[SPAM] Re: [SPAM] Re: Snao G's

[Ed Alt]

Ken:
Depends on the pilot.  Some do Walls at a fairly high airspeed.  I never did them at anything much more then around 40 mph est, but that's a bunch of force right there.  It stops in a big hurry.  I can only guess at the G's, but if you watch from the right angle, you can see the wings bend a fair bit on a 40% model doing this. Ditto with a Parachute - it just depends on what the pilot is willing to attempt.  Blenders aren't a stalled maneuver, they develop from a rolling vertical downline, then at 3D rates you typically slam in full down, full aileron one way, full rudder the other, then you typically take out some aileron to flatten it out.  I have seen airplanes come completely apart, sometimes just crack the wing sheeting (sounds like a rifle shot) or crack the fuselage doing a blender.  I never let mine develop for more than a couple of rolls at a low power setting coming down.  Too risky. 

Usually Waterfals are started from a vertical hover and are really tame.  A really wild variation is a Waterfall started from full power level, with a very rapid pitch-up to about 45 degrees as you yank the power, then hit full down (3D rates ocourse) and knock some throttle back in to get enough propwash over the tail to force it around as it starts to go backwards (same direction really, but the tail & nose positions are getting swapped).  Timed right, it virtually stops in place as it pivots around the pitch axis.  It's dramatic and you can immediately go into anything else like a 3D roller, whatever, where a second ago you were clipping along at 90 mph.  That's a wing tube bender if you overdo it. There's more tricks and variations than this, but there is alot of really stressful stuff in the so-called 3D maneuvers.  I like EFD (Extended Flight Envelope, better, but whatever.

Ed
  ----- Original Message ----- 
  From: Ken Thompson III 
  To: discussion at nsrca.org 
  Sent: Friday, January 28, 2005 5:57 PM
  Subject: Re: [SPAM] Re: Snao G's


  Walls I can see the stress, however I understand that the correct way to enter a wall is at 1/4 throttle or less.  I'm not one of those big ego guys, so correct me if I'm wrong.
  Parachutes are more of a controlled fall, from a partial wall up high, and Blenders begin from a stalled state.  Of course when you slam the throttle to push the plane through the Blender, that could hurt a bunch.

  Ken



  ----- Original Message ----- 
    From: Ed Alt 
    To: discussion at nsrca.org 
    Sent: Friday, January 28, 2005 5:05 PM
    Subject: [SPAM] Re: Snao G's


    Yep, but the transition into it can be stressful.  Stuff like Walls, Parachutes, Blenders, certain brands of Waterfalls put mucho strain in the airframe.  
    Ed
      ----- Original Message ----- 
      From: Ken Thompson III 
      To: discussion at nsrca.org 
      Sent: Friday, January 28, 2005 4:16 PM
      Subject: Re: Snao G's


      Matt,
      I could be wrong, but isn't 3D, by definition, done in a constant state of stall?  Wouldn't that eliminate a lot of the high G's in the maneuvers?  I wouldn't think the airframe would be in as stressed state, when the flying surface is depending on prop wash, not air speed, to do it's thing.

      Ken
        ----- Original Message ----- 
        From: Rcmaster199 at aol.com 
        To: discussion at nsrca.org 
        Sent: Friday, January 28, 2005 1:46 PM
        Subject: Re: Snao G's


        If this accelerometer is finding 13 G loads generated by a Pattern model snap, a relatively low amount really, I imagine that a 3D model set up for a full array of stunts has to be experiencing double that at least.

        Earl could you do any 3D type maneuvers and measurements with the Yak?

        Very informative discussion BTW, and may result in improved more efficient building technique, read-- lightest for the desired strength.

        thanks

        matt

        In a message dated 1/28/2005 1:32:35 PM Eastern Standard Time, d.pappas at kodeos.com writes:
          That's proof of stall!
          If the G loading rises suddenly, and then holds or droops continuously during the roll, then it's probably an accelerated barrel.
          If the profile is sudden rise, sudden drop to maybe 1/2, then onload, you have a real snap.

          Yia,
              Dean

          Dean Pappas 
          Sr. Design Engineer 
          Kodeos Communications 
          111 Corporate Blvd. 
          South Plainfield, N.J. 07080 
          (908) 222-7817 phone 
          (908) 222-2392 fax 
          d.pappas at kodeos.com 

            -----Original Message-----
            From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Rcmaster199 at aol.com
            Sent: Friday, January 28, 2005 11:45 AM
            To: discussion at nsrca.org
            Subject: Re: Snao G's


            Good point. Once in the stall, the model should not see the same continued G load. Should drop dramatically. If the plane doesn't stall to begin with, different story.

            Matt

            In a message dated 1/28/2005 11:23:25 AM Eastern Standard Time, d.pappas at kodeos.com writes:
              Let me add another two cents worth ...
              Earl,
              What is the sampling rate on your data logger?
              Can you see if the maximum 13-Gs at 100 MPH was sustained for the entire half second or so that it took to complete the snap,
              or was it a short spike (like 0.1 second)  and then sustained at say half of that value, for the rest of the snap.
              Of course, if the data logger samples once a second, we have almost no way of knowing.

              Later,
                      Dean
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