The Schreder HP-21 was an American
high-wing
A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes.
A monoplane has inherently the highest efficiency and lowest drag of any wing co ...
,
variable geometry,
V tailed, single seat
motor glider
A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flight ...
project that was designed by
Richard Schreder
Richard E. Schreder (25 September 1915 – 2 August 2002) was an American naval aviator and sailplane developer, responsible for design and development of the HP/RS-series kit sailplanes marketed from 1962 until about 1982. Schreder also fou ...
. None was ever completed or flown.
[''Homebuilder News, ]Soaring Magazine
''SOARING'' is a magazine published monthly as a membership benefit of the Soaring Society of America. It was first published in 1937. The headquarters is in Hobbs, New Mexico. The magazine's article topics include safety issues and accounts of in ...
'', Volume 46, Number 8 page 11, August 1982. Soaring Society of America
The Soaring Society of America (SSA) was founded at the instigation of Warren E. Eaton to promote the sport of soaring in the USA and internationally. The first meeting was held in New York City in the McGraw–Hill Building on February 20, 193 ...
, USPS 499-920[''SSA In Action - Homebuilder News, ]Soaring Magazine
''SOARING'' is a magazine published monthly as a membership benefit of the Soaring Society of America. It was first published in 1937. The headquarters is in Hobbs, New Mexico. The magazine's article topics include safety issues and accounts of in ...
'', Volume 48, Number 4 page 8, April 1984. Soaring Society of America
The Soaring Society of America (SSA) was founded at the instigation of Warren E. Eaton to promote the sport of soaring in the USA and internationally. The first meeting was held in New York City in the McGraw–Hill Building on February 20, 193 ...
, USPS 499-920[''Homebuilders News, ]Soaring Magazine
''SOARING'' is a magazine published monthly as a membership benefit of the Soaring Society of America. It was first published in 1937. The headquarters is in Hobbs, New Mexico. The magazine's article topics include safety issues and accounts of in ...
'', Volume 48, Number 6 page 27, June 1984. Soaring Society of America
The Soaring Society of America (SSA) was founded at the instigation of Warren E. Eaton to promote the sport of soaring in the USA and internationally. The first meeting was held in New York City in the McGraw–Hill Building on February 20, 193 ...
, USPS 499-920
Design and development
The HP-21 project was publicly announced in August 1982 in
Soaring Magazine
''SOARING'' is a magazine published monthly as a membership benefit of the Soaring Society of America. It was first published in 1937. The headquarters is in Hobbs, New Mexico. The magazine's article topics include safety issues and accounts of in ...
. 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 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
Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
spar
SPAR, originally DESPAR, styled as DE SPAR, is a Dutch multinational that provides branding, supplies and support services for independently owned and operated food retail stores. It was founded in the Netherlands in 1932, by Adriaan van Well, ...
with a span of and a chord of only , with
winglet
Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft' ...
s fitted. The wing incorporated a hand-crank operated retractable
Dacron
Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foo ...
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
The wing root is the part of the wing on a fixed-wing aircraft or winged-spaceship that is closest to the fuselage
The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, o ...
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
The HP-22 was a finance-oriented pocket calculator produced by Hewlett-Packard between 1975 and 1978. It was designed as a replacement for the short-lived HP-70, and was one of a set of three calculators, the others being the HP-21 and HP-25, ...
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.
Specifications (HP-21)
See also
References
{{Schreder Sailplanes
1980s United States sailplanes
Schreder aircraft
V-tail aircraft
Motor gliders
High-wing aircraft