Re: IHLG Flappers

From: Bill Gowen <b.gowen_at_earthlink.net>
Date: Sat, 10 Feb 2007 20:32:48 -0500

Randy
Another possibility would be a rigid wing glider with around 60-70 si of area. A really thin wing would help you get the altitude you need. If I were going in that direction I'd probably use a flat bottom airfoil no more than 1/8" thick at the center and make the glider as light as possible to help out the sink rate.

  ----- Original Message -----
  From: rreyno2001
  To: Indoor_Construction_at_yahoogroups.com
  Sent: Saturday, February 10, 2007 7:30 PM
  Subject: [Indoor_Construction] IHLG Flappers


  I have been tinkering with my flappers under our 37-39' ceiling and
  I'm certain I don't have them shaped correctly. If I build lightly
  at 6-7 grams, I can't get them anywhere near the ceiling but I can
  with 9-11gm versions. These are 21-24" gliders.

  Isn't the theory that under launch conditions the flaps will flatten
  out due to air pressure and drop down as the airspeed decreases? If
  so this gives a pretty good undercambered airfoil and a resultant
  slow minimum sinkrate glide, all things being in trim.

  It is likely that flaps need to be very, very limber in the hinge
  area and this likely requires balsa with very few hard grain lines
  so that the material is pretty much homogeneous. In addition, I
  think I work that area much too thick for the flap to actually
  respond properly.

  So here is my question: How do you make the flap as flexible as it
  needs to be and is there a way to judge that? I notice on Kurt's
  website that the airoil detailed there has a top curvature that is
  continuous whereas the undercamber has been carved into the front
  section and it transitions up to a very thin flap.

  So if I build this airfoil such that the flap is very thin and
  flexible will it help get a lighter glider to the roof?

  Thanks, Randy



   

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Received on Sat Feb 10 2007 - 17:33:20 CET

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