|SGS 1-34 with terminal velocity dive brakes deployed|
|National origin||United States|
|Manufacturer||Schweizer Aircraft Corporation|
|Variants||Martin Marietta Model 845|
The 1-34 was designed over a number of years in the mid-1960s and first flew in 1969.
The 1-34 was designed over several years to spread out the development costs. At the time the design work on the aircraft was started the Standard Class was new and described a very simple aircraft with terminal velocity dive brakes, fixed landing gear and no water ballast. By the time the 1-34 had flown in 1969 the Standard Class rules had changed to allow essentially unrestricted sailplanes with a 15-metre (49.2 feet) wingspan.
The 1-34 has air brakes capable of limiting the terminal velocity in a vertical dive to the maximum safe speed as specified in the original Standard Class rules. Developing and testing these proved expensive and time-consuming and this also extended the aircraft's development time.
The 1-34 was the first Schweizer design to depart from using a NACA airfoil. The 1-34 has no wing washout and instead uses a Wortmann FX 61-163 airfoil at the wing root transitioning to a Wortmann FX 61-126 airfoil at the wing tip. The tip airfoil stalls at a higher angle of attack, ensuring that the wing root stalls first.
The one company concession to the changing Standard Class rules was the development of a retractable landing gear version of the 1-34, designated as the SGS 1-34R.
The 1-34 also features in-flight adjustable rudder pedals and a two-way adjustable seat to accommodate pilots of different heights.
During the protracted development process, Schweizer Aircraft was aware that the 1-34 would be overtaken by the changes in class rules and also by the performance of the newer European fiberglass sailplanes, but continued development of the SGS 1-34 anyway. The company identified that there was demand from private owners and especially clubs and commercial operations for a simple, rugged single seat glider with greater performance than the 1-26.
In service the 1-34 has proven to be a popular club aircraft and ideal for the completion of badge flights. If a greater number of 1-34s had been built, Schweizer indicated that it would have become another one-design class, similar to the 1-26.
At least two 1-34s have been highly modified. Bob Park's 1-34R, registered N17974, was damaged when a hurricane passed through Georgia and resulted in a hangar collapse. The 1-34R was rebuilt with a V-tail and ballast tanks mounted in the wings that hold 230 lbs (105 kg) of water. The aircraft was subsequently registered in the experimental Racing - Exhibition category.
A modified SGS 1-34 airframe with tricycle landing gear and powered by a Lycoming TIO-360 piston engine was used as the basis for the pilotless Martin Marietta Model 845 prototype, an entry in the early 1970s USAF Compass Dwell endurance UAV program.
The USAF designation for the SGS 1-34 is TG-6.
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