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Thread: Stall in a turn

  1. #1

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    Stall in a turn

    I have been having a spirited conversation with a couple of friends about stalls during a turn.
    I have seen it in other articles that say the upper wing stalls first.
    It is not logical to me.
    I am assuming a stabilised turn, no aileron input and co-ordinated rudder.
    There should be no reason for the upper wing to stall ahead of the lower.
    Apparently common wisdom is the upper wing will stall in a climbing turn and the lower wing in a descending turn, although how you would stall in a descending turn I don't understand. Most general aviation aircraft are not capable of a pitch up.
    I read an article about the staircase effect and it didn't seem conclusive.
    Is this another one of those arguments,,,,like the up wind down wind turn nobody seems able to prove or disprove.
    I don't have an aircraft I care to spin so am reluctant to go out and try it.


    Is this splitting hairs?

    Someone set me straight on this one.

    Please.

  2. #2
    FlyingRon's Avatar
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    I agree with you. All that matters is ANGLE OF ATTACK not whether the aircraft is turning or climbing or which wing is "higher."
    Now the wing on the outside of the turn is going to produce slightly more LIFT because it's going a little faster, but in coordinated flight (even in a turn) the AOA should be the same. Even that lift change is going to be negligible.

  3. #3

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    The upper wing should stall first if you are holding the wing up with aileron. Because that barn door aileron changes the stall angle of attack to less than normal. So a wing normally stalls at say 15 neutral and say 12 with the aileron deployed down.
    Many modern airplanes have this tamed by design. But old designs are still sold under old rules.
    Last edited by Bill Berson; 07-15-2018 at 09:07 AM.

  4. #4

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    When is a stabilized coordinated turn, lift is the same on both wings. Assuming the horizontal lift component is exactly equal to CF (virtually impossible assumption, but that is the definition of coordinated flight), both wings will stall at the same time.

  5. #5

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    Lift is the same, but each wing can have a different aileron configuration to make that equal lift. Different configurations stall at different angles. Then torque, prop effects and everything else, it's a stretch to make broad one size fits all statements.
    Thats why the topic is so involved and pilots keep killing themselves.

    Post one said assuming no aileron input. But usually there is aileron input because the outer wing is moving faster. Aileron input can trigger the stall or prevent stall, just depends.
    Last edited by Bill Berson; 07-15-2018 at 10:16 AM.

  6. #6

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    Quote Originally Posted by Bill Berson View Post
    Lift is the same, but each wing can have a different aileron configuration to make that equal lift. Different configurations stall at different angles. Then torque, prop effects and everything else, it's a stretch to make broad one size fits all statements.
    Thats why the topic is so involved and pilots keep killing themselves.

    Post one said assuming no aileron input. But usually there is aileron input because the outer wing is moving faster. Aileron input can trigger the stall or prevent stall, just depends.
    Believe it or not, I agree in general with what you are saying, but the variables you rightly mention are negated by the OP's original assumptions. I also agree in those assumptions can only hold true in an academic discussion. Torque, prop effects, and control configurations, etc all have an effect in the real world.

    I also agree that many pilots have insufficient knowledge in this area. Note my thread on LOC - spins. The FAA and AOPA and many other "experts" publish so a lot of false/misleading information. Primary flight instructors rarely teach anything beyond what they have read in a book or have been told. That is, they lack the experience to sense what is happening with the airplane (slip, skid, high angle of attack, etc.) and therefore lack the capability to pass on needed skills to students. I submit the lack of these fundamental knowledge areas and skills is the reason why pilots continue to kill themselves.

  7. #7

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    Totally agree, there is a lack of knowledge and recent experience flying while slow in turns to train the correct reaction to a stall in a turn. I do a lot of turning in gliders with frequent turning stalls.
    And I read Stick and Rudder again each year.
    The recent Sport Aviation had a comment from a prominent expert, but I didn't want to reply and confront an expert.
    Last edited by Bill Berson; 07-15-2018 at 11:14 AM.

  8. #8
    FlyingRon's Avatar
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    Don't get me started on the FAA. Their definition of coordinated flight defies explanation.

  9. #9

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    Years ago I went for some aerobatic training and just plain fun in a Great Lakes Biplane, after loops and rolls and spins the instructor told me there was one more thing he really wanted me to see as he felt ALL pilots should see it. It was the classic base to final turn Stall. He had me climb to 4 thousand feet and set up as though we were landing at 3200 feet. We flew downwind , base and at the turn to final he had me fly it as though we overshot the turn and then try to bring it back to centerline. While in the left turn we turned steeply to bring it around and held the nose up a bit. I was expecting it to roll over to the left into the turn, BOY WAS I WRONG !!!. It snapped over to the right and immediately went into a steep spin. If we had actually been landing at the time we would have left a large smoking hole. I was amazed at how quickly it happend and that it went over on the right wing ( the higher wing ) and immediately spun. There was no time to even react , for a moment I was simply baggage and not a pilot. IT WAS PROBABLY ONE OF THE BEST LESSONS I WAS EVER TAUGHT AND IT LEFT A HUGE IMPRESSION. I now know how pilots crash turning base to final.

  10. #10

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    vafier, Its good you go the spin recognition, but not that way. It was dangerous, first 4000 feet is low to be doing and intentional stall and spin. A full spin can take two turns to recover and get the nose back up to level flight might take 2 or 3000 feet. And you dont say if you had parachutes, and if not your survival was dependent on a full recover. I have flown a Great Lakes some years ago and I recall it handling well, but not all planes would be so benign. A T-6 probably wouldnt and the pilot manual for a P-51 firmly says spins are not to be started below 10,000 AGL.
    As for direction, sounds like you had extra aileron into the turn, and not enough rudder to stay cooridinate, thus the outside wing was lagging and stalled first and you rolled over the top. If you had to spin the over the top way may give you a few seconds more to recover whereas tuckng under might happen even quicker.
    Spins are not to be taken lightly, I wanted to see how my plane spun and recovered. I read the Pilot Notes, no extra caution noted and I asked the factory test pilot who said he expected it to be normal. I went to 15,500 over Fond du Lac and did a spin and recovery in each direction. It was normal but still I would nt want to have it happen at a few thousand feet.
    My friend Jay Cullum made a video of spinning his P-51 and he did it from 17,500 feet near Dallas.
    Last edited by Bill Greenwood; 07-15-2018 at 10:29 PM.

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