PDA

View Full Version : You cant stall in FB/AEP



Air_Mail
03-23-2004, 07:13 PM
yes thats right.......you cant stall in this game. i tested every plne in the game in the power off/power on stall and all it does is go into spins. there must be some sort of auto rudder programed into the planes. watch the slip/skid indicators in the cockpit when you try to stall the plane. at the last second they go full deflection to one side and the plane goes into a spin. this is truely amazing. aparently it is imposible to stall a plane without going into a spin. if you have ever taken any flying lessons one of the first maneuvers the instructor has you do is a stall recovery. you wait for the buffet of the wings and then the nose drops untill air statrs flowing over the wings and then you recover by pulling back up and adding power.

i am a flight instructor and i have flown many different types of planes from a cessna 150 to a king air 350 to a super decathalon and i have never done a stall that went into a spin unless i meant to do it.

in order to go into a spin you have to have 2 conditions.
1. the wings have to be stalled.
2. the plane has to be yawed.

at first i thought it was because of the full power on the engine was producing torque and P-factor but the same thing happens with the engine turned off. sounds like someone at UBI need to do some homework on aerodynamics http://ubbxforums.ubi.com/infopop/emoticons/icon_redface.gifops:

http://www.onpoi.net/ah/pics/users/ah_131_1074072105.jpg

Air_Mail
03-23-2004, 07:13 PM
yes thats right.......you cant stall in this game. i tested every plne in the game in the power off/power on stall and all it does is go into spins. there must be some sort of auto rudder programed into the planes. watch the slip/skid indicators in the cockpit when you try to stall the plane. at the last second they go full deflection to one side and the plane goes into a spin. this is truely amazing. aparently it is imposible to stall a plane without going into a spin. if you have ever taken any flying lessons one of the first maneuvers the instructor has you do is a stall recovery. you wait for the buffet of the wings and then the nose drops untill air statrs flowing over the wings and then you recover by pulling back up and adding power.

i am a flight instructor and i have flown many different types of planes from a cessna 150 to a king air 350 to a super decathalon and i have never done a stall that went into a spin unless i meant to do it.

in order to go into a spin you have to have 2 conditions.
1. the wings have to be stalled.
2. the plane has to be yawed.

at first i thought it was because of the full power on the engine was producing torque and P-factor but the same thing happens with the engine turned off. sounds like someone at UBI need to do some homework on aerodynamics http://ubbxforums.ubi.com/infopop/emoticons/icon_redface.gifops:

http://www.onpoi.net/ah/pics/users/ah_131_1074072105.jpg

Chuck_Older
03-23-2004, 07:14 PM
A spin is a stall in which one wing stalls before the other, or at least that's what they taught me at engineering school http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif


You may have a point though.

I appreciate your flight experience. But may I suggest that the aircraft in FB are modelled to be assumed to be a more high-response aircraft, and are modelled to be more prone to spin.

The only way to really tell is if one of the a/c you are proficient in was modelled in FB, using FB's physics


~edit


I guess what I'm getting at is that I have no way to tell just how much something like calculating the CG of an aircraft in FB changes in-game, or how it is influenced, or what. using that as an example, what does the weight of guns in the wings, or large fuel tanks in the wings and fuselage do to those equations?

I don't know.

But I do hear tell that Oleg Maddox is an aeronautical engineer, himself.
*****************************
Wave bub-bub-bub-bye to the boss, it's your profit, it's his loss~ Clash

Covino
03-23-2004, 07:26 PM
Air_Mail, I'm sad to say that you are correct http://ubbxforums.ubi.com/infopop/emoticons/icon_frown.gif. Post-stall nose drop is something that's strangely missing in this game. Instead, the plane immediatly whips into a spin. I've never thought about this until now. I highly reccomend you post this in Oleg's Ready Room although such a radical overhaul of FM is unlikely.

tsisqua
03-23-2004, 07:41 PM
Originally posted by Air_Mail:
yes thats right.......you cant stall in this game. i tested every plne in the game in the power off/power on stall and all it does is go into spins.

I believe that a spin is simply a stall that involves only one wing losing angle of attack. Admitedly, every stall should not result in a spin, but it does make for an exciting recovery, huh?


there must be some sort of auto rudder programed into the planes. watch the slip/skid indicators in the cockpit when you try to stall the plane. at the last second they go full deflection to one side and the plane goes into a spin. this is truely amazing. aparently it is imposible to stall a plane without going into a spin.

There is alot . . . and I mean ALOT of code in this sim. The flight models aren't perfect, the developer has said so. but the planes DO behave more like what I would expect a real one to than they do in, say, MS FS2002, 2004, CFS, CFS2, or definitely CFS3.


if you have ever taken any flying lessons one of the first maneuvers the instructor has you do is a stall recovery. you wait for the buffet of the wings and then the nose drops untill air statrs flowing over the wings and then you recover by pulling back up and adding power.

I am not a CFI, and I have nowhere near the time in the air as you most likely do, but keep in mind that this is a game. A very complicated simulation, but a game, nonetheless. When I was taught stall recovery, I was taught to slow the plane smoothly, attempting to maintain altitude. When the buffet begins, and I find myself in a nose-down attitude, I follow the procedure that you described. However, the stall speed for a warbird would be much faster than it would in the average private A/C. Sudden stalls are more likely to result (in the game) in a spin. Have you tried the stall with varying degrees of flaps? (I am not disagreeing with you, just saying that I am enjoying the game in spite of its faults, not because of them)

i am a flight instructor and i have flown many different types of planes from a cessna 150 to a king air 350 to a super decathalon and i have never done a stall that went into a spin unless i meant to do it.

in order to go into a spin you have to have 2 conditions.
1. the wings have to be stalled.
2. the plane has to be yawed.

at first i thought it was because of the full power on the engine was producing torque and P-factor but the same thing happens with the engine turned off. sounds like someone at UBI need to do some homework on aerodynamics http://ubbxforums.ubi.com/infopop/emoticons/icon_redface.gifops:

The nice thing about this sim/game is that it is under constant development. Frequent patches are released . . . for FREE! All intended to improve FM, and to make it better. If you go to the Oleg's Ready Room forum, you can post about this issue, and maybe get an answer from the developer in person. Maybe even get this better than it is. Try THAT with Microsoft.

Welcome to the madness.
Tsisqua

http://server5.uploadit.org/files/tsisqua-nedChristie.jpg
Tsalagi Asgaya Galvladi

Chuck_Older
03-23-2004, 07:43 PM
I just tried myself, in a P-51D

I thought I was on the cusp of a stall a few times, but it's always like I'm balancing on a razor's edge, and then I lose one wing or another.

I never really noticed this deficiency myself until now as well. I suppose I had read so much about nasty spin characteristics in many of these planes, so I wasn't looking for anything BUT a spin.

But I also know for a fact that I read many accounts of Warbirds pilots, and military pilots during WWII, performing clean stalls.

I had very much wanted to say I had stalled in FB and not spun- but my experiment of just a moment ago dispelled that...maybe it was in the original Il*2??

I'm gonna go try it in a Hurricane.

PS-

I also just found an unrelated, graphical bug concerning ID markings on P-51Bs. Off to ORR http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

*****************************
Wave bub-bub-bub-bye to the boss, it's your profit, it's his loss~ Clash

Air_Mail
03-23-2004, 08:47 PM
i realize this is a game and there is no way that you can copy every situation into a game but stalling is a pretty damn big chunk to leave out of a flight sim lol.

as far as actuall spins go......it doesnt matter what plane in the world it is (747 or ultralight) you still need to be in a stalled state and be yawed to enter a spin.

i teach aerophysics to my students and the airfiols used on WW2 fighters are mostly built to produce high lift (for wieght) and maneuverable which decreases stability. you will find the same airfoil designs used for fighters are scaled down and lightened for aerobatic planes. i fly aerobatics in high performance aircraft. i practice all recoveries from maneuvers pointed straight down to get as much airflow over the wings as possible to aviod stalling by coming out too early. when you pull out of a vertical dive and pull 3-5 g's there is no tendancy for a wing to drop unless you really pull hard and exceed the critical angle of attack. the way you can actually do this is by doing an accelerated stall by banking the aircraft and slowing it down to increase stall speed. then you will see one of the wings drop and if you try to correct it with aileron then you will go into a spin due to adverse aileron yaw.

the idea that a plane imediatly enters a spin at high angles of attack goes to show that the makers do not understand how an airplane flys. i would post this in olegs ready room but i already told him about this back in beta days and he didnt seem to think i knew anything and blew me off.

http://www.onpoi.net/ah/pics/users/ah_131_1074072105.jpg

essemm
03-23-2004, 09:07 PM
It's good to have an expert opinion here. I would absolutely agree with you. FM changes at this stage of the game is unlikely, but there is still hope for Battle of Britain (1C Maddox's upcoming sim). A post in ORR might convice Oleg that this glaring deficiancy in the flight model should NOT be overlooked for that sim.

I love the pic in your sig. I am a HUGE Maule fan. I prefer the amphib myself, but the Oleo Strut will do. My dream is to own a turbine M7-420 Turbine Amphib. I could move back to Nova Scotia and fly bush in the Annapolis Valley. Ahh...dreams.

http://server3.uploadit.org/files/141103-warloch_small.jpg

WUAF_Badsight
03-23-2004, 09:24 PM
Air_Mail

dont get put off by the replys in this thread or olegs replys in the past

do post your findings in ORR

this is a total valid point that doesnt seem correct

to hear your opinion considering your experience re-affirms this

adlabs6
03-23-2004, 09:40 PM
Air_Mail,

I have often wondered if there is a sort of "auto-rudder" in IL2 myself. Notice that it's very tough to get a plane to skid or slip unless you press the rudder? Most every turn you will make will be fairly coordinated, just using the elevators and ailerons. No need to "step on the ball", at least not enough to matter.

You also can't ground loop in this sim, something that I've read claimed quite a few WW2 pilots and planes.

While there is a lot of good code in this sim, and it does catch alot of the spirit of WW2 flight combat, there are also many compromises. I've come to believe that this sim, like most any "combat" sim, has fun at heart first and foremost. Making gameplay (or "realism") harder to pickup for new players is counter productive to success.

BTW, thanks for the info, it's always nice hear a pilots perspective on a sim.

http://www.geocities.com/adlabs6/B/bin/sigUBI.GIF
My FB/FS2004 Pages (http://www.geocities.com/adlabs6/B/) | IL2skins (http://www.il2skins.com) | OMEGASQUADRON (http://777avg.com/omegasquad/) | ScreenshotArt.com (http://www.screenshotart.com/)

BaldieJr
03-23-2004, 10:02 PM
FB is a game, not a sim.

<pre class="ip-ubbcode-code-pre">
______ _____
(, / ) /) /) , (, /
/---( _ // _(/ _ / __ ,""""]
+----/ ____)(_(_(/_(_(__(__(/____/__/ (__--------,' /---+
| / ( / ,' NR / |
|(_/ ..-""``"'-._ (_/ __,' 42 _/ |
+-.-"" "-..,____________/7,.--"" __]-----+

</pre>

Slammin_
03-23-2004, 10:16 PM
I find it amazing that nobody else noticed this umm, "glaring deficiancy" before. I certainly did not, nor do I think I ever will, especially since I have no real life experience flying planes. I'd imagine an authentic WWII Dora driver could REALLY point out some glaring deficiencies too, especially the code that was inadvertantly left out that causes you to die when shot down.

TX-EcoDragon
03-23-2004, 10:18 PM
I have posted things about this off and on, more towards the release of IL-2, Oleg is a pilot, and as such he also knows that what you say is true. While I think this needs work, the 1G stall regime is far less important in dogfight situations than the accelerated stall mode. I think that FB models this better than any other game or sim, even though the 1G stall, and the inability of the rudder to keep the plane from spinning are pretty annoying.

I would liek to see this sim made perfect with respect to flight fidelity. . . I would rather that than anything else, though I think trying to do that AND appeal to the WWII combat side of the sim, to release bug fixes etc, is a large task, and one that takes time. The nice thing is that Oleg/1C/Ubi continue to support and develop this line of sim, and I expect this to continue, so perhaps in Oleg's next endeavor the FMs will be even more of a simulation of flight. . . won't that be cool!!

S!
TX-EcoDragon
Black 1
TX Squadron XO
http://www.txsquadron.com

Member-Team Raven
http://www.waynehandley.com

First Slot Pilot Aircraft #4 of the Virtual Haute-Voltige Team
http://www.vhvt.com/

http://www.attitudeaviation.com/

http://www.calaggieflyers.com

http://www.txsquadron.com/uploaded/TX-EcoDragon/ravenvert.jpg

[This message was edited by TX-EcoDragon on Wed March 24 2004 at 01:57 AM.]

darkhorizon11
03-23-2004, 10:36 PM
Yeah hes right, though I don't have any time in warbird I've got a lot of hours myself and thought the same thing myself. Its WAY off, pretty much no aircraft (that I know, even in the desperation of WW2) would go into a stall so violently or so fast. I've done normal spins, flat spins, and inverted flat spins in a Cap 10B. Its a small low wing monoplane with a bubble canopy, elliptical wings, similiar power to wieght ratio, and large empennage.
Bottom line is that yaw stability is modeled incorrectly. It actually takes decent amount of effort to spin a plane.
This leads to another topic, dynamic and static stability which are way off too. But thats another topic that I don't want to get into.

[This message was edited by darkhorizon11 on Tue March 23 2004 at 10:22 PM.]

Air_Mail
03-23-2004, 10:44 PM
LOL you read my mind with dynamic stability. that one is a little harder to put into understandable terms but i ll save that one for later. your right on dark. iv done the flat spins, inverted spins, and such and they are hard to get into in the first place.

http://www.onpoi.net/ah/pics/users/ah_131_1074072105.jpg

ucanfly
03-23-2004, 11:11 PM
I've complained about lack or very low adverse yaw a loooooong time ago. Frankly, I hate to say it, but FS2002 (certain payware like the Marhetti SF260) have more realistic FMs than FB, but they don't shoot as well - LOL.

Maybe that is the compromise Oleg had to put put in for frame rates or track recording and all the other crud that FS series doesn't have to worry about- I don't know. I am going to expect better in BOB, don't think we'll see anything dramatic for this engine though.

BlindHuck
03-23-2004, 11:21 PM
I've noticed it, too. Also the rudderless self coordination. Long ago I tried yawing 109 at moderate G to try and induce differential slat operation, no luck. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif Still flyin' and smilin' http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

Someday I'll kill myself groundlooping a 109 http://ubbxforums.ubi.com/images/smiley/16x16_smiley-tongue.gif (I can dream, can't I? http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif )

"I race full real exclusively in IL2:The Forgotten Battles." - Mark Donohue

BlindHuck
03-23-2004, 11:30 PM
Oh - Air_Mail - nice lokin' Sitawb. I had a '46 7AC in high school I ran used (from a friends 185) 8.50's on for off road (8 psi), made up for the short stroke struts. Boy, I used to bottom those things out, even when water skiing'em. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif Oh, the good ole days . . . http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

"I race full real exclusively in IL2:The Forgotten Battles." - Mark Donohue

Tully__
03-24-2004, 03:37 AM
True aerodynamic stall modelling has always proved to problematic in PC sims/games. The developers have traditionally had to settle for a tendancy to spin more than in RL or abandon aerodynamics for the stalled state and use motion scripting.

=================================================


http://members.optusnet.com.au/tully_78th/Corsair.jpg (http://www.mudmovers.com/sturmovik_101/FAQ.htm)

IL2 Forums Moderator
Forum Terms of Use (http://www.ubi.com/US/Info/TermsOfUse.htm)

Salut
Tully

SeaFireLIV
03-24-2004, 03:45 AM
er... I always though when the plane dipped on a turn and went down that that was a stall. After that you went into a spin. Goes to show how much I know.

JG6_Oddball
03-24-2004, 05:07 AM
cant stall...oh really, since i put AEP in thats all ive been doing, my first flight with the 152 looked like a gymnastics routine....stall spin..forward somersault http://ubbxforums.ubi.com/infopop/emoticons/icon_rolleyes.gif then the whole screen went green...thats right, green not black aperantly this is a new feature in AEP ..your pilot will puke all over the cockpit after the 5th aeral cartwheel...oh well atleat i have new planes to puke in http://ubbxforums.ubi.com/images/smiley/crazy.gif
S!

Black Sheep
03-24-2004, 06:24 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
Frankly, I hate to say it, but FS2002 (certain payware like the Marhetti SF260) have more realistic FMs than FB, but they don't shoot as well - LOL.
<HR></BLOCKQUOTE>

Bear in mind though that single aircraft costs as much as FB itself (or near enough).

Don't get me wrong, I think some of the payware addons for FS are incredible - I fly PMDG's 737 for British Airways Virtual - but in most cases you are paying as much for a single aircraft as you are for an entire sim.

For my money, FB provides far more out of the box more than any other sim out there.

Slightly off topic, but those who own FS 2004 and / or those interested in Yaks might like to take a look at this:

http://www.captainsim.com/yak3/

(Edit: spelling)

TugZooey
03-24-2004, 06:29 AM
So, am I not stalling when my plane dips forward and I hear the sound of air rushing? I seem to be able to stall (well, the screen tells me I do), and I do go into spins sometimes.

I know nothing about aerophysics (or whatever the correct term is).

Aaron_GT
03-24-2004, 06:44 AM
A number of WW2 planes were notorious for
dipping a wing on stalling. Maybe the
modelling has been arranged to cope with this
at the expense of other things to keep the
physics complexity down to average PC levels?

I've got a few other sims (Xplane 6 - and
a demo of 7, SDOE, EAW, Janes WW2, CFS2, WBIII
) that include a set of planes that are present
in all of them (I think the P51 is the only
stock/official Warbird in Xplane) so if anyone
wants some testing across multiple sims
for comparasion, I can do that. Just let me
know what to test so everyone knows what
I am testing! Since the P51 is present
in all of them, that makes the most sense.
I think I have the 1% P51 for CFS2 - will need
to check that.

Phoenix1911
03-24-2004, 07:03 AM
As someone with his PPL I've noticed the stall characteristics weren't quite right, however I do have 0 warbird hours logged as well http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif Katanas and C172s are designed to be predictable whereas fighters are less so for maneuverbility....

As a programmer as well though I realize the amount of CPU time required to model flight dynamics, its can get VERY intensive, and to keep FB playable, and model the more important stuff which makes this sim so great we need to make compromises...

I do believe there is a little adverse yaw if you do an F3 flyby, I usually throw a little rudder into the turn for good measure anyways! http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

michapma
03-24-2004, 07:58 AM
I don't know enough here to make actual points, but I'd like to chime in anyway.

First of all, I like to think I know basically what a stall is, and what a spin is. I have something like 20 minutes of piloting experience in a Cessna--so much for speaking from experience--so I learned it from flight sims, but also from books, and especially from John Denker (http://www.av8n.com/how/htm/vdamp.html#sec-stall-intro). As has been pointed out, the behavior at the 1G stall, caused when the airspeed drops below what will deliver the required lift, is of little relevance. I take it that the nose ought to drop, instead in FB one wing or the other drops instead. (Too bad we don't get to manage the fuel system and leave one wing drier than the other, how sweet that would be!)

I also think I know what a spin is. Mr. Denker describes it in some detail (http://www.av8n.com/how/htm/spins.html), and there are plenty of other sources. However, I am missing something when Air_Mail says you can't stall in the game, but rather you enter directly into a spin.

I think what I must not understand properly is the real difference between the two--where a stall turns into a spin. I'll use Denker as my source. What's a spin?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The word ``spin'' can be used in several different ways, which we will discuss below. The spin family tree includes:
<UL TYPE=SQUARE> <LI> ``departure'', i.e. onset of undamped rolling; <LI> incipient spin " i.e. one that has just gotten started; or <LI> well-developed spin, which could be <LI> a steep spin, or <LI> a flat spin. [/LIST]<HR></BLOCKQUOTE>

What's a stall?
http://www.av8n.com/how/img48/power-aoa.png
At the critical AoA, the coefficient of lift begins to reduce, but nothing special happens. The further you go past that angle though, the deeper the stall develops. So it seems to me that you can be in that mushy region where lift is decreasing and drag increasing, but you are not in a spin. So when a wing drops, is that a stall or a spin? I understand the "departure, i.e., the onset of undamped rolliing" to be more than just a wing dropping or a mushiness, it's an actual rotation about an axis. In this early stage of the stall, the spin is easy to recover. A well-developed spin is clear, one wing is stalled more than the other and a stable condition results.

So it seems to me that stalls do exist in FB. I've gotten into a high AoA at high speeds and snapped into a whatever--I'll say stall--without actually spinning. The aircraft then had to descend to recover its speed and re-enter level flight or maneuvers. Is that not a stall? It may not behave just like a real-life aircraft, but it seems like a stall nevertheless.

The mechanics of the situation and the governing mathematics become much more complicated and, I assume, more involved to model accurately. I've heard it claimed that the MS sim engines have a better capability to model in general, but that these capabilities are difficult to exploit and are not used except by some payware modelers. Someone already mentioned that the behavior we have might be the price we pay for the other fun stuff. I don't know, but I doubt it's that Oleg doesn't care or is really incapable of modeling it. He might be, it's a special engine and it certainly has its limitations. For that kind of stuff I guess you need XPlane.

Like someone else said, what bothers me more is the lack of adverse yaw. My guess is that this was so greatly reduced in order to make the sim more enjoyable as a game. I should think that it could be enabled as a difficulty option, but boy would people have trouble handling the real-life torque of some of these beasts.

Oh, and I want carb heat and proper start-up procedures, too. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

C!
Mike

http://www.baseclass.modulweb.dk/69giap/fileadmin/Image_Archive/badges/69giap_badge_chap.jpg (http://giap.webhop.info)

The ongoing IL-2 User's Guide (http://people.ee.ethz.ch/~chapman/il2guide/) | Forgotten Skies (http://www.forgottenskies.com/)
But we are all that way: when we know a thing we have only scorn for other people who don't happen to know it. - Mark Twain, Personal Recollections of Joan of Arc

XyZspineZyX
03-24-2004, 09:37 AM
It seems to me the "stalls" or "spins" are just canned effects. Maybe there's some kind of "severity" setting, such that some planes will spin more readily than others.

Torque, or aerodynamic elements of the individual plane seem to have nothing to do with it.

Also, planes with docile stalls (not spins, but stalls) still get the wicked, pull you inverted left out of a coordinated right hand turn kind of stalls.

Aaron_GT
03-24-2004, 10:44 AM
Stiglr - that reminds me - I can test in
TargetWare too (also has a P51)

XyZspineZyX
03-24-2004, 12:40 PM
Go ahead, it'll be interesting to see what differences there are.

A couple of people over in Targetware land are complaining that the Pony there is too slow. I dunno, I never flew it... but I find it hard to believe that the Pony there would be shafted... the guy behind it is the biggest Stang fan in the world!!!

mortoma
03-24-2004, 03:08 PM
I'm a very low time pilot with only 90 hours since I got my license in 2000 but I know enough about flying to notice this a while back. If a planes wing are level, shouldn't it just do a regular stall and nose drop, like I did dozens of times
in both my primary and instrument training?? If you stalled in a bank, with one wing low, then I can see a spin maybe. Or if you jammed the rudder to one side just before or during the stall. Maybe the higher torque of combat fighters ( as opposed to Cessnas ) makes them drop a wing right away??

[This message was edited by mortoma on Wed March 24 2004 at 02:16 PM.]

FI_Deathsledge
03-24-2004, 03:13 PM
the flight model differs online than it does offline. not by much but it does. i have no problems getting into stalls and/or spins flying online.

mortoma
03-24-2004, 03:13 PM
Ummm, by the way, what is "Targetware" that you guys are mentioning?? Is it pots and pans and stuff like that bought at Target?? Just kidding, but what is it???

TX-EcoDragon
03-24-2004, 03:58 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by michapma:
" . . .I take it that the nose ought to drop, instead in FB one wing or the other drops instead. (Too bad we don't get to manage the fuel system and leave one wing drier than the other, how sweet that would be!). . ."

Well, in many aircraft (especially with a forward CG) a wing may drop if the aircraft is just a little bit uncoordinated (the ball isn't centered/the fuselage isn't aligned with the relative wind) but the key difference is that a quick footed pilot will see/sense this drop at its beginning and correct it with rudder before the drop occurs (lift the dropping wing with rudder, or "step on the ball"). With practice, once you know a particular airplane you can hold wings perfectly level, and maintain heading perfectly, with the stick all the way back against the stop, with the wings fully stalled. I do this with people who are new to aerobatics, new to tailwheel aircraft, or during their primary training to instill in them both the proper responses with their feet, and confidence that an aircraft fully stalled can be stable, and they are in fact still in control.

Most aircraft however will stall more or less straight ahead provided that the pilot is of average ability with respect to maintaining coordinated flight.


"I also think I know what a spin is. Mr. Denker http://www.av8n.com/how/htm/spins.html, and there are plenty of other sources. However, I am missing something when Air_Mail says you can't stall in the game, but rather you enter directly into a spin.

I think what I must not understand properly is the real difference between the two--where a stall turns into a spin. I'll use Denker as my source. What's a spin?"

The stall is the loss of smooth airflow over the top surface of a wing and with this the great majority of lift is also lost, as most of a wing's lift is from the top surface. (bernoulli on top, newton on bottom). This happens because the angle of the wing with respect to the relative wind becomes too great for the air to flow over smoothly, instead it rolls and tumbles, and no long provides much lift (though at the bottom of the wing impact lift still provides a bit of lift which is why I can fly in a full stall at a descent rate of only about 800fpm at idle, and in some aircraft I can actually maintain altitude at minimal airspeed and with a breeze appear to hover).

Here is an example, look for the nose high attitudes, and look at the smoke to evaluate speed and direction of flight. In these instances the wings are fully stalled, but the tons of pilot skill, engine thrust along with newtonian lift keep the airplane in the air.

http://www.oracle.com/broadband/showondemand.html?1684528


A coordinated stall is one where each wing should stall at approximately the same time. think about the rudder as it is deflected, one wing slices forward, and one slices aft. So if you step on the left rudder pedal, the left wing slows down and the right speeds up. This is an easy way to think about it (though its more complex than this). Given this fact, if you were flying just above stall speed and then you apply rudder. . .now one wing is traveling faster than the other. . so one is farther from a stall, and one is closer. You should now be getting an idea of how rudder coordination makes the difference between a stall and a spin. If you aren't coordinated then one wing will stall first, and more deeply than the other, if this persists then a spin will develop. (this is a 1g stall example but its pretty much the same idea in the accelerated mode as well).

So the stall becomes a spin when the aircraft begins to rotate either clockwise or counterclockwise (there are a few phases of a spin but no need to talk about those just yet). This rotation occurs because one wing is more deeply stalled than the other. Once this happens the aircraft may be stable in the spin mode, and therefore be difficult to recover. So the aircraft must first stall, and then either improper rudder use, or deliberate input of rudder may/will start the rotation of the aircraft about the longitudinal axis.

"What's a stall?
http://www.av8n.com/how/img48/power-aoa.png
At the critical AoA, the coefficient of lift begins to reduce, but nothing special happens. The further you go past that angle though, the deeper the stall develops. So it seems to me that you can be in that mushy region where lift is decreasing and drag increasing, but you are not in a spin. So when a wing drops, is that a stall or a spin?"

That is a stall (with delayed rudder response)without proper rudder use to correct this drop, rotation will commence and you will then have a spin.

"I understand the "departure, i.e., the onset of undamped rolliing" to be more than just a wing dropping or a mushiness, it's an actual rotation about an axis."

Yeah, this is going to be different depending on who you talk to, "departure" is often used at the break of the stall. . . others use it to describe the departure from the stall to the spin, both are correct because it is a matter of context to determine what you are departing ;-)

"In this early stage of the stall, the spin is easy to recover." Wait, are we in a spin or a stall? If we are in a stall, and a wing is dropping, we are in a stall. . .and a wing is dropping, if we are spinning around then we are in a spin.

Basically there is a stall, then (provided uncoordinated flight) the incipient spin, and then the developed spin.

The incipient phase of the spin usually lasts about 1 turn (360 heading change), during this time the aircraft is not fully autorotating, and is indeed more responsive to recovery inputs than it is in the developed phase. In an accelerated mode simply letting go of everything is enough much of the time, because if the rudder is neutral, and the elevator isn't causing a wing to stall then you cant have a spin.

A developed spin will usually require all these actions to recover. Power to idle, ailerons neutral, rudder full oposite the rotation, elevator through neutral and just a little forward of neutral depending on the aircraft.

"A well-developed spin is clear, one wing is stalled more than the other and a stable condition results."

Yep

"So it seems to me that stalls do exist in FB." If you count accelerated stalls that dont respond to rudder inputs or coordination of flight.

"I've gotten into a high AoA at high speeds and snapped into a whatever--I'll say stall--without actually spinning. The aircraft then had to descend to recover its speed and re-enter level flight or maneuvers. Is that not a stall?" Its pretty close to an accelerated stall, the only difference is that recovery is instant in accelerated stalls that are coordinated, in FB the aircraft like to roll to inverted or a at least knife edge even with proper recovery inputs. If you are really quick you can get an accelerated stall to just start but then kill it by releasing the stick. . .and this is a pretty accurate mode provided that you don't let the goofy rudder response factor in.

"It may not behave just like a real-life aircraft, but it seems like a stall nevertheless." I wouldnt really call it a stall. The incipient and developed phase of a spin has a roll yaw component and a desire to continue the rotation, a stall has no yaw or roll and will not lead to a rotation if the pilot isn't applying controls to induce a spin. (for the most part), the FB stall is more of a snap roll (an accelerated spin). Being into aerobatics I'm rather happy to have a sim that snaps. . . so don't think im complaining!

"The mechanics of the situation and the governing mathematics become much more complicated and, I assume, more involved to model accurately."

Indeed

"I've heard it claimed that the MS sim engines have a better capability to model in general, but that these capabilities are difficult to exploit and are not used except by some payware modelers."

No, the MS line uses table data for the FM, it is very limited and even the best addons are still not as well done as FB, other than perhaps not leaping into a snap roll or spin isntead of stalling. . .but then, this is because the advanced physics of a snap roll eludes them, for the most part a deliberate snap roll looks very little like a snap roll! Even teh SF260, the 172, and Decathlon that are able to "spin" really dont have anyhting on FB, and beacuse of the way teh FM does this teh actual aerodynamics aren't modeled, it is more or less scripted.

"For that kind of stuff I guess you need XPlane."

I own or have access to pretty much every sim out there, for aerobatics FB is the best, bar none. X-plane has great FM and uses a great method to eploy it, but it still doesnt quite get the aerobatics down as well. (IL-2 1.04 was actually the best aerobatics FM in many respects, though AEP has some thigns that are new and improved too)

"Like someone else said, what bothers me more is the lack of adverse yaw." Yeah, its missing. . .but if this sim was 100% a lot of people would abandon it ;-)

"My guess is that this was so greatly reduced in order to make the _sim_ more enjoyable as a _game._ I should think that it could be enabled as a difficulty option, but boy would people have trouble handling the real-life torque of some of these beasts."

I would love to see the sim add in things like torque, p-factor, gyroscopic precession, and ground handling etc as realism options. . .but we really are talking about more advanced computers at this point. . . if the computers were there I have no doubt it would be Oleg's sim that was leading the pack.

"Oh, and I want carb heat and proper start-up procedures, too. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif"

<HR></BLOCKQUOTE>
Why not ;-)

If you have any questions, I am sure I could answer them better on coms instead of trying to write it out. . .so don't hesitate to ask.

S!
TX-EcoDragon
Black 1
TX Squadron XO
http://www.txsquadron.com

Member-Team Raven
http://www.waynehandley.com

First Slot Pilot Aircraft #4 of the Virtual Haute-Voltige Team
http://www.vhvt.com/

http://www.attitudeaviation.com/

http://www.calaggieflyers.com

http://www.txsquadron.com/uploaded/TX-EcoDragon/ravenvert.jpg

Aaron_GT
03-25-2004, 02:37 AM
"I'm a very low time pilot with only 90 hours since I got my license in 2000 but I know enough about flying to notice this a while back. If a planes wing are level, shouldn't it just do a regular stall and nose drop, "

It's going to depend on torque. If the
engine is still putting out a fair bit of
horsepower that prop wash and torque is likely
to make one wing dip (e.g. the Fw190 snap
roll to left on stall) unless the engine
is idled right back. In Cessnas, etc., the
plane's pretty stable and the engine low
powered so it might not exhibit it.

I'll maybe do some testing on Friday evening
(my next available flight sim slot!) with
the P51 across a range of sims, gentle stalls
with the engine idled and/or off.

Aztek_Eagle
03-25-2004, 03:18 AM
Whats a stall, i cant remember last time i stalled my own plane,this is not because the planes dont stall, but because i am careful , the only time i lose my speed, is landing, doing a brake off manuver, or a hammerhead, ho brake off manuver has save my butt many time, especialy against more manublable planes

Jezzadog
03-25-2004, 03:37 AM
Haven't tried them all, but there is at least one aircraft that will stall (in 1g flight) and that's the ME-262. Admittedly, it's not your classic "nose drop" stall; but you can avoid the "wing drop" if you approach the stall carefully - fairly slowly with the skid ball centred.

Aerodynamic buffet can be seen (and felt with a FFB joystick) as you approach the stall. With full back stick the nose may nod slightly; but the wing will not drop unless you induce it through sideslip (if the aircraft is not balanced - skidball out, maybe a bit of rudder or aileron). What you should notice is a high rate of descent. High ROD is yet another characteristic of a stall (although not as well known as the classic nose or wing drop).

Incidentally, if you are in a "spin", check the airspeed. If it is stabilized around the stall speed, the aircraft is in a spin and you will need to take the normal spin recovery action to recover. If it is well above the stall speed the aircraft is autorotating and the wing is not stalled. In the latter case the aircraft should respond favourably to aileron inputs.

But getting back to the ME-262, it probably doesn't matter if you get into a spin and bail out (height permitting) because at some stage of the flight the engine will catch on fire and you will have to abandon ship anyway!

"The mark of a true combat pilot is that he can throw his aircraft at the ground - and miss"

PikeBishop
03-25-2004, 03:47 AM
Hang on....I just want to be clear on this....Are you saying that when a stall situation is reached the FM automatically slams the controls over forcing your aircraft to go into a spin. So you can't just have the nose drop away still level after the stall buffet.........if indeed the machine you are in gives adequate stall warning as a characteristic of it's FM. I can understand dropping into a spin if one stalls in a tight turn however.

regards

SLP

CyC_AnD
03-25-2004, 04:58 AM
Oh boy... everything that was already when FB comes out... just go install old il2 sturmovik with version 1.2, try there to stall, spin, inverted spin, all whatever you want, only skid to tail is little messed. Now in FB i even dont know which rudder apply to recover those rolls, and i always did in old il2. They messed something with FM in FB dunno know what, but they did. In terms of FM i much better fly in il2 then Fb. Dont spit on me now, just go and try yourselfes.

CyC is my new home!

MatuDa_
03-25-2004, 05:46 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Air_Mail:
LOL you read my mind with dynamic stability. that one is a little harder to put into understandable terms but i ll save that one for later. <HR></BLOCKQUOTE>

Actually here is dynamic stability explained extremely well:

http://142.26.194.131/aerodynamics1/Stability/Page3.html

Lots of other stuff there also. just make sure you have macromedia flash installed

btw I agree with the original post.. even m$flightsim1 had better stalls.. but il2 is a very entertaining sim even with these problems

IDF_Baruchi
03-25-2004, 06:31 AM
Agree with all that planes in FB go to spin rather than stall. But think about it: It is a good habit to dance on your pedals while stall, in order to keep wings level, no mater if it is a real feature or a bug in FB. Just do what u need to keep out of spin - watch for the smallest bank tendancy and kill it before it grows - use rudder !!! This habit may even save your life if you happen to stall in a gusty windy weather.. think about it!

michapma
03-25-2004, 08:30 AM
EcoDragon, your explanations confirm more or less what I've read in Denker and the thoughts I had on stalls and spins. Thanks for the time you invested!

I also want to point out right away that I wrote most of that because of Air_Mail's claim that you can't stall in FB. I'll get back to that.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by TX-EcoDragon:
With practice, once you know a particular airplane you can hold wings perfectly level, and maintain heading perfectly, with the stick all the way back against the stop, with the wings fully stalled.<HR></BLOCKQUOTE>

I have done something similar in IL-2 with the P-39. I held the aircraft in an extreme nose-up situation with lots of buffeting but in level flight. The buffeting indicates that the wings are in a stalled condition but still providing enough lift to maintain the airplane. It did not, however, require any rudder input. What with the small amount of adverse torque and all... I haven't tried it in FB. I did have to watch the stick pressure carefully and noticed that if I pushed it too far the result was that a wing would drop, although the nose did always want to drop dramatically if I relaxed stick pressure a little. It is important to realize that, as you say, even in a deeply stalled condition the wing is producing lift. And not just a small amount. If there were no lift, the airplane would continually accelerate downward, instead of just having a downward velocity.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Most aircraft however will stall more or less straight ahead provided that the pilot is of average ability with respect to maintaining coordinated flight.<HR></BLOCKQUOTE>

As we know, coordinated flight is not such a big challenge in FB. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The stall is the loss of smooth airflow over the top surface of a wing and with this the great majority of lift is also lost, as most of a wing's lift is from the top surface. (bernoulli on top, newton on bottom). This happens because the angle of the wing with respect to the relative wind becomes too great for the air to flow over smoothly, instead it rolls and tumbles, and no long provides much lift (though at the bottom of the wing impact lift still provides a bit of lift which is why I can fly in a full stall at a descent rate of only about 800fpm at idle, and in some aircraft I can actually maintain altitude at minimal airspeed and with a breeze appear to hover).<HR></BLOCKQUOTE>

This is the cause of the stall. The graph above that I linked from Denker's site shows what happens in terms of the AoA. I won't comment on the fluid dynamics involved in the forces on the wing since I'm not qualified, but the turbulence introduced is what causes the change in the lift versus drag. Lift and drag are summed up by the coefficient of lift. At the critical angle, you can see in the graph that the lift starts to drop off. Get much past the critical angle (a greater angle, to the right on the graph) and it starts dropping off rapidly, and as a result so does the rate of climb. So it makes sense that you can actually fly in that stalled regime as you've said. Your nose might not even drop and you can fly straight on, perhaps also descending. I believe you can do this in FB as well as IL-2, as I've implied above.

Clearly though, FB does not model the stalled condition as precisely as we'd like it to.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Here is an example, look for the nose high attitudes,
http://www.oracle.com/broadband/showondemand.html?1684528
<HR></BLOCKQUOTE>

Sorry, I just get a blank page. Is it a movie?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>So if you step on the left rudder pedal, the left wing slows down and the right speeds up. This is an easy way to think about it (though its more complex than this).<HR></BLOCKQUOTE>

Right, it is all about the angle of attack. The angle of incidence of the two wings is the same, but because of the yaw the angle of attack of the two wings is different. In fact, the angle of attack along the length of a given wing changes, so some parts of the wing are more deeply stalled than the other parts.

The fact that parts of a wing can stall also helps it make sense that you can be in various stalled conditions, and that the wing as a whole can still produce lift when you are stalled. Denker talks about boundary layers on the wing and so on. He also talks about plenty of other stuff. There is a whole chapter on stalls and spins! http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif He enters the section on spin entry as follows:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
Case 1: In normal flight, rolling motions are very heavily damped, as discussed in section 5.4. Even though the static stability of the bank angle is small or even negative, you cannot get a large roll rate without a large roll-inducing force; when you take away the force the roll rate goes away.

Case 2: Near the critical angle of attack, the roll damping goes away. Suppose you start the aircraft rolling to the right. The roll rate will just continue all by itself. The right wing will be stalled (beyond max lift angle of attack) and the left wing will be unstalled (below max lift angle of attack).

Case 3: At a sufficiently high initial angle of attack (somewhat greater than the critical angle of attack), the roll will not just continue but accelerate, all by itself. This is an example of the "departure" that constitutes the beginning of a snap roll or spin. The resulting undamped rolling motion is called autorotation.<HR></BLOCKQUOTE>

The static roll stability in case 1 is part of what is missing in FB, it's why in an aircraft you can roll the plane into a bank angle and then relax sideways pressure on the stick/yoke, just holding it in position with backpressure and rudder. You can't often do this in FB, you have to give some aileron input to hold the bank angle. I noticed this during my 20 minutes of stick time. http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

Anyway, it is this is such interesting stuff and so relevant to the topic, I think I'll just cite most or all of the section!

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>At a high enough angle of attack, the ailerons lose effectiveness, and at some point they start working in reverse. Figure 18.4 shows how this reversal occurs. Suppose you deflect the ailerons to the left. This raises the angle of attack at the right wingtip and lowers it at the left wingtip. Normally, this would increase the lift on the right wing (and lower it on the left), creating a rolling moment toward the left. Near the critical angle of attack, though (as seen in the left panel of the figure), raising or lowering the angle of attack has about the same effect on the coefficient of lift, so no rolling moment is produced (for now, at least).
http://www.av8n.com/how/img48/stall-lift-drag.png
Figure 18.4: Lift and Drag at Departure

We see that at this angle of attack, anything that creates a rolling mo-ment will cause the aircraft to roll like crazy, and indeed to keep accelerating in the roll-wise direction. There will be no natural roll damping, and you will be unable to oppose the roll with the ailerons.

There are two main ways of provoking a spin at this point:

[list=1]<LI>Suppose the airplane is in a steady slip to the left. That is, you are steadily pushing on the right rudder pedal. Then the slip/roll cou-pling (as discussed in section 9.1 and section 9.2) will cause it to spin to the right.
<LI>Suppose the airplane is not in much of a slip, but you suddenly cause it to yaw to the right. The left wingtip will temporarily be moving faster, and the right wingtip will temporarily be moving slower. This difference in airspeeds will create a difference in lift, causing a spin to the right. The initial yawing motion could come from a sudden application of rudder, or from adverse yaw, or what-ever. Note that in the right panel of figure 18.4, the ai-leron deflection has a tremendous effect on the drag. This means that ailerons deflected to the left cause a yaw to the right which in turn provokes a roll to the just the opposite of what ailerons normally do.
<HR></BLOCKQUOTE>

Pretty cool stuff, and pretty much in line with what you wrote. Again, the link:
http://www.av8n.com/how/htm/spins.html

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>So the aircraft must first stall, and then either improper rudder use, or deliberate input of rudder may/will start the rotation of the aircraft about the longitudinal axis.<HR></BLOCKQUOTE>

Or adverse yaw, which in the case of the aircraft of FB might well aggravate it. But as you've said, several sources of adverse yaw are either missing or rather downplayed.

On a related issue, I have a hard time understanding how to keep some aircraft on a constant heading with the wings level and the ball centered. For example, the P-39. Often when the ball is centered there is a significant amount of yaw, enough to couple with the roll axis and cause the wings to tilt. If I relax the rudder trim, the wings stop banking and there seems to be no slip, but the ball is not centered. It drives me nuts. Maybe I'll make a track and send it to you.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
"What's a stall?
http://www.av8n.com/how/img48/power-aoa.png
At the critical AoA, the coefficient of lift begins to reduce, but nothing special happens. The further you go past that angle though, the deeper the stall develops. So it seems to me that you can be in that mushy region where lift is decreasing and drag increasing, but you are not in a spin. So when a wing drops, is that a stall or a spin?"

That is a stall (with delayed rudder response)without proper rudder use to correct this drop, rotation will commence and you will then have a spin.<HR></BLOCKQUOTE>

Ah-ha! So you can stall. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>"In this early stage of the stall, the spin is easy to recover." Wait, are we in a spin or a stall? If we are in a stall, and a wing is dropping, we are in a stall. . .and a wing is dropping, if we are spinning around then we are in a spin.<HR></BLOCKQUOTE>

Whoops, slip of the spin. I should have written "this early stage of the spin, it is easy to recover."

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Basically there is a stall, then (provided uncoordinated flight) the incipient spin, and then the developed spin.<HR></BLOCKQUOTE>

And if I understand correctly, the complaint is not that you cannot stall, but rather that 1) the stalls are not modeled to represent real stalls very well and 2) it is "too easy" to enter into a spin after a stall.

Is that correct everybody? Air_Mail?

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The incipient phase of the spin usually lasts about 1 turn (360 heading change), during this time the aircraft is not fully autorotating, and is indeed more responsive to recovery inputs than it is in the developed phase. In an accelerated mode simply letting go of everything is enough much of the time, because if the rudder is neutral, and the elevator isn't causing a wing to stall then you cant have a spin.<HR></BLOCKQUOTE>

I think this is represented rather well in FB!

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>A developed spin will usually require all these actions to recover. Power to idle, ailerons neutral, rudder full oposite the rotation, elevator through neutral and just a little forward of neutral depending on the aircraft.<HR></BLOCKQUOTE>

I also think fully developed spins are rather well modeled in FB. Did you realize that in real life the P-39 had a special spin recovery procedure? It's quite different than the normal ones. Normal is relative, each plane has its own stall characteristics. A large part of the Cobra's special characteristics stem from its engine placement and the resulting CoG. In IL-2 I found that, whereas the normal recovery procedures worked poorly for the Cobra, the actual recovery procedure in the P-39 pilot's notes worked rather well! In fact this seemed sometimes the only way to get it out of a fully developed flat spin. This says to me that the forces modeled in IL-2 are quite well done. I haven't practiced stalls and spins much in the Cobra in FB, but I was downright astounded in IL-2. The ability to recover aircraft in various spin modes, the ability to force the aircraft into inverted spins, and the way you can recover or not recover from developed spins causes me to reject the notion that spins in FB are canned effects as Stiglr suggests.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>"So it seems to me that stalls do exist in FB." If you count accelerated stalls that dont respond to rudder inputs or coordination of flight.<HR></BLOCKQUOTE>

Right, well Air_Mail's claim was that you can't stall:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>yes thats right.......you cant stall in this game. i tested every plne in the game in the power off/power on stall and all it does is go into spins. there must be some sort of auto rudder programed into the planes. watch the slip/skid indicators in the cockpit when you try to stall the plane. at the last second they go full deflection to one side and the plane goes into a spin. this is truely amazing. aparently it is imposible to stall a plane without going into a spin.<HR></BLOCKQUOTE>

So his complaint seems to be that there is something in the modeling of forces affecting the yaw axis that cause the aircraft to always go into a spin after the onset of a stall. I'd be interested to see a track of some of his tests. Because it's not that I doubt his expertise or want to play down his complaints, it's just that I want to learn more about precisely what is lacking and how it should be. I don't have anything else to compare it to.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Its pretty close to an accelerated stall, the only difference is that recovery is instant in accelerated stalls that are coordinated, in FB the aircraft like to roll to inverted or a at least knife edge even with proper recovery inputs.<HR></BLOCKQUOTE>

So an accelerated stall is a high-speed stall brought on by a high AoA during a &gt; 1G turn? What you describe then confirms Air_Mail's complaint that something "always" happens to yaw the aircraft into a spin, even if the aircraft is coordinated in the stall.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>If you are really quick you can get an accelerated stall to just start but then kill it by releasing the stick. . .and this is a pretty accurate mode provided that you don't let the goofy rudder response factor in.<HR></BLOCKQUOTE>

Can you clarify this? I'm not sure I understand. I've been in plenty of high-G stalls that didn't develop into spins because I released backpressure. This is actually what I was trying to describe, although I think I wasn't very clear. I am turning at well over 1G, start to buffent and even exit my trajectory. This is something like dropping a wing, only in what I guess is the "accelerated stall". I don't enter a spin, or perhaps I should say I was only in the departure stage of the spin but recovered before the incipient spin? In any case, the aircraft ends up with a different heading and descending. I really think I should prepare a track that we can analyze, or maybe I'll take you up on the comms offer and we can even meet in HL.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>I wouldnt really call it a stall. The incipient and developed phase of a spin has a roll yaw component and a desire to continue the rotation, a stall has no yaw or roll and will not lead to a rotation if the pilot isn't applying controls to induce a spin. (for the most part), the FB stall is more of a snap roll (an accelerated spin).<HR></BLOCKQUOTE>

Ah-ha on me this time. I won't change what I wrote above, but as I've written this post what I've already read becomes clearer in my mind. So the complaint really is that there is always a yaw and roll component associated with any stall? (Besides the stalled condition in which you can continue to hold the nose up.)

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>No, the MS line uses table data for the FM, it is very limited and even the best addons are still not as well done as FB, other than perhaps not leaping into a snap roll or spin isntead of stalling. . .but then, this is because the advanced physics of a snap roll eludes them, for the most part a deliberate snap roll looks very little like a snap roll!<HR></BLOCKQUOTE>

Well those are my thoughts too, but I'm not exactly the expert. There was at least one heated debate between a member of the 1% team and Oleg over at the SimHQ forums. It is still archived even if the images are missing (the SimHQ boards have been moved since). There are 6 pages but you can skip over many of the posts, might be quite an interesting read and I'd be quite interested in hearing more points of view on it! Here's the link. (http://www.simhq.com/simhq3/sims/boards/bbs/Forum82/HTML/000801-3.html)

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>I own or have access to pretty much every sim out there, for aerobatics FB is the best, bar none.<HR></BLOCKQUOTE>

http://ubbxforums.ubi.com/images/smiley/16x16_smiley-surprised.gif http://ubbxforums.ubi.com/images/smiley/16x16_smiley-surprised.gif http://ubbxforums.ubi.com/images/smiley/16x16_smiley-surprised.gif http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR><BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>"Oh, and I want carb heat and proper start-up procedures, too. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif"<HR></BLOCKQUOTE>
Why not ;-)<HR></BLOCKQUOTE>

Because we aren't gonna get it.... http://ubbxforums.ubi.com/images/smiley/16x16_smiley-sad.gif Oleg has said that he considers most people aren't interested in it. Even though we clamor for it, even the people who are capable of doing it would 99% of the time just want to jump into the plane and take off. I guess that's true, but I'd LOVE to have start-up procedures and more CEM.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>If you have any questions, I am sure I could answer them better on coms instead of trying to write it out. . .so don't hesitate to ask.<HR></BLOCKQUOTE>

How does Saturday look? I have lots of free time reserved for flying Saturday and you could show me a thing or two. I'm GMT+1 though, so that will put some restrictions on us.

C!
Mike

http://www.baseclass.modulweb.dk/69giap/fileadmin/Image_Archive/badges/69giap_badge_chap.jpg (http://giap.webhop.info)

The ongoing IL-2 User's Guide (http://people.ee.ethz.ch/~chapman/il2guide/) | Forgotten Skies (http://www.forgottenskies.com/)
But we are all that way: when we know a thing we have only scorn for other people who don't happen to know it. - Mark Twain, Personal Recollections of Joan of Arc

Air_Mail
03-25-2004, 01:22 PM
lol its pointless to try to explain to us that you are able to stall in this game without spinning. you can warp words around as much as you want but it doesnt change that fact that everytime you stall in FB you go into a spin WHICH IS NOT CORRECT.

if you dont believe me then call the local FAA office in your area and ask them what conditions are needed to enter a spin. they will tell you no matter what plane.

1. YOU HAVE TO BE IN A STALL.
2. YOU HAVE TO YAW THE PLANE.

some of you are confused about what a stall is and you think that an ACCELERATED stall will lead to a spin but it does not. if you do an accelerated coordinated stall (no yaw) the plane will nose down until it regains lift and it will not bank at all.

i wish i could take all you non-believers up in a Citabria to show you the difference between stall entry and recovery and spin entry.

YOU CAN NOT STALL A PLANE IN THIS GAME WITHOUT SPINNING.

and it is not a factor of torque either because you can shut the engine off in the game and the same thing will happen. try it at idle power also....same result.

http://www.onpoi.net/ah/pics/users/ah_131_1074072105.jpg

BTZ_Bonehead
03-25-2004, 01:30 PM
Im sure your right that you cant stall these aircraft I havent tried, but I have flown a couple of warbirds and on many of the old piston powered jobbies (Harvard for example) they have more washout on one wing than the other which very often results in serious wing drop at the stall.
I know its not a spin, but it can seem like it, especially if the unwary pilot were to try and pick the wing up with ailerons which will only make things worse http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Many of the people who have mentioned what happens in real aircraft here are talking about spam cans (cessnas etc) and the Decathlon are designed to be user friendly, it is a requirement that a training aircraft be docile even at the stall. Modern aerobatic aircraft, and I suppose I could include the Decathlon in this too would be of no use if it had a tendancy to drop a wing at the stall if the slip ball is being kept in the middle using rudder. THe aircraft needs to go where its pilot wants it to go not where it feels like it, what use would a competition aircraft be if you could not decide which way you wanted to enter a spin?

Older aircraft and especialy fighters didnt have to be so kind.

However, a wing drop is not a spin, but it will be if its mishandled.

One other point, if you fly most aircraft in a balanced turn and then snap the stick back to make it stall 90% of the time the aircraft will roll in the opposite direction of the turn. Sometimes entering autorotaion.

I have just tried flying the spitfire in AEP and it does seem to fall one way or the other it doesnt seem possible to fly the aircraft in such a way that it will stall with a clasic nose drop. I would guess that trying model aerodynamics into a game that can account for all the forces acting on the aircraft is either too difficult or time consuming. It would be easier to make it do the same thing if the angle of attack is above a certain point each time than model each aircraft individualy taking account of wing loading, slight yaw and all other factors. Anyway a spin looks better than a straigt forward mush or hammer head http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

[This message was edited by BTZ_Bonehead on Thu March 25 2004 at 01:12 PM.]

BaldieJr
03-25-2004, 01:47 PM
I'm sorry, but I can't stand it any longer and simply must say something about BTZ_Boneheads sig.

WTF IS WRONG WITH YOU!?!? Why is there an ugly man wearing a bra in your sig?

Every time I see that guy my stomach turns.

<pre class="ip-ubbcode-code-pre">
______ _____
(, / ) /) /) , (, /
/---( _ // _(/ _ / __ ,""""]
+----/ ____)(_(_(/_(_(__(__(/____/__/ (__--------,' /---+
| / ( / ,' NR / |
|(_/ ..-""``"'-._ (_/ __,' 42 _/ |
+-.-"" "-..,____________/7,.--"" __]-----+

</pre>

BTZ_Bonehead
03-25-2004, 02:10 PM
Its there just to annoy you!

You obviously have experience of men wearing bras? Its a woman! Just cos shes got more muscles in her arms than you you feel threatned http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif Ill try and find a better pic.

In fact here is one: http://www.battle-fields.com/downloads/bobi/2.jpg

Does she still look like a bloke?


Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

[This message was edited by BTZ_Bonehead on Thu March 25 2004 at 01:22 PM.]

BaldieJr
03-25-2004, 02:14 PM
and a damned fine job it does!

YELCH!!!!11

<pre class="ip-ubbcode-code-pre">
______ _____
(, / ) /) /) , (, /
/---( _ // _(/ _ / __ ,""""]
+----/ ____)(_(_(/_(_(__(__(/____/__/ (__--------,' /---+
| / ( / ,' NR / |
|(_/ ..-""``"'-._ (_/ __,' 42 _/ |
+-.-"" "-..,____________/7,.--"" __]-----+

</pre>

BTZ_Bonehead
03-25-2004, 02:57 PM
I have just tried the HE111, it does stall but once again with a wing drop, it certainly isnt a spin unless you keep the stick back.

No matter what I do I cant stop it dropping a wing though.

Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

Jetbuff
03-25-2004, 04:39 PM
You CAN stall without a spin - not even a wing-drop. Try this, load up an IL-2-3M with 6x100FAB bombs. Now in-game, fly it with a lot of tail-heavy trim so that it climbs at a steep angle until it stalls out. If you don't touch the stick there's a 50/50 chance that it will drop the nose and not a wing.

This leads me to believe that the problem lies in the inadequacy of feedback and imprecision of our joysticks. We can't really stay there on the razor's edge without falling off to one side or the other because our inputs are not precise enough to keep us totally wings level.

That said, I have no idea whether inducing a standard stall in a real WWII warplane requires that much precision. I'm only noting that it is indeed modelled, albeit very hard to reproduce.

BTW, another wings level type stall can be induced at the bottom of a loop on most aircraft in FB.

http://members.rogers.com/teemaz/sig.jpg

ZG77_Nagual
03-25-2004, 05:06 PM
this may be one of the only problems with the P38 flight model.

TX-EcoDragon
03-25-2004, 06:53 PM
I have time in the PT-17, T-6, and TF-51 (P-51D with two place cockpit and dual controls) They like every other plane I have flow flew like airplanes, they have their unique traits, and of course that big prop on the 51 offers loads of torque, but in the end, fast footwork will keep things from pivoting just like it always does. An abrupt power change at the stall in the 51 will however provide enough torque to get her rolling, but the sensation is much like that of a torqued hammerhead, just ease off the power and all is well. That is one reason why many Unlimited level aerobatics aircraft have composite props.

michapma wrote:
"quote:
--------------------------------------------------------------------------------

"What's a stall?
http://www.av8n.com/how/img48/power-aoa.png
At the critical AoA, the coefficient of lift begins to reduce, but nothing special happens. The further you go past that angle though, the deeper the stall develops. So it seems to me that you can be in that mushy region where lift is decreasing and drag increasing, but you are not in a spin. So when a wing drops, is that a stall or a spin?"

That is a stall (with delayed rudder response)without proper rudder use to correct this drop, rotation will commence and you will then have a spin.
--------------------------------------------------------------------------------

Ah-ha! So you can stall. "

Not the way it happens in FB, IMHO. Lets get on comms.

"I have done something similar in IL-2 with the P-39. I held the aircraft in an extreme nose-up situation with lots of buffeting but in level flight. The buffeting indicates that the wings are in a stalled condition but still providing enough lift to maintain the airplane. It did not, however, require any rudder input. What with the small amount of adverse torque and all... I haven't tried it in FB. I did have to watch the stick pressure carefully and noticed that if I pushed it too far the result was that a wing would drop, although the nose did always want to drop dramatically if I relaxed stick pressure a little. It is important to realize that, as you say, even in a deeply stalled condition the wing is producing lift. And not just a small amount. If there were no lift, the airplane would continually accelerate downward, instead of just having a downward velocity."
The buffetting often occurs just before the stall, in the sim, the buffeting also occurs before a stall. What you descibe is nota stall, but simply flight just above the 1G stall speed.

"This is the cause of the stall. The graph above that I linked from Denker's site shows what happens in terms of the AoA. I won't comment on the fluid dynamics involved in the forces on the wing since I'm not qualified, but the turbulence introduced is what causes the change in the lift versus drag. Lift and drag are summed up by the coefficient of lift. At the critical angle, you can see in the graph that the lift starts to drop off. Get much past the critical angle (a greater angle, to the right on the graph) and it starts dropping off rapidly, and as a result so does the rate of climb. So it makes sense that you can actually fly in that stalled regime as you've said. Your nose might not even drop and you can fly straight on, perhaps also descending. I believe you can do this in FB as well as IL-2, as I've implied above."

The example you gave sounded like minimum controllable airspeed flight and not a stall. Keep in mind that a rapid descent rate will occur in most aircraft (though you can often hold a nose up attitude) other than the few aerobatic aircraft that are powerful enough and light enough to maintain alt. Warbirds do not fall into this category.

I will try this IL-2 example as posted above, overall though, the FB stalls are better called either snaps or spins in almost every instance and rudder inputs do not oppose the yaw sufficiently.


For those who want to see what the problem is, slow the plane down, power at idle, keep the ailerons neutral, maintain altitude until the stick hits the stop or the plane "stalls" once it does hold the elevator there, and then keep the plane from rolling with rudder, or more simply just keep it from spinning by giving it opposite rudder to whatever yaw it has.

Can you?

Despite this point, I still do not think that this detracts significantly from the sim, because the accelerated stalls are the ones we will typically encounter, and for the most part those in the sim behave like you might expect (though the planes usually roll a bit mroe than real aircraft do before recovery).

S!
TX-EcoDragon
Black 1
TX Squadron XO
http://www.txsquadron.com

Member-Team Raven
http://www.waynehandley.com

First Slot Pilot Aircraft #4 of the Virtual Haute-Voltige Team
http://www.vhvt.com/

http://www.attitudeaviation.com/

http://www.calaggieflyers.com

http://www.txsquadron.com/uploaded/TX-EcoDragon/ravenvert.jpg

JG27_BLACKHART
03-25-2004, 07:28 PM
The thing I hate most about FB is the fact that you can't produce a decent hammer head stall. The nose either tips forward and you have to turn out of it than rudder or yaw out of it and the nose never ever completely goes solidly to the ground with out haveing to force it ... Gravity should occur right after complete verticle stall right?

http://home.earthlink.net/~eaglz/sitebuildercontent/sitebuilderpictures/bh.jpg

AB_Mormac
03-25-2004, 07:34 PM
Look at the bright side it is a good way to practice spin recovery.{sort of}

TX-EcoDragon
03-25-2004, 11:43 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG27_BLACKHART:
The thing I hate most about FB is the fact that you can't produce a decent hammer head stall. The nose either tips forward and you have to turn out of it than rudder or yaw out of it and the nose never ever completely goes solidly to the ground with out haveing to force it ... Gravity should occur right after complete verticle stall right?

http://home.earthlink.net/~eaglz/sitebuildercontent/sitebuilderpictures/bh.jpg <HR></BLOCKQUOTE>

Yes, the pivot is not crisp in the sim, the plane seems to fly through the pivot so getting a crisp one is tough, and because the rudder isnt as effective with only propwash as it is in real aircraft especially the large rudders on aerobatic planes, you cant use just the propwash alone to picot, you must have a great speed at the rudder kick.

Also because the aircraft flies through the pivot the rotaion is damped, in real aircraft I must give lots of opposite rudder against the direction of the pivot to stop the rotation perfectly nose down, in FB you have to hold rudder in to keep the nose heading down. . . this changes between patches though, back in 1.04b the hammerhead and tailslides were great, the best I have seen in a sim, it seemed that there was even control reversal when going backwards!

S!
TX-EcoDragon
Black 1
TX Squadron XO
http://www.txsquadron.com

Member-Team Raven
http://www.waynehandley.com

First Slot Pilot Aircraft #4 of the Virtual Haute-Voltige Team
http://www.vhvt.com/

http://www.attitudeaviation.com/

http://www.calaggieflyers.com

http://www.txsquadron.com/uploaded/TX-EcoDragon/ravenvert.jpg

karost
03-26-2004, 01:14 AM
Wow .....
Hi , Air_Mail and friends


I'm not a real-pilot but like to read alot of good thing from a real-pilots.
and if they agree at the same way , then we will know , who are wrong....

Thanks, Air_Mail..... you not give up to tell us what the true is....

S!

BTZ_Bonehead
03-26-2004, 01:23 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> "What's a stall?
http://www.av8n.com/how/img48/power-aoa.png
At the critical AoA, the coefficient of lift begins to reduce, but nothing special happens. The further you go past that angle though, the deeper the stall develops. So it seems to me that you can be in that mushy region where lift is decreasing and drag increasing, but you are not in a spin. So when a wing drops, is that a stall or a spin?"
<HR></BLOCKQUOTE>

One other very important thing happens and it is the thing that defines the stall, the centre of pressure on the wing moves rapidly backwards giving the characteristic (sp cx http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif) nose drop.

Stick shake, buffet, low airspeed, high nose attitude and less wind noise around the aircraft are all signs of the approaching stall, it doesnt mean the aircraft is stalled, it means its about to. The aircraft is stalled when you get symptoms of the stall, which are nose and or wing drop.

FB seems to model the wing drop fine, it just doesnt seem to do the nose drop without a wing drop as well. However, its a fighter sim, and you shouldnt be flying that slow http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

'Bobi@ isnt a bloke http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif http://www.battle-fields.com/downloads/bobi/2.jpg

BTZ_Bonehead
03-26-2004, 02:07 AM
If its a spin the "wind noise" inside the cockpit increases (especially if its an inadvertant spin near the ground!) followed by "seat cushion nibbleing" http://ubbxforums.ubi.com/images/smiley/16x16_smiley-surprised.gif http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

'Bobi@ isnt a bloke http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif http://www.battle-fields.com/downloads/bobi/2.jpg

lindyman
03-26-2004, 06:08 AM
One thing just occurred to me about this, that I have not seen mentioned in any discussion yet.

The stall always develops from the back end of the wing, where the airflow first becomes turbulent. As the AoA increases, the turbulence zone moves further forward. This both decreases lift and moves center of lift forwards. The latter effect is the reason why it is so important to have the CoG a fair amount in front of CoL, since otherwise your plane may become aerodynamically unstable when stalled.

This effect of CoL moving forwards is what made me curious, since this move should give a greater torque to *LIFT* the nose, not the other way. Now, of course, anyone who has piloted a plane through a stall knows that this is not what happens (at least not in any plane that I've ever heard of.) So, why are the planes dipping the nose?

What hasn't been discussed, however, is what happens to the tail, or more precisely the horisontal stab. If the H-stab is tuned to the wing, so that it too begins to stall at roughly the same time as the wing does, then it will not be able to push the tail down, and the nose will drop.

Can it be that stab stall is not modeled, and that is why the planes behave oddly?

BTW, I disagree that you need yaw to spin. You need assymetry in lift and drag when stalling. Yaw is one way to achieve this assymetry, but it's not the only one. The assymetric airflow from the prop is another.
_
/Bjorn.

michapma
03-26-2004, 06:36 AM
Hi Air_Mail,

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Air_Mail:
lol its pointless to try to explain to us that you are able to stall in this game without spinning. you can warp words around as much as you want but it doesnt change that fact that everytime you stall in FB you go into a spin WHICH IS NOT CORRECT.
<HR></BLOCKQUOTE>

I've already said that I'm not a pilot, and that I am just trying to develop my understanding of what is deficient in FB, because I have no experience with which to compare it. When I "explain" something here, please take it as me offering my understanding, not so that everyone else will be enlightened, but so that my perception can explicitly be corrected by those who really do know what they're talking about, including yourself. If I question something you've said, it's not because I am out to prove you wrong and show how great FB is. It's that I'm trying to understand more precisely exactly what the problem is.

To repeat myself a bit, I don't have first-hand experience, so I am asking those who do about what is up in FB. Reading back over my message, I can see how it can be perceived that I am trying to say you are wrong. Now that I've said I'm not, let me try to restate my questions. When you see mistakes in my understanding, please laugh at me but also correct the misunderstanding in detail. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif


If I may quote myself:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by michapma:
Right, well Air_Mail's claim was that you can't stall:

....

So his complaint seems to be that there is something in the modeling of forces affecting the yaw axis that cause the aircraft to always go into a spin after the onset of a stall. I'd be interested to see a track of some of his tests. Because it's not that I doubt his expertise or want to play down his complaints, it's just that I want to learn more about precisely what is lacking and how it should be. I don't have anything else to compare it to.
<HR></BLOCKQUOTE>

This statement takes for granted what is clear about entering a spin, which is something we all agree on:

1. YOU HAVE TO BE IN A STALL.
2. YOU HAVE TO YAW THE PLANE.

What I understand you as saying is that in FB, whenever there is a stall condition it inevitably leads to a spin. Since the plane has to be yawed in order to enter a spin, I assume that there is something in the modeling of FB that always causes that yaw to be present when the plane stalls. Hence my words, "his complaint seems to be that there is something in the modeling of forces affecting the yaw axis that cause the aircraft to always go into a spin after the onset of a stall." It could simply be that the amount of yaw required to enter a spin is so small that it's essentially always present. Actually, an alternative explanation would be that the onset of the spin is not modeled correctly in FB, so that in FB no yaw is required for the spin, just the stall condition. What is your idea of what might cause the spin to always follow a stall in FB?


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>some of you are confused about what a stall is and you think that an ACCELERATED stall will lead to a spin but it does not. if you do an accelerated coordinated stall (no yaw) the plane will nose down until it regains lift and it will not bank at all.<HR></BLOCKQUOTE>

I think part of my confusion about stalls has been the difference between parts of the wing being in the stalled regime and what is called the actual stall itself. As I now understand it, when the AoA goes past the critical angle and the coefficient of lift has been reduced, the controls get mushy, there is buffeting and so forth, no actual stall has yet occured. I was thinking that this was part of the stall, sort of like an early stage of the stall before nose drop or wing drop occurs (or should occur). I was calling this the "stalled regime". Bonehead wrote, "The aircraft is stalled when you get symptoms of the stall, which are nose and or wing drop." So if what Bonehead writes is correct, this is one point that had to be cleared in my head.

In trying to consider what in FB might be a stall, I thought of the wing dropping. This is clearly not a spin, and is often not followed by a spin in FB. So I considered it to be a stall. But it seems not to be, and there remains for me the question of how to understand what it is. Among all the rest you can pick out this exchange between TX-EcoDragon and me:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Me: So when a wing drops, is that a stall or a spin?

TX-EcoDragon: That is a stall (with delayed rudder response)without proper rudder use to correct this drop, rotation will commence and you will then have a spin.

Me: Ah-ha! So you can stall.

TX-EcoDragon: Not the way it happens in FB, IMHO. Lets get on comms.<HR></BLOCKQUOTE>

TX-EcoDragon also wrote, "I will try this IL-2 example as posted above, overall though, the FB stalls are better called either snaps or spins in almost every instance and rudder inputs do not oppose the yaw sufficiently."

If I have understood correctly, FB recognizes under what condition a wing stalls. The problem comes with what happens to the aircraft when that condition is met. Either a wing drops (a snap), or a spin is entered (either because it only needs a tiny amount of yaw to spin or because the requirements of spinning are not modeled correctly in FB). What [I]should happen, in Bonehead's words, is that "the centre of pressure on the wing moves rapidly backwards giving the characteristic [spelled correctly!] nose drop." It is this that seems to be missing from FB. Since we don't know exactly how FB is modeled, I will risk offering my best guess. I figure that the stall is too computationally intensive and also too much work to model in detail for each wing type. Possibly Oleg was satisfied to have just the wing drop/snap and the spins since he found a way to model these fairly well, and as a good engineer made a compromise between the resources available (CPU speeds and overall task loading) and the goal of the calculations.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>i wish i could take all you non-believers up in a Citabria to show you the difference between stall entry and recovery and spin entry. <HR></BLOCKQUOTE>

That would be fun! But we'd have to leave my wife on the ground, she can't handle pulling G's too well, and I'm sure we'd want to do some more interesting maneuvers as well. Actually I probably wouldn't handle the G's so well either... but I'm not a non-believer, honest. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>YOU CAN NOT STALL A PLANE IN THIS GAME WITHOUT SPINNING.<HR></BLOCKQUOTE>

Now I want to call you on this. We've noted at least one exception, that of the wing drop. Probably you mean you cannot stall and have the nose drop, but that a spin results instead?

There seems to be another exception, the IL-2. This makes sense because it was originally the only aircraft planned to be flyable, so its flight model might remain somewhat unique. Indeed it seems nigh impossible to spin.

I also hope you will explain a bit more about this (yes I've already quoted it):

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>some of you are confused about what a stall is and you think that an ACCELERATED stall will lead to a spin but it does not. if you do an accelerated coordinated stall (no yaw) the plane will nose down until it regains lift and it will not bank at all.<HR></BLOCKQUOTE>

Would somebody please clearly explain what an accelerated stall is. I guessed that they are high-airspeed stalls (in a turn) where the elevator authority forces the wings above the critical AoA. I'm asking: is that correct? If so, then what you say makes sense to me that if the turn is coordinated, the behavior should be just the same as in a 1G stall. The plane won't enter a spin mode without yaw.


I'm really learning here! http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

http://www.baseclass.modulweb.dk/69giap/fileadmin/Image_Archive/badges/69giap_badge_chap.jpg (http://giap.webhop.info)

The ongoing IL-2 User's Guide (http://people.ee.ethz.ch/~chapman/il2guide/) | Forgotten Skies (http://www.forgottenskies.com/)
But we are all that way: when we know a thing we have only scorn for other people who don't happen to know it. - Mark Twain, Personal Recollections of Joan of Arc

michapma
03-26-2004, 07:23 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by lindyman:
Can it be that stab stall is not modeled, and that is why the planes behave oddly?

BTW, I disagree that you need yaw to spin. You need assymetry in lift and drag when stalling. Yaw is one way to achieve this assymetry, but it's not the only one. The assymetric airflow from the prop is another.<HR></BLOCKQUOTE>

On the first question, it could be. However, if as I guess in my last post the calculations of stalling are simplified, it would help explain why the nose does not drop. For example, if the calculations do not involve the placment of the stall on the wing and thus the COL does not change in the stall. We don't know whether sections of the airfoil stalling is modeled, although from the variations you can obtain in spin recovery it does seem that there's some interesting modeling going on.

Concerning the requirement of yaw for a spin: I believe you are wrong, you do need yaw to enter the spin. Look back at the parts I quoted from Denker, cases 1-3 and the rest. Here's the link again. (http://www.av8n.com/how/htm/spins.html#sec-spin-types)

Assymetry in lift between the wings will cause a rolling motion. At the critical angle of attack, the roll damping goes away, and the assymetry of lift will cause the wings to "depart", or snap, as in a snap roll. "The resulting undamped rolling motion is called autorotation."

But what about drag, what will assymetry of drag do? Drag is a force, and a force is a vector. In what direction is the drag force applied? In the direction of the relative wind, more or less. If the plane is flying essentially forward, an assymetry of drag will the result in... yaw. This is just my own analysis, so yeah I could be wrong.

http://www.baseclass.modulweb.dk/69giap/fileadmin/Image_Archive/badges/69giap_badge_chap.jpg (http://giap.webhop.info)

The ongoing IL-2 User's Guide (http://people.ee.ethz.ch/~chapman/il2guide/) | Forgotten Skies (http://www.forgottenskies.com/)
But we are all that way: when we know a thing we have only scorn for other people who don't happen to know it. - Mark Twain, Personal Recollections of Joan of Arc

CO_Eagle_31stFG
03-26-2004, 07:31 AM
Well I hate to differ with the opinions but I have in fact stalled a P40 in this game while doing flights on our demo team. I have done the hammerhead stall many times and it did not result in a spin of any kind. The plane did exactly what it was suppose to do in this situation.

If you cant do the hammerhead stall as its suppose to be done then perhaps you are doing somthing wrong or you have your game set to the easy settings.
Go Hard settings http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

lindyman
03-26-2004, 08:46 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by michapma:
Concerning the requirement of yaw for a spin: I believe you are wrong, you _do_ need yaw to enter the spin. Look back at the parts I quoted from Denker, cases 1-3 and the rest. http://www.av8n.com/how/htm/spins.html#sec-spin-types
<HR></BLOCKQUOTE>

Try a perfectly coordinated descending turn. The inner wing travels slower and with higher AoA than the outer wing. You can demonstrate this by bringing a board to a spiral stair case, stand above it, looking down, and put the board flat on the railing. Because of this, the inner wing will also have more drag, causing the plane to want to auto-rotate inwards, and less lift, causing the plane to want to drop the inner wing. Continue to pull the elevator until you can no longer stabilise the flight. You enter a spin, while being perfectly coordinated.
_
/Bjorn.

michapma
03-26-2004, 09:46 AM
That's a rather interesting thought exercise! I had to read, think, re-read, realize what you were actually saying, re-read, think some more... http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

But I finally understand it to a certain point. In the spin itself, the wings will have similarly but more exaggerated dissimilar angles of attack. Which way the angles are depends on the type of spin.

Are you sure that the spin is what would result, and not a snap? I'll want to think some more about this, although I doubt I'll come up with any answers without reading it somewhere. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif

http://www.baseclass.modulweb.dk/69giap/fileadmin/Image_Archive/badges/69giap_badge_chap.jpg (http://giap.webhop.info)

The ongoing IL-2 User's Guide (http://people.ee.ethz.ch/~chapman/il2guide/) | Forgotten Skies (http://www.forgottenskies.com/)
But we are all that way: when we know a thing we have only scorn for other people who don't happen to know it. - Mark Twain, Personal Recollections of Joan of Arc

effte
03-26-2004, 09:47 AM
Bj¶rn,
the CoL of the wing will move forward. However, the wing also rapidly loses total lift while the stab does not, moving the total CoL rapidly backwards. Thus the nose drops.

Cheers,
Fred

Air_Mail
03-26-2004, 10:02 AM
a bank to the left doesnt mean that you are going to spin to the left. in fact, i teach my stundents how to do cross control stalls and even spins. if you set up in a left bank, hold the nose level, and hold right rudder pressure, the plane will go from a left 30 degree bank into a right spin. so to make it clear again......yes you do have to be yawed to enter a spin. it doesnt have to be as a result of rudder deflection but a plane will not spin if it is coordinated. that might be a case of confusing spins with deep spirals.

like you guys are saying......you can have a wing drop and it is not a spin. but it is the entry to the spin. you have to catch the wing drop with imediate opposite rudder pressure to prevent the spin as a result of the yawing force being created by the lower wing.

here is a direct quote from the William Kershner who is a aerodynamic god. "If the nose is allowed to yaw during the stall, the plane will begin to slip in the direction of the lowered wing, and will enter a spin. An airplane must be stalled to enter a spin".

http://www.onpoi.net/ah/pics/users/ah_131_1074072105.jpg

BTZ_Bonehead
03-26-2004, 10:08 AM
Wow! this is getting interesting, or am I just sad http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

I can remember who said something about the horizontal stab stalling but just a point of note:

On every aircraft I have heard of the stab has a lower angle of attack (perhaps negative AoA) to provide a downforce which is what keeps the nose up in level flight. For this reason the wing will always stall before the stab. If it didnt the aircraft would be unstable and unrecoverable in a stall situation. So basically the stab does create lift but in a negative sense.

Regarding accelarated stalls:

The stalling speed of an aircraft is not fixed. It alters based on several factors. Reduce the throttle in level flight and try to maintain height and our theoretical aircraft stalls at say 80 knotts (KPH, potatoes it doesnt matter) Increase the weight of the aircraft and it will stall at a higher speed. One way to increase the weight of an aircraft is to increase the G acting on it.

Tight turns hard pulls will do this and all of a sudden an aircraft that stalled at 80 kts before will now stall at say 90kts, and it will be a lot more exciting http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

There is a formula to work this out (cosine is involved in it somewhere) and I'm sure someone will come up with it in here but its irrelevant really, it just does.

Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

'Bobi@ isnt a bloke http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif http://www.battle-fields.com/downloads/bobi/2.jpg

TX-EcoDragon
03-26-2004, 11:47 AM
Lots of info in this thread! A couple things pop out in my mind before I'm off for the day:
It is true that there are shifts in the the center of lift of the wing, however most designs still retain a center of lift aft of the CG, the tail may be blanketed by the sheilding effects of the main wing (especially if flaps are extended), and oscillations may occur because of this, also in spins the tail may also be blanketed by disturbed air. . .yet the nose drops, in some aircraft the tail cant stall before the wing, in some it does, in both cases, the nose drops (AoA decreases), or at least "wants" to drop (for different reasons). In short, while the center of lift may shift, it does not shift so far forward as to become equal to the CG, it is probably easier to think of a flying wing (no tail to add in any other effects), and the dynamic is much the same (though they arent extremely stable, and have far less tendency to weathervane). This is a very interesting point though, and one that will vary between aircraft designs and loading. Of course if your CG is too far back you can get the CL in front of the GC and this is of course a very bad thing.


Someone mentioned asymmetric lift leading to spins. I simply can't agree from a practical perspective. This would suggest that a stall or accelerated stall while turning or rolling would lead to spin initiation without recovery, which is not the case. It still comes down to yaw, you can be in a level 60 degree left turn and spin either way. The deciding factor is, you guessed it. . . yaw! The theory may be reasonable, but there are more aerodynamic stability and damping factors that come into play, in all cases I know of it doesn't happen in this way. As I said before (I think) if you stall and are coordinated, and then abruptly add power in something like a metal bladed P-51 you will get a significant roll and yaw momment, but even then the aircraft doesnt really want to spin even if your feet are on the floor, it wants to roll. In the P-51 it does like to roll though, even to inverted, there is some yaw, but the entry is not much like an incipient spin phase in my judgement. If you stall the wing, and the ball isn't deflected or deflecting, your not going to spin in any reasonable case I can think of or have flown through. Even if it is due to asymmetric thrust from a dead engine in a twin, the first response is going to be to get rudder in to stop the yaw, and this is the only thing (other than a reduction in the critical angle of attack)that is going to prevent a spin while near the critical angle of attack.

All these musings aside, that point brings up an interesting suggestion that might be useful in the FM if someone did opt to make a change, namely that the elevator loses effectivness before the main wing, then, if nothing else the 1G stall behavior might seem more accurate at the 1G stall, though this would throw some other significant problems into the mix and hurt the accelerated stall, and the aerobatic capability of the sim, and would do nothing to change the impact yaw has on the virtual aircraft's behaviour. (this is just what Burt Rutan did with the Var-Eze/Long-Ez aircraft)
I think this could be one of those times where we have it pretty good now, in regard to the flight envelopes that WWII combat aircraft actually saw, or should see, and tampering might lead to an alternative that would be worse. ;-)

The only other thing that keeps poping in my head, and also explains why it is so difficult to describe whay some think there is "no stall" and others do, is the way that we are trying to define the stall. I can't say a wing drop or a nose drop, because in the real world you can stall and keep either of these from happening, in the end the thing that defines the stall is the loss of smooth airflow over the top surface of the wing, and a subsequent increase in pressue over the wing back to ambient, this leaves gravity, thrust, and newtonian lift (due to the physical impact of airflow against the bottom surface of the wing, much like you might have sticking your hand or a sheet of plywood out of a car window, and this is not much lift, if it was you would see planes with flat wings, RC planes can do this with extreme angle of attack and huge power to weight ratios, but full scale highly modified aircraft, if capable at all, can only do this to a very limited extent, and with an exceptional pilot at the controls).

In the end it simply is that the aircraft response to the stall is as if the rudder is fully deflected one way or the other, and that opposite rudder is more or less inneffective to prevent a wing drop and spin entry.

copy and paste this to your browser (the first one needs this), this will demonstrate the type of flight that can, with TONS of power in a LIGHT airplane, happen due only to newtonian lift and thrust. This will also demonstrate that a stall can be stable and not spin if rudder is used to prevent yaw, yet rolling moments and asymmetric lift do not lead to spins.

http://www.rcsites.net/kyle300s/kyle%20hey%20ya.wmv

http://www.3dbatix.com/videos/nolimit.wmv

and this thing, no airfoil here! Its all newton, (though Bernoulli gets some action on the prop!)

http://www.3dbatix.com/videos/vtolxwing.wmv

S!
TX-EcoDragon
Black 1
TX Squadron XO
http://www.txsquadron.com

Member-Team Raven
http://www.waynehandley.com

First Slot Pilot Aircraft #4 of the Virtual Haute-Voltige Team
http://www.vhvt.com/

http://www.attitudeaviation.com/

http://www.calaggieflyers.com

http://www.txsquadron.com/uploaded/TX-EcoDragon/ravenvert.jpg

[This message was edited by TX-EcoDragon on Fri March 26 2004 at 11:01 AM.]

Two_Hawks
03-26-2004, 12:24 PM
Very informative post. I just happen to have been reading a book on FW190 before seeing this post.

it stated..."let the speed fall below 127mph and, virtually without warning, the port wing, would drop so violently that the the FW190 all but turned on its back. Pull into a G-stall in a tight turn and it would flick over into opposite bank and you had an incipient spin on your hands."

maybe some planes can spin as they are stalling??

FW190.........
"As soon as the engine faltered, the nose pointed earthwards, followed by the rest of the airframe in close formation."
FW190s were know to fall like a brick once the prop stopped spinning, yet in FB ive glided it down. And some real life pilots stated they could glide a no-power FW190 safely down to earth.

Physicists, mathematicians, computers...etc. say that a bumblebee cant fly......yet it does. Is the bumblebee over-moldeled?????

[This message was edited by Two_Hawks on Fri March 26 2004 at 11:58 AM.]

effte
03-26-2004, 01:57 PM
They figured out what keeps the bumblebee aloft years ago... the bastards! Ruining a good joke like that... hmmpf!

And all lift is always newtonian... even though bernoulli's principle is valid. Sorry, was that your can of worms I just opened? http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Cheers,
Fred

Two_Hawks
03-26-2004, 02:18 PM
[QUOTE]Originally posted by effte:
They figured out what keeps the bumblebee aloft years ago... the bastards! Ruining a good joke like that... hmmpf![QUOTE]

Does the bumblebee fly better now? http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif

TX-EcoDragon
03-26-2004, 03:34 PM
I wouldnt call it a can of worms, because I don't need to choose one theory over the other like many feel compelled to, there are still ongoing debates regarding bernoulli vs newton, while it seems obvious that both participate. I have no problem with that. I wouldnt say that lift can be described in either category exclusively, but when we are talking reduction in pressure and venturi effect vs impact. . . well . . . for simplicities sake I don't intend to break it down any further than I have already, but there is penty of literature out there for anyone who wants to participate in that debate.

S!
TX-EcoDragon
Black 1
TX Squadron XO
http://www.txsquadron.com

Member-Team Raven
http://www.waynehandley.com

First Slot Pilot Aircraft #4 of the Virtual Haute-Voltige Team
http://www.vhvt.com/

http://www.attitudeaviation.com/

http://www.calaggieflyers.com

http://www.txsquadron.com/uploaded/TX-EcoDragon/ravenvert.jpg

BTZ_Bonehead
03-26-2004, 04:20 PM
Eco Dragon, you said "namely that the elevator loses effectivness before the main wing"

What do you mean by effectiveness? If the eleavtor lost the ability to pitch the nose of the aircraft you would end up in an unstable situation where it would no longer be possible to lower the nose (forgetting power for now ) to recover from a stall, surely?

Like for example having an extreme rear CofG and then stalling.

Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

'Bobi@ isnt a bloke http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif http://www.battle-fields.com/downloads/bobi/2.jpg

ZG77_Lignite
03-26-2004, 05:53 PM
I feel embarrassed to even poke my head in here due to the high level of discourse, which is all very interesting to by the way, but I've got two minor points:

Though I'm not sure of exact testing procedures (made worse by the lack of a cockpit) I find the Fi-156 Storch in FB to stall without any sort of wing drop, just a nose drop until speed/authority has returned.

Also, unless I'm mistaken I believe Oleg has said that engine-off flight regimes are not/can not be modeled with as high fidelity as engine-on flight regimes. This is simply a programming compromise/limitation in FB. Unsure where this was seen (possibly Il-2 days though I thought it was in conjunction with He-111 debates) but it is in my memory.

Jezzadog
03-26-2004, 06:20 PM
"This is simply a programming compromise/limitation in FB"

Sums it up very nicely, thank you!

"A true combat pilot can throw his aircraft at the ground - and miss"

E_Temperament
03-26-2004, 07:23 PM
I just tested the Bf109G-6/AS with dead engine, with 20% throttle and 40% throttle respectively and the outcome is similar. Applying elevator very smoothly and carefully I can keep the plane in a wings level, nose high, ROD without either wing wanting to drop and there is also quite a lot of buffeting. Handle the elevator more aggressively and usually the right wing will drop then the nose drops, handle it very aggresively and the right wing drops quickly with the nose dropping also. Very simple to recover just apply forward elevator and a little opposite rudder. Looks to me to be a standard stall and to enter a spin from this state you would have to be using too much elevator while trying to recover.

olaleier
03-26-2004, 07:41 PM
What a great thread! I don't stick my head in here much these days, but aerodynamics beats .50 cal dispersal any day! http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif


One of the first things that struck me with the IL-2 demo was the lovely spin characteristics....I could enter and recover just like I've read about. (cause reading about it is the only thing I've done http://ubbxforums.ubi.com/infopop/emoticons/icon_razz.gif )

I learnt a thing or two reading this I can tell you...

I watched some WW2 pilot instruction videos...the Corsair is described as having a very heavy wing drop tendency in a level stall, while the P-39 does not. Check them out:
http://www.zenoswarbirdvideos.com/main.html

I play Lock On: Modern Air Combat alot, and in my own uneducated armchair opinion, it has some terrific flight models and stall characteristics.

In the F-15C, you can peg the AoA limiter at slow speed (you get a nice rushing air sound) and mush through the air like a wooden spoon in a porridge pan, but if you give aileron to one side, the wing will continue to drop and the plane will start yawing.
This first seemed to me to be a spin evolving, but when I think about it, it could also just be a yaw induced by the low wing. (make sense?)

Adverse yaw is not modelled in normal flight, but most modern jet have yaw dampers. (although you can't see any rudder movement on the 3D model, this might be a case of "one minus one equals zero need for modelling", which makes sense, sim-/money-/time-wise.)

Now, once the wing has started dropping, and one already is at low speed and very high AoA, ailerons are pretty useless. You have to step on the ball, but if you counter too much, the wing drops to the other side. I've done this several times, fooling around over some airfield (very fun!) usually at low altitude.

Panic sets in, 200 feet, mushy mushy max AoA, full burners and dancing along, balancing on the rudder. At some point one regains control (usually with loads of forward stick) and can breathe a sigh of relief, before trying some other crazy stuff. http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Does this make any sense as far as "the real deal" is considered?

There are two "scripted" aerodynamical events in Lock On, the Cobra and the tailslide.

When you execute the cobra (below a certain speed), the nose will pitch up very fast, max out at 100-110 deg AoA, before returning to level, slight decent.

In the tailslide, you point the nose 70 deg up, throttle to idle and come to a vertical stop, sliding forward. This is where the "script" kicks in, yawing the plane to the right. This happens in the real Su-27 too, because of the gyroscopic effect from the turbines, both spin in the same direction.

You can counteract the yaw by using assymmetric thrust (rudders are ineffective), although the key combo can be hard to find in the heat of the moment. http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

This is done by simple parameter-matching (I think) and the result is impressive. You can read an interview with some famous Russian aerobatic ace, and then open the game and do it yourself.

==================================
http://img2.photobucket.com/albums/v30/olaleier/cobrasig.jpg
==================================
Marvin in hyperlobby

BuzzardHead
03-26-2004, 09:31 PM
Amen!I thought I was playing CFS3 or someone had changed my stick settings.
Please go back to old FM,please.

You can run but...You'll only die out of breath.

BTZ_Bonehead
03-27-2004, 03:03 AM
"mush through the air like a wooden spoon in a porridge pan"

What a great expresion! http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

"Does this make any sense as far as "the real deal" is considered?"

With regard to the rudder in a jet, with extreme angles of attack the most of the fin and rudder are in turbulent air so are very inefective. With regard to using max power (within limits) yes. The correct recovery from an approaching stall is to use power to minimise the loss of height. At the stall or just after it applying full power in a powerful prop aircraft can just agrivate it (well in any prop aircraft really)causing a spin, and with full power set a very exciting spin as well.

The diference between a jet and a prop aircraft at low speeds is the lack of prop wash, making the rudder useless on the jet.

Here is something for you to consider:

As you may know a force applied to a gyroscope acts at 90 degrees to the force in the direction of travel.

So in a spin (the aircraft is the gyroscope) applying rudder will cause the nose to pitch http://ubbxforums.ubi.com/images/smiley/16x16_smiley-surprised.gif

Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

'Bobi@ isnt a bloke http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif http://www.battle-fields.com/downloads/bobi/2.jpg

Tully__
03-27-2004, 03:17 AM
Nice informative discussion, way to go guys. Michapma as always is doing a superb job of eloquently summarising other's input in a form that most can understand.

=================================================


http://members.optusnet.com.au/tully_78th/sig.jpg

IL2 Forums Moderator
Forum Terms of Use (http://www.ubi.com/US/Info/TermsOfUse.htm)

Salut
Tully

olaleier
03-27-2004, 03:29 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
As you may know a force applied to a gyroscope acts at 90 degrees to the force in the direction of travel.

So in a spin (the aircraft is the gyroscope) applying rudder will cause the nose to pitch
<HR></BLOCKQUOTE>

If the rudders get something to bite in that is. http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

I got it explained to me the other day by helicopter pilot, not unfamiliar to this forum. *ahem* Tricky to get my head around all of that...


I forgot to add the most on-topic part in my post above...a simple stall in Lock On is just the nose dropping, and you can force the nose up and really mush.

Once you get familiar with it, you can really play around alot with stalls and spins....90 deg climb, power off and just as you slow past 200 knots, full rudder and full back stick and before you know it you are spinning like a leaf in fall. (or autumn http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif )

I haven't played much FB lately, but one area where it beats Lock On hands down is the ground collision physics, which is as good as absent in Lock On.

I wonder if the stall characteristics in FB is a compromise in order to emphasize the problems one encounter in dogfighting...any ideas on that?

==================================
http://img2.photobucket.com/albums/v30/olaleier/cobrasig.jpg
==================================
Marvin in hyperlobby

lindyman
03-27-2004, 09:55 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by effte:
Bj¶rn,
the CoL _of the wing_ will move forward. However, the wing also rapidly loses total lift while the stab does not, moving the total CoL rapidly backwards. Thus the nose drops.

Cheers,
Fred<HR></BLOCKQUOTE>

You're losing me here, Fred. The stab does not normally produce lift, it pushes the tail down to counter the nose-down torque from the CoG being forward of the CoL. I don't think that this downwards force should be the same when you nose-over. What the reason is, however, I'm not sure of, but a tail-stall seems to make sense.
_
/Bjorn.

lindyman
03-27-2004, 10:36 AM
Regarding my example with the stall while in a descending turn.

I do not mean a death spiral dive. Rather a gentle power-off descent with 30-45 degrees banking turn, in which the speed is gradually lowered with the elevator, untill the stall sets in.

One error on my side, however. The stall will occur on the inner wing, if coordinated. This is not a spin. It's the inner wing dropping, since it's more stalled then the outer wing is. It can, however, quickly become a spin if you don't counter it, or if you try to counter it with the aileron.

On the few planes I've tried this in AEP, it is correctly modeled, btw.
_
/Bjorn.

BTZ_Bonehead
03-27-2004, 12:57 PM
Like I said in an earlier post the tail does produce lift but its in the opposite sense to the lift produced by the wing, it gives a down force to counteract the aircrafts forward CoG.

The tail will not stall before the wing, its not possible, unless someone knows of a manouver that I havent thought of yet http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Its this principle that makes aircraft stable.

Another theory for you and I have tried it in several aircraft and it works, appart from in the DH Chipmunk and I'm sure one or two others.

One way to recover from a spinb is to just let go of the controls, like I say most aircraft will recover on their own.

Dedicated gaming www.battle-fields.com (http://www.battle-fields.com) home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

'Bobi@ isnt a bloke http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif http://www.battle-fields.com/downloads/bobi/2.jpg

TX-EcoDragon
03-27-2004, 08:40 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by BTZ_Bonehead:
Eco Dragon, you said "namely that the elevator loses effectivness before the main wing"

What do you mean by effectiveness? If the eleavtor lost the ability to pitch the nose of the aircraft you would end up in an unstable situation where it would no longer be possible to lower the nose (forgetting power for now ) to recover from a stall, surely?

Like for example having an extreme rear CofG and then stalling.

Dedicated gaming http://www.battle-fields.com home of UK-DEDICATED, why not make it your home too?
http://www.battle-fields.com/staff/bone/ubisig.jpg

'Bobi@ isnt a bloke http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif http://www.battle-fields.com/downloads/bobi/2.jpg&lt;HR&gt;&lt;/BLOCKQUOTE&gt; (http://www.battle-fields.com/downloads/bobi/2.jpg<HR></BLOCKQUOTE>)

That quote was regarding something someone else said, and about what could be done in the sim to give what might be a better 1G stall response. Though as I said it would hurt the other areas of stall/spin modeling.

However, there are many aircraft which can stall the tail surfaces without the main wing being stalled, and there are some designs which use this as a means to prevent the main wing from stalling by limiting the ability of the pilot to introduce any greater AoA. And as you suggest there are also tumbling maneuvers that stall the tail and not the wing. . but thats another story.

As far as stalling and stability goes, the tail isn't what is going to lower the nose, as I suggested in that post, it might be clearer to think about a flying wing, if it stalls, it does just what most aircraft do when stalled, begins a descent and pitches nose down because of the relationship between the CoL/CP and the CG. This is also why stall recovery normally happens without pilot input. Your example is a good one about the aft CG stall issue, and makes this point perfectly, an aircraft with too far aft of a CG cant recover from a stall/spin very easilly if at all becasue the thing that DOES cause a nose down pitching moment is no longer there. . . ie. the CG is not in front of the CoL/CP anymore. The tail is very effective at aft CG and yet it does nothing of use in this situation.

Look at the Rutan designs, they also use the technique of having the pitch control surface stall before the main wing does, by doing this he was able to make aircraft that can not be stalled in the traditional sense. (though in the canard designs both surfaces provide lift in upwards directions)

S!
TX-EcoDragon
Black 1
TX Squadron XO
http://www.txsquadron.com

Member-Team Raven
http://www.waynehandley.com

First Slot Pilot Aircraft #4 of the Virtual Haute-Voltige Team
http://www.vhvt.com/

http://www.attitudeaviation.com/

http://www.calaggieflyers.com

http://www.txsquadron.com/uploaded/TX-EcoDragon/ravenvert.jpg

[This message was edited by TX-EcoDragon on Sat March 27 2004 at 07:51 PM.]

olaleier
03-27-2004, 11:06 PM
Hmmmm,

the CG and CoL thing...isn't that what caused the infamous "Sabre dance"?

(F-86)

==================================
http://img2.photobucket.com/albums/v30/olaleier/cobrasig.jpg
==================================
Marvin in hyperlobby

WWMaxGunz
03-28-2004, 05:57 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by ZG77_Lignite:
Also, unless I'm mistaken I believe Oleg has said that engine-off flight regimes are not/can not be modeled with as high fidelity as engine-on flight regimes. This is simply a programming compromise/limitation in FB. Unsure where this was seen (possibly Il-2 days though I thought it was in conjunction with He-111 debates) but it is in my memory.<HR></BLOCKQUOTE>

Maybe at least some of the torque is a constant?

Perhaps that could be checked by switching torque off?


Neal

effte
03-28-2004, 06:06 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by TX-EcoDragon:
I wouldnt call it a can of worms, because I don't need to choose one theory over the other like many feel compelled to,<HR></BLOCKQUOTE>

And yet, you did...

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by TX-EcoDragon:
The stall is the loss of smooth airflow over the top surface of a wing and with this the great majority of lift is also lost, as most of a wing's lift is from the top surface. (bernoulli on top, newton on bottom).<HR></BLOCKQUOTE>

Check six! http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Just pulling your leg, mate.

Cheers,
Fred

effte
03-28-2004, 06:57 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by lindyman:
You're losing me here, Fred. The stab does not normally produce lift, it pushes the tail down to counter the nose-down torque from the CoG being forward of the CoL. I don't think that this downwards force should be the same when you nose-over. What the reason is, however, I'm not sure of, but a tail-stall seems to make sense.
<HR></BLOCKQUOTE>

The stab does produce lift. It is simply negative. The crux of the matter here is that the tail will remain on the non-stalled part of the cl curve, while the wing drops off the stalled end.

To put it another way: The positive lift of the wing will decrease rapidly as it exceeds the critical AoA, while the positive lift of the tail (which is normally at a negative value) continues increasing more or less linearly with the increasing total AoA and decreasing negative AoA of the tail... which is the same as the negative lift of the tail decreasing.

Clear as mud? http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Cheers,
Fred

MornJW
04-08-2004, 08:53 AM
http://www.zenoswarbirdvideos.com/P-39.html
http://www.zenoswarbirdvideos.com/P-51.html Here, this video shows the stall and spin charactistic of these aircraft well, the web site features videos on most american fighters of the war too.
http://www.zenoswarbirdvideos.com/main.html
Hey, the P-51 seems to turn to the side in a stall, but not fast enough to get into a spin, the P-40 actually ends up in a spin in all stalls, though not as quick as in il2! The P-39 seems pretty stable in regards to turns and spins on cleans stalls, although in a turn it spin with ease. From what I see in these video's anyway. Clearly they aren't as stable as modern civillian aircraft but not as bad as in il2.

worr
05-14-2004, 06:16 AM
Great thread, Air-Mail!

I take it still no chance the people who made IL2 are going to address this...let alone respond to it?

Worr, out

AWL_Spinner
05-14-2004, 06:31 AM
Thanks contributors, this thread's been really interesting. As another civvy plot who's done some aeros, I find this discussion fascinating.

At the end of the day, even if it spins all the time in IL2, I prefer the all round flight sensation to anything else on the market.

Every new release of MSFS, the first thing I do is take a light single up and see if I can spin it (NOT the Pitts). Every time I am disappointed.

Cheers, Spinner

http://www.alliedwingedlegion.com/members/signatures/spinner_sig.jpg

tsisqua
05-14-2004, 07:26 AM
Spinner said:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>At the end of the day, even if it spins all the time in IL2, I prefer the all round flight sensation to anything else on the market.<HR></BLOCKQUOTE>

Amen

http://server5.uploadit.org/files/tsisqua-nedChristie.jpg
http://ubbxforums.ubi.com/images/smiley/784.gif Welcome To The Madness http://ubbxforums.ubi.com/images/smiley/784.gif