F-86 Stall/Spin behaviour doesn't seem correct.

[drack]

Hi Folks,

 

I took the F-86 up for a 'spin' last night and noticed some behaviour that doesn't seem correct.

 

I'm no test pilot and I know its in Beta, so don't take this as criticism, I'm just trying to help out with an observation.

 

I'm finding that when I take it up to 20,000ft, point the nose 80 degrees up and cut the throttle, wait for it to stall and put full left rudder, full left and back stick in, it settles in to a right hand rotation.

 

Shouldn't the rotation be to the left?

 

I've tried this in the SU25A this morning and I get a left rotation as expected.

 

I've got an evening off today so I'm going to test it on the F15, A10C, SU25T and P51.

(Nice opportunity to explore DCS weather as well).

 

I'll also try this in the X Plane AMX, T28 and F-4 (F4 likely to result in non recoverable spin.)

 

I've got a feeling the F86 will be the only one that will rotate to the right......

 

Will post the finding tomorrow.

 

Any thoughts?

 

Hope your all well............

[Buzpilot]

I think it has something with the torque when the engine decelerate down to idle.

The Su-25 engine rotates clockwise and the J-47 in Sabre runs counterclockwise.

 

Those flying a WW1 rotary engine, or FW-190 knows what I mean, if you speed up they will move to a side, the same thing happens when a jet slows down.

 

Look from 3:00 and you'll see what I mean.

Edited September 3, 2014 by Buzpilot

[GV-Spotted]

put full left rudder, full left and back stick in, it settles in to a right hand rotation.

Shouldn't the rotation be to the left?

 

From my knowledge the aircraft is supposed to spin to the right when left stick is applied.

 

It doesn't really seem right, but when you put the stick full left the right aileron is going to go down. The right aileron going down increases the angle of the "chord"(attached image) of the right wing, thus increasing the angle of attack on the right wing and decreasing the angle of attack on the left. Stalling is caused by the angle of attack of the "chord" of the wing being too great, so the wing stalls. Because the angle of attack is higher in the right wing with full left stick, it will stall first, thus the spin to the right.

 

Also you might be able to help the aircraft spin by pushing the rudder in the direction of the desired spin while turning the ailerons the opposite direction.

 

This may not be correct with the F-86, but its just my knowledge from spins in cessnas/pipers.

 

Hope I could help!

[SgtPappy]

The reversal of control is indicative of many swept wing planes. It was even moreso pronounced on the later F-4 Phantom.

 

The span wise flow becomes more and more marked along the span as AoA increases, thereby detaching the flow at the outer portion of the wings. This leads to the downward aileron producing lots of drag; enough to yaw the plane in the other direction. The adverse yaw motion then increases lift on the other wing and the plane rolls and yaws in the direction opposite of the input as a result.

[drack]

Thanks for the input guys.

 

A lot to look into and examine there.

 

I suppose thats what makes it such a great hobby, always something new to get interested in and learn.

 

Thanks again and I hope your enjoying the 86 as much as I am.

[RyanBurnsRed]

So when I'm going into a spin I should put the stick and the rudder in the direction the plane is spinning?

[Zabuzard]

So when I'm going into a spin I should put the stick and the rudder in the direction the plane is spinning?

 

Hands of the stick! Usage of ailerons will slow down the recovery process. You can use a bit of Forward or Backward Stick to push your nose down to gain some speed again but not more than that, cut the throttle to reduce altitude loss and apply full rudder to the outer of the spin. As soon as you applied the rudder completely take hands of the stick.

 

The spin speed then will speed a bit up (don't think you're doing it wrong), at about 1 full turn it will slow down and after about 3-4 turns the plane should get out of the spin by itself. Immediately neutralize rudder input or you'll enter another spin in the other direction. If not you may open the throttle a bit to regain some speed.

 

If gained too much airspeed during dive recover, cut the throttle and extend speedbrakes, if you lost to much airspeed open the throttle and gain some speed, both variants BEFORE you're doing a dive recovery or you'll may up crashing into the ground.

 

For example if your height after spin recovery is ~10.000ft, IAS is about 540 Knots and you're in a vertical dive a 4G pullout will end up in crashing, only a 6 G pullout will end up ~1.000ft above the ground.

 

A 1 turn recovery (best case) + 4 G pullout will result in a loss of ~6.500ft altitude. So if you enter a spin below 7.000ft eject. Training should be made between 30.000-35.000ft because a worst case recovery (4 turns) will end up loosing about 10.000-20.000ft.

 

Spin recovery in the F-86 Sabre is not as easy as for example in the P-51D, you will need 1-4 complete spin turns before recovery can be successfull.

[drack]

Hi Folks,

 

 

With the recent update the bird will now sustain a rotation to the left if you move the A/C & controls as in post #1.

 

 

It doesn't take much for it to still want to snap into a rotation to the right though.

 

I wonder if that is due to some of the theories put forward?

 

 

All very interesting stuff. Lovely bird to fly.

 

Many thanks Belsimtek.

[CookPassBabtridge]

Hi Folks,

 

 

With the recent update the bird will now sustain a rotation to the left if you move the A/C & controls as in post #1.

 

 

It doesn't take much for it to still want to snap into a rotation to the right though.

 

I wonder if that is due to some of the theories put forward?

 

 

All very interesting stuff. Lovely bird to fly.

 

Many thanks Belsimtek.

 

I've just been watching videos about civil aviation crashes caused by spin stalls in the pattern, and the guy was talking about snap rolls, though of course not in relation to swept wing, sonic capable aircraft :D

 

He said that a snap roll happens because you have not unloaded the aircraft before applying opposite rudder, e.g. you enter incipient spin but still have a high wing loading (stick back or centre, I presume). So if I understand correctly, the first things you should do in spin recovery is reduce power, AoA and wing loading by pushing the stick forward slightly. Ailerons should be neutral.

 

Then as mentioned above, apply full opposite rudder and allow the aircraft to dive, then recover. This video starts off by ramming that message home:

 

 

Also fun:

 

Edited October 12, 2014 by CookPassBabtridge

[Kwiatek]

Well regarding spin of F-86 i think i post here some my thoughs but someone delete my post???

 

 

I read RL manuals for F-86 and there is that F-86 was nothing unusall in stall/spin characteristic and its behaviour was typical as for a fighter plane.

 

Tryin DCS F-86 i found that rather F-86 dont behave in typical way. There is hard to spin it to the same side as rudder input. Maby rudder is too less effective in F-86 ( these is another topic about these) thats why DCS F-86 behave these way?

[Winfield_Gold]

Chuck Yeager's air combat says " max throttle, Nose down & apply opposite rudder" Works every time....

[Kwiatek]

Problem is not with recovery procedure which is ok in DCS F-86 but rather with enter in correct spin in right direction.

[SUBS17]

I wonder what limitations there are regarding the F-86s engines in conditions such as stalls/spins/AoA that might cause a flame out? It would be interesting dogfighting when you have such limitations.:music_whistling:

[SUBS17]

Chuck Yeager's air combat says " max throttle, Nose down & apply opposite rudder" Works every time....

 

That's exactly what I do apart from when I fully departed the F-15C in a dogfight, absolutely nothing worked I even tried rocking it like the F-16 departure recovery method and it did not work lol.:joystick:

[KL0083]

Tryin DCS F-86 i found that rather F-86 dont behave in typical way. There is hard to spin it to the same side as rudder input. Maby rudder is too less effective in F-86 ( these is another topic about these) thats why DCS F-86 behave these way?

 

All what you said is all what I see when compare with flight reports and in-game control character.:thumbup:

 

But before asking why,however,make sure the officals really care what we've concern about!!!!!:megalol:

Edited October 16, 2014 by KL0083