Empirical Evaluation Of Optimum Piston Tube Length For A Floating-Head Piston Launcher - Abstract



Copyright © 1997 by Chuck Weiss (cbweiss at frontiernet dot net) and Jeff Vincent (jeffvincent at verizon dot net).
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Abstract - Empirical Evaluation Of Optimum Piston Tube Length For A Floating-Head Piston Launcher

The Crunch Birds Team - NARAM-30

The optimization of piston tube length utilizing a floating head piston launcher, as recommended by these same authors in their NARAM-28 research and development report, was studied. The performance of the launcher was evaluated using an improved speed determination apparatus capable of monitoring launch velocity as a function of engine burn time from the moment of ignition. The launch mass of the test models represented a typical 1/2A streamer competition model. The models were flown with no piston (controls), a 9 inch piston tube and an 18 inch piston tube. Graphs of velocity versus time showed that at a 7 inch piston tube is required to achieve the optimum benefit of the floating head piston launcher with a nine inch piston tube being desirable to allow a margin of safety. No significant additional benefit was observed for piston tubes of longer length. Control models flown with no piston showed that thrust produced during the first 0.1 seconds of engine burn was insufficient to significantly accelerate a model and that the gases produced are essentially wasted. These same gases were effectively used by the floating head piston launcher to accelerate a model to velocities of approximately 26 feet per second in 0.04 seconds.

The apparatus developed to evaluate launcher performance proved highly effective and it is recommended that it be utilized for future research in optimizing other floating-head piston launcher design parameters and studying their relationship to other competition conditions.

Chuck Weiss
Email: cbweiss at frontiernet dot net

Jeff Vincent
Box 523
Slingerlands, NY 12159
(518) 439-2055
Email: jeffvincent at verizon dot net


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Last modified January 26, 2006

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