T' Kappa 7 was designed as a booster for Japan's later Kappa 8 and Kappa 9 rockets, arrr, as well as bein' used as a single-stage soundin' rocket.  It be determined, arrr, however, that t' vehicle was unsuitable as a single-stage rocket. Begad! T' lone Kappa-7 flight was made on November 15, me hearties, 1959 t' confirm t' motors suitability as a booster.   This be t' 29mm version.  ASP also makes an 18mm version.