Recovering From A Stall

[MorgothNL]

Originally Posted by SgtPappy

For all intents and purposes there are 2 kinds of stalls. here's a simple explanation of them

Low speed stalls and high speed stalls; the latter of which does not actually always happen at high speed.

Low speed stalls are created when your aircraft simply runs out of sufficient speed to maintain flight and create stability. When the aircraft moves too slowly through the air, the strongest force exerted on the plane it the torque on the fin/rudder. This causes the plane to simply tumble out of the sky, and, depending on the orientation of the plane at the time, it can result in a flat spin, or a simple wing-over.The latter is preferable because it allows the plane's nose to be pointed down so you can gain speed, and thus, lift. A flat spin can be difficult to get out of, but it is possible. It is always advisable to point the nose down, in any case and hard rudder in the opposite direction.

High speed stalls are likely what you are encountering the most. This happens when the aircraft is pulling so much angle of attack (a.k.a. Alpha, a.k.a. AoA) that the airflow over top of the wing is disrupted to a point that it no longer flows down the trailing edge. This is known as airflow separation. The lift at this point is destroyed over the affected area of the wing and, once again, the torque overpowers the minimal lift (or lack thereof) created under the wings. For this stall, simply push down on the stick with both opposite rudder and opposite aileron.

BUT here's where the torque can save you, at least in real life. On an aircraft with a clockwise spinning engine (seen from the cockpit), the torque itself will push the plane the left, inducing a left spin when lift is minimal. Thus, if you manage to enter a spin to the left, cutting throttle is a good idea so that the torque's gyroscopic effect lowers. If in a spin to the right, INCREASING throttle will help. Of course, for other planes that have props spinning in the opposite directions, the opposite applies.

I dont want to bitch at you, but many of what you say is kind off against a lot of what I learned at flight school.

If you talk about 'all purposes' there are more types of stall then just high and low speed. (think about accalerated stall, deep stall, departure stall). Many can be put under either high or low speed stall category, but not all. (like the accelerated stall)

My teacher always used to say: stall has nothing to do with speed. (ofcourse an exageration) but what he meant was that the whole stall principle is no based on speed, but on angle of attack, shockwaves, boundarylayer seperation etc. Speed plays a role, but it is not the key to understanding stalls.

In the low speed stall you talk about speed. But the priciple of low speed stall is all about angle of attack. If you stall at 50 kts, you probarbly prevent that stall by increasing angle of attack.

The high speed stall you explain, is actually a accelerated stall. definition accelerated stall:An accelerated stall is a stall that occurs while the aircraft is experiencing a load factor higher than 1 (1g), In these conditions, the aircraft stalls at higher speeds than the normal stall speed. This is indeed what happens most of the time in the game. You fly fast, and put a sudden input of controls (for instance increasing AoA like you say).
Stall speed = stall speed 1g x (square root load factor). This type of stall is no per se at high speeds, as you can see in the formula. Imagine flying just above stall speed in level flight. If you put a sudden input in controls now, creating 2g, your stall speed increases by a factor of 1.5. thus making you stall if you were allready close to stall speed.

For good order: a high speed stall happens at HIGH speeds. We are talking about near sonic speed here. This stall caused many WW2 pilots their life, because this stall was still unknown in WW2. It happends when going so fast, that you actually start reaching local speed of sound somewhere on you plane. This will cause a small shockwave, wich seperates the boundary layer from you wing. This seperation occurs for instance half way your wing, in that case your ailerons will not have a boundary layer any more, and thus the can be moved all you like, but nothing will happen.
The P-38 lightning had this problem often because of its tail stabilisor. It would sometimes go so fast in a dive, that a shockwave would disrupt all the airflow before it reached the tail. Thus making his elevator useless, and making him unable to pull up out of the dive.

Sorry, dont want to be mr smartypants, but I felt this had to be clear