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View Full Version : How NOT to two stage a Maniac...


luke strawwalker
03-22-2008, 09:24 PM
:eek:

Well couldn't just let well enough alone... Love the smell of burning BP in the morning...

So, I decided to launch one of my recently reworked Maniacs (Geez I HATE that name; what a STUPID name for a kit, tacky decals and all... at least the old Challenger II it's based on was a classy looking kit, but I digress) The Maniacs made a super Astrocam carrier back in the old pre-BAR days and I recently went thru them and airfoiled the plastic fins, rounded the ends of the plastic fin cans to blend into the base of the tube, filled, sanded, painted, watched the plastic bleed thru color into the paint (for some reason, STILL scratching my head over THAT one) repaint, rebled, sanded, repaint, finally covered, then painted flourescent orange overall, color sand, and pretty much call it done.

Well, I didn't have anything in the motor box but D12-0's and D12-7's so I figured "what the heck let's send her up as a two stager. One of my Maniacs seperated at about 1000 feet, thanks to that lousy 'rubber' shock cord, on it's third flight years ago and dropped her streamlined in and accordioned the tube and then the tube BLEW OUT like a shotgun shell, splitting it to within about 3 inches of the fin unit. So, I salvaged what was left and put a homemade coupler in the end of it, to use it as a booster stage.

So, no time like the present, loaded the booster up with the D12-0 and decided since it was gap staged and the homemade coupler wasn't very tight, that I'd cut a couple ports in the side to relieve the blowthru pressure to help sustainer ignition. Thanks to Dave and his handy X-acto a couple ports were quick work, and a pretty clean job. Loaded the sustainer with a D12-7, a borrowed nylon chute, dog barf, and ignitor. Out to the pad she went.

54321 blastoff and up she goes, about 100 feet or so, heels over due south to nearly horizontal and accelerates like a bat out of... well you know. Anyway, she stages just about then, clean as a whistle, and hustles out of there like there's no tomorrow. About 300 yards down the field gravity wins and pulls her down into a hard prang and bounce that raises a cloud of dust probably 10 feet high or so. We jump on the golf cart to view the remains...

Dunno what happened. I've Rocksimmed it a hundred times, and it works good every time. Maybe a gust of wind or too short of a rod. When I looked at the Rocksim this afternoon, I did notice quite a bit of 'waggling' near first stage burnout...

Oh well, at least the booster survived unscathed... the Eliminator (sorry Maniac- did I mention I hate that name) is probably a write off- cone split lengthwise into 3 pieces and the base, with the swivel and shock cord, with about a 2 square inch piece of BT-56. The plastic fin unit is toast. Maybe I'll rebuild the booster into a new Eliminator, plug the ports, etc... :)

Hope yall have better luck! Keep em pointed up! OL JR :)

luke strawwalker
03-22-2008, 09:26 PM
Before, after, and the booster stage...

Here's the rocksim if anybody wants to play with it... :) OL JR :)

snaquin
03-22-2008, 10:44 PM
Before, after, and the booster stage...

Here's the rocksim if anybody wants to play with it... :) OL JR :)

Bummer about the demise of your "__________ " insert name here ;)

I think you may have just had a stroke of bad luck with your flight. I approximated a Maniac in RockSim and flew a two-staged version of it years ago with parts from an Estes Longshot with the upper stage converted to D/E engine mount. I seem to remember it is stable in a two-stage configuration with D engines in both stages without any added nose weight, that's how I flew mine.

Your RockSim file is showing a little too much span dia. and needs to be reduced some. I can't locate my RockSim for the Maniac or two-staged Maniac, but I did find my Longshot file and attached it for you. If you delete the upper most 12" airframe and coupler from the design and use the booster engine mount in the sustainer instead of the 18mm mount of the Longshot kit you should have a pretty good approximation of your two-stage model.

In your photo of the booster am I looking at a body tube or a coupler with the pass-port hole in it? It appears to have a coupler above that. I'm trying to figure out where to place your upper stage motor in the design to see how the CG/CP looks.

I always liked the Manic kit. My son had one and we flew it twice in the same day with G55 single use motors at a very large field back in 1994. That picture is when I dropped him off at the end of the day following two successful very high altitude flights. If you look at the picture closely, you can see where the very tip of the nose cone is slightly deformed from the heat generated from filling the tip with epoxy and BB's before I had a chance to dunk it in ice water to cool it down before it deformed during the 5-min. epoxy curing.

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