Power On / Power Off Stalls and Spins

[funked]

Try this experiment in a single engine fighter:

Build up a lot of speed, then zoom the plane vertically at full throttle.  Keep the throttle open and let the stick go as the plane starts to stall at the top.  It flops, rolls a little, then enters a stable dive.

Do it again but cut the throttle before the plane stalls.  I get a flat spin usually.  

Now try the same experiment in WarBirds, using the same plane.  In WB you get the flop and stable dive whether power is on or off.

I don't know enough about spins to say which is better, but those who think spins and stalls are modeled identically in WB and AH have another think comin'.  

[This message has been edited by funked (edited 07-17-2000).]

[Toad]

I can't speak for the "heavy iron" but I will tell you that in a PT-19 and a BT-13 power on stalls are _vastly_ different from power off stalls.

With power off stalls in the PT, you can do a "full aft stick" stall and fall straight down gently, keeping the nose pointed straight ahead by ever so gently walking the rudders; you get lots of warning too...it buffets early. Try that with power on and you get a quick buffet and then you flip over on your back into a spin so fast and so tight it will wring the sweat from your undies in less than two turns.

The BT is like that....only way more vicious in both cases. Little warning and and a quick wing drop in either case. Cage your eyeballs before trying this at home.

I've talked to guys that have spun the Mustang and they say it's a pretty eye-opening experience with power off and more so with power on. 6000' was the minimum mentioned number.

[Andy Bush]

Interesting thread!

Let's not forget that a plane will not spin if it is not stalled.

If we do as funked said...release the controls at the apex of the climb...then there is no reason to expect a spin since the airplane will not stall itself UNLESS it has been grossly overtrimmed.

The resultant pitch and roll movements will probably be unpredictable, and will vary depending on throttle position as the issue of engine torque is factored in.

The situation reminds me of one we used to see in the F-104 Fighter Weapons School. We would take the students out in a two-seater and have them run the jet out of airspeed in a vertical attitude. The idea was to show them that a F-104 was no different than any other airplane. It recovered from this exactly as any airplane should...pitch oscillations and some rolling due to torque but no dreaded spinning! (Spinning the 104 was not recommended!).

Now, if the pilot continues to hold the nose up as the speed drops off...then Katy bar the door...as Toad said!!

Andy

[Thog]

Good reading.  Question in ignorance; if you are having to release the controls at apex to avoid exiting controlled flight altogether, how do you go about a Hammerhead stall?  I understood this was a vertical or near-vertical stall with hard rudder, that would snap the plane over into a nose-down position.  And, not surprisingly, I haven't been able to pull it off in AH, though I did in WB.

Thog

[Westy]

 In the P-47, P-38 or P-51 when you get to about 90mph going straight up use full rudder to pull your tail around so you're nose down- with the 51 or 47 go with the torque of your engine for faster reversal. Hammerheads are very easy here, after some practice.

-Westy

[Andy Bush]

Thog

I did not mean to imply that the controls had to be released to avoid a stall in this situation. That is not the case...if the pilot is careful to maintain a neutral stick position and not accidentally add back pressure.

The aircraft is not stalled when performing the Hammerhead, at least not in the normal sense. It is just out of speed. A stall is due an excessive angle of attack...in the Hammerhead, there is no reason to push the AOA limits.

Andy

[funked]

Another thing to keep in mind in that in AH if you release the stick, the controls are neutralized to whatever neutral position you have trimmed for, and stay neutralized until you move the stick again.  In a real plane, releasing the stick may or may not cause the controls to neutralize.