stunthanger.com
Design => Stunt design => Topic started by: Jim Pollock on July 21, 2009, 04:36:11 PM
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Hey there Paul or Howard,
How about an expose on the reason for the tip chord reduction on the Impact?
After all, this is the designing forum and that is a new design feature of the Plane!
Jim Pollock, Moderator
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Paul is the guy to answer the question, but I can tell you about my stabs. Here are pictures of my last two dogs. The white one's stab is per the original plans. The yellow one's stab has half the tip chord of the original. Paul built a couple planes with the reduced tip chord, including the one with which he won every contest it entered, including the world championships. At the time I built the stab on the yellow dog, Paul favored the smaller chord, so that's what I used. He has since reverted to the original chord. I can't fly the yellow plane very accurately. The flaps are the chief suspect, but if new flaps don't help, I might try changing the stab.
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Hi Howard,
Do you think the aerodynamic balance on the flaps is causing the inaccuracy?
There's probably nothing better than a stock Impact from the original plans balanced exactly where Paul says the CG should be, sporting a VF .40 and an 11.3 inch Eather CF prop. Although; if you were looking for better wind penetration,......well, you know!
Jim Pollock H^^
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Maybe. I'll try reducing tab gain tomorrow, but the plane was as bad or worse with the tab linkage disconnected and the tabs fixed to the flaps.
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Some years ago, I asked PW about the smaller stab tip chord, and he replied that the "Sweden stab" plane would do either a hard corner or a softer corner, without any trim changes, other than a mental adjustment. Just locked into whatever radius he wanted. I'd rather fly a hard corner, and the heck with what the Judges want. I would not try to predict what the Judges would like or dislike.
I've watched Paul and Howard flying the .40VF's and later the RO-Jett .65's (or .61's?). The BEST match I've seen for the .40VF, in my opinion, is Randy Smith's Shrike (630 sq. in.). The ImpAct is awesome with the RO-Jett, whichever one it is. But I'm thinking that it would also be awesome with a Stalker .76RE. ;D Steve