re big amateur rockets let s see these aren t in a strict sense amateur rockets that term denotes rockets the engines of which are constructed by the user the rockets you describe are called hpr or high power rockets to distinguish them from smaller model rockets they use factory made ammonium perchlorate composite propellants in phenolic plastic engines with graphite nozzles the engines are classified by impulse a d engine for example can have no more than newton seconds of impulse an f engine can have no more than ns each letter corresponds to a doubling of the maximum impulse so far engines up to size o are available pretty much off the shelf engines of size h and above are shipped as class b explosives and as such are controlled engines of size f and below are shipped as class c explosives and are not as controlled class f engines btw are not hpr engines but model rocket engines class g engines go in and out of legal limbo there is an hpr society the tripoli rocket society i believe which holds events at various sites throughout the year with all legalities faa waiver included taken care of the national association of rocketry is more concerned with engines below h though it is involved in hpr as well these societies certify users of hpr rockets and companies will not sell to uncertified individuals bottom line it s legit i suggest you send for a catalog but forget the dynamite will ya larry c
