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Speed,Combat,Scale,Racing => Speed Talk => Topic started by: Motorman on December 23, 2014, 09:36:23 PM
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How thick do you need to make the wing on a 21 proto? If I remember on my 21 speed there was just enough room for a 1/4" wing between the tank and the mini pipe. I thought a bigger wing would need to be 3/8" so, I'm wondering what is usually done.
Thanks,
MM
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Need to make a top for this.
(http://i889.photobucket.com/albums/ac93/giffy6/protopan.jpg) (http://s889.photobucket.com/user/giffy6/media/protopan.jpg.html)
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Do a search for Tom Wilk. Then PM him as he has cd's for speed planes showing the plans. Might go on the NASS(North America Speed Society) and check them out.
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Mine is still a glued-up blank, custom sawed, .338" thick at the center. I think we were looking at 5/16" finished. The plane was mostly designed by Tom Knoppi. It's got 1/64 or 1/32 plywood edges, and a fair amount of taper, and was going to be covered with .6 oz FG and epoxy. The block of balsa we sawed up was right around 6 lb density. We intended to use K&B .21 ABC Ducted Fan engines (rear intake). Then Tom had his car wreck. The plans got lost, along with a lot of enthusiasm. :'( Steve
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Carl China's Viper II wing was just thick enough to hold the control unit, barely 1/4".
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Must have been basswood.
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Must have been basswood.
According to the construction plan the wing has a 1/4 h x 1/8 w bass spar. The balance is balsa. Harry Roe built his pretty much the same way. In his article Carl specified the fabricated wing w/ Monoline unit @ 3.5 oz. This did not include the finish. These planes were very light.
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Ok but, the reason I'm asking the question is because I've seen wings that were built too light. When they get up to speed the tips flex up and put on the brakes.
MM
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Ok but, the reason I'm asking the question is because I've seen wings that were built too light. When they get up to speed the tips flex up and put on the brakes.
MM
Viper II was designed to the class minimum 24" span. The root chord is 7.25" and the tip chord is 3.25". The quarter chord line has no sweep. The resulting aspect ratio is 4.48. I launched for both Carl & Harry and was around for a lot of their test activity. I don't recall that the wing gave any problems.
I could see though that a higher aspect ratio wing might need more thickness, especially if the plane was a bit on the heavy side.
P.S. You might want to look at Jimmy Delany's and Tom Lauerman's Emanon. They held the B Proto record when the class was retired. It was certainly no slouch.