generally sorted more or less in the same way relative to each other (i e, Corsairs didn€t outturn Zeros). The individual variations between aircraft of the same type would have been large anyway, for starters. Secondly, you fly with what you are given. If your aircraft is not what your historical data suggests it should be, accept that and adjust your tactics accordingly instead of having a fit and pointing at test charts from 1942 while taking the silk elevator down, after being shot down by an aircraft which outclimbed you even though your charts show a 50 fpm climb advantage for you. Perhaps the pilot was lighter. Perhaps you had a bum spark plug, perhaps your piston rings were worn, perhaps your engine was reaching TBO while the other guy€s engine only had a few hours on it. Live with what you got, work with it and, if you go with the book figures rather than the actual figures, die with it.

SkyChimp
11-13-2004, 08:23 AM
The reason I assert that F4U-1D in the BuAer test didn't use neutral blower in the combat power climb is because the chart reflects that low blower was engaged at or very near sea level, not 2,000 feet as the previous poster states. The left point of the more horizontal line doesn't represent the shift point from one blower gear to another. That shift point would be more in the middle or right of the more horizontal line. That's because there was a significant lag before a desired power could be reachieved after switching blower gears. Blower gears were switched after only a few inches of manifold pressure were lost. And it took time to get the manifold pressure (and performance) back up after switching gears - it wasn't instantaneous. If it were instantaneous, then I'd agree the left point would be the shift point. And if it were instantaneous, then the climb lines would have had much shorter horizontal sections because the pilot could have immediately reestablished power after he noticed it dropped off. But it wasn't, so it's not. (This EFFECT can be seen with RPMs when switching gears in an accelerating car.) And since it wasn't instantaneous, it wouldn't make sense for a pilot to let his MP to get very low before switching gears. After all, this was a combat-power climb (or as close to it as possible), not a combat-power, then military-power, then back up to combat-power climb.

Reference the F4U-1D climb lines: the lower, most vertical portions of the lines represent climb in neutral blower. Where that line -first- begins a sharp left turn to a more horizontal line represents that initial drop in power due to the inability of the blower to maintain manifold pressure in that mode. At that point, more likely just after it, the shift to a higher gear would have taken place. The remaining portion of the more horizontal line up to the very initial portion of the up-turn to a more vertical line would represent the lag in the reestablishment of power after switching gears. Therefore the shift point of the blower is not the left-most point on the more horizontal line. It would have been more to the center, and more likely closer to the right. Therefore, if neutral blower was used, it was switched to low at or very near sea level.

This effect hold true for any geared, multi-speed, mechanical blower. This effect can be seen in F4F, F6F, and P-51 Mustang climb charts. In fact, the information I have on a P-15 climb that includes an engine power chart with a climb-rate chart illustrates very nicely that the engine must rebuild power after a switch from a lower blower gear to a higher and that performance isn't reestablished until manifold pressure is reestablished.

In a perfect test, the climb lines in that BuAer document would have been represented by curves, not nice straight lines with crisp angles as we see. We need to visualize it as a curve. What we have here is a typical representation of a climb-rate chart extrapolated from a time-to-climb test. A case of connect the dots €" a case of averaging. Had a time been taken at every 10 feet (which would have been practically impossible), we would have a much more curved, fluid line.

===

As for bringing up the F4U-1 chart, if that comment was directed at me, that was done in response to another poster specifically referencing his tests with the F4U-1 and comparing them to the F4U-1 BuAer document. That chart clearly shows there was never any switch from neutral to low, be it at sea-level or 10 feet. And that was the point I was trying to illustrate.

==

As far as testing these planes against different documents and trying to make a simulation out of it is, as one can imagine, an almost impossible task. We're left wondering which test was used, whether it was valid, etc... As far as most people here are concerned, all the planes over perform in climb. The Bf-109, Spitfire, whatever. I'd don't see that it really matters much as long as proper characteristics are maintained. If all planes over-climb by 10%, then what difference does it really make, a Bf-109 will still out climb a P-51 - just the way it did in real life. But if we were to correct just ONE plane, then you reduce its historical advantage disproportionately to all others. Buzzsaw states that F4U-1D over-climbs. OK, for the sake of argument say it does. It's just as likely then that it doesn't over-climb enough when compared to other over-modeled planes, than over-climb

Kurfurst__
11-13-2004, 09:04 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
As far as most people here are concerned, all the planes over perform in climb. The Bf-109, Spitfire, whatever. I'd don't see that it really matters much as long as proper characteristics are maintained. If all planes over-climb by 10%, then what difference does it really make, a Bf-109 will still out climb a P-51 - just the way it did in real life. But if we were to correct just ONE plane, then you reduce its historical advantage disproportionately to all others. <HR></BLOCKQUOTE>

95% agree. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif The trouble is that they are not uniformly overmodelled... a good time back then, it did not make much difference between late 109s and the La-5s/7s, because the relative climb characteristics vs altitude were still true... but then with new planes, it stirred up, the Spit V is still ridiculus at altitude, the late109s La-7s Spit9s still climb better than they should at all altitudes, but the difference isnt just 10% in all cases.. The P-51D wouldnt bother me at all, but the fact that the P-51 is somewhat overmodelled in ROC _and_ that the 109G-6 (which would supposed to be the most important and most common model of the entire 109 series..) is quite a bit undermodelled with climb results in the end that the Mustang can escape the Gustav in climb! So does the SpitV, which was anything but a stellar altitude performer.. So as I said, we have an uncontrollable bleeding of the FM in our hands. Simply theres way too many planes to keep them under control.. why not change the developers policy to: NO new planes until the old ones are fixed 100% ?

SkyChimp
11-13-2004, 09:10 AM
Like you said earlier, what hope do we have that a PF plane will be fixed while a 3 year old IL2 plane is still porked.

OldMan____
11-13-2004, 01:57 PM
Lets calm down and organize our thinking. think is important here to elect ONE chart.. perform a test with the same weight and power setting as this chart and see if it matches. THAN if there is anotehr chart that uses another power setting and another weight.. test it too. If ANY of the two are FAR away from test results.. so something IS wrong. Simple as that. Do not take that because ONE CONDITION test is correct the hole model is too. Also pay attention in fuel load.. the wheight in charts is not FULL fuel in some tests.

People here are arguing when one uses a WEP power test and the other a Combat power test. Each one please.. make BOTH tests.

I won´t say what my tests gave in results.. it does not help to post it here.


And yes there are BOTH in red and blu side over modelled climb rates. Both should be corrected when they are very far from reality.

effte
11-14-2004, 02:26 AM
SkyChimp,
9 for the effort, 2 for the technical content and accuracy.


First, the basics

You climb at a constant MAP. Here, we find another departure from reality in Il-2. Whereas, in reality, we€d be setting the throttle (effectively the position of the throttle valve), in Il-2 we are setting the MAP. Full throttle gives the MAP for full mil power, sans WEP if present. In real life, slamming the throttle to the forward stop at low altitude would overboost the engine and blow the gaskets or even blow the cylinder heads off.

In real life, you carefully set the MAP to the desired pressure. Throughout the climb, you will then open up the throttle slowly to maintain this MAP. At one point, the throttle valve is fully open. You have then reached the limit of the current charger stage. The only method of regaining MAP is to shift the charger up a gear.

However, there€s also a reason not to leave the charger in high gear all the time. To drive the charger, you extract power from the engine. In other words, to have the charger running at a higher RPM there will be less brake horse power available on the prop shaft. If it wasn€t for this, we€d probably have the chargers in high constantly and restrict the MAP by using the throttle. Now, we€re about ready for The Chart.

http://w1.127.comhem.se/~u12700035/images/BHP%20altitude%20plot.jpg

Here, you can see how the BHP available increases with altitude as long as the charger can still supply the desired MAP. This is due to the ambient (outside) pressure lowering. On the exhaust stroke, the ambient pressure is the pressure against which the engine has to push out the exhaust gases. A higher ambient pressure means the engine has to do more work to get rid of the exhaust. This is also where you see the power loss to a turbocharger, the charger turbine increases the exhaust manifold pressure.

There are two constant MAP curves, one for high blower and one for low. These are rather linear, and this is as it should be. The high blower curve has a slightly lower BHP output at all altitudes. This is due to the power loss associated with driving the compressor at a higher RPM.

At the critical altitude for the low blower gear, the throttle lever reaches the forward stop. The throttle valve is fully open and the MAP will start to drop off as you climb further. However, this is not where you switch up to the next blower gear! This is only done as your BHP curve intercepts the high blower BHP curve. Switching before this point would mean dropping from the €˜low blower, dropping MAP€ curve straight down to the corresponding point on the €˜high blower, constant MAP€ curve. You€d get less than the maximum possible BHP output.

So yes, unless wasting power sounds like a good idea to you, it does makes sense to wait until the BHP has dropped a bit before switching.

When switching blower gears, the only delay before getting your MAP back is having the charger speed up to the new operating RPM, charger pressure multiplication factor being largely a function of charger RPM.

Looking at the clean combat power climb plot (1), we see the steeper low blower and high blower constant MAP segments. In between them is the flatter segment representing the low blower, dropping MAP part of the climb. The latter covers roughly 2000 feet of altitude. The climbrate in that segment is around 2750 feet. This means that around 40 seconds will be spent in this segment. SkyChimp claims that this flatter segment is due to the lag before regaining power when switching blower gears. This is, to put it bluntly, an asinine suggestion. It does not take 40 seconds for the blower to get up to the new RPM.

And again, yes, low blower was engaged at the left point of the first flatter segment in the F4U-1D clean combat power climb(1). Up to that point, neutral blower was used. And yes, that point is at 2000 feet.



A little knowledge is a dangerous thing...

Edit: The depicted chart, while valid for demonstrating the effects discussed, contains an error. It is left as an exercise for alert readers to find it. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Kurfurst__
11-14-2004, 04:17 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by effte:
Edit: The depicted chart, while valid for demonstrating the effects discussed, contains an error. It is left as an exercise for alert readers to find it. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif <HR></BLOCKQUOTE>

yeah, you dont get higher powers in the high blower. High blowers takes MORE power AWAY from the engine. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif Nice chart and text BTW. It made me to appreciate the DB hydraulically driven superchargers even more. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

effte
11-14-2004, 05:13 AM
And Kurfurst gets the grand prize, a cup of coffee. Served locally, transportation not included. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Kurfurst__
11-14-2004, 06:04 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by effte:
And Kurfurst gets the grand prize, a cup of coffee. Served locally, transportation not included. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif <HR></BLOCKQUOTE>

I luv coffee. And coffee loves me, too. We make a great team, coffee and me. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

BTW, re:corsair, you should check out this simhq thread, great read, great guy (if he is what he says he is)!

EDIT : Took the time to read page 2 as well, and decided he ain`t that great. http://forums.ubi.com/groupee_common/emoticons/icon_redface.gif Oh well, that`s what happens when you always want to have more info, more first hand accounts, LOL. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

http://www.simhq.com/simhq3/sims/boards/bbs/ultimatebb.php?ubb=get_topic;f=114;t=001292;p=1

k5054
11-14-2004, 09:22 AM
Colonel Damir P Fillen? I love the smell of BS in the morning.

I can crack the 'april fool' part of the anagram of his name, but not the remaining letters.

WWMaxGunz
11-14-2004, 09:43 AM
So Effte.... where is that neutral blower part of the curve?

Think you might owe the Chimp one extra point there.

SkyChimp
11-14-2004, 11:34 AM
Thanks Max. Maybe even 2 points, huh? There's some significant errors his post. I'm going through my documents on the R-2800-8W/10W and its supercharger. I'll post my rebuttal by this evening. Right now it's beautiful fall day here in Virginia, and my sons want to play some football.

effte
11-14-2004, 11:57 AM
WWMaxGunz,
it is the flatter segment up to 2000 feet in the F4U-1D climb. Incorrectly pointed out to be in low blower at first, forcing a switch to another chart later to cover it up. No points awarded for claiming this to be the time it takes the compressor to get up to RPM... http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

k5054,
good to see that I'm not the only one who stepped back and said "hey now" after his initial few posts. I recognize all those 'facts' from certain camps in years and internet forums gone by. He's full of it, that's my conclusion. I'd be interested in hearing the full story on how he got people to send him money. Oh yeah, googling also shows up a member in the unofficial Manowar fan club. Yay! But nothing about flying outside of the PC... http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Regards,
Fred

SkyChimp
11-14-2004, 07:10 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
SkyChimp,
9 for the effort, 2 for the technical content and accuracy.
<HR></BLOCKQUOTE>

Thanks for the critique. For now it€s been civil, I hope we can keep it that way.


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First, the basics

You climb at a constant MAP. Here, we find another departure from reality in Il-2. Whereas, in reality, we€d be setting the throttle (effectively the position of the throttle valve), in Il-2 we are setting the MAP. Full throttle gives the MAP for full mil power, sans WEP if present. In real life, slamming the throttle to the forward stop at low altitude would overboost the engine and blow the gaskets or even blow the cylinder heads off.
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Yes and no. This applies to SOME engines, not to others. It doesn€t apply in this case. I€ll explain why in a moment.


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In real life, you carefully set the MAP to the desired pressure. Throughout the climb, you will then open up the throttle slowly to maintain this MAP. At one point, the throttle valve is fully open. You have then reached the limit of the current charger stage. The only method of regaining MAP is to shift the charger up a gear.
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As stated, this is correct for some aircraft, not for others. It€s not correct in this case.

The F4U-1D had the Pratt & Whitney R-2800-8W engine. This was a €œB€ series engine. All R-2800 €œB€s had automatic boost control that kept the pilot from having to €œthrottle up slowly to maintain MAP €" throughout the climb.€ In the F4U the pilot set the MAP by placing the throttle at the desired setting and the prop at the desired pitch for the appropriate RPM. The automatic boost control took care of the rest and prevented undesired over-boosting beyond the power setting chosen. This was accomplished by valves installed ahead of the carburetor that would bleed off pressure that would have otherwise boosted the engine to a MAP in excess of that chosen.

In a climb, say a combat power climb, ostensibly the pilot would set the throttle at sea-level to the combat-power setting and he wouldn€t touch it again until he needed to shift blower gears. SOP was to reduce throttle by several inches of MAP before shifting gears, then carefully throttling back up to the desired setting after the shift..

Unless the engine was modified, the typical service-grade R-2800-8W (or -10W in the Hellcat) could have its throttle €œfire-walled€ on the ground and no more than combat-power could be achieved. The automatic-boost control made sure no more MAP was developed than was desired.

If this game departs from reality, it does it only for a few planes, such as the P-39, where there was no automatic-boost control and the pilot really did have to throttle-up throughout the climb. With regards to THIS aspect, this game treats the F4U properly.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
However, there€s also a reason not to leave the charger in high gear all the time. To drive the charger, you extract power from the engine. In other words, to have the charger running at a higher RPM there will be less brake horse power available on the prop shaft. If it wasn€t for this, we€d probably have the chargers in high constantly and restrict the MAP by using the throttle.
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I agree with this. It€s an issue of efficiency. While there is no mechanical reason this couldn€t be done, it would seem to sap BHP if high were engaged too low.



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Now, we€re about ready for The Chart.

Here, you can see how the BHP available increases with altitude as long as the charger can still supply the desired MAP. This is due to the ambient (outside) pressure lowering. On the exhaust stroke, the ambient pressure is the pressure against which the engine has to push out the exhaust gases. A higher ambient pressure means the engine has to do more work to get rid of the exhaust. This is also where you see the power loss to a turbocharger, the charger turbine increases the exhaust manifold pressure.

There are two constant MAP curves, one for high blower and one for low. These are rather linear, and this is as it should be. The high blower curve has a slightly lower BHP output at all altitudes. This is due to the power loss associated with driving the compressor at a higher RPM.

At the critical altitude for the low blower gear, the throttle lever reaches the forward stop. The throttle valve is fully open and the MAP will start to drop off as you climb further. However, this is not where you switch up to the next blower gear! This is only done as your BHP curve intercepts the high blower BHP curve. Switching before this point would mean dropping from the €˜low blower, dropping MAP€ curve straight down to the corresponding point on the €˜high blower, constant MAP€ curve. You€d get less than the maximum possible BHP output.

So yes, unless wasting power sounds like a good idea to you, it does makes sense to wait until the BHP has dropped a bit before switching.

When switching blower gears, the only delay before getting your MAP back is having the charger speed up to the new operating RPM, charger pressure multiplication factor being largely a function of charger RPM.

Looking at the clean combat power climb plot (1), we see the steeper low blower and high blower constant MAP segments. In between them is the flatter segment representing the low blower, dropping MAP part of the climb. The latter covers roughly 2000 feet of altitude. The climbrate in that segment is around 2750 feet. This means that around 40 seconds will be spent in this segment. SkyChimp claims that this flatter segment is due to the lag before regaining power when switching blower gears. This is, to put it bluntly, an asinine suggestion. It does not take 40 seconds for the blower to get up to the new RPM.

And again, yes, low blower was engaged at the left point of the first flatter segment in the F4U-1D clean combat power climb(1). Up to that point, neutral blower was used. And yes, that point is at 2000 feet.
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Asinine? We don€t know each other so let€s not get personal. €œIgnorant€ may be better?

At any rate, I don€t really disagree with anything you€ve written above. I hadn€t really thought about the shift before the full drop in MAP, but I think you are right in that regard.

Your chart, however, is not quite right, so I€ll post a chart that speaks directly to the R-2800-8W:

http://members.cox.net/us.fighters/power.jpg

The chart I posted shows BHP remaining constant at sea-level up to the critical altitude of the power setting, at that point it begins to drop. Switching the blower from neutral to low (for instance at Military power) stabilizes the power-loss and the power again remains virtually constant (only a SLIGHTEST increase) up to the next critical altitude where it begins to drop again. Switching to high blower arrests the power loss and the power remains virtually constant up to the last critical altitude where it begins to drop again. At this point there is no more throttle left and no more blower settings to go to, and power loss continues up to the plane€s ceiling. However, at NO POINT does the power increase beyond that achieved at sea-level up to the 1st critical altitude as your chart shows. BHP will be highest at the neutral stage's critical altitude, less high at the low-blower critical altitude, and even less at the high-blower critical altitude. I€d be happy to post actual Navy engine power charts for the Hellcat€s R-2800-10W (exactly the same as the -8W in the Corsair except for the carb-air flow direction) that illustrates that further.

So while inconsequential details are wrong, nevertheless I agree with the substance of 99% of what you€ve written so far.

Where I differ is that the left-most point of the most horizontal line represents the shift point. It€s important to understand that the climb-rate chart isn€t a Horsepower vs. Altitude chart, and lacking the Horsepower vs. Altitude chart that would go with that, it€s impossible to state that the shift points would correlate precisely with the left most points on the horizontal lines of the climb-rate chart.

I don€t believe the left most point on the horizontal lines necessarily represents the shift point from a lower blower mode to a higher blower mode. I think it€s more to the right. Not all the way, but somewhere on the horizontal line. Above I stated that the switching of the blower from one mode to a higher mode arrests power loss. The arrest is not instantaneous. If it were instantaneous, then I€d agree that the left point represents the shift point. If it€s not instantaneous, then it can€t be the left-most point.

Shifting from neutral to low didn€t result in an instantaneous operation of the blower. Shifting from low to high didn€t result in immediate operation in high. The F4U-1D had a mechanical 2 stage, 2 speed blower. As you know, only the auxiliary stage could be speed controlled. The auxiliary blower simply wasn€t clunked into gear. There had to be a way to accelerate the blower from 0 rpm to 18,000 rpm. Simply engaging a clutch would have resulted in a burned clutch, or stripped drive-gears. To overcome this issue, a fluid coupling was used to cushion the violent acceleration of the supercharger impeller. When the pilot selects low blower, a time delay prevents oil flowing to the low blower clutch. Instead, oil is directed to the fluid coupling or €œaccelerator.€ Once the time delay timed out, the impeller was at, or close to, its geared speed, at which time the clutch was engaged with little or no accelerating load to accommodate. This took time.

In addition to the time it took to engage the blower, or shift it, there was the issue of having to reduce the throttle before engaging or shifting the blower. The throttle had to be pulled back reducing MAP even further. The blower was then engaged or shifted, then the throttle had to be returned to the desired setting. This took time as well.

So, even if you disagree, I hope you understand why I disagree the left-most point represents the shift point.


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Incorrectly pointed out to be in low blower at first, forcing a switch to another chart later to cover it up.
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You said something about that in another post, and I explained why I brought it up. Now you bring it up again.

I posted the other chart because another poster comapred his test to it, but failed to post the chart. I posted it because he didn't.

Clear on this?

RAF74_Buzzsaw
11-14-2004, 08:40 PM
Salute

All of this obsessive ad nauseum analysis of exactly what supercharger speed was used at what altitude, or how manifold pressure is best maintained is completely irrelevant to the actual issues.

Which are:

1) What is the best climbrate the historical aircraft could achieve?

2) What is the best climbrate the simulated aircraft can achieve?

If 1) and 2) do not align, as they clearly do not, then there is a problem with the current Corsair simulation and it should be revised.

The fact is, there is no possibility of achieving, within the boundaries of this current game simulation, the realities of the actual aircraft. So, understanding that, we should focus on the important issue. Which is how they perform compared to their historical counterpart.

Anything else is so much hooey.

SkyChimp
11-15-2004, 12:29 PM
After reviewing more documents (NACA supercharger report), I have to say effte is right, and I am wrong regarding the location of the supercharger shift point on the horizontal line.

faustnik
11-15-2004, 12:56 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74_Buzzsaw:


The fact is, there is no possibility of achieving, within the boundaries of this current game simulation, the realities of the actual aircraft. So, understanding that, we should focus on the important issue. Which is how they perform compared to their historical counterpart.

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Great post Buzzsaw. Thanks for your effort here.

effte
11-15-2004, 02:38 PM
SkyChimp,
I'll get back later, but the offer to tone the rethorics down to a more normal level is happily accepted. My tone up to now has been harsh, in part due to your initial posts not being what you'd call diplomatic and in part due to my allergy to information being presented as facts when it isn't. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

We have been on the same side of the fence in many fruitful discussions before, and on different sides in other possibly more fruitful debates. Back to banter-level it is!

Perhaps the time and tools (UDPGraph) have finally come to make a more structured flight testing effort worthwhile?

Cheers!
/ft