Spin characteristic prop planes in DCS or rather spin proof.

I guess it's an neverending quest for finding a sweet spot between simple spin scripts of old games on one hand, and advanced CFD spin simulations (requiring monster computers) on the other.

Modelling supercritical flight regimes in a way which looks plausible but doesn't murder our CPUs is always a major programming challenge for devs I presume. Well, as long as DCS code is being improved and tuned, we'll get there.

and you can run the engine on ground or in the air at low power settings, for prolonged periods of time without risking any spark plugs fowling...

Wrong, at least for the P-51. I assume the other props are the same.

I'm a little late to the game here, but... at the warbird musuem where I volunteer, the pilots say the AT-6 trainer is very easy to get into a spin, but that our F6F, P-47D, SBD, Helldiver, TBM, F4U, TF-51D etc are all EXTREMELY forgiving and not very spin prone at all, and also much easier to recover in a stall than the AT-6 trainer.

 

Bottom line is, those heavy ass warbirds are NOT aerobatics aircraft, and while they CAN spin, they are far more forgiving overall and much easier (generally speaking) to recover, so... expecting DCS simulated prop jobs to be super spin happy does not seem realistic.

 

We don't have a Bf-109 or FW-190 in our hangar of course so... can't really speak to those, but... again, a single seat combat aircraft which is easily spin prone would not likely have made the cut for production back then...

Interesting! thanks for the post, a lot of it makes good sense :D

I'm a little late to the game here, but... at the warbird musuem where I volunteer, the pilots say the AT-6 trainer is very easy to get into a spin, but that our F6F, P-47D, SBD, Helldiver, TBM, F4U, TF-51D etc are all EXTREMELY forgiving and not very spin prone at all, and also much easier to recover in a stall than the AT-6 trainer.

 

Bottom line is, those heavy ass warbirds are NOT aerobatics aircraft, and while they CAN spin, they are far more forgiving overall and much easier (generally speaking) to recover, so... expecting DCS simulated prop jobs to be super spin happy does not seem realistic.

 

We don't have a Bf-109 or FW-190 in our hangar of course so... can't really speak to those, but... again, a single seat combat aircraft which is easily spin prone would not likely have made the cut for production back then...

Nobody says that these planes should spin like the crazy but at certain situations plane should spin ( like i said even spinproof C152 could do it). In DCS some planes ( D-9 or K-4) instead make a spin they mostly do only some "mechanical" quarter of flick roll then suddenly stop even if you got stick full back. So it looks for me that they lack some spin interia.

P-51 is the most natural here and in such situation as i describe it spin but D-9 or K-4 dont want to do it.

109 surly should be most gentle from all these fighters here casue also it has slats which covers airleons area which allow higher CLmax and higher critical angle of attack. But still when you pass critical angle of attack plane should spin in certain situations as any other plane.

About Fw 190 i read that pilots used it prone to spin characteristic in turns to shake opponent from tail. I think it work like just half flick roll in turn which casue opposite turn direction ( something like half flick roll in aerobatic). But still i think that after initiating such manouver ( stick back and kick rudder) pilot need to quick recover (stick forward and probably opposite rudder). It work exacly like half flick roll in any other plane. But as i said it need to be counter to get out of these ( at least stick forward but i think rudder was need too). Flick roll is the same like one full spin. So it work in the same manner.

So if you initiate such manouver ( half flick roll) you still need to recovery it very fast to not continue full spin. E.x in DCS D-9 if you make these and even if you still keep stick full back plane stop flick byself which is wrong i think. It should continoue rotation until you prevent by controls ( stick little forward and opposite rudder).

I think it should work that way.

Often pilots dont exacly remember what they are doing with controls of plane. They do it automatically and when you ask pilot how he did it he could not even remember that he e.x give little stick forward or use some rudder in some manouver. He just feel how the plane is react and make some things automatickly ( dont know if said it clearly )

About Fw 190 i read that pilots used it prone to spin characteristic in turns to shake opponent from tail. I think it work like just half flick roll in turn which casue opposite turn direction ( something like half flick roll in aerobatic). But still i think that after initiating such manouver ( stick back and kick rudder) pilot need to quick recover (stick forward and probably opposite rudder). It work exacly like half flick roll in any other plane. But as i said it need to be counter to get out of these ( at least stick forward). Flick roll is the same like one full spin. So it work in the same manner.

What Eric describes and Yo-Yo is trying to tell you is the effect is caused by a deliberate uncoordinated power off aileron turns.

You pull the power, hard roll entry in one direction followed by immediate and very hard roll in the opposite direction without any rudder input.

There is no rudder input.

Here you go Kwiatek

http://forums.eagle.ru/showthread.php?t=136596&page=5&highlight=Crumpp

Yo-Yo says:

Anton flick rolled out of turn if the engine was set to idle before this maneover and there was no rudder input. Two sequental flick rolls turned defence to offence . But the first roll must be at 450-500 kph.

Crumpp says:

That is interesting!

 

So no rudder input means the roll was uncoordinated making aero-elasticity effects the likely cause of it.

Yo-Yo says:

Any slight deviation from coordinated turn (that always presents) leads to increasing yaw-roll because of negative damping at post-stall AoA, moreover, abrupt AoA increasing leads to instant rate of turn increasing and can cause instant out-of-coordination condition equivalent of out-of-turn pedal input.

Crumpp says:

 

I understand Yo-Yo and agree that the dynamics of an uncoordinated turn certainly contribute in no small way to this interesting phenomenon in the FW190.

 

Those effect are universal and in my humble opinion does not fully explain the violence in this behavior compared to the aircraft's lift polar or other aircraft in the same conditions of flight.

 

The Germans investigated this in "Die Entwicklung der Tragwerkkonstuktion FW190" Bericht 176 der Lillenthal-Gesellschaft, 2 Teil, January 1944.

 

From that Report, which I do not have a copy of but have being meaning to get on my next trip to the Paul Gerber Facility, it was concluded that aero-elasticity was removing the washout of the wing causing the entire wing to stall lending an even larger moment and more abrupt AoA change for the instant the wing is deformed.

 

The entry velocity requirement of 450-500kph and uncoordinated entry certainly set up the conditions for this to occur.

Yo-Yo understands what is causing the effect Kwiatek and is working to improve all these FM's.

What Eric describes and Yo-Yo is trying to tell you is the effect is caused by a deliberate uncoordinated power off aileron turns.

 

You pull the power, hard roll entry in one direction followed by immediate and very hard roll in the opposite direction without any rudder input.

 

There is no rudder input.

As Kwiatek has pointed out, pilots often didn't remember exactly what they did with the controls, so it may very well be that there were variations in exactly how Fw 190s evaded their pursuers and/or counterattacked. What Eric & Yo Yo is describing is one variation, there were probably others that used the 190's excellent aileron control and rate of roll as a basis.

And as Kwiatek has pointed out, pilots often didn't remember exactly what they did with the controls, so it may very well be that there were variations in exactly how Fw 190s evaded their pursuers and/or counterattacked. What Eric & Yo Yo is describing is one variation, there were probably others that used the 190's excellent aileron control and rate of roll as a basis.

I think you are coming late to the conversation because your comment makes little sense in the context of the discussion. However, I agree that are other methods to evade and counterattack.

What is not correct is linking this behavior as "typical" of the design. One can simply look at the lift polars to see there are no violent post stall behaviors in coordinated flight.

Eric's description of the control inputs set the aircraft up for a uncoordinated condition which explains things Fredrich.

If you understand how to read the shape of a polar curve, there is no argument that can be made the FW-190 had a violent stall in coordinated flight.

I think you are coming late to the conversation because your comment makes little sense in the context of the discussion. However, I agree that are other methods to evade and counterattack.

Crumpp is coming even later "into the conversation", so this red-herring has very little to do with anything.

What is not correct is linking this behavior as "typical" of the design. One can simply look at the lift polars to see there are no violent post stall behaviors in coordinated flight.

Since when did I link "this behaviour as "typical" of this design?" I said that pilots probably used other, similar methods of evasion, using the Fw 190's good aileron control and roll rate.

Eric's description of the control inputs set the aircraft up for a uncoordinated condition which explains things Fredrich.

 

If you understand how to read the shape of a polar curve, there is no argument that can be made the FW-190 had a violent stall in coordinated flight.

Again, no such statement about a "violent stall" from me, so why bring it up twice, except as an opportunity to indulge in some condescending comments and a needless lecture?

Very interesting... specially because the last thing I would think of was aero elasticity playing such an important role on the wings of a Fw190 ...

I do consider it many times when flying the Nimbus, and it played nasty even in the Cobra 15, but we're talking gliders and their rather flexible wings there :-)

Anyway, does this mean the wings of the Fw190 in DCS are actually modeling this effect too ?

Yes, and this roll is induced with post-stall gyration.

I understand that it could something like just stall in turn when wing drop after. But still i think that when pilot don't easy on stick in these manouver plane will get into spin rotation. It shound't be stopped byself like it is now in D-9.

I read in " Fw 190 Aces of Eastern Front " that pilot used similar manouver to shake opponent from their tail. But it was just spin during the turn where pilot just pull stick full back ( didnt mention any rudder input) and plane get into spin. But there was need some alt to recover from these so it was not used at low alts. Pilots said that manouver shoudn't be done below 1000 m.

Some power off straght flight stall of FW 190 A - 6:40

It looks rather violent even with some flaps and power off. I think power on stall in clean cofiguration was even more violent.

BTW i known one pilot in my country who bought old fashion ZLin 526AFS and was killed at low alt when he was turn at one direction and banked to opposite turn ended into spin. He didn't have chance to recover and crash.

I found some videos showing planes spin interia during uncoordinated stall happend:

t looks rather violent even with some flaps and power off. I think power on stall in clean cofiguration was even more violent.

It is not a Cessna 172.

It is typical of a high performance low wing taildragger to drop ~30 degrees of wing in the stall IF you do not lift the wing with rudder.

It is a combination of propeller effects that cause it with spiral slipstream being the largest contributor.

Here....at 5:36...the Mustang does the exact same thing. Listen to the instructor in the few minutes before talk about how gentle the Mustang stalls. He also cautions this pilot about NOT using any lateral input but only use rudder to lift the wing.

My Thorp does the exact same thing.

It is exacly my point. Warbirds are not Cessna, not such stable. But even common Cessna could suprise pilot with unintentional spin ( like i wrote earlier about one accident in my country - both crew was died after Cessna make full spin at low alt during climbing turn).

I thinks these video could show some things :) :

https://www.youtube.com/watch?v=uaL1NcJs1jw

Expecially 10:30

It is exacly my point. Warbirds are not Cessna, not such stable. But even common Cessna could suprise pilot with unintentional spin ( like i wrote earlier about one accident in my country - both crew was died after Cessna make full spin at low alt during climbing turn).

If you do spins, it is actually harder than you think to get into one. Try teaching them

Yes, pilots do inadvertently enter them from time to time. IMHO, you have to be pretty distracted and behind the airplane for that to happen.

The spin entry is fine in DCS with the exception of the power on spins to the right.

Yo-Yo is tweaking things in the FM, let's not compound problems by rushing off to fix a secondary effect that is not the problem!

Just watch the video Crumpp it nice shows a problem with power on spins and acclerated stall which warbids ( and any normal plane) could have :)

It's more like this, and I believe the Bf109 K4 in DCS World should be a lot closer to an Extra than to a C172 or even a Yak-52...

And in the "heavier" GAs...

which gliders, due to increased adverse yaw effect, are very prone to.

One of the worst accidents here in Portugal, in the early nineties, involving a Mucha glider, happened right during the turn from base to final. The glider almost instantly flipped on the out wing, and ended upside down in an inverted spin, till it banked 90º before hitting the ground with the right wing.

The pilot survived.

which gliders, due to increased adverse yaw effect, are very prone to.

One of the worst accidents here in Portugal, in the early nineties, involving a Mucha glider, happened right during the turn from base to final. The glider almost instantly flipped on the out wing, and ended upside down in an inverted spin, till it banked 90º before hitting the ground with the right wing.

The pilot survived.

I thinks these video could show some things

Pay attention....notice how many times they say, "carelessness and ignorance".

Again, it is not that easy to get into a spin, the airplane is designed to fly and wants to fly.

Pay attention....notice how many times they say, "carelessness and ignorance".

 

Again, it is not that easy to get into a spin, the airplane is designed to fly and wants to fly.

I think you still dont get a problem here :).

Simple test - hard turn in D-9, full stick back and keep it ( you could call it ignorance or carelessness :P ) . It show directly problem with some lack spin interia in DCS. Try the same with K-4.

In such condtions plane expecially such as warbird or areobatic one will spin.

In DCS these planes just make some quarter of half flick then suddenly stop or recovery byself.

IRL pilot need to do recovery by proper control technic.

I think you show some ingorance here ragarding spin possiblity in warbirds like some pilots in these video :P

I joke of course :)

I got also some carelsessnes in my RL flying when i made some spins in my ZLin526 at quite low alt want to drop alt after aerobatic zone before landing. My ZLin make some more spin turns then i supposed before i managed to recover :)

I think you still dont get a problem here

I do get it.

Go back a couple of pages and look for Yo-Yo's answer.

http://forums.eagle.ru/showpost.php?p=2322005&postcount=12