Experimental Investigation into Beam-Riding Physics of Lightcraft Engines: Progress Report

A twin Lumonics K922M pulsed TEA CO(2) laser system (pulse duration of approximately 200 ns FWHM spike with 1 us tail) was employed to experimentally measure beam-riding behavior of Type #200 lightcraft engines, using the Angular Impulse Measurement Device (AMD). Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam angular and lateral offset from the vehicle axis of symmetry; b) laser pulse energy (12 to 36 joules); c) pulse duration (100 ns and 1 us); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (C(M)) of 135 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 us duration) results indicated 15-30 N-s/MJ-an improvement of 4.5x to 9x. Maximum axial C(M) performance with the K922M is likely to be 4x to 7x larger than lateral CC(M) values, but must await confirmation in upcoming tests.