Trim does nothing but move or apply force to the elevator. Have you found the trim has the ability to fully-deflect the elevator? If not, no stall. Yeah, you can continue to slow down at constant trim until the airplane pitches over. But that pitch over is going to be a parabolic pitchover at less than critical AOA, not a stall nose drop. Someone should easily be able to video an actual hands-off trim stall.
Full Flap Full Power Stall
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Trim does nothing but move or apply force to the elevator. Have you found the trim has the ability to fully-deflect the elevator? If not, no stall. Yeah, you can continue to slow down at constant trim until the airplane pitches over. But that pitch over is going to be a parabolic pitchover at less than critical AOA, not a stall nose drop. Someone should easily be able to video an actual hands-off trim stall.
So what? You still say nothing of a stall. I can pitch my airplane up to a full power 60 degree climb and hold it. Airspeed will decay very rapidly, but it will not stall.
Stewartb
Final Approach
Mine will. If you read back I also have stated that the exercise to take it to a stall is misguided.
I agree that the exercise is misguided as the reactions required for it are the same as any other stall. No need in adding the extra loads possible to the flaps in practice.
Then anyone who has not actually done this should not use the term trim "stall". IMO, people should have a full understanding of how their airplanes fly, and the dynamics under variations flight conditions. If your trim system is powerful enough to cause near full elevator deflection and a true stall, fine. Most don't. People should know what really happens in the airplanes they fly, otherwise they are fearing the unknown.
The reality is that for most, the go-around is an exercise in airspeed control, not stall avoidance. I don't want to hear that they are the same thing. Anyone who flies aerobatics understands this.
Stewartb
Final Approach
You may be onto something there. I have jackscrew trim, not a wimpy trim tab. I can't remember the last time I stalled an airplane that didn't have a jackscrew.
I could not produce the effect in a 182A with the jack screw tail. I was demonstrating slow flight with full flaps and full trim and was still holding back to get to stall buffet.
![brian]](/community/data/avatars/m/21/21096.jpg?1456258959){kind=avatar}
brian]
Cleared for Takeoff
Yea, at some point, the answer is no for me. I've done a stall like this in a C172 and remember it feeling awkward. Now I have a "baby bo", but I've heard descriptions from owners pushing a 36 like this - it's the 90 degree wing drop that makes me believe that I have better things to do ....
Stewartb
Final Approach
I could not produce the effect in a 182A with the jack screw tail. I was demonstrating slow flight with full flaps and full trim and was still holding back to get to stall buffet.
Demonstrating slow flight at full power?
RotorAndWing
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brian];1672909 said:
Not that big of a deal really. While attitude may scare you, it is not independently indicative of danger. As long as the total energy stays in the aircraft operating envelope, you are fine and dandy. While it may be scary, this is not high risk. You have 3 total energies combined that you work with, chemical (engine), Kinetic (airspeed), and Stored Gravity (altitude).
Since extra energy is always a good thing, if you store up plenty, you have yourself covered for the bottom of the envelope. The other end is governed by kinetic energy.
This maneuver begins at the bottom of the kinetic energy envelope while we are producing maximum chemical energy, and when the nose drops, we instantly take gravity as a resistance, and swap it to a combining force. At this point gravitiy is accelerating you 19kts per second which is a pretty nice rate, so no need to add engine power; pull the throttle. As we pull back in recovery we are adding drag at a nice rate managing the acceleration until acceleration and drag meet and we have to bring the throttle back in.
All pitch attitude is is another throttle. It is the throttle you use for gravity rather than chemistry.
dtuuri
Final Approach
Is this good enough, fast forward to 14:30? https://www.youtube.com/watch?v=0oms3r1q6Gs
On a go-around, the usual pitch attitude with flaps up is too steep for what it should safely be with flaps down, don't you agree with that? Whatever the reason might be (extra elevator authority due to propeller wash; true horizon not visible) for getting in that situation, a stall will follow if the pitch is held, say in an attempt to out climb rising terrain, IMO.
EDIT: Similar in theory to a whip stall.
dtuuri
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Pitch attitude with full flaps will naturally be different, you change the whole lift profile of the wing. Pitch attitude alone is irrelevant to stall. You have to mate it to relative wind to indicate something.
dtuuri
Final Approach
The assumption is the pilot forgot to retract flaps during a go-around, the question is, "Could that cause a stall?" The answer is, "Yes!"
dtuuri
All I ask is that someone demonstrate it to me so I can do this. It doesn't happen to me and I'm trying to figure out why.
when I trim for 60kts on final with full flaps, and I give it full throttle, I climb as well as the plane will climb with full flaps at 60kts.
dtuuri
Final Approach
Are you using the same pitch attitude you'd have used if you didn't forget the flaps?All I ask is that someone demonstrate it to me so I can do this. It doesn't happen to me and I'm trying to figure out why.
dtuuri
That silly video doesn't show a stall. And a 'whip' stall takes an extreme nose high attitude such that the airplane will actually tailslide a bit. I'd have to test to see what kind of attitude it takes to transition from a parabolic arc to an actual whip stall. I'm going to guess over 60 degrees. Non-aerobatic pilots will think that is vertical. If your trim system is so powerful that it pops you up to a 70 degree attitude or so, then you'll probably whip stall. 45 degrees won't do it. Even 45 degrees is steeper than most GA pilots will ever see messing around with stalls and such. Remember the regs require chutes for all occupants for over 30 degrees of pitch. GA pilots will find 30 degrees very steep.
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I use whatever pitch attitude the trim leaves me with. When I retract the flaps I have to make adjustments, but until then I just let it do it's thing and control the lateral and yaw axis while I let power and trim balance my pitch transition at best performance until I start cleaning up, then I have to manage pitch.
So long as I have sufficient climb performance, I am in no rush to clean up.
dtuuri
Final Approach
I didn't think you'd be satisfied.
Well, I said "similar in theory", meaning the wing stalls because of the downward pitching movement when the upward momentum is lost. I used to make use of that trick when teaching power off stalls in a Piper Colt. It didn't have enough elevator to stall from straight and level flight, so I'd enter from a climb attitude and then remove power. It stalled fine that way and didn't require anywhere near the aerobatic deck angles you mention. The only "parabolic" flight regimes I'm familiar with induces zero "g". I don't see any connection between a go-around, flawed or not, with that type of maneuver. With full power and full nose-up trim even full forward elevator pressure might not be enough to create a parabolic flight path. A Learjet might even try to do a loop!
dtuuri
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dtuuri
Final Approach
It seems we are talking past each other. You are addressing whether or not an airplane, stabilized with full nose-up trim and power, will stall. I'm addressing whether a pilot who forgets to retract flaps on a go-around can inadvertantly stall the airplane. I have witnessed the latter during a stall demo on a flight test. The OP's DPE may have, also, and therefore cared more about the OP's welfare than about the PTS. I think he did the OP a service.I use whatever pitch attitude the trim leaves me with. When I retract the flaps I have to make adjustments, but until then I just let it do it's thing and control the lateral and yaw axis while I let power and trim balance my pitch transition at best performance until I start cleaning up, then I have to manage pitch.
dtuuri
I am not doubting that you have seen the effect, I am trying to understand the mechanism by which it happened.
Stewartb
Final Approach
Reality.
dtuuri
Final Approach
The pilot. Imagine making an approach to an upslope runway where the real horizon is well below the ridge line above the airport. Short strip, pilot's too high, nervous, goes around, but forgets to retract flaps. Tunnel vision, loses awareness of configuration and airspeed and stalls. Just didn't seem like the nose was too high. Darn it.What made the pitch go beyond the trim pitch?
dtuuri
Stewartb
Final Approach
There is no assumption that the pilot forget to retract flaps. If I have to go around, and I occasionally do if I'm bucking the wind, I have to go over obstacles in a narrow slot where the mechanical turbulence is beating me around. I don't have time to retract flaps until I'm over the obstacles and stabilized. What happens? I'm dropping in slow with full aft trim (nose up) and full flaps. If I don't like what I see... in with full throttle and be prepared to do a literal push up against the yoke because that's what it takes to get the nose down enough to maintain flying speed. Once I'm over obstacles I'll milk off a couple of notches of flap and reduce power and that relaxes the required force so that I can lean down and adjust trim and get prepared for another try. The inference that this pitch up is momentary is incorrect. I have to hold the yoke in for as long as I keep the flaps out and the power in. As to why? I'd guess 275hp and an 86" prop blowing on fully extended flaps and a fully tilted tail make the plane behave differently than it did moments before with near zero thrust. All I know is it does the same thing every time.
But they had to pull the yoke to do that, that had nothing to do with a "trim stall". That was a pilot pulling it into a stall because he lacked the climb performance due to forgetting flaps. That's different from adding throttle and the plane pitching up into a stall if the pilot did not intervene with what the trim commanded.
dtuuri
Final Approach
I'm responding to the OP's situation which was a go-around stall, flaps down. But I'm sure an elevator trim stall can and does happen without any pilot assist. The sudden thrust/propwash can induce an unsustainable excessive pitch attitude resulting in a stall. I've got the FAA on my side, so if it ain't true--you'll have to prove it to them. Of course, if you've got a lot of blow-by in your cylinders from running at WOT you might not have enough power to hurt yourself.
dtuuri
bflynn
Final Approach
Full flaps stall can occur on a go-around.
It not technically the second thing. First full power, establish air speed, then incrementally retract flaps. If you try to retract flaps right away, you run the risk of stalling and dropping to the (hopefully) runway under you.
But, if someone doesn't do that and instead does power + pull to go up, then pulls harder and/or tries to trim off the pressure, you're into a go-around stall condition. Some airplanes will climb very poorly and power won't help much. Pull hard and you're stalling instead of going around.
We went through this during training. It's a bit difficult to do without realizing it, but I can see how someone could be under stress and lose it.
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I'm responding to the OP's situation which was a go-around stall, flaps down. But I'm sure an elevator trim stall can and does happen without any pilot assist. The sudden thrust/propwash can induce an unsustainable excessive pitch attitude resulting in a stall. I've got the FAA on my side, so if it ain't true--you'll have to prove it to them. Of course, if you've got a lot of blow-by in your cylinders from running at WOT you might not have enough power to hurt yourself.
dtuuri
The sudden thrust on the flaps is behind CG and leverage says it exerts a pitch down force.
I have just never had a plane take on a pitch that was not associated with the trim speed it was configured at without me adding an input, and that is the definition of the elusive "trim stall". If people say it exists, fine, explain the mechanism to me because I am confused.I have never added power and had the plane pitch up into a stall due to the trim setting, and that is a 'trim stall' as I have heard it described. "If I don't push forward when I add power, the plane will pitch up into a stall."
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poadeleted20
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You've got the cart before the horse. When you're on the back side of the power curve, if you slow down, yes, you need more power to maintain altitude. However, merely adding power will not slow you down -- it will, in fact, cause you to climb at the same speed. The problem occurs when you're already at max power and sinking at that speed. With no available power to add, the only way to recover at that point is lowering the nose and trading altitude for airspeed.
brian]
Cleared for Takeoff
Question: If the flaps are down and you decide to do a go-around and push the throttle full in - won't the nose pitch up like crazy on most aircraft? (Ok if you use any kind of trim at all.) With my limited experience - that tends to get your attention that the yoke/stick must go forward - now!
poadeleted20
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Whether it will "pitch up like crazy" is rather a subjective judgment, but any time you add power, the airplane will attempt to accelerate, but the trim system will pitch the nose up to try to maintain the trimmed speed, resulting in a pitch up and climb. There may be some initial oscillations around the trimmed speed, but eventually it should settle out in a higher pitch attitude, higher vertical speed/lower sink rate, and approximately the same calibrated airspeed.brian];1673623 said:
dtuuri
Final Approach
The hands off trim airspeed will be the hands off trim airspeed regardless the vertical speed. Why would it stall if you don't pull back from the trim induced pitch?
MAKG1
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If you say so. I've experimented with the effect of power on airspeed hands off in a slow 182. Have you?
I find the "trim airspeed" idea to be simplistic, a decent first approximation to teach a student. Not fundamental.
MAKG1
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What made the pitch go beyond the trim pitch?
There is no such thing as a trim pitch, not even approximately.
Jim Logajan
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I had wanted to run a slightly related exercise (engine out on takeoff - will it stall if the pilot doesn't push down elevator, or will it stay near trim speed on its own) a couple months ago, but work deadlines, weather, and holidays have conspired to keep me grounded. If only I knew someone else who was a pilot with access to a plane and a video recorder, but that's a mighty rare combination, and I don't know where such critters exist. :wink2:
Fortunately some good weather in the forecast this week in my neck of the pacific northwet, though another work deadline needs to be crossed first. Sigh. I'll shoot for a try on Friday.
I think a video with clear view of the yoke, throttle, airspeed, altimeter, and artificial horizon would provide all the needed information. View out the windows would be less valuable I think. That seem reasonable? I'd have access to a C-152 or C-172.
Yes, yes I did, that's why I bring up the question. After having someone demonstrate slow flight to me by doing 65kts with full flaps in a C-182A. I asked her for the plane and proceeded to trim it all the way nose up, hit the throttle to full and had to keep pulling the nose up to get to the stall horn for slow flight, and that is not yet stalled. If I let go of the yoke, the nose would drop away.