RS-15 Soaring

December 1971

NEW SCHREDER DESIGN You wand to build, and you can't make up you mind: Standard or Open Class? As the saying goes, "Ya pays yer money and takes yer cherce." Not so, according to Dick Schreder, guru of U.S. sailplane homebuilders. The enthusiast can now have both in one machine, thanks to Dick's latest creation, the RS-15. (RS is for Richard Schreder, of course, and the 15 refers to the ship's basic 15-meter span.) Here's how it works: The RS-if pod-and-boom fuselage is designed so lengths can be adapted to match spans varying from 12 to 20 meters or more. The ship can even be modified from a single to two-place configuration by substituting a side-by-side pod. The two elements that permit these combinations are a six-inch diameter aluminum tail boom and a fiberglass pod. According to the Bryan Aircraft spec sheet, existing fittings, fairings and controls are utilized without change and load factors remain the same. With basic 15-meter wings, the RS-15 boasts an empty weight of 350 lbs., dry. But it is designed to accept 200 lbs. of water ballast, a payload of 300 lbs., and a 6'6" pilot. Under these conditions wing loading would be 7.61 lbs./sq. ft.; but, dry, with a 170-lb. pilot and 20-lb. chute, the loading drops to a minimum of 4.87 lbs./sq. ft. Incidentally, those 15-meter wings are borrowed from the HP-16, which employed metal skins bonded to structural plastic foam ribs. The extra reach for Open-Class spans is obtained by optional center sections. Performance figures for the 15-meter version quote smooth air max. at 150 mph, and rough air max. at 120 mph. An L/D of 36 and minimum sink of 2.0 ft./sec. Are listed, while a 90 degree flap-setting is said to reduce the normal 42 mph stall to 35 mph (at 600 lb. gross weight.) Of particular interest to home-builders will be the designer's statement that the RS-15 can save "several hundred man hours of assembly time." With only hand tools, a rivet gun, electric drill, and air compressor, Bryan Aircraft estimates that just-under-$3500 kit can be built in approximately 500 hours by a constructor of average mechanical aptitude. No jigs are required; wings and tail surfaces are built on saw horses. Kit goodies include pre-machining of main wing spars and pre-sculpturing of all caps, webs, stiffeners, and fittings: completion of all items requiring welding; prefabricated fuselage pod, canopy, structural plastic foam ribs, and many other time-consuming items.