Stall?

[BKLronin]

Just one question.

 

When I flew sailplane a long time ago there was a stall that was circular towards the earth when you got too slow. I havent seen this on many flight sims except Il2 I think it was. The A10C is also unstallable that way, is that because of the construction of most planes or is it just not simulated?

 

Also most planes in X-plane are unstallable.

[effte]

What do you mean by "circular"? The aircraft dropped a wing in the stall? Or spun? Some aircraft do, other aircraft are much less prone to this. Some aircraft can remain in the stall more or less indefinitely, just mushing on down wings level.

[RogueRunner]

It's called a spin and the A10 does it well.

 

Pull nose up and let the speed drop below 140 and then kick full right rudder. She'll spin and you'll prob loose both engines from airflow disruption too. t least plenty of compressor stalls (watch the fan RPM gauges :) )

[BKLronin]

What do you mean by "circular"? The aircraft dropped a wing in the stall? Or spun?

 

I meant the spin that one you can only escape by counterwise Rudder and nose drop down.

I made the A10C spin nicely already but it was easy to get out of that state.

 

So at least not many planes stalls end up with a spin, or to say it with other words end up in a "death spiral"

 

Ok then will have a look at the RPM gauge. Never got the engines into a stall I think.

 

Thank you both!

[tusler]

Oh you are referring to the old Flat spin like this

 

http://www.liveleak.com/view?i=d1a_1251060179

[sobek]

I don't think that all aircraft designs are prone to 'deep stalls' that require special (special to the plane) procedures to get out of. Since the a-10 has a very forgiving flight behaviour, it might not fall in this category.

[Frederf]

Around 10,000' or so you can see the pilot actually start wrestling the airplane out of the flat spin, arresting the yaw rate, and getting some pitch down. It's a shame he didn't have a another 20,000' to work with.

 

Most if not all airplanes suffer from this problem. When both wings are near stalling and there is yaw applied, one wing will go faster and one will go slower. The slower wing stalls and loses a lot of lift. The faster wing continues to fly and provide lift. The result is the airplane wants to fly itself around in tight circles as if it only had a wing on one side.

 

Plenty of IL-2 (game) aircraft can be thrown into spins. Here's a video of not only a spin but a flat spin.

 

The DCS A-10 is pretty forgiving and it's hard to get a departure even when trying. I guess you could argue that few if any (X-plane might be an exception) sims do real stalls because stalls are delaminations of airflow from the airfoil. Modeling airplane/air interaction in a turbulent flow situation accurately is beyond the scope of real time simulators. DCS likely has some sort of Lift vs. AoA curve that drops off steeply after the critical AoA and has the general effect of a stall.

[Avilator]

I don't think that all aircraft designs are prone to 'deep stalls' that require special (special to the plane) procedures to get out of. Since the a-10 has a very forgiving flight behaviour, it might not fall in this category.

 

Given the straight wings and low-mounted horizontal tail, the A-10 really can't get into a "deep stall." Also, we can't forget the effect the center of gravity has on spinning characteristics of an airplane. i.e., rearward CG=flatter spins. So it's not only the design that determines how it stalls, but the CG as well.

[BKLronin]

Oh you are referring to the old Flat spin like this

Exactly

 

Well according to the altitude at least my A10 is moving most of the time I´m a bit happy that it can´t really spin or even flat spin.

 

When both wings are near stalling and there is yaw applied, one wing will go faster and one will go slower.

 

As far as I can remember from flight school also an aileron input can lead to spin since you got a similar effect (transverse displacement) to the use of yaw in that moment.

[Avilator]

As far as I can remember from flight school also an aileron input can lead to spin since you got a similar effect (transverse displacement) to the use of yaw in that moment.

You are correct. This applies more when the aircraft is already in a turn and the pilot applies aileron to level the wings, while also holding opposite rudder. The inside wing, which is going slower, will attempt to generate more lift. The increase in angle of attack by the aileron will stall the inside wing first. The outside wing then snaps over the top, resulting in an erect (normal) spin. A flat spin will result if you botch the control inputs or have a very aft CG.

 

Of course, all of this applies only if you are going near stall speed first. It also excludes snap rolls, which are a type of spin as well, usually only feasible in aerobatic aircraft.

[Frederf]

Yeah, there's a few ways to exceed the critical AoA on one wing and not the other. Anything that changes the chord line could do it too like a control surface.

[Slayer]

It should go into a spin like that if one of the wings is blown away by a sam or AAA :)

[bogusheadbox]

I don't think that all aircraft designs are prone to 'deep stalls' that require special (special to the plane) procedures to get out of. Since the a-10 has a very forgiving flight behaviour, it might not fall in this category.

 

Swept wing are usually inherent for a deep stall this can be compounded by high tail or T tail. None of which the hog has.

 

A normal wing will produce a nose down moment at the stall.

 

A swept wing will do the opposite and produce a nose up moment (tip stall). Transport aircraft are required to have a nose down pitching moment at the stall so the swept wing has to undergo design fixes to provide this downward pitching moment. However at very high alpha (angle of attack) a completely stalled swept wing will provide a nose up pitching moment again.

 

A deep stall may have a normal attitude of the aircraft however the aircraft is moving in a downward motion creating a angle of attack of about 25-35 degrees. As the aircraft (swept wing) has lost its natural tendancy for nose down moment a much greater force will be required by the tail to counter for this. This is the deep stall

 

This brings me back to the tail and the problems of the T tail. (a picture is helpfule here) so draw a plane with a high tail and swept wing at about 35 degrees nose up, then draw horizontal wind vector lines across the plane. Depending on the position of the wing and the angle of attack you will find that with a T tail the disturbed flow from the stalled wing will flow directly over the tail. This will therefore reduce greatly the effectiveness of the tail and consequently the tails ability to provide enough elevator forces to counter the nose up pitch.

 

 

T-tails usually incorporate a stick pusher. A stick pusher is not a warning device of the stall like a stick shaker but positively corrects for an impending stall. It does what it says on the tin and swiftly pushes the control colums forward preventing the stall. This prevention will keep you away from deep stall.

 

There are pros and cons to high tails over conventional tails. but that is another umpteen pages of typing.

Edited November 22, 2010 by bogusheadbox

[effte]

Given the straight wings and low-mounted horizontal tail, the A-10 really can't get into a "deep stall." Also, we can't forget the effect the center of gravity has on spinning characteristics of an airplane. i.e., rearward CG=flatter spins. So it's not only the design that determines how it stalls, but the CG as well.

 

Not to mention the mass distribution.

[Dimebag1]

Not to mention the mass distribution.

 

Lol, cg, mass distribution, same thing, or were you trying to be funny?

[aphelion79]

Maybe needed? xD

[Yellonet]

Lol, cg, mass distribution, same thing, or were you trying to be funny?

It is not the same thing.

[aphelion79]

More like same difference, the weight of the contents of the aircraft affect the CG directly (hence weight and balance calculations). I believe this is what Dimebag was getting at... not that mass distribution IS the CG, but that they are closely related.

 

Especially when

i.e., rearward CG=flatter spins.

was mentioned, more weight in the rear of the aircraft will result in a reward CG thus flatter spins.

[effte]

More like same difference, the weight of the contents of the aircraft affect the CG directly (hence weight and balance calculations). I believe this is what Dimebag was getting at... not that mass distribution IS the CG, but that they are closely related.

 

Especially when was mentioned, more weight in the rear of the aircraft will result in a reward CG thus flatter spins.

 

And more weight towards the nose and the tail will result in flatter spins, even if the overall CG stays the same. I'll go to bed now and leave you lot to ponder that one for 20 hours. :P

[Frederf]

Aye, a stick with two weighted balls on the end weighs the same as a stick with two weighted balls at the middle. They don't behave the same with regards to rotational momentum, accel, etc.

[Hereje]

hello!in my case, can be possible that when i try to take a 360 degrees vertical turn, the a-10 cant do that??i mean, i go up with no more than 90 degrees at full speed(320 aprox), the warthog just cant do that. am i doing something wrong?

pd: without armament. full speed. the airplane arrive at 90 degrees in STALL practicaly

[Avilator]

And more weight towards the nose and the tail will result in flatter spins, even if the overall CG stays the same. I'll go to bed now and leave you lot to ponder that one for 20 hours. :P

I really don't need to ponder this one, but it really doesn't apply here. What plane has the vast majority of its mass concentrated at the front and back?

 

hello!in my case, can be possible that when i try to take a 360 degrees vertical turn, the a-10 cant do that??i mean, i go up with no more than 90 degrees at full speed(320 aprox), the warthog just cant do that. am i doing something wrong?

pd: without armament. full speed. the airplane arrive at 90 degrees in STALL practicaly

What exactly do you mean by a vertical turn? A loop? If so, you may be pulling too many Gs at the beginning, causing you to lose energy early. Try pulling a little less.

 

Can anyone that has looped the Hawg comment on how many g's to pull to start a loop?

[Hereje]

mmm.. maybe haha. i pull too strong. thinking...i am pulling too strong and taking the loop too fast. Avilator, it was simple Fisics, thanks!!!!!!! i am stupid, the others airplanes, eagles ,falcons flankers flys at 1000 km/h, but warthog just above 320!

i am happy that you understand my english! :) i know i make some mistakes in my words thanks

[BKLronin]

To sum it up a little.

 

For A10C

If wing count = 2, tail =1 and nose=1, dangerous stall = <1

 

:)

[Dimebag1]

Wikipedia:

 

"The center of mass or mass center is the mean location of all the mass in a system."

 

Mean location refers to the mean distribution of mass. This is pure semantics you are arguing over. The centre of gravity directly represents how the mass is distributed in a body.