 It is not known whether the HP-17 actually flew, but the wing spars that Schreder developed for it found good use on Schreder's next and most popular kit sailplane, the HP-18.First flown in 1974, the HP-18 was available in kit form in 1975, and in 1976 was featured in a series of six articles in "Soaring Magazine" that described every detail of its construction.In the spirit of the "Popular Mechanics" article from which Schreder built his first glider at age 9, the "Soaring" articles reproduced the HP-18 plans and assembly instructions in sufficient detail for a resourcful and mechanically-inclined individual to build the aircraft almost from scratch.