The performance of a piston launcher employing an operational design modification was compared to the standard zero volume piston launcher. Test results showed that the modified launcher performed 34% better than the standard piston.
The design modification was derived from a deficiency noted in the standard piston after a theoretical consideration of the principles of its operation. This deficiency is responsible for the deceleration of a model prior to its separation from the launcher, resulting in significant velocity loss. The modified launcher employs a floating piston head to overcome this deficiency. The piston head can float freely off the support rod allowing the forward motion of the piston and model to continue until the model separates from the pressurized tube. This minimizes velocity loss.
The performance of the piston launcher was determined by measuring the velocity of the model at a fixed point in flight. Velocity was determined by a novel method utilizing an infrared emitter/detector pair mounted in the path of a passing fin. The time required for a fin of known chord to traverse the IR beam was measured by a computer and velocities were directly calculated. The method was expedient and trouble-free and should prove extremely useful in future research projects where velocity measurements are required.
Other performance benefits observed with the floating
head piston launcher include a greater degree of reproducibility
and little incidence of model tip-off that is associated
with the standard design. It is recommended that these
benefits along with the optimization of the floating head
design be investigated in future research and development
Email: cbweiss at frontiernet dot net
Slingerlands, NY 12159
Email: jeffvincent at verizon dot net