F4U turn performance, flaps, the real plane, etc (discussion)

[mtnman]

<Shrug> I guess we'll just have to agree to disagree, clearly we are having a very different qualitative experience in AH. I'm not sure why that is.

I think it's because we're not running the same tests, using the same method.

We may also be looking for different answers... 

I'm trying to see how closely the AH F4U stall characteristics match what is described in the training video.

It looks like you're taking that further to see if you can find cases where you can make the AH stall NOT match reality, and maybe then to see if "what happens next, or as a consequence of" of those cases matches your notion of how it "should" be.

First of all, I think that jumping to "what happens next", or how the stall can be "conquered" is premature without first seeing if the "basic" stall matches up in AH vs. reality (what we see in the video, and described in test reports).

Second, I find the terminology "abusing it pretty hard" and "able to work it to the point" and "used the ailerons and rudder to keep the wings roughly level" to be descriptions of testing that goes way beyond testing "basic stall" characteristics.  Again; premature at the very least, and I'd also argue this to be massively outside the testing parameters shown in the film.

Different results?  I'd hope so!  It sounds like you're comparing apples to asteroids.

At what altitude did you do your tests?

Yes you are right it was the wrong model. I took the early one up with 100% fuel, three notches, gear out and power off, as you suggested.

The stall speed was higher as expected and this one it felt like either wing wanted to go. In all honesty, it still felt very communicative to me.

Trouble started way after the buffet was fully set in.

I was abusing it pretty hard and was able to work it to the point were I could maintain full back pressure on the stick (yes to the stop) and used the ailerons and rudder to keep the wings roughly level.

I didn't try to fight the stall, or keep it from happening. 

I didn't get the sense they were trying to keep the stall from occurring in the video.  I didn't visually or audibly get the sense that the pilot was doing everything he could to NOT stall. 

I certainly didn't get the impression that the pilot was "abusing it pretty hard" and was trying to work it to the point were he could maintain full back pressure on the stick (yes to the stop) and was trying to use the ailerons and rudder to keep the wings roughly level.

Rather, I felt they were TRYING to get the plane to stall in the video, in a basic and "normal" sense, in order to show new pilots what they could expect and how to correct it once it had occurred.  The easiest, most predictable and repeatable way to do that is to slow down with the wings level, and bring the stick straight back until the plane stalls.

I was simply trying to realistically recreate the stall I saw on the video, by mimicking the conditions as closely as possible.

If you're not doing the same basic thing, you're not running the same test that I am (nor are you testing what is shown in the training video).

I then repeated the test with the second model, this one seems a little less docile, but conversely responded quicker to inputs.

Admittedly, this is where things get trickier.  We don't have readily available footage of the second model (I'm assuming you mean the -1A?).  If we cannot reach a consensus with the more-complete evidence for the -1, I don't have much hope at all for agreeing with even less documentation.

However, based on the stall strip/spoiler improvement, we should expect to see the opposite of what you found.  The stall in the -1A should be MORE docile.  As far as response to control inputs, we shouldn't see any major difference.  The -1 did go through numerous aileron changes though, and I'm not sure which ailerons were used on the plane in the video.  For that reason, I guess maybe there could be some differences between the film and AH, but I'd expect there to be no difference between the various AH F4U's.

I didn't recheck the film to look at the cowl flaps but both the first and second model in AH have those modelled exactly the same graphically. Both the skins I have have that green paint inside. The cowl flap in line with the antiglare strip is closed on both, the other ones open (top ones at least).

The cowl flaps in AH are not functional.  They are graphically modeled closed or very slightly open.  I have no idea whether their effects are modeled, but based on the fact that we don't notice buffeting of the tail surfaces I would say they're not modeled.

In normal operation, full open would be used for ground cooling, 2/3 open for take-off and climb, and closed (or opened slightly if required) in flight.






In order to clarify things I think we need to more clearly delineate between the different facets of the stall.

The buffet (I'm considering this to be more or less synonymous with "warning" of an impending stall)-

I also agree that the buffet seems to begin too early, but I don't know of a way to measure that against reality.  Of course I don't know, but I suspect that HTC has modeled the buffet somewhat "generically", and that it may set in at a fairly standard "speed above stall" threshold for many or maybe all fighters/planes?  If so, maybe it sets in "too early" on some planes to give an accurate representation of RL?  So maybe we get too much warning in the F4U (or maybe many planes?).  Not sure.

Departure-
When I run the test in the manner described above (and which I believe to be the method used by the pilot in the film), I get a stall departure very similar to that shown in the training film.  I'm curious to see how many others get the same result.

Recovery-

Recovery in both models even when it snapped right over I found easy, had it back in under control and upright in around two seconds (estimated).

I agree, I can also recover easily and very quickly. 

However, after entering a stall as described above, I felt like it took significantly more piloting in AH to recover than I saw or heard described in the video. 

Not that it was difficult, or that "prompt positive action and normal technique won't bring about normal recovery", but that the nose appeared to drop further in the training film than it does (for me) in AH.  In AH the nose kind of "got stuck" rather than swinging down as far.  This (I feel) results in more required control to recover than it would if the nose fell further.

Regardless, the flight tests show "easy recovery" in a clean condition, without a terrible loss of altitude (I also believe the test pilot in the film dove more than he needed to in order to recover...). 

They also show a tendency to fall off on either wing (which you also found to be true in the AH model). 

It looks like landing configuration with throttle closed gives the least amount of warning/buffeting (which is a condition we'd seldom see in a fight in AH); coupled with the increased buffeting and reduced effectiveness of the elevator and rudder in that condition, I wonder if we've now "pegged" the real issue that caused an occasional pilot to flip over in a stall and crash on landing?

Further, that may be another clue that the AH F4U isn't so far off...  The complaints we hear over and over and over result from people flying the corsair in a non-landing config, with high throttle; nowhere near the "worst case" conditions of low, slow, low throttle, cowl flaps open that resulted in the plane being dubber the "Ensign Eliminator".  I haven't seen anything that would lead me to believe POWER ON stalls with flaps deployed should be all that violent? 

[mtnman]

I want to point out that I do not believe the flaps are of such a great benefit to the F4U. At least, not as much as the gear are. To understand what I mean you have to look at the cycle time of the landing gear of a real F4U and the landing gear of the F4U in game. Realize also that there is a center-of-gravity issue in real life that becomes much more manageable because of the reduced cycle time, as well as a drag issue that is likewise greatly influenced by the sequence.

Someone wished for fast landing gear speeds so they could go from zero-to-hero in less time. Now the gamers can use it to their advantage.

By CoG issue, are you referring to the trim changes that we might expect as a result?

[mtnman]

A myth. The relative angle of the wing makes no difference. If it did it would be less draggy on one said and more draggy on another.

I don't understand what you mean by this.

The "less draggy" aspect of the wing mount is explained as "the wing root being joined to the fuselage at a ninety degree angle which was the most efficient design for both maximizing strength and minimizing drag".  I'm not sure what you mean by less draggy on one side and more on the other?

[mtnman]

not to steal your thunder mtnman but I remember several fights with you were we would get in a rolling scissors and both of us would be way below 100 mph at the top of the barrel rolls.

I've been looking through a bunch of films...  I have a few films of us fighting in the MA, and a long one (45 minutes) of us in the DA.

What I've found so far all supports my argument that below 120mph, I'm not doing much to maneuver at all.  There were some maneuvers in the DA where we were low in speed at the top of maneuvers (into the 55mph range) but all I'm doing at that point is "coasting" over the top, waiting for enough speed to rebuild so that I can do something.

I'll freely admit that I use my trajectory to my advantage...  But I'm not doing much maneuvering at all.  I almost never leave myself "hanging" in those scenarios, because I use the little control I have in the 110-90mph window to direct my trajectory such that I'll rebuild speed.

That is supported by several occasions where I was behind you as you zoomed.  Essentially, all I had to do was slightly adjust my nose to land hits on you, but at 80-90mph I don't have enough control of the plane to fine tune my aim the few degrees it would have taken to kill you.

So yes, I coast through maneuvers at less than 100mph, but don't have enough control to do much of anything if I'm under 120-130mph.

If you happen to have any films showing otherwise, I'd honestly like to see them.

[nrshida]

We may also be looking for different answers...  

I don't have anything invested in the F4U. Respectfully you don't seem any more objective than I.

I also agree that the buffet seems to begin too early, but I don't know of a way to measure that against reality.  

Well again, consider this statement from the training film:-

"Stalls are abrupt, and preceded by very little warning in the nature of buffeting".

In AH the buffet is firmly established long before the wing drops which to me is 'plenty of warning' not 'very little warning'. Of course I also let the stall develop without fighting it as a first step but that really wasn't very interesting and isn't what you'd do if you stalled in a fight. Those further experiments were to see just how much I flirt with the stall listening to the communication from the aircraft as to what those wings are doing. I started my tests at 16k for both models.

Of course I don't know, but I suspect that HTC has modeled the buffet somewhat "generically", and that it may set in at a fairly standard "speed above stall" threshold for many or maybe all fighters/planes?  If so, maybe it sets in "too early" on some planes to give an accurate representation of RL?  So maybe we get too much warning in the F4U (or maybe many planes?).  Not sure.

That's why I kept bringing up the Fw190, it can't be an across the board design choice if some AH aircraft are genuinely 'abrupt and without warning'. How about the short-nosed Spitfires (Marks I and V), they depart decidedly without warning or buffet in certain configurations and you have the Devil's own job to get those back.

I feel the discussion has now stagnated into an attack and defence situation which is a shame. I'm not campaigning to have the AH F4U knobbled, through the course of the discussion I felt an inconsistency was revealed which I found interesting to investigate / discuss. I am probably being unrealistic in expectation.

Think I'll stop here.


Shame no one else contributed to the angle of sustained turn gallery.

[mtnman]

I don't have anything invested in the F4U. Respectfully you don't seem any more objective than I.

No, I'd argue that I'm easily more objective than you.  We're just not (or weren't) testing the same thing.

I was testing to see if the AH F4U shows the same stall characteristics as it does in the training film.

You weren't.  You described a test method seeing if you could make it NOT stall the same way as shown in the film.

Both are valid, and your test is important/valid.  It was just premature until we'd established that the plane does stall as shown in the film, if it's flown the same way as shown.

Now, once we establish whether the stall itself is correct or not, we open the door to much deeper discussion into other aspects.  One should obviously be the ability to avoid the stall through control manipulation.  Another would be "non-basic" stalls.  Should the plane stall differently in different conditions than we see it doing?

I feel the discussion has now stagnated into an attack and defence situation which is a shame.

It's a shame you feel that way.  That's not my intent.

Disagreeing with you is not attacking you.  Disagreeing with your methods (or at least with my interpretation of them based on your statements) is also not an attack.

I'll continue to point out inconsistencies as I see them though.

Well again, consider this statement from the training film:-

"Stalls are abrupt, and preceded by very little warning in the nature of buffeting".

In AH the buffet is firmly established long before the wing drops which to me is 'plenty of warning' not 'very little warning'. Of course I also let the stall develop without fighting it as a first step but that really wasn't very interesting and isn't what you'd do if you stalled in a fight. Those further experiments were to see just how much I flirt with the stall listening to the communication from the aircraft as to what those wings are doing. I started my tests at 16k for both models.

This discussion is what I would consider "pre-stall characteristics".  I agree with your findings so far, and I believe the objective info you need to make an objective argument is available in the shots I posted above.  More evidence is in the documents I linked to.

That's why I kept bringing up the Fw190, it can't be an across the board design choice if some AH aircraft are genuinely 'abrupt and without warning'. How about the short-nosed Spitfires (Marks I and V), they depart decidedly without warning or buffet in certain configurations and you have the Devil's own job to get those back.

This is extremely exciting info (to me anyway).  It tells me that if you/I/anyone else can pose an objective argument, HTC would be able to (and likely would, based on other plane types) be willing to make adjustments to the model.  I haven't tested this (yet), so I don't know.

Not that I believe the evidence points to the F4U stall being difficult to get out of.

[nrshida]

No, I'd argue that I'm easily more objective than you.  We're just not (or weren't) testing the same thing.

I was testing to see if the AH F4U shows the same stall characteristics as it does in the training film.

You weren't.  You described a test method seeing if you could make it NOT stall the same way as shown in the film.

Well my interpretation of your actions is that you have systematically tried to dismiss or devalue evidence and findings right from the start of this discussion. First you dismissed the official training film as having no merit because it was anecdotal and non-quantitative. Once I pressed that point you tried to dismiss my testing simply because I went further exploring how it isn't behaving how they describe it in the film. Now you seem to intend to pursue an ad nauseam argument by dissecting what defines a stall and buffeting  

Even in the 'don't fight it' mode of flying (which as I said I also tested (first)), the buffet begins waaaaaaay before the wing drops and even after that, just before the wing does drop it's telling you it's about to drop with an obvious little wiggle. I just can't see that constitutes 'very little warning', not by any normal definition and not with comparison with other AH aircraft.

It was just premature until we'd established that the plane does stall as shown in the film, if it's flown the same way as shown.

But we haven't established that. That's my point. Discussion cannot progress if we disagree about the communicative nature of the aircraft and sequence of the buffet and stall. There's just nothing further to say. We disagree.

It's a shame you feel that way.  That's not my intent.

Disagreeing with you is not attacking you.  Disagreeing with your methods (or at least with my interpretation of them based on your statements) is also not an attack.

Actually I was rather interpreting your responses as defensive & your apparent impression that I was attacking your favourite aircraft. That wasn't my intent either. I find I learn more in these discussions, but if positions become entrenched then it is no longer productive to continue. If I disengage from the discussion that is not me conceding my position either.

[mtnman]

Well my interpretation of your actions is that you have systematically tried to dismiss or devalue evidence and findings right from the start of this discussion. First you dismissed the official training film as having no merit because it was anecdotal and non-quantitative.

You haven't really come up with any evidence though, have you?  You don't like the evidence I've presented, and won't even read through it thoroughly enough to understand that the evidence you need to argue your point is right in front of you.

You just fall back on the same ol' argument that's been poorly presented over and over.

Talk about being entrenched!  Sheesh!  Pot, meet kettle...

The film is subjective and anecdotal, yes.  It does have value though, and can be used to support the more objective evidence available.  It can be used to argue your point, just as I've used it to argue mine.  That's the beauty/trap of subjective evidence.

Now you seem to intend to pursue an ad nauseam argument by dissecting what defines a stall and buffeting  

Odd.  I want to break it down into sections (i.e. sequence) so that we can take a more definitive look at it.  You don't like that, but then you say we can't progress unless we agree on it?

...communicative nature of the aircraft and sequence of the buffet and stall.

You're probably right, no point in going any further with you.  You seem unwilling to work at understanding the conversation and then want to quit when it gets tough.

I suspected that with your comments to FLS, but still held out hope for you.  My mistake.

[mtnman]

Anyone have time/motivation to run a few tests?  I have to do a bunch of traveling over the next few weeks so I won't be able to do it myself.

I think a strong argument could be made to support nrshida's point that the F4U communicates its impending stall too early.  This "extra" warning probably makes it too easy to detect and avoid the stall.

I suspect the actual stall itself isn't the problem; it's the behavior that leads up to it that may be questionable.

According to the flight test reports I found and posted above, the buffet probably shouldn't begin until around 4mph (or less) before the plane stalls, depending upon the configuration.

If the AH F4U could be shown to begin the buffet much before that, I think it could be argued that the advantage of this extra warning is swaying things too far in favor of the F4U.  If HTC could then be swayed with some objective evidence, maybe the model could be adjusted?

The implications of an adjustment like that could be huge...

[nrshida]

You haven't really come up with any evidence though, have you?  You don't like the evidence I've presented, and won't even read through it thoroughly enough to understand that the evidence you need to argue your point is right in front of you.

Your position is that I haven't come up with anything that satisfies your condition for being evidence, apparently. The definition of evidence is: facts or observations presented in support of an assertion, not statistical and quantifiable data which can be measured and compared.

Your printed evidence pertains to the later model I understood (perhaps I have mixed the model numbers?) and is no less anecdotal than the training film. But I should pay more attention to your evidence while you dismiss my previously presented evidence out of hand?

You just fall back on the same ol' argument that's been poorly presented over and over.

The 'same ol' argument' (thanks for attempting to belittle it, again) hasn't been addressed and there is no point moving further into a deeper discussion until the contradiction between training film and AH characteristics have been properly investigated. You DIDN'T want to do this you moved directly to imply that you had ESTABLISHED they matched. Which you haven't.

The film is subjective and anecdotal, yes.  It does have value though, and can be used to support the more objective evidence available.  It can be used to argue your point, just as I've used it to argue mine.  That's the beauty/trap of subjective evidence.

My comments and observations are subjective. Anyone can repeat my test: watch the film, listen to the account of the stall and then put the AH Corsair into the same condition and report if the characteristics match the training film.

I don't think the training film is subjective, that would imply it was the position of an individual whereas this was apparently an official training film. I don't think it's unquantifiable as you suggest either, it describes a sequence which I say our Corsair doesn't match.

Others might make an effort and contribute too. I took the time to add to your 'lean angle' flight test, no one else did, not even you. No one else has even challenged my observations about the AH Corsair.

Odd.  I want to break it down into sections (i.e. sequence) so that we can take a more definitive look at it.  You don't like that, but then you say we can't progress unless we agree on it?

You systematically tried to dismiss everything I brought to this discussion up to this point and now I'm supposed to accept your implication that I am being obstructive?

I suspected that with your comments to FLS, but still held out hope for you.  My mistake.

You held out hope for me that I would behave in accordance with your values? How extremely condescending of you. FLS was implying he understood a technical question and had explained it satisfactorily when in fact he hadn't. Then he 'laughed' and left the discussion. Hardly a professional deportment. Should I not direct such comments to a trainer, even when he behaves this way is that what you mean?

You're probably right, no point in going any further with you.  You seem unwilling to work at understanding the conversation and then want to quit when it gets tough.

This is your second attempt to devalue my points on grounds of character. I've confined my comments to technical issues and my interpretation of other people's subjectivity and haven't got personal about it at all. Should I continue to try and forward my observations in an unreceptive and now bordering on insulting environment? Would this be an intelligent use of my resources? You accept no responsibility for your pattern of behaviour throughout this discussion, it has been dragged down to the dismissive and then personal level and you berate me for wishing to disengage?

If my observations are valueless and without merit, then they would be trivially dismissed without getting personal about it.

[nrshida]

.

[mtnman]

Your printed evidence pertains to the later model I understood (perhaps I have mixed the model numbers?) and is no less anecdotal than the training film.

Yes, I think you've missed the model numbers.  The printed information is from different model numbers, and different individual aircraft.  I simply grabbed those small sections to save you the effort of doing the research yourself.

Anyone can repeat my test: watch the film, listen to the account of the stall and then put the AH Corsair into the same condition and report if the characteristics match the training film.

I ran the test as I saw it done and heard it described in the film, and got the results shown in the film.

I can also change my test method to the one you describe (which doesn't match the film) and get the results you get (which don't match the film).

You held out hope for me that I would behave in accordance with your values?

Absolutely not!  If I led you to the conclusion that I was judging your values or comparing them to mine, I apologize.  I don't know enough about you as an individual to even come close to doing that.

[mtnman]

Continued digging has raised more questions...

In particular, I've been looking into the issues of "warning", and the ability to control the plane through the stall (or not).

It's not difficult to find reference to "little warning" of an impending stall, but it sounds like there are three types of warnings in question; "buffet", stick forces, and the stall warning light (closest thing to the buzzer in AH?).

For the most part, the references to the "little warning" are either not identified as to which warning type is being discussed, or is linked to the stick forces-

In RL-"While the elevator forces are generally normal in direction, they vary only a small amount in approaching a stall with power on, and the control movement is very small.  Thus the elevator control force and position do not provide the normal degree of "feel" or warning of change in air speed or angle of attack".
In AH- We get nothing as far as a warning, since we don't feel stick forces.

That's actually pretty descriptive, and may go a long way to answering the "little warning" question.  It's more descriptive then any reference I could find to the warnings given via stall light or buffeting.  Unfortunately (?) if this is the culprit when it comes to "little warning", AH is arguably less forgiving than RL. We don't get little warning; we get none! (when it comes to stick forces).

Next, we have the stall warning light / buzzer.
In RL- The stall warning light should operate 4-8 knots above the stall in landing condition, and 14-18 knots above the stall in clean condition.  This is designed to operate regardless of the load condition of the plane, the acceleration (in turns or pull-outs), the throttle opening, or the flap setting, all of which cause the indicated speed to vary from that in straight flight at normal load with throttle closed.

In AH- The stall horn can be made to operate at a wide range of speeds depending upon attitude, etc, from as high as 140mph or more, right down to no warning until stall.  It would take some work to dial this in through testing (which I haven't done conclusively yet).

Last, we have warning of impending stall through "buffeting".
In RL (as shown by the shots posted earlier) we could expect the controls to buffet 2-4 mph above stall depending upon configuration.  Buffeting will also be caused by the cowl flaps...  Buffeting in the real plane is described as "ample" in the clean condition, to "late" in the landing condition.
In AH, does the physical buffeting we have model the controls buffeting?  Or the plane itself?  Seems like the plane to me, but that may/may not equate to the controls?  FWIW, I got buffeting from 0-4mph above the stall.

I'm not sure I see anything massively wrong with the warning we get, or the actual stall departure vs. RL?

That does leave the question of controlling the plane "through" the stall though (or at least being able to avoid the stall by controlling).

To answer that we'd need to look at the effectiveness of the elevator, rudder, and ailerons right up to the stall.  At what point should those controls lose effectiveness to the point where control should be lost, and the stall is unavoidable?

In theory, if you could maintain control and keep the plane right above stall, you'd avoid the stall.  But...  Should the F4U have enough rudder, elevator, and aileron effectiveness at 2-4mph above the stall to maintain that control?

There's (some) info in print on that, too.

[FLS]

You don't have to be at 1G stalling so you could have a very low stall speed.

With flaps out your ailerons wouldn't be as close to stalling, lower AOA.

The stall is at a particular AOA so the stall horn is likely also set at a particular AOA in AH and RL.

Stalling without warning sounds like they maintained control up until they suddenly stalled. Like we do.

[mtnman]

You don't have to be at 1G stalling so you could have a very low stall speed.

With flaps out your ailerons wouldn't be as close to stalling, lower AOA.

The stall is at a particular AOA so the stall horn is likely also set at a particular AOA in AH and RL.

Stalling without warning sounds like they maintained control up until they suddenly stalled. Like we do.

That correlates with what I'm finding too.

"Elevator maintains effectiveness at all speeds".

"Rudder is heavy at low speeds, with a reasonable amount of control right down to the stall" (engine on).

"Ailerons are light and lack feel at low speeds, but are still very effective".

IMO, I'd expect the ailerons to lose effectiveness first in a power-on stall, since the prop is blowing air across the tail surfaces.  And it sounds like the aileron remain effective right up to the stall.