Schreder HP-18

The HP-18 is a Richard Schreder-designed metal Racing Class sailplane that was offered as a kit for homebuilding during the 1970s and 1980s.

Design and development
The HP-18 is a flapped (15-meter) sailplane featuring a V-tail and 90-degree flaps for glidepath control. The fuselage is composed of a prefabricated composite forward fuselage and a semi-monocoque aft fuselage, and features steeply reclined seating and a side-stick controller although modifications using a conventional stick have been made.

Major features:
 * Very low cockpit with reclining seating position
 * Sidestick (changed to conventional stick by some homebuilders)
 * Two-piece canopy (changed to single piece forward opening by some homebuilders)
 * V-tail that folds upwards for easy storage
 * Wing structure composed of spars with caps pre-machined from solid aluminium plate and aluminium wing skins bonded to closely spaced foam ribs
 * Fiberglass fuselage pod, wing tip skids and tail fairings
 * Aluminium tail cone
 * Winglets added by some homebuilders
 * Water ballast carried inside the hollow aluminium wing spars
 * Typical Schreder trailing edge flaps/airbrakes partially interconnected with the ailerons

Variants
As most homebuilts, the HP-18 has been constructed with many variations in detail. Perhaps the most significant version is the Super HP-18 developed by Canadians Ed Hollestelle and Udo Rumpf, which features a modified wing airfoil, winglets, a front-hinged canopy, conventional control stick and higher ballast capacity.

Aircraft on display

 * EAA Airventure Museum, Oshkosh, Wisconsin
 * National Soaring Museum, Elmira, New York
 * US Southwest Soaring Museum, Moriarty, New Mexico