 Unlike Schreder's HP-series gliders, the RS-15 was intended to achieve more modest performance, sacrificing performance for a shortened build time.Early RS-15 models featured wings that were essentially the same as the HP-16, and using the same one-piece machined aluminum I-beam wing spar.Later units were supplied with wing kits nearly identical to those of the HP-18, using that ship's riveted aluminum box spar.