Power-On Stalls

[AC560]

The PTS is not a training syllabus.

I didn't say it was. You made the comment "The allowance to use only 65% during a checkride". Had you said training I wouldn't have commented.

From a training perspective you can see from my previous post that I don't dispute what you are saying "Probably true but the purpose is to handle departure stalls so unless you regularly plan on taking off at 65% or less power you might want to be able to cope. Amish gave some good advice on how to master the maneuver, try working through that in conjunction with your instructor. You will get more satisfaction and be a better pilot."

Peace out.

 

[nosehair]

You sure you want to stick to that?

Yeah...

I would actually contend that as one wing falls of, you should only counter that with yaw. By yawing the airplane in the direction you need to roll to bring the low wing up, you're restoring a little airspeed to that side, therefore balancing the stall out over the entire wing again. Theoretically, yaw could prevent a spin, whereas aileron will only aid one.

Yeah, that's what I said. No yaw = no spin. If yaw begins to occur, sufficient rudder to stop the yaw prevents the spin.

 

[svcta]

an issue of semantics, perhaps, but I don't believe that yawing motion actually causes a spin as a blanket statement. It WILL if you use ham-fisted rudder inputs. However, aileron will absolutely do it, especially in airplanes that aren't trainers. In some airplanes improper use of ailerons(as in any at all) will lead to control reversal, and aggravate a stalled situation very badly. I suggest you learn to do stalls without aileron....especially if you want to train beyond your training, as has been mentioned above.

 

[nosehair]

Nosehair,

Are you saying it's okay to cross the controls in the stall to keep it on heading? That's what I was doing and it worked fine. But everywhere I've read it says not to do that.

That's why I said I have never read about the "assymetrical thrust" in any flight training material I know of. I only figured it out because of experience.
So I try to pass it on.

It's the same theory that multi-engine pilots talk about when operating on one engine. If the thrust line is not in line with the airplane fusalage, that thrust provides a yawing motion which must be corrected with rudder, but the rudder horizontal lift makes the airplane slide sideways through the air and you bank slightly, 3-5 degrees to make the airplane fly straight through the air in the direction the nose is pointed, but the ball will be out about a half of a ball width.

We should apply that same technique to climbing in a single. The P-Factor in 100HP engine at normal climb speeds is almost not noticable, so the technique is missing, but when you get to 225HP or so, you really notice it.

The only time you should be concerned about "coordination" or keeping the ball centered is in a turn. That's right - in a turn.

When you make that base-to-final turn, (or any turn, really) you should be concerned that you have the correct bank angle for the rate of turn that you are inducing.

When you practice the turning stalls, the focus should shift from the heading to the ball.

When you are flaring for a landing, rotating for a take-off, or practicing a straight-ahead stall, which should simulate something like a landing or take-off, you aren't concerned with the ball, are you? I hope not. Those times are strictly rudder-controls-heading, and ailerons control bank, regardles of the ball. You land in a slight slip in a crosswind. You might make the entire approach in a slip correcting for crosswind, and the ball is hanging down in the inside of the slip.

But, look, this type of "crossed-controls" does not allow yaw. As long as you have rudder authority to hold the nose straight, you ain't gonna roll over into a spin.

Of course, you have to maintain rudder authority. If you run outta rudder as you stall, then you are gonna yaw, and maybe spin.

So, now when you do your practice turning stalls, the ball becomes the controlling factor of how much rudder to apply.

If you do a power-on stall in a 20 degree banked turn to the right, you will wind up with the controls severely crossed.

Start a 20 banked climbing turn, with the ball centered, then ease the nose up to about a 20 degree nose-up attitude and maintain this attitude while holding a constant bank angle and keeping the ball perfectly centered.

As the speed slows, the ball will try to slide down inside the turn and you will have to add right rudder which will cause the bank to try to increase, and you will have to add left aileron to keep a constant bank so that by the time you stall, you will have a good bit of right rudder and a very significant amout of left aileron. But the bank is constant and the ball is centered. When the stall occurs the airplane rolls left - towards level.

Of course, if you continue to hold that large aileron input, the airplane would roll past level into a spin/spiral to the left, but of course you would neutralize the ailerons as you roll level.

The point is: there are lots of times you will be "uncoordinated" :
1) crossed-controls to keep the ball centered in turns, and
2)having the ball out of center when in a straight ahead-wings-level situation.

 

[caliginousface]

You sure you want to stick to that? The only reason we use rudder to induce a spin is because it's the easiest way to do it. What you need is a stalled wing and one side more so than the other. By kicking the rudder(yawing the airplane) you accelerate one wing through the air and increase its airspeed while decreasing the other wings airspeed. Sort of like retreating blade stall in a helo.

If you utilize a little theory, you can see how having the ailerons in play in a stalled situation will increase one wing's angle of attack while reducing the other's, resulting in having one wing further stalled than the other. Especially as one wing begins to fall, you try to counter that with aileron and the stall on that wing is further developed. I would actually contend that as one wing falls of, you should only counter that with yaw. By yawing the airplane in the direction you need to roll to bring the low wing up, you're restoring a little airspeed to that side, therefore balancing the stall out over the entire wing again. Theoretically, yaw could prevent a spin, whereas aileron will only aid one.

Now again, in the trainers that we're talking about, we have to impart a yaw on the airplane(usually) to force it to spin(to accelerate one wing and decelerate the other). But this is NOT the case in every airplane.

So if the right wing is dropping during a power-on stall, I would need to reduce right rudder or use left rudder rather than correct the bank with aileron, then neutralize them, and reduce some of the rudder pressure?

Is that what you're saying?

 

[svcta]

You're asking for trouble by correcting roll with aileron exclusively when stalled. Trainers are, of course, very forgiving. But other planes may not be, and old habits die hard.

 

[caliginousface]

You're asking for trouble by correcting roll with aileron exclusively when stalled. Trainers are, of course, very forgiving. But other planes may not be, and old habits die hard.

I meant before the stall occurs, but yes I agree.

 

[MauleSkinner]

I meant before the stall occurs, but yes I agree.

Before the stall occurs, you should be using coordinated aileron and rudder for roll correction...keeping in mind that at the airspeeds involved, it could take a LOT of rudder to coordinate a little aileron.

Fly safe!

David

 

[Amish RakeFight]

For you practicing CFI's out there, I've got a good exercise that will keep your students from using that forbidden alieron.

Next time you go out to practice power-on's, demonstrate one where you maintain your heading solely by use of the aileron. Zero rudder input. Keep pitching up with full power and maintain heading with aileron input only. When that baby hits the stall, let'em see how bad an idea it is to use aileron. They'll be sure to be more assertive with rudder inputs in the future.

 

[VNugget]

For you practicing CFI's out there, I've got a good exercise that will keep your students from using that forbidden alieron.

Next time you go out to practice power-on's, demonstrate one where you maintain your heading solely by use of the aileron. Zero rudder input. Keep pitching up with full power and maintain heading with aileron input only. When that baby hits the stall, let'em see how bad an idea it is to use aileron. They'll be sure to be more assertive with rudder inputs in the future.

Funny. After reading most of this thread, that is exactly what I did with a student today, with good results*, and came here to post exactly what you did.

*By good results, I mean it did what I expected and went into a spin. Don't you hate when you tell the student to do something and such-and-such bad thing is gonna happen, and it doesn't happen? Argh!