Power-On Stalls

[midlifeflyer]

Remember right rudder.

Also, per PTS I think you need a minimum of 65% power for the stall. I typically have my students do it around 2000 RPM in a C152 so we don't pitch up as much.

If you need to go less than full takeoff/departure power to induce a takeoff/departure stall in a 152 at a reasonable "too high" pitch, I think you're doing something wrong. Most common thing I see is entering the maneuver at too high an airspeed.

 

[nosehair]

Ahh, I love this one. Especially in a higher powered airplane where it is more pronounced.

The big common error, which is not taught or dicussed in most flight training material that I know of, is that you cannot "keep the ball centered" in a straight climb.

Because of "P-Factor", the propeller thrust moves to the right side of the prop, causing the nose to turn left.

Now, what follows may not be exactly aerodynamically correct, but the bottom line is, you cannot hold a constant heading with the wings level and the ball centered when you have P-Factor.

You push right rudder to hold a heading, but that adds drag to the right side and decreases lift so the right wing comes down, so you add left aileron to hold the wings level. This crosses the controls, but is not a cross-control situation that will result in a spin.

The necessary component to a spin is yaw.

The nose must be yawing, either too much or not enough rudder to keep the nose constantly straight. If the nose is pointed straight and not allowed to yaw, a spin will not result no matter how much the controls are crossed.

One of the purposes of stall traing is to learn to hold a constantly straight heading throughout the entry and recovery of the stall - no matter where the ball is. Just like a landing. You keep the nose pointed straight down the center line with rudder and hold the wings level with the aileron. Period. You don't give a whit about the ball.

That's how you should stall.

 

[svcta]

If the nose is pointed straight and not allowed to yaw, a spin will not result no matter how much the controls are crossed.

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.

 

[Joshrk22]

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.

 

[MauleSkinner]

Technically, as Nosehair indicated, a power-on stall in a single-engine airplane is aerodynamically similar to an asymetric (engine out) stall on a twin. In other words, "ball in the center" doesn't have the airplane's flight path in line with its longitudinal axis. If you stall the airplane with wings level and ball centered, the right wing SHOULD drop.

The way to get the airplane to stall straight ahead is with a slight bank to the right (just like "into the good engine" on a twin) with the ball slightly out to the right.

Sparky Imeson explains it much more clearly than I do in "Taildragger Tactics", a book I recommend whether you fly taildraggers or not

Fly safe!

David

 

[oldxfr8dog]

Full power on stall in a AC560 is 29mph, would definitely be an E-Ticket ride doing one (an probably a one way ride).

I know you mean IAS, which at that pitch is unreliable, but do you mean full-power stalls are some kind of suicide ride in an 560?

 

[Metro752]

Should be able to do it just fine in a C152 at full power, as well as a 160HP or lesser C172.

 

[AC560]

I know you mean IAS, which at that pitch is unreliable, but do you mean full-power stalls are some kind of suicide ride in an 560?

You aren't going to get 29 mph at full power without a pitch way in excess of what would be safe (probably in excess of 60 degrees). You won't drop a wing when it breaks you will probably roll inverted. I also don't like the idea of being way below VMC in an 50 yr old airplane. If Bob Hoover was riding along maybe....

 

[svcta]

I'm one of the largest commander fans I know but those poor things are just getting tired. And cold-bent spars aren't standing the test of time. I'm wichoo on that one AC.

 

[AC560]

I'm one of the largest commander fans

probably the greatest light twin ever made.

 

[CFI2766]

One of the purposes of stall traing is to learn to hold a constantly straight heading throughout the entry and recovery of the stall - no matter where the ball is. Just like a landing. You keep the nose pointed straight down the center line with rudder and hold the wings level with the aileron. Period. You don't give a whit about the ball.

That's how you should stall.[/quote]


I just don't think this is the best logic. True enough, light GA planes used for training, and to some extent, a 182, are difficult to stall. That being said, a coordinated ball will ward off a lot of evil things.

 

[Joshrk22]

You think if you kept the ball centered and the wings level when you stalled the plane, it would still fly on the same heading...

 

[nosehair]

As to the power setting for a power-on stall, read the Airplane Flying Handbook. Not the PTS.

The AFH is the training handbook. When you teach the maneuvers required in 61.107 or 61.127 for pvt. and comm. certs.; when you make the endorsement that "you have trained and consider him/her proficient", you are saying you have trained in all the maneuvers indicated in the AFH, not just the "snapshot" maneuvers listed in the PTS, which are specifically designed to be standardized to be evaluated. But you, as instructor, and you as a student, should be covering, as a minimum, all the maneuver scenarios outlined in the AFH.

The AFH description of power-on stalls uses the terms "full power" and "take-off power", and "climb power".

Is there anyone out there that does not want to be proficient at being in full control authority if you happen to approach a full power stall during your take-off sequence?

The allowance to use only 65% during a checkride is for those high-power airplanes that might climb a couple thousand feet in a very steep pitch attitude which would be unsafe to climb through a large piece of sky with the nose way up.

You don't need to do that in most trainers, certainly not a 152.

And even in the high powered airplane, I am going to have the student do full power stalls for his/her own personal proficiency, and also do 65% power-on stalls for the checkride.

 

[AC560]

The allowance to use only 65% during a checkride is for those high-power airplanes that might climb a couple thousand feet in a very steep pitch attitude which would be unsafe to climb through a large piece of sky with the nose way up.

You could use 65% regardless of the airplane it is the minimum listed in the PTS. The high performance exception is for power less then 65%.

C. TASK: POWER-ON STALLS (ASEL and ASES)
NOTE: In some high performance airplanes, the power setting may have to be reduced below the practical test standards guideline power setting to prevent excessively high pitch attitudes (greater than 30° nose up).

REFERENCES: FAA-H-8083-3, AC 61-67; POH/AFM.

Objective. To determine that the applicant:
1. Exhibits knowledge of the elements related to power-on stalls.
2. Selects an entry altitude that allows the task to be completed no lower than 1,500 feet (460 meters) AGL.
3. Establishes the takeoff or departure configuration. Sets power to no less than 65 percent available power.

 

[nosehair]

C. TASK: POWER-ON STALLS (ASEL and ASES)
NOTE: In some high performance airplanes, the power setting may have to be reduced below the practical test standards guideline power setting to prevent excessively high pitch attitudes (greater than 30° nose up).

So, if you're using an airplane that you have to get the nose up above 30 degrees, then you can use less than 65% - ok, since most civilian proppeller airplanes, including what we call High Performance, and most HP airplanes are in the 200 plus area, 300hp at best, that little notation isn't even in our area of consideration.

REFERENCES: FAA-H-8083-3, AC 61-67; POH/AFM.

Note the reference to FAA-H-8083-3 which describes the use of full power for power on stalls.

Objective. To determine that the applicant:
1. Exhibits knowledge of the elements related to power-on stalls.

The knowledge of power on stalls is outlined in the above referenced handbook. This includes the knowledge of full-power on stalls. As a matter of fact, the AFH does not mention 65% power.

3. Establishes the takeoff or departure configuration. Sets power to no less than 65 percent available power.

OK. "Establishes takeoff or departure configuration".
Is that with less than take-off or departure power?

"Sets power to no less than 65%." Not to 65%. To not less than 65%.

Now, it is up to you, Mr. Instructor. Do you really think it is good for a pilot to not be trained in handling the equipment he is flying??

The PTS is not a training syllabus.

When you endorse a pilot applicant, your endorsement says you find that person competent - wait, here it is in the front of every PTS:

FLIGHT INSTRUCTOR RESPONSIBILITY

An appropriately rated flight instructor is responsible for training the pilot applicant to acceptable standards in all (bold in book, not mine) subject matter areas, procedures, and maneuvers included in the TASKs within each AREA OF OPERATION in the appropriate PTS.

ALL subject matter...with the references given for each task.

Your endorsement says you have done that and find him/her competent and proficient in all areas referenced for that task.

And, of course, the defining person is you, the CFI.

Are you really comfortable teaching only the rote minimums of the PTS, even if you are in the camp that says the minimums of the PTS are good enough?