Schreder HP-18

{{Short description|American glider}} {{Redir|HP-18|the Hewlett-Packard calculator|HP-18C}} {{Use mdy dates|date=May 2022}} {{Use American English|date=May 2022}}  {{Infobox aircraft | name = HP-18 | logo = | logo_size = | image = File:Schreder HP-18 4X-GHD at Habonim Israel 27-06-2014.jpg | alt = | caption = An HP-18 dis-assembled prior to display at the Paradive Flight Gallery in Habonim | long_caption = | other_names = | aircraft_type = Club (formerly 15 metre) class Sailplane | aim = | outcome = | related = | national_origin = | manufacturer = Homebuilt | design_group = | designer = Richard Schreder | builder = | issuer = | status = | owners = | primary_user = | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = 180 kits sold<ref name="SoaringNov83">Said, Bob: ''1983 Sailplane Directory, Soaring Magazine'', page 23. Soaring Society of America, November 1983. USPS 499-920</ref> | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }}

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.<ref name="ActivateMedia">{{cite web|url = http://www.sailplanedirectory.com/PlaneDetails.cfm?PlaneID=165|title = HP-18 HP Aircraft, LLC|accessdate = 2008-07-24|last = Activate Media|year = 2006|url-status = dead|archiveurl = https://web.archive.org/web/20080303025015/http://www.sailplanedirectory.com/PlaneDetails.cfm?planeID=165|archivedate = 2008-03-03}}</ref>

==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<ref name="ActivateMedia"/> 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<ref>{{cite web|title=Bryan/Harris HP-18 Sailplane|url=http://museum.eaa.org/collection/aircraft/Bryan_Harris%20HP-18%20Sailplane.asp#TopOfPage|accessdate=28 March 2011|url-status=dead|archiveurl=https://web.archive.org/web/20110719095807/http://museum.eaa.org/collection/aircraft/Bryan_Harris%20HP-18%20Sailplane.asp#TopOfPage|archivedate=19 July 2011}}</ref> *National Soaring Museum, Elmira, New York<ref name="NSMCollection">{{cite web|url = http://www.soaringmuseum.org/collection.html|title = Sailplanes in Our Collection|accessdate = 26 February 2011|last = National Soaring Museum|authorlink = |year = 2011|archive-date = May 16, 2011|archive-url = https://web.archive.org/web/20110516142717/http://www.soaringmuseum.org/collection.html|url-status = dead}}</ref> *US Southwest Soaring Museum, Moriarty, New Mexico<ref name="SWSMCollection">{{cite web|url = http://swsoaringmuseum.org/collection.htm|title = Sailplanes, Hang Gliders & Motor Gliders|accessdate = 26 May 2011|last = US Southwest Soaring Museum|authorlink = |year = 2010|archive-date = November 20, 2022|archive-url = https://web.archive.org/web/20221120055021/http://swsoaringmuseum.org/collection.htm|url-status = dead}}</ref>

==Specifications== thumb|right {{Aircraft specs |prime units? = imp |crew=One pilot |length m=7.07 |length ft=23 |length in=2.4 |span m=15.00 |span ft=49 |span in=2 |wing area sqm=10.5 |wing area sqft=113 |aspect ratio=21.4 |empty weight kg=213 |empty weight lb=470 |gross weight kg=446 |gross weight lb=970 |max speed kmh=240 |max speed mph=150 |glide ratio=38 |sink rate ms=0.6 |sink rate ftmin=126 }}  {{aircontent  |related= |similar aircraft= |lists= |see also= }}

==References== {{Reflist}} *[http://www.soaridaho.com/Schreder/ Schreder Designs webpage] *R Johnson, ''A Flight Test Evaluation of the HP-18W Sailplane'', Soaring, July 2003

==External links== *[http://www.soaridaho.com/Schreder/HP-18/HP-18_Soaring_Review.html HP-18 Reference Info Link]

Category:1970s United States sailplanes Category:Glider aircraft Category:Schreder aircraft Category:Homebuilt aircraft Category:V-tail aircraft