Some Diagrams

[Keith Black]

I'm glad you mentioned this Bob. When I was just getting started in pattern (my second pattern contest) I asked an experienced judge why he had downgraded my 1/2 reverse Cuban turn-around so much (I wasn't complaining, just trying to learn). He told me it was too flat and informed me that 45 degree angles at the end of the box will appear steeper from the center vantage point, therefore I need to fly the angle so it looks more like 60 degrees in order for it to actually be 45 deg. This was a surprise to me but I accepted his explanation since I knew of his background. 

Since that time I've flown the end of box maneuvers steeper to compensate for the difference in perception. However, on a few occasions people have commented that my angles at the end of the box are too steep (and they probably are sometimes), but your comment makes me wonder whether others are looking for the end of box angles to "appear" to be 45 degrees, or if it's a commonly know fact that they will appear steeper when actually 45 degrees. In other words, what do most judges look for? The appearance of 45 degree angles or what they know through experience is the "steeper" appearance that is actually 45 degrees? 

Keith Black
  ----- Original Message ----- 
  From: Bob Pastorello 
  To: discussion at nsrca.org 
  Sent: Saturday, August 21, 2004 1:09 PM
  Subject: Re: Some Diagrams


  EXCEPT that the manuevers must APPEAR to have 45 deg, or 60, or 90 - whatever - as this is judged by the viewers PERCEPTION of those angles.

  Bob Pastorello
  rcaerobob at cox.net
  www.rcaerobats.net


    ----- Original Message ----- 
    From: Wayne Galligan 
    To: discussion at nsrca.org 
    Sent: Saturday, August 21, 2004 9:30 AM
    Subject: Re: Some Diagrams


    Exactly Ted...

    Like when doing a 1/2 Cuban eight on the ends in Intermediate.   The 45 degree line will appear to be steep if it is done at 45 degrees. When done to look right the angle will be shallower and the plane will also finish the maneuver closer to center depending on how far out the maneuver was started. 
    OR the figure 8 on center.  The new square 8 in Master is going to be an interesting one to judge too.

    Good points and something that should be discussed in judging seminars.

    Wayne Galligan
      ----- Original Message ----- 
      From: Ted Sander 
      To: discussion at nsrca.org 
      Sent: Saturday, August 21, 2004 8:26 AM
      Subject: RE: Some Diagrams


      Very interesting Bob!  A few years ago I was messing around with a 3D animation program (Bryce 3), and tried my hand at making a clip showing a plane tracing out a basic loop while following a "ribbon in the sky" - ie, the path looked like those shown in the maneuver descriptions in the AMA rule book.  It allowed for perspective effects, placement of viewpoint and all the other usual stuff a 3D program can do.  So, on to my point:  When I mathematically made the loop perfectly round, it had a distinct egg shape to it when the view point was moved from the same level as the center of the radius, to a more typical 5 ft from the ground, looking up.  In order to get a loop that looked round from a typical judge/pilot position, I had to squish it from the top a fair bit - indicating to me that as we fly our planes over the top, it's not enough to keep the radius consistent, we actually have to pull harder on the top side, to keep everything looking right - in other words, we don't actually fly a true constant radius loop, because of perspective effects.  Makes it all so much harder than just keeping airspeed and angle of attack constant - because we have to vary the shape to make it look right.  While I didn't go back to look at other maneuvers in more detail, it has always stuck with me that this effect also rears it's head everywhere else too.  Kind of the visual version of the upwind/downwind debates - so much depends on the frame of reference.  Would be interesting to hear others take on this subject..



      Ted Sander 



      -----Original Message-----
      From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On Behalf Of Bob Pastorello
      Sent: Tuesday, August 17, 2004 6:14 PM
      To: NSRCA
      Subject: Some Diagrams



      After getting some feedback about geometry, I thought I'd draw out a few of my more problematic ones.  They may help you, too....

      http://www.rcaerobats.net/ManueverDiagrams.htm


      Bob Pastorello
      rcaerobob at cox.net
      www.rcaerobats.net




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