Displacement during snap rolls (was Why is it so quiet?)

[Ed Alt]

Karl:
When the wing exceeds its critical angle of attack, it is in a stalled condition.  This can be brought on at any airspeed (assuming sufficient pitch control is available) and from any starting attitude.  Learned this many years ago when I was becoming a Cessna driver.  Lot's of times the ability to enter a stalled condition has much to do with technique.  If you gradually bring in the pitch change, you may never get the break at higher airspeeds.  The rate and amount of pitch change is really important to achieve a stalled condition and then get a real autorotation to happen when you blam in the rudder.  Side note - you can do a snap without any aileron input, though it really helps make the whole thing cleaner and more controllable.

Ed
  ----- Original Message ----- 
  From: Karl G. Mueller 
  To: discussion at nsrca.org 
  Sent: Wednesday, December 29, 2004 10:17 AM
  Subject: Re: Displacement during snap rolls (was Why is it so quiet?)


  All,


  I have a question on the aircraft to be in a "stalled condition during a snap roll":
  How do you get the airplane into a stalled condition on a vertical downline snap?

  Karl G. Mueller
  kgamueller at rogers.com

    ----- Original Message ----- 
    From: Archie Stafford 
    To: discussion at nsrca.org 
    Sent: Wednesday, December 29, 2004 9:56 AM
    Subject: RE: Displacement during snap rolls (was Why is it so quiet?)


    Last year at the NATS the biggest thing they were looking for was the break.  You really had to show a VERY clean break.  The rule book doesn't specify how much break, but it was obvious last year that you really had to show a VERY clean break, even on the avalanches, which is very tough to do at the top of a loop and give a good break, or in FAI the snap at the bottom of the loop.  I talked to Andrew Jesky as well and he said the FAI judges were being the same way, the you really had to show a very definite break.

     

    I think the key to the displacement is how much rudder is in the snap.  From my experience if you have too much rudder the plane will displace from one side or the other.  You can take out some of the rudder and still have a truly stalled maneuver.  You use the elevator to stall the aircraft.

     

    I do have a question though.  How can an aircraft be "semi-stalled?"  Either the aircraft is stalled or it isn't. 

     


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    From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On Behalf Of Randy
    Sent: Wednesday, December 29, 2004 9:32 AM
    To: discussion at nsrca.org
    Subject: Re: Displacement during snap rolls (was Why is it so quiet?)

     

    Man I would love to see a video of different snaps and the judges scores from last years NATs.

    Randy

      ----- Original Message ----- 

      From: John Ferrell 

      To: discussion at nsrca.org 

      Sent: Wednesday, December 29, 2004 9:19 AM

      Subject: Re: Displacement during snap rolls (was Why is it so quiet?)

       

      As near as I can tell Somenzini's secret is in the setup, not the snap itself. 

      The only place I see to downgrade for offset is in presentation.

       

      I admit to being one of his fans.

       

      I think the question is a very good one!

       

      John Ferrell    
      http://DixieNC.US

        ----- Original Message ----- 

        From: Bob Pastorello 

        To: discussion at nsrca.org 

        Sent: Wednesday, December 29, 2004 6:47 AM

        Subject: Re: Displacement during snap rolls (was Why is it so quiet?)

         

        Good points, David, but my question is based on a LATERAL, and "Parallel" shift in the track.  Assume that I get 'lucky', and nail the line before the snap, definitively BREAK during the snap, nail the exit on the original heading/track, but shifted sideward maybe 3 feet.

            My experience is that a properly-executed snap manuever - anyplace - MUST translate some forward momentum into angular sideward momentum, thus shifting the track of the manuever.

            If this is a "downgrade", where is the criteria, how much are the downgrades, and since we're not talking about an "angular" offset, the point per 10 or 15 degree deviation rule doesn't seem to fit.

            In fact, I would argue (and I'm confident there are aerodynamicists out here who could calculate and prove it so) that NO appropriately-executed snap manuever CAN occur without offset of the original track.

         

            If someone does the imitation/fake "snap roll" ( the rapid, low-rudder, high-aileron, semi-stall ROLL) there ISN'T an offset, usually.  At least in the fake ones I judged LAST season.


        Bob Pastorello
        NSRCA 199  AMA 46373
        rcaerobob at cox.net
        www.rcaerobats.net

         
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