Schreder HP-21
{{short description|American motor glider project}}
{{Use mdy dates|date=January 2022}}
{{Use American English|date=January 2022}}
| {{Infobox aircraft begin
| name=HP-21 | image= | caption= }}{{Infobox aircraft type | type=Glider | national origin=United States | manufacturer= | designer=Richard Schreder | first flight=none | introduced= | retired= | status= | primary user= | more users= | produced= | number built=none | developed from= | variants with their own articles= }} |
The Schreder HP-21 was an American high-wing, variable geometry, V tailed, single seat motor glider project that was designed by Richard Schreder. None was ever completed or flown.Homebuilder News, Soaring Magazine, Volume 46, Number 8 page 11, August 1982. Soaring Society of America, USPS 499-920SSA In Action - Homebuilder News, Soaring Magazine, Volume 48, Number 4 page 8, April 1984. Soaring Society of America, USPS 499-920Homebuilders News, Soaring Magazine, Volume 48, Number 6 page 27, June 1984. Soaring Society of America, USPS 499-920
Design and development
The HP-21 project was publicly announced in August 1982 in Soaring Magazine. Schreder said at that time: "the HP-21 will out-perform any other factory-built 15-Meter racer now in production."
In April 1984 the design was revealed as a high performance V-tailed single seater, with a retractable KFM 107e powerplant of {{convert|25|hp|kW|0|abbr=on}} for self-launching, mounted behind the cockpit and retracting rearward to lie in a bay. The propeller remained exposed when the engine was retracted. The non-tapered wing had a carbon fiber spar with a span of {{convert|49.2|ft|m|1|abbr=on}} and a chord of only {{convert|18|in|cm|0|abbr=on}}, with winglets fitted. The wing incorporated a hand-crank operated retractable Dacron sailcloth flap that was intended to be extended for thermalling and retracted for glides. The flap was of triangular shape and when deployed would extend from the wing root to a point just inboard of the ailerons. The flap retracted by winding around a chrome-moly steel tube located inside the wing.
Schreder went on to start work on the HP-22 before the HP-21 was finished and, even though the prototype HP-21 carried the registration of N38100, it was never registered and there is no indication that it was ever completed or flown.{{Cite web|url = http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=38100|title = Make / Model Inquiry Results|accessdate = 20 April 2011|last = Federal Aviation Administration|authorlink = |date=April 2011}}{{Cite web|url = http://registry.faa.gov/aircraftinquiry/AcftRef_Results.aspx?Mfrtxt=&Modeltxt=HP-21&PageNo=1|title = Make / Model Inquiry Results|accessdate = 20 April 2011|last = Federal Aviation Administration|authorlink = |date=April 2011}}
Specifications (HP-21)
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