Bowlus SP-1 Paperwing

{{Short description|American glider}} {{Use mdy dates|date=January 2022}} {{Use American English|date=January 2022}}  {{Infobox aircraft | name = SP-1 "Paperwing" | logo = | logo_size = | image = File:Bowlus SP-1 Paper Wing - Redondo beach - December 1929.jpg | alt = | caption = William Hawley Bowlus launching in the Bowlus SP-1 at the Redondo Beach Glider Meet in December, 1929 | long_caption = | other_names = | aircraft_type = Glider | aim = | outcome = | related = | national_origin = United States | manufacturer = William Hawley Bowlus | design_group = | designer = William Hawley Bowlus | builder = | issuer = | status = Sole example no longer exists | owners = | primary_user = | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = One | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = January, 1929 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }} The '''Bowlus SP-1 Paperwing''' was an American high-wing cantilever monoplane, single-seat, glider that was designed in 1928 and completed by William Hawley Bowlus on January 1, 1929. The SP-1 was Bowlus' sixteenth glider, and was test flown at Lindbergh Field in San Diego in January, 1929.<ref>Fogel, Gary. 2000. ''Wind and Wings: The History of Soaring in San Diego''. Rock Reef Publishing House {{ISBN|0-9670339-5-0}}</ref> Later tests were also made from hillsides near Bonita, California, in April, 1929. SP-1 received identification mark "493" from the United States Department of Commerce and was one of the first licensed gliders in the United States. Many refer to the Bowlus SP-1 as the first sailplane of U.S. design and construction.<ref>Benbough, Richard "The Paperwing Bowlus Sailplane" ''Soaring'', May, 1982, pp. 85-90</ref>

==Design and development== The SP-1 received two nicknames, the first "Old Number 16" as the sixteenth Bowlus glider, and "Paperwing" because its wing rib webs were fabricated from craft paper. The ribs of both the rudder and the elevator were also made with paper webbing.<ref>Bowlus, William H. "How to Build the Bowlus Sailplane" ''Modern Mechanics and Inventions for January'', 1930, pp. 140-148.</ref> Otherwise the aircraft was predominantly wood and doped aircraft fabric.<ref>Bowlus, William H. "How to Build the Bowlus Sailplane" ''Modern Mechanics and Inventions for January'', 1930, pp. 140-148.</ref> The aircraft originally had a {{convert|44|ft|m|1|abbr=on}} span wing with a USA 35-A airfoil with conventional aileron control and landing wheels for the rough dirt surface at Lindbergh Field.<ref>Fogel, Gary. 2000. ''Wind and Wings: The History of Soaring in San Diego''. Rock Reef Publishing House {{ISBN|0-9670339-5-0}}</ref> The wing was later redesigned to include tip-ailerons, extending the wingspan to {{convert|47|ft|m|1|abbr=on}}. The aircraft achieved a very low empty weight for its size of {{convert|160|lb|kg|1|abbr=on}} and a matching low wing loading as well.<ref name="Incomplete">{{Cite web|url = http://www.ae.illinois.edu/m-selig/ads/aircraft.html|title = The Incomplete Guide to Airfoil Usage|accessdate = 1 August 2011|last = Lednicer|first = David|year = 2010|archive-url = https://web.archive.org/web/20100420012244/http://www.ae.illinois.edu/m-selig/ads/aircraft.html|archive-date = 20 April 2010|url-status = dead}}</ref> Bowlus's lightweight construction techniques and design philosophies significantly influenced future glider designs, contributing to the evolution of sailplane wing design.<ref>https://www.researchgate.net/publication/269235279_The_Evolution_of_Sailplane_Wing_Design</ref>

==Operational history== Bowlus flew the SP-1 in several regional glider meets in Southern California including two in Pacific Beach, San Diego, and one in Redondo Beach, California, in 1929. On October 5, 1929, Bowlus established a new U.S. soaring endurance record in SP-1 above the cliffs in Point Loma, California, near the Old Point Loma Lighthouse with a flight of 14 minutes and 10 seconds. On October 19, 1929, Bowlus extended this to 1 hour and 21 minutes, to make the first soaring flight over 1 hour duration in the US.<ref>''Popular Mechanics'' Oct, 1929</ref> SP-1 was used for glider instruction at the Bowlus Glider School in San Diego. Many of the first licensed glider pilots in the U.S. learned to fly in SP-1.<ref>Fogel, Gary. 2000. ''Wind and Wings: The History of Soaring in San Diego''. Rock Reef Publishing House {{ISBN|0-9670339-5-0}}</ref>

==Variants== The Bowlus SP-1 sailplane served as a prototype for a series of other Bowlus designs, first with the Bowlus SP-D, then the Bowlus model "A" and S-1000. Only the single SP-1 sailplane made use of paper ribs, all subsequent Bowlus sailplanes used completely wood and fabric construction.<ref>Benbough, Richard "The Paperwing Bowlus Sailplane" ''Soaring'', May, 1982, pp. 85-90</ref> The latter designs also used a larger 60 foot wingspan and were the type used by Charles A. Lindbergh<ref>Bowlus, William H. "Lindbergh Learns to Glide" ''Popular Mechanics'' April, 1930, pp. 530.</ref><ref>"Lindbergh Clips Wings and Flies His First Sailplane" ''San Diego Sun'' January 20, 1930</ref> and Anne Morrow Lindbergh<ref>"Mrs. Lindbergh Awarded Glider Pilot's License" ''San Francisco Chronicle'' January 30, 1930</ref><ref>Fogel, Gary. 2014. ''The Torrey Pines Gliderport (Images of America Series)'' Arcadia Publishing, {{ISBN|9781467131360}} pg. 16-17.</ref> to establish their glider licenses in 1930.<ref>Teale, Edwin Way "How to Get Into Gliding" ''Popular Science'' April, 1930, pp. 24.</ref> Bowlus later used a Bowlus model A sailplane design to set several other endurance records, while student Jack Barstow used a Bowlus model A to set an unofficial world record for glider endurance of 15 hours and 13 minutes at Point Loma in 1930.<ref>Teale, Edwin Way 1930 ''The Book of Gliders'' E.P. Dutton & Company, Inc.</ref><ref>''San Diego Union'' January 7, 1930</ref><ref>''San Diego Union'' January 13, 1930</ref><ref>''New York Times'', January 14, 1930</ref><ref>"Sets Glider Record in Nine-Hour Flight" ''New York Times'' February 25, 1930</ref>

Many variants patterned from the Bowlus SP-1 through Bowlus S-1000 series were constructed, including the ''Silver King'' by Harland Ross, and the ''Nighthawk'', a sailplane flown by William A. Cocke to a world endurance record of 21 hours 34 minutes in 1931. The ''Nighthawk'' is in the collection of the Los Angeles County Museum of Natural History and was, for a time, displayed at the Santa Monica Museum of Flying.<ref>{{Cite web |url=http://esoaring.com/nighthawk1931.htm |title=Nighthawk1931 |access-date=2015-11-14 |archive-url=https://web.archive.org/web/20160304140728/http://esoaring.com/nighthawk1931.htm |archive-date=2016-03-04 |url-status=dead }}</ref>

==Aircraft on display== *San Diego Air & Space Museum – Bowlus SP-1 (replica)<ref name="SDASM">{{cite web|url = http://www.sandiegoairandspace.org/exhibits/map.php|title = Museum Map|accessdate = 1 July 2011|last = San Diego Air & Space Museum |author-link = |year = 2011}}</ref> *Wings of History Museum – Bowlus S-1000 (317W; original) in storage

==Specifications (SP-1) == {{Aircraft specs |ref= |prime units?=imp  |genhide= |crew=one |capacity= |length m= |length ft= |length in= |length note= |span m= |span ft=44 |span in= |span note= |height m= |height ft= |height in= |height note= |wing area sqm= |wing area sqft=179 |wing area note= |aspect ratio=11:1 |airfoil=USA 35-A |empty weight kg= |empty weight lb=160 |empty weight note=with landing gear 180 lbs |gross weight kg= |gross weight lb=305 |gross weight note= |more general=  |perfhide= |max speed kmh= |max speed mph= |max speed kts= |max speed note= |cruise speed kmh= |cruise speed mph=22 |cruise speed kts= |cruise speed note= |stall speed kmh= |stall speed mph= |stall speed kts= |stall speed note= |never exceed speed kmh= |never exceed speed mph= |never exceed speed kts= |never exceed speed note= |g limits= |roll rate= |glide ratio= 20:1 |sink rate ms= |sink rate ftmin= |sink rate note= |lift to drag= |wing loading kg/m2= |wing loading lb/sqft=1.7 |wing loading note= |more performance= |avionics= }}

==See also== {{aircontent  |see also= |related= |similar aircraft= |lists= * List of gliders }}

==References== {{Commons category|Bowlus SP-1 Paper Wing}} {{reflist}}

Category:1920s United States sailplanes Category:Aircraft first flown in 1929