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What causes a tailspin?

Discussion in 'AviatorChat.com' started by Texas Forever, Oct 25, 2020.

  1. Texas Forever

    Texas Forever Four Time F1 World Champ
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    Speculation is the trainer that went down in Alabama had a "tailspin." As a non-pilot, I was wondering what causes a tailspin. I'm guessing they were doing a maneuver that went wrong?
     
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  3. Bob Parks

    Bob Parks F1 Veteran
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    A good and complex question. Basically it is caused by lack of lift that is caused by two things; loss of forward airspeed with uneven lift across the span of the wing, one half of the total span of the wing advances ahead of the opposite side to cause asymmetry of lift and the airplane drops into a spin. Loss of airspeed can be caused by a too high angle of climb with or without power. It can also be caused in level flight when there isn't enough forward speed (power) to produce lift and the pilot tries to maintain level flight by pulling back on the stick. The airflow changes from running over the upper surface to an increased angle under the wing and eventually breaks away from the leading edge and kills the lift. This will cause a stall and spin if the airplane yaws to the left or right. The other cause is a 'high speed stall" when the a pilot yanks back on the stick too fast when the airplane has good speed . The airflow cannot react fast enough to stay attached to the leading edge and breaks away , destroying lift. Again, any yaw will kick the airplane into a spin due to unequal pressures on the wing. I hope that I did a simple enough explanation without aero guy terms.
     
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  4. Texas Forever

    Texas Forever Four Time F1 World Champ
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    Thanks. My dad used to investigate these crashes out of Pensacola when he was in the Navy. Sounds like somebody did something they weren't supposed to do. I guess that's why they are trainers.
     
  5. Bob Parks

    Bob Parks F1 Veteran
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    I don't know if I explained this question adequately so if you could check Google and type in Viscous Flow it might help.
     
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  6. Texas Forever

    Texas Forever Four Time F1 World Champ
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    Will do.


    Sent from my iPhone using FerrariChat
     
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  8. kylec

    kylec F1 Rookie
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    Usually it’s just called a spin or stall/spin
     
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  9. Jon Bebbington

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    This discussion addresses maneuvers. Couldn’t the accident have been caused by hydraulic failure or control surface failure? Also, why didn’t the crew eject?
     
  10. tazandjan

    tazandjan Three Time F1 World Champ
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    Wow, made friends in a hurry.
     
  11. Bob Parks

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    Yes, indeed, but the question was , what causes a spin. In flight mechanical or structural failures cause more than just spins and has no relation to the question, in my mind. I have seen incidents where spins were induced by high speed stalls, poor controlling at low speed, but none from in-flight failures. Good point, though.
     
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  13. kylec

    kylec F1 Rookie
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    it’s possible but more likely they were doing maneuvers and lost control

    We’ll have to wait until the report comes out. It’s possible they were maneuvering at at too low an altitude.

    It’s also entirely possible that eyewitness accounts are all wrong and something entirely different was going on.
     
  14. tazandjan

    tazandjan Three Time F1 World Champ
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    What most folks do not realize is that a high performance aircraft in a spin can see extremely high descent rates in the 10s of thousands of fpm. Not much time to figure out what to do.
     
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  15. Bob Parks

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    Eye witness accounts are notoriously the most unreliable versions of what actually happens. "Expert speculation" is another untrustworthy explanation. We should wait for the report.
     
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  16. Bob Parks

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    I got to thinking about spins and how they sometimes are misunderstood and confused with a spiral dive. The spin is a stalled maneuver where the wing hasn't enough airflow to produce enough lift to sustain controllable flight. The airplane goes into what the aero guys call "auto rotation".The wing on one side is moving faster than the other and produces a bit more flow than the other side. The fuselage is not pointed down but it maintains an angle to the vertical, spinning around like a plate. I spun every airplane that I flew if it wasn't placarded against spins. Just a few turns to effect a recovery to see what the airplane will do if a spin is initiated. In most cases it is a docile and controllable maneuver but there are some that demand early and aggressive responses to effect a recovery. The Cub and Stearman will recover if you simply take your hands off the controls. It will take some time but they will do it. The PT19 and PT22 will quickly break into and lock into a spin that can be tight and get tighter if you don't make an early stop. I had to apply almost full power and full opposite controls for a long time to stop a PT19 once. That'll get your attention. I remember that I had to do spins left and right with a precision recovery in a Cessna 140 for my PPL flight exam. I often wonder how well I would do now at 94. Be fun to try but my pacemaker might get scrambled. Might do it anyway.
     
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  17. kylec

    kylec F1 Rookie
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    They don’t make you do spins until CFI anymore. I only did a few in a 172 with an instructor. I’d like to find an aerobatic school and do upset recovery.
     
  18. jcurry

    jcurry F1 World Champ
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    Just don't do it in a Tomahawk.

    Find a place that uses Decathlon's. Good airplane to learn in, with moderate stick forces, that makes you do maneuvers correctly.
     
  19. tazandjan

    tazandjan Three Time F1 World Champ
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    The only time they tried to spin an F-111, they lost the airplane. Crew ejected successfully after the chase plane pilot yelled at them over the radio to eject.
     
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  20. Bob Parks

    Bob Parks F1 Veteran
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    Taz, I can't imagine trying to spin that airplane. With the wings extended there is still a lot of nose out there and the short coupled tail I imagine would be blanked, also. From what I was told , the aero guys have never been able to fully analyze and quantify the physics of a spin. Moment arms, blanking air flow, asymmetrical lift and flow, tail volume, wing twist, and gremlins change with every configuration. I know that some airplanes don't get bothered about doing spins and will readily recover while others will lock into it and get so tight that there is no way to effect a recovery. You can feel it when they hit that slot and lock into it and start to wind up tighter. It is an evasive design phenomenon that can only be quantified by the good old spin test. A late old friend and Boeing Preliminary Design engineer designed and built a small low wing wooden homebuilt powered by a VW engine. Before he released the plans he decided to perform a spin test. He wisely donned a chute and acquired the adequate altitude and put the airplane into a spin. It would not recover after he tried everything that he could do. He bailed out and and in his descent he kept hearing a ticking sound. He said that, "The damn airplane was spinning around beside him and I heard the engine still idling ". He maneuvered the chute away from it and landed safely without injury to his body but he said that his pride took a hit. Jim W...... was 75 years old at the time.
     
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  21. jcurry

    jcurry F1 World Champ
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    The F-14 that self corrected and almost 'landed' itself after the crew ejected during a flat spin is a classic.
     
  22. tazandjan

    tazandjan Three Time F1 World Champ
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    Bob- Funny thing is that F-111 had a spin chute installed, but whoever did the math screwed that up pretty badly. The crew popped the drag chute, but it immediately ripped completely off. No help there in getting the nose down.
     
  23. Bob Parks

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    Yep, how many times have we seen that with dragsters , too. Spins were fun in certain airplanes and I used to do them in the Stearman by holding a snap roll into a spin. That airplane would give you the impression that, " Okay, I'll do it just to entertain you ." It made you work, however, to do a slow roll.
     
  24. Ak Jim

    Ak Jim F1 Veteran
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    Trying to remember some aero. Isn’t a spin caused when one wing is stalled and the other isn’t? I remember doing spins in the T-37. The first flight that I did spins in is the only time I’ve ever puked in an airplane. There was a bold face procedure for spin recovery. It was 7 or 8 steps long and you had to say it and write it verbatim from memory. When you got really good you could stop the spin and it would be a very gentle maneuver. A lot of the time though the recovery could be somewhat violent.

    As a side note I can honestly say the T-37 was probably my most favorite airplane I’ve ever flown.
     
  25. kylec

    kylec F1 Rookie
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  26. jcurry

    jcurry F1 World Champ
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    No, I was referring to a F-14 flying out of Pax River. I hadn't heard about the F-106. Very cool, and similar circumstances.

    Can't find the full video on the F-14. However it did not quite make the full recovery like the example you posted. The F-14 was just slightly nose low when it contacted the ground, so not a good outcome for the airframe.
     
  27. Bob Parks

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    F-106 delta wing, flat lift?
     
  28. Hannibal308

    Hannibal308 F1 Rookie
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    Throttles – Idle

    Rudder and Ailerons – Neutral

    Stick – Abruptly full aft and hold

    Rudder – Abruptly apply full rudder opposite spin direction (opposite turn needle) and hold

    Stick – Abruptly full forward one turn after applying rudder

    Controls – Neutral after spinning stops and recover from dive
     
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