Schweizer SGS 1-35
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| Manufacturer | Schweizer Aircraft Corporation |
| Type designation | SGS 1-35 |
| Competition class | 15 Metre |
| Designer | Leslie Schweizer[1] |
| First flight | April 1973[2] |
| Number built | 101[1] |
| Crew | 1 |
| Length | 19 ft 2 in (5.84 m) |
| Height | 4 ft 5 in (1.35 m) |
| Wingspan | 49 ft 2 in (15.0 m) |
| Wing area | 103.8 sq. ft. (9.64 m²) |
| Aspect ratio | 23.29 |
| Wing profile | Wortmann FX 67-K-170/150 |
| Empty mass | 400 lb. (181 kg) |
| Water ballast | 320 lbs (145 kg) |
| Maximum mass | 660 lb. (299 kg) |
| Maximum speed | 139 MPH |
| Maneuver speed | 88 MPH |
| Stall speed | 41 MPH |
| Minimum sink rate | 2.0 fps at 45 MPH |
| Best glide ratio | 38 at 55 MPH |
The Schweizer SGS 1-35 is a United States 15 Metre Class, single-seat, mid-wing glider built by Schweizer Aircraft of Elmira, New York.[1][3]
The 1-35 was first flown in 1973 and a total of 101 were completed by the time production was completed in 1982.[1][2][3][4]
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[edit] Background
By the early 1970s competition in the open, standard and 15 meter classes was dominated by fiberglass sailplanes. Schweizer Aircraft evaluated the use of fiberglass for sailplane construction but rejected it for several reasons:[5]
- The high cost of demonstrating to the Federal Aviation Administration that this new material could safely be used for aircraft primary structure.[5]
- Problems with crash resistance of fiberglass structures in high impact accidents.[5]
- The unknown service life of fiberglass.[5]
- The high degree of manual labor required to do fiberglass lay-ups at that time and the associated cost.[5]
The company believed that it could get equivalent performance to fiberglass from the material that it knew best, aluminum. Experiments with the laminar flow wing Schweizer SGS 1-29 in the late 1950s had shown that there was laminar flow potential in metal wings.[5][6]
One of factors that convinced the company that there was a market for a US-made competition sailplane was the great loss of value of the United States Dollar in the early 1970s which had made European sailplanes prohibitively expensive to US buyers.[5]
[edit] Development
Schweizer Aircraft started construction of the 1-35 prototype in late 1972 and it first flew in April 1973. The company carried out side-by-side comparisons with fiberglass sailplanes as part of 50 hours of flight evaluations before making the decision to proceed with manufacturing the design on 10 May 1973.[5]
The 1-35 is an all-metal aircraft with a monocoque fuselage. The wing has a single spar and the stressed skin features multi-stringers for stiffness, to best retain airfoil shape and laminar flow. The aircraft's elevator and rudder are fabric covered. The 1-35 carries 320 lbs (145 kgs) of water ballast in two wing tanks.[1]
Because the 15 Metre Class allows flaps, the SGS 1-35 is equipped with plain flaps that can be selected from -8 to +32 degrees for soaring and inter-thermal speed and +32 to +82 degrees for landing.[1][3]
The 1-35 received type certificate G4EA on 25 April 1974.[7]
The type certificate is currently held by K & L Soaring of Cayuta, New York. K & L Soaring now provides all parts and support for the Schweizer line of sailplanes.[7][8]
[edit] Variants
- 1-35
The original 1-35 model has water ballast and retractable landing gear[1]
- 1-35A
The "A" model incorporated several minor changes, including a sharper nosecone but retained the water ballast and retractable landing gear of the 1-35.[1][7][9]
- 1-35B
There was no 1-35B model[7]
- 1-35C
The "C" stood for "Club" as this model was intended to be a high-performance sailplane for recreational, as opposed to competition, flying. It was designed to appeal to private owners, commercial rental operations and gliding clubs. The "C" has fixed landing gear and no provisions for water ballast.[1][7]
[edit] Competition use
The 1-35 was only competitive for a very short period of time in the early 1970s before European sailplanes such as the Schempp-Hirth Mini-Nimbus and the Glasflügel Mosquito, both introduced in 1976, out-classed it. The metal wing, while of good quality construction, just could not be made to hold an airfoil profile to the same accuracy as a fiberglass wing.[3]
The SGS 1-35 would mark the last attempt by the company to produce a competition sailplane.[3]
The 1-35 quickly found a home as a club and personal glider and, other than in national or world-class competition, has proved popular due to its rugged metal airframe and aesthetic appeal.[3]
[edit] In service
In May 2008 there were still 81 1-35s registered in the USA including:[10]
- 44 SGS 1-35
- 2 SGS 1-35A
- 35 SGS 1-35C
There are also five SGS 1-35s registered in Canada.[11]
[edit] Museum aircraft
The prototype SGS 1-35, N17900 is on display in the National Soaring Museum.[12]
[edit] Aircraft type club
The 1-35 has an aircraft type club, The Schweizer SGS 1-35 Club.[4].
[edit] See also
[edit] References
- ^ a b c d e f g h i Activate Media (2006). SGS 1-35 Schweizer. Retrieved on 2008-06-01.
- ^ a b Federal Aviation Administration (June 2008). FAA Registry. Retrieved on 2008-06-01.
- ^ a b c d e f Said, Bob: 1983 Sailplane Directory, Soaring Magazine, page 33. Soaring Society of America, November 1983. USPS 499-920
- ^ a b Rent, Tom (undated). Schweizer 1-35 Home Page. Retrieved on 2008-06-01.
- ^ a b c d e f g h Schweizer, Paul A: Wings Like Eagles, The Story of Soaring in the United States, pages 159-209. Smithsonian Institution Press, 1988. ISBN 0-87474-828-3
- ^ Said, Bob: 1983 Sailplane Directory, Soaring Magazine, page 32. Soaring Society of America, November 1983. USPS 499-920
- ^ a b c d e Federal Aviation Administration (September 2007). TYPE CERTIFICATE DATA SHEET NO. G4EA. Retrieved on 2008-06-01.
- ^ K & L Soaring (undated). K & L Soaring, LLC. Retrieved on 2008-04-05.
- ^ Rent, Tom (undated). Schweizer 1-35 Types. Retrieved on 2008-06-01.
- ^ Federal Aviation Administration (June 2008). FAA Registry. Retrieved on 2008-06-01.
- ^ Transport Canada (June 2008). Canadian Civil Aircraft Register. Retrieved on 2008-06-01.
- ^ Munson, J. (undated). Sailplanes in Our Collection. Retrieved on 2008-04-15.
[edit] External links
- Side view photo of SGS 1-35 prototype N17900 in the NSM
- Front view photo of SGS 1-35 prototype N17900 in the NSM
- Photo of an SGS 1-35C
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