Schweizer SGS 1-29

The Schweizer SGS 1-29 is an American single-seat, mid-wing, experimental laminar flow airfoil glider built by Schweizer Aircraft of Elmira, New York.[3]

SGS 1-29
Paul Schweizer's 1-29 at the 1963 US Soaring Championships at Harris Hill, Elmira, NY
Role Experimental Standard-class sailplane
National origin United States
Manufacturer Schweizer Aircraft Corporation
Designer Ernest Schweizer[1]
First flight 1958[2]
Number built 1

The 1-29 is a development of the Schweizer SGS 1-23 that utilizes a 1-23 fuselage and a newly constructed set of 49.2 foot (15.0 m) span wings.[1][3]

The aircraft was constructed to study the feasibility of producing improved boundary layer laminar flow on a metal-winged sailplane. Only one SGS 1-29 was produced and the project was not pursued further.[1][2][3]

Background

In the mid-1950s the SGS 1-23 was in full production and through successive models was performing very well in competition. By 1957 the development of fiberglass-reinforced plastic affected the production of many sporting goods, such as boats and fishing rods. Schweizer Aircraft thought it was only a matter of time before a fiberglass sailplane was produced. This concern was borne out in 1965, when two German fiberglass sailplanes were entered in the world championships.[2]

Schweizer Aircraft evaluated the use of fiberglass for sailplane construction and rejected it for several reasons:[2]

  • The high cost of demonstrating to the Federal Aviation Administration that this new material could safely be used for aircraft primary structure.[2]
  • Problems with crash resistance of fiberglass structures in high impact accidents.[2]
  • The unknown service life of fiberglass.[2]
  • The high degree of manual labor required to do fiberglass lay-ups at that time and the associated cost.[2]

The company decided to concentrate on getting the best performance from the material that it knew best, aluminum.[2]

Schweizer created several design studies of new sailplanes in the mid-1950s. These included:[2][4]

  • Schweizer 2-27[4]
  • Schweizer 7-28[4]
  • Schweizer SGS 1-29[4]

Of these, only the SGS 1-29 proceeded to prototype stage.[2][3]

Design and development

The 1-29 was constructed using a modified SGS 1-23G fuselage. New wings were built for the aircraft to determine if better laminar flow could be achieved on a metal wing.[1][3]

The wings were all-metal and of constant chord. The wing ribs were identical and created from a single master die to ensure uniformity. The wing features a thick, deep spar to reduce wing flexing and "oil-canning" that might interrupt laminar flow. The wing was assembled using flush rivets and has balanced top and bottom dive brakes.[1][3]

The aircraft first flew in 1958 and flight testing was reported by Schweizer Aircraft as on-going through 1959.[2]

The 1-29 program did yield positive results. The standard production model SGS 1-23H-15 with the same fuselage and wingspan as the 1-29 and a NACA 43012A airfoil, produced a best glide ratio of 29:1. With its laminar flow wing and NACA 63-618 airfoil the 1-29 recorded a 34:1 glide ratio, an improvement of 15%.[3]

The 1-29 design was never certified and the sole aircraft that was built is an experimental aircraft in the "racing, exhibition" class and registered as N3898A.[3][5]

Operational history

The 1-29 was flown in at least three US national competitions by Paul A Schweizer, Bill Ivans and Tom Smith.[3]

Aircraft on display

Once the 1-29 test program was complete, the aircraft was donated to the National Soaring Museum where it is currently listed as being in storage.[6]

Specifications

General characteristics

  • Crew: One
  • Wingspan: 49 ft 3 in (15.00 m)
  • Wing area: 154 sq ft (15.3 m2)
  • Aspect ratio: 15.75
  • Airfoil: NACA 63-618
  • Empty weight: 465 lb (224 kg)
  • Gross weight: 750 lb (340 kg)

Performance

  • Maximum glide ratio: 34 at 52 mph (83 km/h)
  • Rate of sink: 123 ft/min (0.63 m/s)
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See also

Related lists

References
  1. Activate Media (2006). "SGS 1-29 Schweizer". Archived from the original on 2007-08-08. Retrieved 2008-05-27.
  2. 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
  3. Said, Bob: 1983 Sailplane Directory, Soaring Magazine, page 32. Soaring Society of America, November 1983. USPS 499-920
  4. Smithsonian Institution (2004). "Directory of Airplanes". Retrieved 2008-05-13.
  5. Federal Aviation Administration (May 2008). "FAA Registry". Retrieved 2008-05-27.
  6. Munson, J. (n.d.). "Sailplanes in Our Collection". Archived from the original on 2011-05-16. Retrieved 2008-04-15.
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