Aerodynamical question

[SvAF/F16_Goblin]

Hi mates,

I'm not a RL pilot but have studied fluid dynamics and propulsion in naval applications so I have a slight understanding of "matters"

 

I have a question to those with knowledge and are willing to educate me.

 

When I fly the Fw190 with the wing tip pointing towards ground and very gently increase the tightness of the turn i come to the point where
an abrupt stall occurs and the aircraft flick 180 degrees to the left. I wonder why it always occurs to the left! If the right tip is towards ground
it flicks left and with the left tip towards ground it flicks left.

 

I maintain the horizon in the centre of the screen compensating to make the turn in the same plane all the time and the throttle is even.

 

I really would like to know what design and aeronautical phenomenon cause the flick to be in the same direction every time.

 

Regards

[JG13_opcode]

Was the ball centered?  Due to P-factor, there exists a yaw asymmetry at high angles of attack.

[SvAF/F16_Goblin]

Would the effect of a slightly non centred ball whilst performing this manoeuvre cause a constant flick over left wing in all scenarios?

It was my understanding that a wing would stall out before the other due to differences in AoA and I find it intriguing that I always stall
the left wing regardless of position.

Edited September 17, 2016 by I./ZG1_Goblin

[JG13_opcode]

Would the effect of a slightly non centred ball whilst performing this manoeuvre cause a constant flick over left wing in all scenarios?

 

It might.  If there's an asymmetry in yaw, then your wings are not at the same angle of attack.  The wing at a higher AoA always stalls first.

Edited September 17, 2016 by JG13_opcode

[SvAF/F16_Goblin]

Yes, I follow you on that. I'm just puzzled that I always get the left wing stall.

Have to really investigate how I perform that manoeuvre both left and right some day

Edited September 17, 2016 by I./ZG1_Goblin

[JG13_opcode]

So was the ball centred or not?

[SvAF/F16_Goblin]

I will try it again in a few days and make a track as well. I'm atm concentrated on a glass of wine

Edited September 17, 2016 by I./ZG1_Goblin

[JG13_opcode]

Got curious, hopped into Berloga and tried it.

 

First of all:  what you're seeing is prop effects.  If you try it with the throttle at idle (power-off stall) then you'll see the right wing drop as expected.  However with power on, I actually could not get the right wing to drop in the Fw 190 at all, even with full rudder deflection.

 

Something is rotten in the state of Denmark.

[SvAF/F16_Goblin]

OK, It could be that  there is something weird then?!

We should be able to get a stall in the right wing with power applied, that is if I understand the books I have properly.

Edited September 17, 2016 by I./ZG1_Goblin

[JG13_opcode]

OK, It could be that  there is something weird then?!

We should be able to get a stall in the right wing with power applied, that is if I understand the books I have properly.

 

It works in the Yak, so yeah, it seems not all is right, hence my Hamlet quote.  Without knowing the details it's hard to speculate on what exactly is wrong.  I'm told by credible people that the sim uses a vortex-panel method for the FM, which is quite complex.

Edited September 17, 2016 by JG13_opcode

[SvAF/F16_Goblin]

A quote from Lange says the following:

 

"A dangerous characteristic of the Focke-Wulf was that in very tight high G-turns it would sometimes, suddenly and with no warning, whip into a turn into the opposite direction. In a dogfight or near the ground, this could have a very bad result."

 

That statement seems to indicate that in a tight high g turn to the left it would flick to the right and not as it is now to the left.

[JG13_opcode]

 

 

That statement seems to indicate that in a tight high g turn to the left it would flick to the right and not as it is now to the left.

 

 

Does it?  That's the problem with using pilot anecdotes instead of hard data.

 

Does that quote imply that it should snap roll in the opposite direction of turn, no matter the turn direction?

[SvAF/F16_Goblin]

I don't know, It could be. If I had flown a plane that snapped into a dangerous immediate roll to the left I would have made instructions not to turn
violently in that direction but to make the turn the other way. At least I wouldn't then wind up in a departure from controlled flight upside down.

 

If something behaved equally, on the other hand,  the anecdote from Lange is how I would have described it. If you turn hard it will flick opposite.
In the meaning it doesn't matter in what direction you pull hard it will flip and reverse.

 

It seems a pretty weird engineering coincidence that it would always flick left regardless of situation in a high G turn. My believe it would flick
to the side where AoA dictated, right or left depending on turn and bank and not just left. But, it's just my belief and nothing more.

 

On the other hand, if it always had the predictable left flick and change of turn it is something that could be put to a tactical advantage by
an experienced pilot aware of it and well trained on the plane.

 

I guess we will never know unless a tactical manual shows up But it's fun to discuss because there is always something new to be learned.

Edited September 17, 2016 by I./ZG1_Goblin

[JG13_opcode]

There's definitely something wrong with it.  That much is certain, despite what certain people who are in maximum damage-control mode will say.

 

With power on I couldn't get the right wing to drop, even in climbing or descending turns.  It just kinda stalls straight forward.

 

I'd spend the time and maybe do some proper flight testing if I cared, but now that the sim is going to the Pacific why would I waste my time?

[III/JG52_Otto_-I-]

When I fly the Fw190 with the wing tip pointing towards ground and very gently increase the tightness of the turn i come to the point where

an abrupt stall occurs and the aircraft flick 180 degrees to the left. I wonder why it always occurs to the left! If the right tip is towards ground

it flicks left and with the left tip towards ground it flicks left.

 

The wing drop occur when you have different lift forces in each wing, due to different airspeeds, or different AoA, and slip attitude.

The majority of tapered wings designs, stall first at the wing tip, and after stall at the wing root.

 

In airplanes with propeller rotation in clockwise direction (view from cockpit) when aircraft is in a turn at full throttle,if ailerons are up or down, and wing tips stalls (depending on turn side), propeller torque effect spin the fuselage to the left , 

Willy Messerschmitt equiped his Bf-109 with automatic leading edge slats in the outer wing sections, mainly for minimizing the wing drop, at low speed combat maneuvers, and landings.  For same reasons, Soviets copied the slats in theirs La-5FN too, because they could not outclass the Bf-109 in maneuverability. 

 

But I think that the flight model of the Fw-190 in this game is not full realistic.

It seem that red stars painted in some airplanes enhancing a lot of the aerodynamic.  

 

[unreasonable]

There is also the issue that it might be scripted behaviour to match the Eric Brown report:

 

"...the stall came suddenly and virtually without warning, the port wing dropping so violently that the aircraft almost inverted itself. In fact, if the German fighter was pulled into a g stall in a right turn, it would flick out into the opposite bank and an incipient spin was the inevitable outcome if the pilot did not have its wits about him."

 

Or the combination of slipstream (propwash) and torque is actually modeled correctly and overcomes the normal tendency of the inside wing to stall first?

[SvAF/F16_Goblin]

I'm getting three volumes on the Fw190 next week that will be most interesting to read. As far as I have been able to find the authors and the books are some of the best there is on the Fw190. Unfortunately volume 4 with all available technical drawings was never finalized and published but I have bought some technical and construction instructions from Germany earlier.

 

It's Volume 1 to 3 by Smith and Creek.

V1: https://www.amazon.co.uk/Focke-Wulf-FW190-1-1938-43/dp/1906537291

V2: https://www.amazon.com/Focke-Wulf-Fw-190-Vol-1943-1944/dp/1906537305

V3: https://www.amazon.com/Focke-Wulf-Fw-190-Vol-1944-1945/dp/1906537313

[JtD]

It looks to me as if you could get the right wing to stall first, if you use enough rudder. However, thereafter, almost immediately the aircraft follows the prop momentum and goes into the spin over the left wing. The basic theory is fine, but I think it is considerably exaggerated.

 

You will find reports of stalls in turns noting both, drop of left and drop of right wing, as a result. Typically, it would be the wing on the inside of the turn, as can be expected. The flick roll to the opposite side was a noteworthy exception, not the rule.

[SvAF/F16_Goblin]

The problem is we cannot get right wing to drop, at all, under power even if it's the inside wing in the turn.

[JtD]

Yes, it is what I was responding to. What else would I respond to?

[F/JG300_Gruber]

I'm getting three volumes on the Fw190 next week that will be most interesting to read. As far as I have been able to find the authors and the books are some of the best there is on the Fw190. Unfortunately volume 4 with all available technical drawings was never finalized and published but I have bought some technical and construction instructions from Germany earlier.

 

It's Volume 1 to 3 by Smith and Creek.

V1: https://www.amazon.co.uk/Focke-Wulf-FW190-1-1938-43/dp/1906537291

V2: https://www.amazon.com/Focke-Wulf-Fw-190-Vol-1943-1944/dp/1906537305

V3: https://www.amazon.com/Focke-Wulf-Fw-190-Vol-1944-1945/dp/1906537313

 

 

Good buy mate

I own all 3 and currently reading the second book.

However, so far there is not much valuable information to argue about FM in the books.

[JG13_opcode]

It looks to me as if you could get the right wing to stall first, if you use enough rudder.

Not sure what you mean exactly

[JtD]

Rudder to the right, right wing drops first. As soon as it does, the plane shows a very strong tendency to completely depart over the left wing.

[JG13_opcode]

Rudder to the right, right wing drops first. As soon as it does, the plane shows a very strong tendency to completely depart over the left wing.

I tried that in a descending turn and the right wing wouldn't drop at all, which doesn't seem right to me.

[Crump]

The RLM and Focke Wulf attributed the violent stall/spin of the FW-190 series to aeroelasticity effects.  If you ask the FW-190 pilots what they did to use this characteristic as an escape maneuver you will find they entered under moderate G loads in aggressive asymmetrical flight.  It is the same control input required for snap roll to stall the wing.

 

They bottomed out the rudder and pulled hard....

 

David Lednicer nicely covers the effects in an article published in the January 1999 Edition of the EAA's Sport Aviation magazine.  

 

Aeroelasticity effects remove the aerodynamic twist from the wing so that the "snap" was especially crisp.

 

The key requirement is that heavy input of rudder or uncoordinated flight, without it the aggressive stall will not happen.

EAAjanuary1999.pdf

[Crump]

 

 

I tried that in a descending turn and the right wing wouldn't drop at all, which doesn't seem right to me.

 

It is not right.  Whatever rudder pedal you step is the side that stalls.

 

Step on the right...the right wing stalls and the left wing flies.  The aircraft begins a snap roll to the right.

 

In this case of the FW190, the right wing is not completely stalled as it still has the wingtip not stalled and the wing is producing lift, just a lot less lift than it did before you stalled it.    An accelerated stall is just a slow snap roll.

 

If the other wing has enough load factor to remove the washout from the flying wing it leads to a premature stall of that entire wing and vola!!

 

You have a left hand spin to the opposite side you entered the accelerated stall.

 

I think the game is trying to reproduce that effect.  Instead of being an occurrence found under very specific conditions though, it is a caricature found in all accelerated stalls in the BoS FW-190.  

One wing partially stalled and the other completely stalled = SPIN

[SvAF/F16_Goblin]

Never mind, you've read that thread as-well

Edited September 18, 2016 by I./ZG1_Goblin