Power on Stall?

[marcoseddi]

So we were doing power off stalls and power on last night, it was my second hour.. I had no issue with the power off stall although the power on stall, when he showed it to me the plane G'ed out to the right! Kind of makes me sick. I'm sure ill get used to that, thats no issue really he let me try it a few times..
Feels like I am waiting for the plane to go to the right, but then your not in the right direction.. Are we actually waiting for that to happen or once we bring up the angle of attack enough that it starts to beep.. should i right away bring the nose down, or that swing to the right is proper.. Any help on this would be great.

 

[denverpilot]

You can do a power on stall without any turning. Your instructor will demonstrate.

It requires your feet have a synaptic pathway to brain, which for some of us is a significant challenge. I fought with a non-rare malady you may have heard of that is called Rectal Cranial Inversion, but I got treatment for it in the form of falling leaf stalls, and my head slowly worked its way out of the incorrect positioning in the cockpit, which lowered the pressure on my lower back and allowed my feet to connect with my brain.

(In other words, at 2 hours you haven't started working on much coordination with rudder yet, and you'll find power on stalls don't need to be violent in any way with proper control inputs. And we've all been there.)

 

[Hobobiker]

Others will chime in, but since I'm a student going thru the same thing right now I'll comment. I train in a Cherokee, which doesn't drop a wing near as much as other planes during a stall (which is what I THINK you are talking about). I flew the Cessna 172 at our school just for comparison purposes, and it ALWAYS wants to drop a wing on stall. Just remember that if a wing drops, DON'T try to correct with aileron as you would be tempted to do. Keep the ailerons level and be prepared to immediately correct a dropped wing with the opposite rudder.

If I misunderstood what you were referring to, please disregard my entire post.

 

[JordanDelaney]

The reason you turned is because you weren't using enough rudder. You can do power on stalls all day and night and as long as you're coordinated you will stay level.

You should start recovering once you have actually stalled the airplane. The stall horn sounds about 5-10 kts above stall speed (depending on the weight of the airplane), once you feel the plane start to buffet, you then are in a stall and initiate a recovery.

Ask your instructor to demonstrate. It will feel uncomfortable to you at first, but after a few of them it will be just another maneuver. Have fun!

 

[Mafoo]

once you feel the plane start to buffet, you then are in a stall and initiate a recovery.

Really? I was under the impression I had to wait for the plane to drop before I could recover.

Didn't know I could do it when I felt the buffet.

 

[poadeleted20]

For practical test purposes, the power-on stall maneuver must be continued until the wing actually stalls, i.e., you get the stall break and the nose drops, after which you commence the recovery by moving the stick/yoke forward to reduce angle of attack below stall.

Throughout the maneuver (i.e., from the entry through the recovery), you should use rudder to keep the nose from yawing in either direction in a wings level stall, whether power-on or power-off. You can use outside visual cues like clouds or objects in the distance (either ahead if you can see over the nose or to the side if you can't) to tell you if the nose is yawing. If there's no yaw at the stall, neither wing should drop at the stall unless the airplane is bent.

The tricky part of the power-on stall is that you'll need increasing right rudder (unless you're flying a Yak or Wilga or something like that where the engine turns the other way) through the entry as the airplane decelerates and the left-turning tendency becomes more pronounced at the same time rudder effectiveness is decreasing due to reduced airspeed. Then when you recover, and AoA comes down while speed increases, you'll need to relax that rudder to keep the nose from yawing right (and the right wing from dropping -- which it sounds like is happening to you).

You also have to be able to demonstrate stalls (both power-off and power-on) with up to 15 degrees of bank. It's best to leave that until you've mastered wings-level stalls, but once you do, you will start to feel the coordination between rudder and aileron so the ball stays in the center during the approch to the stall.

 

[JordanDelaney]

Really? I was under the impression I had to wait for the plane to drop before I could recover.

Didn't know I could do it when I felt the buffet.

That's what I was taught at least. It's pretty hard to get the airplane to go into a full stall like that at full power for more than a few seconds

 

[poadeleted20]

Really? I was under the impression I had to wait for the plane to drop before I could recover.

Didn't know I could do it when I felt the buffet.

Not on a practical test. You are required to continue through the buffet (which starts around 5 knots before stall on most light singles) to the stall break for the Sport, Rec, and Private PTS's.

That's what I was taught at least. It's pretty hard to get the airplane to go into a full stall like that at full power for more than a few seconds

You're going to have to get past that to the stall break before you take the practical test.

 

[bbchien]

Mafoo, stall does not happen all at once, unless you are in a elliptical wingplan aircraft or such. The buffet indicates part(s) of a wing have stalled (flow separation). A well designed GA aircraft doesn't all stall at once, or it'd be like a Spitfire, or more like a twin.

At the PVT pilot level, you recover at the first sign of a stall. We are required to teach to the break, however.

I think it's idiotic, for example, to not teach at least one spin recovery (in an a/c legal for that). Here we are teaching the students "stay away for the dragon's lair". (Dragon = the spin).

If the student is distracted or in a situation unplanned and keeps pulling at the yoke, VOILA, the dragon is upon him.

I personally think the student needs introduction to the dragon, else the first time he encounter it he be alone. But for inital stall training, the CFI is likely to let you see the drop just to let you know what the doorstep of the dragon's den feels like.

If you stall fully, and co-ordinated, NO SPIN. But that requires rudder to center the ball. Thus the lesson. Center the ball and you'll manage to get WAYYYY into the stall.

 

[JordanDelaney]

Not on a practical test. You are required to continue through the buffet (which starts around 5 knots before stall on most light singles) to the stall break for the Sport, Rec, Private, and Commercial PTS's.
You're going to have to get past that to the stall break before you take the practical test.

When I took the PP practical I only did it to the buffet, it was very close but not completely into a stall.

 

[poadeleted20]

At the PVT pilot level, you recover at the first sign of a stall.

The Private PTS speaks more clearly to that:

6. Recognizes and recovers promptly after a fully developed
stall occurs.

This wording was changed in Change 3 Nov 2011 based on input from the field. The old wording ("Recognizes and recovers promptly after the stall occurs") was apparently not clear enough about the desired performance.

 

[poadeleted20]

When I took the PP practical I only did it to the buffet, it was very close but not completely into a stall.

You are lucky your examiner did not follow the PTS. Don't anyone count on that happening, because as noted above, the PTS is now more clear than ever on this point.

 

[ja_user]

Really? I was under the impression I had to wait for the plane to drop before I could recover.

Didn't know I could do it when I felt the buffet.

Well, for checkride purposes it depends on the PTS...
Currently the Private wants a stall, and Commercial want before a stall.. But for all purposes, you need to experience both (and a few spins), otherwise how would you really understand what you are seeing?

 

[poadeleted20]

Well, for checkride purposes it depends on the PTS...
Currently the Private wants a stall, and Commercial want before a stall.. But for all purposes, you need to experience both (and a few spins), otherwise how would you really understand what you are seeing?

Correct. The latest edition of the Commercial PTS includes this new note:

In accordance with FAA policy, all stalls for the Commercial

Certificate/Rating will be taken to the “onset” (buffeting) stall​

condition.

 

[Mafoo]

Well the actual full stall part is the best part (on power on stalls anyway), so I don't mind demonstrating it.

We have not done a spin, and I don't think we will do one.

 

[wabower]

I always thought ball centered for stalls was the answer until I bought a 172 for teaching and discovered wing would drop. Holding half-ball right solved the problem, but I thought it was rigging and never knew why until I read Sparky's book that explained it. So now I use half-ball right for all stall work and wings never drop.

 

[marcoseddi]

Tons of responses love it guys, thank you it really helps.. I've read about keeping right rudder on those stalls never knew why, I dont see why the tendency is for the left wing to be pulling and needing right rudder.. What makes that happens?

So techincally when i have full AoA and speed is lowered and then he jams up the speed so it will stall, basically you are just trying to keep the plane straight with some right rudder but whats, recover point you know with power off you hold it up and hit the gas once its nose diving.. But on power off whats the recover point when it drops, what are you suppose to do? Are you suppose to drop the nose to pick up speed and then pull up? Im going to have to call up my CFI today also this is bothering me.. I need to understand. I mean i only did it for a few minutes..

 

[redtail]

Tons of responses love it guys, thank you it really helps.. I've read about keeping right rudder on those stalls never knew why, I dont see why the tendency is for the left wing to be pulling and needing right rudder.. What makes that happens?

So techincally when i have full AoA and speed is lowered and then he jams up the speed so it will stall, basically you are just trying to keep the plane straight with some right rudder but whats, recover point you know with power off you hold it up and hit the gas once its nose diving.. But on power off whats the recover point when it drops, what are you suppose to do? Are you suppose to drop the nose to pick up speed and then pull up? Im going to have to call up my CFI today also this is bothering me.. I need to understand. I mean i only did it for a few minutes..

The torque of the engine causes a left rolling tendency. For each and every action, there is an equal and opposite reaction. As viewed from the cockpit, the crankshaft on an American-made engine rotates clockwise. The opposite reaction is for the airframe to roll to the left.

Slipstream
The propeller propels air currents around and about the airframe in a clockwise direction (as viewed from the rear). The airstream strikes the left side of the vertical stabilizer and rudder, yawing the nose of the airplane to the left.

Gyroscopic precession from the rotation of the crankshaft and propeller causes the airplane to yaw to the left.

In nose high attitudes, a left-turning tendency results from the fact that the descending propeller blade takes a bigger bite out of the air than does the ascending blade, which is on the left. This P-factor adds to the left-turning tendency when the airplane is in a nose-high attitude.

 

[Mafoo]

The torque of the engine causes a left rolling tendency. For each and every action, there is an equal and opposite reaction. As viewed from the cockpit, the crankshaft on an American-made engine rotates clockwise. The opposite reaction is for the airframe to roll to the left.

Slipstream
The propeller propels air currents around and about the airframe in a clockwise direction (as viewed from the rear). The airstream strikes the left side of the vertical stabilizer and rudder, yawing the nose of the airplane to the left.

Gyroscopic precession from the rotation of the crankshaft and propeller causes the airplane to yaw to the left.

In nose high attitudes, a left-turning tendency results from the fact that the descending propeller blade takes a bigger bite out of the air than does the ascending blade, which is on the left. This P-factor adds to the left-turning tendency when the airplane is in a nose-high attitude.

That's a great explanation. And while I knew all this, one thing I don't know, is of those factors, what contributes the most? I am thinking P-factor, but am not sure.

 

[redtail]

Power on stall, you're already at full throttle, just lower the AOA (which will happen as the nose drops) and accelerate.

Power off stall, release the back pressure at the break, full power, slowly raise nose, accelerate while cleaning up the flaps.

Just don't do what I did on my first lesson! At the stall break(power off stall), I pushed the throttle AND yoke full forward
We were 90 degrees nose down, looking at the planet!!!

 

[dukeblue219]

So techincally when i have full AoA and speed is lowered and then he jams up the speed so it will stall, basically you are just trying to keep the plane straight with some right rudder but whats, recover point you know with power off you hold it up and hit the gas once its nose diving.. But on power off whats the recover point when it drops, what are you suppose to do? Are you suppose to drop the nose to pick up speed and then pull up? Im going to have to call up my CFI today also this is bothering me.. I need to understand. I mean i only did it for a few minutes..

Sounds like your instructor hasn't really discussed what's happening in a stall and how to recover. I'm sure he/she will eventually. Stalls are all about the angle of attack -- the angle with which the air passes over the wing. For a power on stall you'll slow the airplane down and then increase the throttle and pull back quickly to increase the angle of attack until the air no longer flows smoothly over the wing. When that happens, the wing loses its ability to generate lift. The way to recover is to reduce that back pressure and allow the nose to drop enough that the wing begins to fly again. It's not a matter of "hitting the gas" at all.

Similarly for a power-off stall, you just slow down in landing configuration and hold the nose level until you slow so much that the angle of attack becomes too high. Remember, the wings will look level but you're going to be sinking so the relative wind is hitting the wings from in front and below, just like in a power-on stall, so the angle of attack is still high! You can recover from that stall just by letting off the back pressure on the stick/yoke and the reduced angle of attack will allow the wing to fly again. You don't strictly *need* to "hit the gas" to recover, but that's how we practice it because the idea is that you're on an approach to landing and need to climb quickly. But it's not the throttle that's recovering the stall, it's the reduced angle of attack first.

 

[bflynn]

That's what I was taught at least. It's pretty hard to get the airplane to go into a full stall like that at full power for more than a few seconds

Check the PTS standards - Objective 3 for Power On Stalls states that you must set the power to no less than 65 percent available power. If you talk to the examiner before you leave the ground about why you want to do this and why it helps more accurately demonstrate the stall condition, it seems pretty reasonable to me that they should permit it. But there's probably still a few there would be a few who won't. If they want to see it at full power, then you show them at full power and climb 700' while trying to get the airplane to break. Isn't that really an accelerated stall?

You're simulating a situation where the power isn't enough for the airplane load...for these purposes we'll say that the power isn't there as opposed to the airplane being overloaded .

With less power input into the airplane, you can negotiate a full break to a stall much easier than with full power.

 

[Mafoo]

That's what I was taught at least. It's pretty hard to get the airplane to go into a full stall like that at full power for more than a few seconds

To add to what Brian is saying....

The main reason we simulate those two stalls, is because it's an example of what would happen if you came in too slow on a landing (power off stall), or climbed out too steep on a takeoff (power on stall).

Because of this, I think it's important to do a power on stall like you would take off (full power) so you know what it would be like if you ever really did it.

Now, that's for training. In real life, I could never see myself pointing the plane up as high as you need to, in order to do a power on stall, but I don't know much yet. Maybe that's something someone has a need to do.

It sure feels like the only way you could really achieve that senario in real life, is if you're just being stupid.

 

[redtail]

That's a great explanation. And while I knew all this, one thing I don't know, is of those factors, what contributes the most? I am thinking P-factor, but am not sure.

Well in the power on stall, I'd say all of them except Gyroscopic precession, unless you aggressively push the nose over which would put a force at the top of the spinning prop, which the resultant force would be 90 degrees in the direction of rotation (3 o'clock), that would cause the nose to yaw to the left.

I experienced that recently during my tailwheel training. During the takeoff roll, if you raise the tail too abruptly (by pushing forward on the stick) applying a force at the top of the prop, you get a definite pull to the left due to gyroscopic precession!

After a couple of takeoffs, I learned to smoothly raise the tail:wink2:

 

[MDeitch1976]

So techincally when i have full AoA and speed is lowered and then he jams up the speed so it will stall,

He is not adding power to stall. He is slowing you down to the speed you would be climbing out on takeoff. Then he is adding full power as if you were at take off power. Just imagine that you are departing the runway, not several thousand feet AGL. This is a simulation at a safe altitude for recovery.

Power on stalls are a definitely exciting. The break is abrupt. But it is over fairly quickly. When the planes stalls, there is not much airspeed that needs to be gained to exit the stall.

 

[MassPilot]

Really? I was under the impression I had to wait for the plane to drop before I could recover.

Didn't know I could do it when I felt the buffet.

On my checkride he had me recover from the power-on stall at the first sign of the stall, which was the first blip of the stall horn. He had me recover from the power-off stall at the break. My CFI said I could be asked to recover at any point and it was completely up to the DPE. When with my CFI, we always did full break.

 

[Mafoo]

On my checkride he had me recover from the power-on stall at the first sign of the stall, which was the first blip of the stall horn. He had me recover from the power-off stall at the break. My CFI said I could be asked to recover at any point and it was completely up to the DPE. When with my CFI, we always did full break.

When did you do your check ride? f you read Ron's post #11, it looks like what you're saying was common enough for them to change the wording in late 2011.

 

[MAKG1]

That's a great explanation. And while I knew all this, one thing I don't know, is of those factors, what contributes the most? I am thinking P-factor, but am not sure.

Yes, in a power-on stall, it's mostly P-factor. That depends on angle of attack and throttle, and you'll have both cranked up as high as they will go.

You feel gyroscopic effects (FYI, that's also a torque, but it's not usually labeled as such in this domain) during (not after) rotation. Rotating slipstream is there all the time -- it's a high power thing, and you'll feel it over P-factor if you're straight and level at full power. Engine torque is something you feel with changes in throttle, not at constant full power.

A stall break is rather subtle on a Cherokee, but it's there. If you see any uncommanded drop of the nose, you're there. It does not take place at the stall warning, but rather several knots slower. On a Cessna, there is a much more obvious break, but not a whole lot of buffeting.

 

[Sac Arrow]

On of the common mistakes in a power on stall is not slowing enough before adding power and performing the stall, resulting in an excessive pitch angle.

When I was a student pilot, my power on stalls more resembled hammerhead stalls until I got that figured out.

 

[Hobobiker]

Just don't do what I did on my first lesson! At the stall break(power off stall), I pushed the throttle AND yoke full forward
We were 90 degrees nose down, looking at the planet!!!

Glad it wasn't just me! I thought I was to PUSH the yoke forward and give her full throttle. Similar situation as yours and the ONLY time I've ever noticed my CFI get excited.

Now I know the key is to "Release Back Pressure" rather than shove the yoke forward. To make matters worse, I'm a 260-lb guy who likes to lift weights a few times a week. My CFI was afraid he wouldn't be able to pull the yoke back if I really wanted it forward.

 

[redtail]

On of the common mistakes in a power on stall is not slowing enough before adding power and performing the stall, resulting in an excessive pitch angle.

When I was a student pilot, my power on stalls more resembled hammerhead stalls until I got that figured out.

 

[poadeleted20]

Now I know the key is to "Release Back Pressure" rather than shove the yoke forward.

That's aircraft-dependent, although most light single-engine trainers will recover if you just let go. Move up to higher performance aircraft, and the situation changes (in the F-4 and F-111, it was full forward on the stick*), so get in the habit of a positive forward movement, not just releasing pressure.

*F-4 Out of Control memorized boldface circa 1980:
Stick - Forward
Ailerons and rudder - Neutral
If not recovered, maintain full forward stick and deploy drag chute
(not bad for not having flown one in over 30 years...)

 

[redtail]

Glad it wasn't just me! I thought I was to PUSH the yoke forward and give her full throttle. Similar situation as yours and the ONLY time I've ever noticed my CFI get excited.

Now I know the key is to "Release Back Pressure" rather than shove the yoke forward. To make matters worse, I'm a 260-lb guy who likes to lift weights a few times a week. My CFI was afraid he wouldn't be able to pull the yoke back if I really wanted it forward.

I levitated the poor guy twice in a row before I got it right! When we got back to the flight school, I was sweating bullets

That was the first time I questioned whether or not I really wanted to do this flying thing that I've fantasized about since 4 years old

 

[poadeleted20]

I levitated the poor guy twice in a row before I got it right! When we got back to the flight school, I was sweating bullets

That was the first time I questioned whether or not I really wanted to do this flying thing that I've fantasized about since 4 years old

If you're levitating things in a light single, you're being too aggressive on the recovery. :wink2:

 

[redtail]

That's aircraft-dependent, although most light single-engine trainers will recover if you just let go. Move up to higher performance aircraft, and the situation changes (in the F-4 and F-111, it was full forward on the stick*), so get in the habit of a positive forward movement, not just releasing pressure.

*F-4 Out of Control memorized boldface circa 1980:
Stick - Forward
Ailerons and rudder - Neutral
If not recovered, maintain full forward stick and deploy drag chute
(not bad for not having flown one in over 30 years...)

That's a good point. I've never flown high performance aircraft but I always think about what I'd do if the engine quit right after takeoff!

I think it would be best to use positive forward pressure, correct?

 

[redtail]

If you're levitating things in a light single, you're being too aggressive on the recovery. :wink2:

Indeed, but it was my first or second flight lesson

 

[MassPilot]

When did you do your check ride? f you read Ron's post #11, it looks like what you're saying was common enough for them to change the wording in late 2011.

I did mine this past April. Maybe the fully developed power-off stall we did was enough to meet the requirements.

 

[denverpilot]

If you're levitating things in a light single, you're being too aggressive on the recovery. :wink2:

Or trying to launch a paper airplane from the glareshield to the back seat.

 

[poadeleted20]

That's a good point. I've never flown high performance aircraft but I always think about what I'd do if the engine quit right after takeoff!

I think it would be best to use positive forward pressure, correct?

Single-engine fighter? Ejection handle - squeeze and pull. Twin-engine fighter? Throttle (good engine) - afterburner.

But if you're talking light planes, it wouldn't matter -- even a Cessna 150 requires dropping the nose if the engine quits on initial climbout to obtain/maintain best glide speed. In fact, it's probably more important to get the nose down in the lower performance fixed gear types since they have more parasite drag and will lose airspeed more rapidly. Go out with your instructor and try it to see what I mean -- establish a Vy climb, and pull the throttle. And do this at least 1500 AGL, please.

 

[redtail]

Single-engine fighter? Ejection handle - squeeze and pull. Twin-engine fighter? Throttle (good engine) - afterburner.

But if you're talking light planes, it wouldn't matter -- even a Cessna 150 requires dropping the nose if the engine quits on initial climbout to obtain/maintain best glide speed. In fact, it's probably more important to get the nose down in the lower performance fixed gear types since they have more parasite drag and will lose airspeed more rapidly. Go out with your instructor and try it to see what I mean -- establish a Vy climb, and pull the throttle. And do this at least 1500 AGL, please.

Yeah I need to practice that. When I do air work, I usually just do power on/off stalls, etc. My engine out drills are basically just establishing the ABCs, never really any simulated departure engine outs at Vy.

Oh yes, I always climb to at least 3000 AGL for any air work