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Thread: AT-6 / SNJ spins

  1. #1

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    AT-6 / SNJ spins

    I have a question about spins in the AT-6 or SNJ-4. I have seen some aircraft placarded against spins and others not. In my SNJ manual, all it says about spins is to not do them if on the left tank. Are some OK to spin and others not? If so, how do we know? I have avoided doing any spins more than 1 turn because I wasn't sure.
    Thanks

  2. #2

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    T-6s, Harvards, and SNJs were full advanced military trainers and made good pilots. You may believe they did spins and spin training.I have not spun one myself, but thousands have.
    This placard against spins is a recent one , put in by the FAA. I am not sure why, if it is there is a real danger or if it is just a change in bureacracy and some overhanded paperwork.
    I would be very careful , and find out more about a particular plane, and if I did spin one, I'd be real high, perhaps 10,000AGL, with lot's of air under me and room to recover.
    Note, it only prohibits "intentional spins", so I guess if you fall out of a loop by accident into a spin and recover, that is approved.

  3. #3
    RetroAcro's Avatar
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    I'm no expert on the T-6/SNJ, but I've had a little dual in an SNJ and I was told that the plane recovers spins without issue, but does not recover quickly enough once fully-developed to meet FAA spin testing criteria. For this reason, we did only incipient spin recovery, which was positive, but still lost a surprising amount of altitude compared to your typical light utility/acro plane.

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    My understanding is the FAA requirement is that in the worst CG loading (usually aft CG), an aircraft must be able to do a two turn spin (in the worst direction, again usually left for US airplanes), and with "normal" spin recovery control inputs, stop rotating in no more than one additional rotation. If the airplane takes longer to recover, it must be placarded "Intentional Spins Prohibited." I believe that some variants of the T-6 have been placarded for many years. Some have more fuel than others, and there is other equipment that will affect spin behavior. Perhaps someone who is more familiar with the history will post some info.

    Regards,

    Wes
    N78PS

  5. #5

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    The pilot manual for T-34 A allows spins, but as I remember if says to recover within 2 turns. The FAA was doing a seminar on spins at EAA one year and emphasized that the first part of a spin, ( I think it was 2 turns), is only the entry to a spin or the incipient stage. Many planes, if not most,will recover easily if recovery is started in this incipient phase.However, some like the T-34 get more resistant to recovery after 2 turns when the plane enters the full established phase of the spin. Then it may take longer to recover, if at all once the anti-spin corrections are put in. A P-51, for instance is reported to take a couple of turns to recover from a full spin.
    Note, that only T-34A is approved for acro. The B model can do it mostly as well, but near aft cg it will not recover from the spin. That was what the Beech factory found in their testing back in the 50's. Some T-34 B owners did not want this restriction, and about back in the 90's hired a test pilot to repeat the spin tests. All was well , starting at forward cg, and moving back, but just as the factory said, once you got near the aft limit it would not recover.
    Being near the aft limit of cg can be dangerous in any plane, and you should be extra careful when doing acro to be in the middle or forward part of the loading envelope.
    Everyone who wants to be a complete pilot should do spin training and practice recognizing the start of a spin, ( ie an uncoordinated stall) and how to recover.
    Spins can be complicated, not room to go into all here.
    BUT, KNOWING A QUICK SIMPLE STALL RECOVERY PROCEDURE IS VITAL.
    1. Power all the way off. (note in some planes like Pitts or P-51 even a little throttle open may prevent recovery. You have to get power off to get the nose down to get airflow over the controls.
    2. Release the stick or yoke, just let go of it. ( note you need to have neutral ailerons and neutral or down elevator for recovery from an upright spin). If you just quit pulling on the control that got you into the stall/spin in the first place, the elevator will release the back pressure.
    3 Push and hold full opposite rudder to the direction of the spin. Hold until the spin stops, then release the rudder.
    The plane should come out of the spin nose down and accelerating and you can smoothly regain control and level flight, if you have altitude to spare. That is one reason not to do vertical acro like loops down low.

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    My first spin and recovery lesson was with my first flight instructor was in a Piper Tomahawk. I was too new to know we should have worn chutes, but I was smart enough to make sure we were up high and he assured me he knew how to recover.
    We did a couple ok, it did recover ok. The thing that really hit me was unlike most stall practice , once the spin started it was pretty abrupt. It didn't just yaw, it also rolled into the entry and really dropped the nose.I have done spins in Piper J3 Cub, T-34, and a fighter. The fighter also rolls going into the spin and comes out nose down also.
    Some planes are said to recover from the spin entry, like a 172, if you just release the controls.
    Some time after doing the spins in the Tomahawk, the FAA came out with an AD due to some fatal stall/spin accidents in Tomahawks. I can't recall if they prohibited spins, but they did require a stall strip on the wing leading edge.
    We, of course did not know that at the time I did my initial training. Thankfully someone was watching over us.

  7. #7

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    I have to offer the advice that before you go and do any type of stall or spin maneuver in any aircraft please !READ THE FLIGHT MANUAL!

    I say this because the generic spin recovery procedure offered above does not work in all aircraft. Some aircraft, the Zlin family for instance, will happily spin into the ground if you sit there hands off. The flight manual states a specific set of control inputs the pilot must do in order to stop the spin and recover to wings level flight. I know of at least one incident where some pilots almost crashed "trying out" spins. Once back on the ground reading the flight manual to find a clue as to where they went wrong, they found some very surprising info. They should have read the directions BEFORE they went flying, not after.

    I will also note for the folks who might poke at acro that a very like place to spin is a hammerhead. NOT due to kicking for the turn late, but rather due to kicking early when the airplane still has plenty of energy to respond to incorrect control inputs. Before you try a hammer in a new airplane, please compare the control inputs for the turn at the top of a hammer with the control inputs for an outside snap roll. As an aerobatic competitor, I can report that unexpected inverted spins at a safe altitude are interesting. If you have never done an intentional inverted spin, the adjective that you apply to your hammer-spin might be more colorful, if you recover successfully.

    Y'all be carefull out there.

    Wes
    N78PS

  8. #8
    RetroAcro's Avatar
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    Quote Originally Posted by Bill Greenwood View Post
    BUT, KNOWING A QUICK SIMPLE STALL RECOVERY PROCEDURE IS VITAL.
    1. Power all the way off. (note in some planes like Pitts or P-51 even a little throttle open may prevent recovery. You have to get power off to get the nose down to get airflow over the controls.
    2. Release the stick or yoke, just let go of it. ( note you need to have neutral ailerons and neutral or down elevator for recovery from an upright spin). If you just quit pulling on the control that got you into the stall/spin in the first place, the elevator will release the back pressure.
    3 Push and hold full opposite rudder to the direction of the spin. Hold until the spin stops, then release the rudder.
    The plane should come out of the spin nose down and accelerating and you can smoothly regain control and level flight, if you have altitude to spare. That is one reason not to do vertical acro like loops down low.
    This is the Beggs-Mueller recovery technique. Gene Beggs writes in his book about certain spin modes in certain aircraft that do not recover using this technique. Highly valuable reading. There are many airplanes that may not have had extensive testing done using this technique. And it's not simply whether or not an airplane will recover a plain-vanilla upright spin. Spin characteristics can vary depending on whether they're left rudder, right rudder, inverted, upright, normal, flat, or accelerated. So there are a number of different spin modes, which most folks will likely never experience unless they seek advanced spin training in a suitable aerobatic aircraft.
    Last edited by RetroAcro; 11-15-2011 at 07:56 AM.

  9. #9

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    Yes guys, I think that anyone should read the pilot manual before flying any airplane, especially doing acro or spins. Also ought to wear a seat belt and a few other basics that I didn't think to mention.
    And if you are a big time acro pilot, you may not need any basic method of recovering from a spin. You may be accomplished enough to push the yoke or stick forward or pull it back as needed, rather than releasing the back pressure.
    By the way , which way do you move the control if you are not sure if the spin is upright or inverted? Myself I have only done standard upright spins.
    And since we are looking for the exceptions, how do you recover from a spin in a helicopter that has lost its tail rotor?

    At the AOPA convention I heard a pilot talk about spin recovery and almost spinning a Pitts into the ground because he short cutted one of the basic steps. He is/was a 2 time nat acro champ.

    I still think the basic method is good for most pilots to know, who may be flying most planes and get into an accidental spin.
    I agree that for left handed lesbians from Latvia who drive a Lincoln and fly a Lancaster in Liberia , the basic method may not work, and they need something more than us mere mortals to recover form a spin.

  10. #10
    RetroAcro's Avatar
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    Quote Originally Posted by Bill Greenwood View Post
    By the way , which way do you move the control if you are not sure if the spin is upright or inverted? Myself I have only done standard upright spins.
    If you're unsure about this, it likely means you're confused, not in control, and your stress level is rising...and time to invoke emergency recovery. I don't mean to discredit the Beggs-Mueller technique - it is likely to get the spin stopped in most airplanes and is a good technique to use in this situation....much better than randomly slamming the stick around hoping something works. If we're talking about positive (non-emergency) recovery inputs, which way you move the stick would depend on your spin mode. If you're in an inverted accelerated spin, you'd need to first move the stick forward before applying opposite rudder and finally moving the stick aft toward neutral after the rudder has had a chance to slow the rotation a bit. If you're in a normal inverted spin, you probably already have the stick forward and just need to move it aft a little after opposite rudder has been applied. Of course, if you're unsure if you're upright or inverted, it's probably best you don't move the stick at all, and use Beggs Mueller.

    Quote Originally Posted by Bill Greenwood View Post
    At the AOPA convention I heard a pilot talk about spin recovery and almost spinning a Pitts into the ground because he short cutted one of the basic steps. He is/was a 2 time nat acro champ.
    I assume he was too quick to unload the stick (before applying full opposite rudder) and accelerated (or crossed over) the spin? There's an emergency spin recovery technique that works in the Pitts 100% of the time, in any spin mode, as long as the airplane is within the weight & balance envelope. It is accomplished by simply pulling power off and visually neutralizing both the stick and rudder. The spin will stop a few moments later and you can pull out. The nice thing about this technique is that it does not require the pilot to recognize the correct anti-spin rudder to apply, as Beggs Mueller does. I'd imagine this technique works in many other airplanes, but there are no guarantees without completing the full spin testing matrix for each a/c type.
    Last edited by RetroAcro; 11-17-2011 at 02:39 PM.

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