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P-51 stall characteristic


Kwiatek
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HI!

 

After some DCS P-51 flight and combat test i found that plane is very prone to stall even at medium speed range ( 300-250 mph) and not so much stick deflection. I know that P-51 has laminar wing profile (which is not good in high angle of attack ) but i still wonder if it is correct that she stall so fast?

 

As a real life pilot with some aerobatic plane experience ( ZLin 526) it is quite hard to belive for me that real P-51 stall so much like in DCS i mean it happend so fast comparing to stick movement. I wonder if developers didn't overdone some stall characterisic in P-51?

 

These is the most questionable thing in DCS P-51 flight model engine for me, maby also some take off problems which in DCS are unexpectedly more problematic then landings :)

 

But generally flight model and immersion from flying is very high in DCS P-51.


Edited by Kwiatek
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HI!

 

After some DCS P-51 flight and combat test i found that plane is very prone to stall even at medium speed range ( 300-250 mph) and not so much stick deflection. I know that P-51 has laminar wing profile (which is not good in high angle of attack ) but i still wonder if it is correct that she stall so fast?

 

As a real life pilot with some aerobatic plane experience ( ZLin 526) it is quite hard to belive for me that real P-51 stall so much like in DCS i mean it happend so fast comparing to stick movement. I wonder if developers didn't overdone some stall characterisic in P-51?

 

These is the most questionable thing in DCS P-51 flight model engine for me, maby also some take off problems which in DCS are unexpectedly more problematic then landings :)

 

But generally flight model and immersion from flying is very high in DCS P-51.

 

Any non-swept wing suffers from max CL decreasing as the Mach numbers increases. And this effect starts from relatively low Mach numbers. This effect was researched in wind tunnel and flight experiments since 40' and were described in NACA reports. So this data is carefully reproduced in the FM.

And that's why you can get accelerated stall easier.

 

Static longitudinaly stability charts were available too, so FM is adequate regarding this item.

 

If you are interesting about the reasons - I think it's because the P-51 is not an aerobatic plane. The fighter must be able to keep flying and land after serious damages of the control surfaces, so the control effectveness must be higher.

 

Then the second reason, maybe the main - real stick movement is much longer than your joystick has :).

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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It is also the fact that it is a laminar airflow wing. If you see some planes have turbulator strips on the top of them that actually turbulate the air on the upper surface of the wing. This allows the air to "stick" better to the surface and creates a taller boundary layer. This provides a more graceful stall. They are even called "stall strips" sometimes.

 

The P-51 has a laminar airfoil shape for its wing and, I believe does not have any form of flow disruption. What this means is that when the a/c stalls...it stalls for real and not gracefully.

 

This is a good website that describes the behavior better than I can...

 

http://www.allstar.fiu.edu/aero/wing31.htm

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I know next to nothing about stall data and all that. But I did hear that the P-51 had a tendancy to stall on takeoff with a full tank behind the pilot. I gather the wieght of the fuel threw off the center of gravity or something. I heard that new pilots really had an issue with this in the early days employing the Mustang. Is this true? Is it modeled. Sorry if this is offtopic.

 

PS.

Interesting article CaptSmiley, I just learned something about airfoils.


Edited by racketyjack
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Is it modeled.

 

Set up a mission with full tanks and give it a shot. I don't know about the stall issue but your aircraft is quite a bit different on take-off.

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Then the second reason, maybe the main - real stick movement is much longer than your joystick has :).

 

Yes I agree - I have an amateur modified stick (which I first got for Black Shark).

It is about 1.5 ft long.

The difference is quite remarkable and close to real life (flown a T6 a couple of times).


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well i was talking to a pilot and he said that the A2A model is way more easier to fly and acts just like the real thing, the one in DCS is way to sensitive.. This is from a pilot who has flown all of the P51's and A2A Sim and DCS... In other word it reacts to his test stall controls and yaw controls... I guess?

I have only flown a 172g and it want's to fly, compared to DCS, a lot of the planes in here act like there stuck to the runway.

he is over at A2A simulations...:pilotfly:


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well i was talking to a pilot and he said that the A2A model is way more easier to fly and acts just like the real thing, the one in DCS is way to sensitive.. This is from a pilot who has flown all of the P51's and A2A Sim and DCS... In other word it reacts to his test stall controls and yaw controls... I guess?

I have only flown a 172g and it want's to fly, compared to DCS, a lot of the planes in here act like there stuck to the runway.

he is over at A2A simulations...:pilotfly:

 

If he compared joystick movement and real stick movement he could be right.

DCS Mustang has static stability charachteristics identical to real Mustang. It means that the plane will be triimed at the certain speed with the same stick position as the real plane. Or that you have certain stick movement at certain IAS to get certain G-load. If you compare real stick travel and joystick travel you will see the great difference.

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Hmmm, I never thought about that, the stick in a real P-51 compared to what we have sitting on our desk, sorta makes sense. We should be able to calibrate the sensitivity to make that better though, shouldnt we? I will have to play around with that. Its just a matter of leverage now right, if we decrease the sensitivity of our flight sticks it should get us closer?

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Hmmm, I never thought about that, the stick in a real P-51 compared to what we have sitting on our desk, sorta makes sense. We should be able to calibrate the sensitivity to make that better though, shouldnt we? I will have to play around with that. Its just a matter of leverage now right, if we decrease the sensitivity of our flight sticks it should get us closer?

 

What some people do is extend their flight-sticks with a piece of pipe or the like. In other words, you have the base mounted on the floor and the flightstick at waist-height - lot more precise or so I'm told.

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well i was talking to a pilot and he said that the A2A model is way more easier to fly and acts just like the real thing, the one in DCS is way to sensitive.. This is from a pilot who has flown all of the P51's and A2A Sim and DCS... In other word it reacts to his test stall controls and yaw controls... I guess?

I have only flown a 172g and it want's to fly, compared to DCS, a lot of the planes in here act like there stuck to the runway.

he is over at A2A simulations...:pilotfly:

 

Interesting.

 

I haven't flow real P-51 yet ( :P) but i flew aerobatic planes and gliders and from my feeling DCS P-51 could be harder to fly in the air then real one. I have some doubts that real thing could stall so easly expecially at medium speed range 200-300 mph and with not too much stick deflection. I think it could be possible with aft COG ( full rear fuel tank fillled) but with normal condition to combat it should be more easier. It looks like for me that DCS P-51 has very low critical angle of attack which is very easy to pass in game. Yes i know that our sticks have much less movement than real sticks but still i think it shouldn't be the case.

 

But it is only my feeling as a RL pilot ( unfortunately not P-51 one).


Edited by Kwiatek
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What some people do is extend their flight-sticks with a piece of pipe or the like. In other words, you have the base mounted on the floor and the flightstick at waist-height - lot more precise or so I'm told.

 

Well the wife already makes fun of the Track-IR, not sure I could handle the comments if I told her my flight stick was too short :D

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Well the wife already makes fun of the Track-IR, not sure I could handle the comments if I told her my flight stick was too short :D

 

:megalol:

 

You'd have to rely on the age-old tried-and-tested 'Honey, it's not the size that matters but the technique' retort when confronted by such comments, although, giving it some second thought, in this instance size, or length, does indeed matter....

 

Yes, best you stay quiet - I know I would :D

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:megalol:

 

You'd have to rely on the age-old tried-and-tested 'Honey, it's not the size that matters but the technique' retort when confronted by such comments, although, giving it some second thought, in this instance size, or length, does indeed matter....

 

Yes, best you stay quiet - I know I would :D

 

 

Ahh yes but wouldn't you rather go into battle with a LANCE.. Instead of a dagger?

 

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:megalol:

 

You'd have to rely on the age-old tried-and-tested 'Honey, it's not the size that matters but the technique' retort when confronted by such comments, although, giving it some second thought, in this instance size, or length, does indeed matter....

 

Yes, best you stay quiet - I know I would :D

 

I am old enough to know when silence is the best offense :)

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Interesting.

 

I haven't flow real P-51 yet ( :P) but i flew aerobatic planes and gliders and from my feeling DCS P-51 could be harder to fly in the air then real one. I have some doubts that real thing could stall so easly expecially at medium speed range 200-300 mph and with not too much stick deflection. I think it could be possible with aft COG ( full rear fuel tank fillled) but with normal condition to combat it should be more easier. It looks like for me that DCS P-51 has very low critical angle of attack which is very easy to pass in game. Yes i know that our sticks have much less movement than real sticks but still i think it shouldn't be the case.

 

But it is only my feeling as a RL pilot ( unfortunately not P-51 one).

You may try a stall test mission, record the trk and make a ACMI. Then you will find the critical AOA.

The feeling of your control can be very different with different joystick and different curve setting.

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You may try a stall test mission, record the trk and make a ACMI. Then you will find the critical AOA.

The feeling of your control can be very different with different joystick and different curve setting.

 

What mean ACMI?

 

It is not only my feeling but also coming from my mates which use different joysticks even one got much longer moded stick although they are not a RL pilots and have only combat sims experience.

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Interesting.

 

I haven't flow real P-51 yet ( :P) but i flew aerobatic planes and gliders and from my feeling DCS P-51 could be harder to fly in the air then real one. I have some doubts that real thing could stall so easly expecially at medium speed range 200-300 mph and with not too much stick deflection. I think it could be possible with aft COG ( full rear fuel tank fillled) but with normal condition to combat it should be more easier. It looks like for me that DCS P-51 has very low critical angle of attack which is very easy to pass in game. Yes i know that our sticks have much less movement than real sticks but still i think it shouldn't be the case.

 

But it is only my feeling as a RL pilot ( unfortunately not P-51 one).

 

P-51 has very noticable signs of stall (shaking) so if you do not force the plane to gain AoA very fast (inertia!) you can hold it near stall quite easily.

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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P-51 has very noticable signs of stall (shaking) so if you do not force the plane to gain AoA very fast (inertia!) you can hold it near stall quite easily.

 

Yea it is true that DSC P-51 has noticable and nice sings of stall (buffeting) but still in my opinion in combat expecially in turns or pull ups it happened where it shouldn't be yet expected - i mean i too early with stick/elevator deflection.

 

These is just my personal feeling and guess but im wonder what could say RL P-51 pilot.

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Yea it is true that DSC P-51 has noticable and nice sings of stall (buffeting) but still in my opinion in combat expecially in turns or pull ups it happened where it shouldn't be yet expected - i mean i too early with stick/elevator deflection.

 

These is just my personal feeling and guess but im wonder what could say RL P-51 pilot.

 

Real P-51 pilot with significan experience both in real P-51 and in our sim said: Yes! :)

 

All reasons why you feel the stick this way I wrote before. :)

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Another reason, I think, for the P-51's early stall (which is an attribute of any high-speed fighter from that era) is the speed and mass. Its high speed allows you to more easily pull high Gs with small stick movements. Stall speed is linked to G-load, yes? And mass raises stall speed, and the P-51 weighs over 10,000 lb. Aerobatic airplanes are much slower and many times lighter.

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What some people do is extend their flight-sticks with a piece of pipe or the like. In other words, you have the base mounted on the floor and the flightstick at waist-height - lot more precise or so I'm told.

 

When I am King, we will all have floor-mounted sticks. A good floor-mounted stick, with good wide-set pedals, is the ultimate flight sim control. However, simply extending a cheap joystick and floor-mounting it may not help anything, because most joysticks don't have the center precision for it. Example: if you have a 2-millimeter hard dead zone in the middle (measured from the top), and you extend the stick from 6 inches to 18 inches, then you now have a 6-millimeter dead zone, which will make precise flying absolutely impossible.

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It looks like for me that DCS P-51 has very low critical angle of attack which is very easy to pass in game.

That shouldn't be surprising given it's airfoil. Laminar flow is easier to separate than turbulent flow. This is why most modern fighters are designed to create massive turbulent vortices at high AoA.

 

The P-51 basically does the opposite, in an attempt to reduce drag, the flow is kept laminar as long as possible. This increases the wing's sensitivity to stall.

 

Though as far as flying the DCS P-51, I don't find it that big of a deal. I can usually jam the stick right up to critical AoA. I know when to stop from the visual cues (buffet).

 

It's a bit of a shame that the Mustang lacks an AoA gauge, but with some experience you can roughly back out how close you are to stall by looking at airspeed and g.

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That shouldn't be surprising given it's airfoil. Laminar flow is easier to separate than turbulent flow. This is why most modern fighters are designed to create massive turbulent vortices at high AoA.

 

The P-51 basically does the opposite, in an attempt to reduce drag, the flow is kept laminar as long as possible. This increases the wing's sensitivity to stall.

 

Though as far as flying the DCS P-51, I don't find it that big of a deal. I can usually jam the stick right up to critical AoA. I know when to stop from the visual cues (buffet).

 

It's a bit of a shame that the Mustang lacks an AoA gauge, but with some experience you can roughly back out how close you are to stall by looking at airspeed and g.

 

It is wide spread but wrong statements. NACA conducted wind tunnel and flight test to find out how max CL value depends on M.

 

P-51 low-drag airfoil has better CL behaviour around 0.5-0.7M range comparing to F-6F, P-38, P-39 and even YP-80. Though these airfoils steadily diminish CLmax with M increasing low-drag airfoil CL increases after 0.55M and has its second maximum near 0.66M.

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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