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]
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 1-23Gfuselage. 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]
1 2 3 4 5 6 7 8 9 10 11 12 Schweizer, Paul A: Wings Like Eagles, The Story of Soaring in the United States, pages 159-209. Smithsonian Institution Press, 1988. ISBN0-87474-828-3
1 2 3 4 5 6 7 8 9 Said, Bob: 1983 Sailplane Directory, Soaring Magazine, page 32. Soaring Society of America, November 1983. USPS 499-920
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