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.
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.
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.
Schweizer Aircraft evaluated the use of fiberglass for sailplane construction and rejected it for several reasons:
Of these, only the SGS 1-29 proceeded to prototype stage.
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.
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.
The aircraft first flew in 1958 and flight testing was reported by Schweizer Aircraft as on-going through 1959.
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%.