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049 racer

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Old 03-04-2010, 12:31 AM
  #26  
skaliwag
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Default RE: 049 racer

Here's some reading.

http://en.wikipedia.org/wiki/Washout_%28aviation%29

Think of it as a twist in the wing like a prop... So the tip "digs in" = down.
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Old 03-04-2010, 08:30 AM
  #27  
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Default RE: 049 racer

hmm, anyone has pictures of a downwashed wing? i know wad the wiki is talking about but i have no idea on how to execute it..

by the way, i've started on the fuselage!
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Old 03-04-2010, 10:46 AM
  #28  
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Default RE: 049 racer

i have another question, does the inboard flat bottom airfoil and the outboard semi sym airfoil help much?? it reduces the amount of tip weight needed?

and guys, do u reckon i should sandwich one side of the fuselage with 1/32 ply? or 1/64?

thanks a bunch guys!

Reeve
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Old 03-04-2010, 03:31 PM
  #29  
Jim Thomerson
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Default RE: 049 racer

Your tank looks good. Racers need to be strong to survive the stresses of getting them down and into the hands of the pitperson. What I would do on your wing is, on the last maybe 3 in, move the trailing edge up until you have an inverted airfoil at the tip. The wing shaping is to help keep the airplane on the end of the lines when you go into strong wind or up high to pass. The wing weight is, I think, still needed, particularly for the take off. On the take off with conventional engine turning counterclockwise and airplane flying counterclockwise, the airplane tends to torque roll into the circle on release. Your pilot should be whipping the airplane to keep it from coming in. With an otherwise good airplane and experienced pilot, this is not a real problem. I've seen several photos of racing airplane coming out of the pit, always with inner wing down a little.
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Old 03-05-2010, 09:19 AM
  #30  
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Default RE: 049 racer

jim could u please explain wad do u mean by moving the trailing edge up?, by the way, could u see if wad u meant about the wheel being 15 deg infront of the c.g is correct in my previous drawing?

thanks!
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Old 03-05-2010, 12:56 PM
  #31  
Jim Thomerson
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Default RE: 049 racer

If you are making a symmetrical airfoil on a 1/4 sheet wing, the trailing edge goes down the center of the back side of the wing. So if you move the trailing edge up at the tip, you get washout. On your drawing, the 15 degree line needs to go through where the wheel touches the ground. It won't hurt to put it a little far forward, and bend it back if you get bouncy landings. My last mouse racer was a profile Goodyear racer with the wheels way far forward of where they should be. The guys all criticized it: however, it landed and took off beautifully. I used a set of aluminum landing gears which weren't made right and thought I would have problems, but did not.
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