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Old 05-05-2006, 11:05 AM
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Default RE: 1/2a speed plane wing design

Chris, you could cut and paste this thread to the 1/2A forum, it should have equal interest here and there. The bladders for 1/2A can only take up to 1 oz of fuel, if you try for more they either burst or develope aneurisms, and loose pressure during a run, which can fry your motor while you helplessly watch. If you try to use a bigger bladder, the pressure drop off is out of the little motors' range as the bladder empties. This is the downside of running bladders. Sometimes the high frequency vibration has caused my bladders to roll as they unload and twist them selves shut! Solution is to either eliminate the vibration, or rig the bladder so it can't roll inside the fuel cell. The other part about running the GZ that you might want to be prepared for in advance is the need for extra head shims so you can tune the engine to only blow plugs every 3rd run or so. Otherwise, you better start ordering extra P/L sets, cirlclips, and rods, too. If you're getting detonation at 35,000, not only will you be making calls to Bill Hughes a lot, but you're losing rpm and possibly causing vibration. One oz of fuel goes quickly, you might be better off taking an inch out of the nose [back to 6 inches instead of 7] and trying a soldered tin tank with a fixed pick up and make it big enough to hold 2 ozs..this set up is good enough for the C/L speed guys, the down side is they have to send the planes off richer, and anticipate the pressure build up as the speed increases. This is what makes suction, suck. It is more guess work, and you aren't hand launching with enough power. With a bladder, I launch on the pipe, and as rich as it will tolerate and still be in resonance.