M.Hardy. Gliders & Sailplanes of the world

Ryson ST-100 Cloudster

  The ST-100 Cloudster tandem two-seater motor glider is believed to be the first American type in this category to be designed for production, and was created by the Ryson Aviation Corporation, founded by T. Claude Ryan, who until 1969 was chairman and chief executive of the Ryan Aeronautical Co (now Teledyne Ryan Aeronautical); his son Jerome D Ryan is Executive Vice-President of Ryson and Mr Ladislao Pazmany is Chief Engineer. The ST-100 is a cantilever low-wing monoplane of all-metal construction, with a T-tail, a fixed spatted undercarriage and a conventional engine installation in the nose. It differs from European types such as the Scheibe SF-25 Falke and Sportavia RF4D and RF5 in being rather larger and more powerful, with a proven certificated aircraft engine (the Continental O-200) instead of a modified Volkswagen engine, and in being of all-metal construction rather than wood and fabric to suit the needs of the American market. Design work started on 18 March 1974 and construction of the prototype, registered N2RY, began on 11 July that year; it made its first flight on 21 December 1976 in the hands of test pilot Ray Cote. The ST-100 is designed to be aerobatic and to meet the current FAR Part 23 gust load requirements and, in addition to being flown as a conventional powered aircraft, can also be used as an aero-tow aircraft for unpowered sailplanes. It has towed a Schweizer SGS 1-26 single-seater to 13,000ft with an initial climb rate of 450ft/min and, with two people aboard, it has also towed a Schweizer SGS 2-33 with two occupants at an initial rate of climb of about 400ft/min. In the summer of 1977 Ray Cote made a notable economy-record flight in the ST-100 from El Mirage, California, to the EAA display at Oshkosh, Wisconsin, covering the 1,676 miles on 28 of the 32 available US gallons of fuel in 18 hours of soaring flight and 13 hours of powered flight. This was followed by a 4,300 mile flight around the perimeter of the United States. Production of the ST-100 by a licensee is planned when FAA type certification is awarded.
  The wings are all-metal safe-life structures, with some fail-safe features, and have a single main spar located at the 40% chord line, the point of maximum thickness, and an auxiliary spar at 80% chord; dihedral is 4°. Both ailerons and trailing edge flaps are of aluminium with a foam core, the flaps being electrically-operated and can be lowered to 72° when used as air brakes; the ailerons, like the flaps, can be raised 12° and they can be drooped 8° in conjunction with the flaps. No spoilers or trim tabs are fitted, and the wings can be folded back alongside the fuselage, leading edges down, for hangarage or transportation. The fuselage is a semi-monocoque structure with extruded aluminium longerons, and sheet metal frames, bulkheads and skinning. The pilots sit in tandem under a one-piece Plexiglas canopy that opens sideways to starboard; there is baggage space aft of the rear seat, and the rear occupant has flight controls but not an instrument panel, as he can see the instruments over the front pilot's shoulders. The cantilever T-tail has a sweptback fin and rudder, a fixed-incidence tailplane and a one-piece balanced elevator. The rudder and elevator are aluminium-covered, with sheet metal and foam ribs, and the elevator tips can be removed when the aircraft is being transported; the elevator has an anti-servo and trim tab. A conventional fixed tailwheel landing gear is featured, with streamlined glassfibre fairings on the main gear legs, main wheels and tailwheel, which is steerable. The main wheels have Cleveland hydraulic disc brakes and Ryson oleo-pneumatic shock absorbers. Powerplant is a 100hp Continental O-200-A 'flat four' engine driving a two-blade three-position Hoffman HO-V-62 feathering propeller with composite blades. There are two integral fuel tanks in the wing centre section leading edges with a total capacity of 32 US gallons (26.6 Imp gallons.)


Span: 57 ft 8 in
Length: 25 ft 6 1/2 in
Height: 5 ft 10 in
Wing area: 213.0 sqft
Aspect ratio: 15.61
Empty weight: 1,212 lb
Max weight: 1,650 lb
Max speed at sea level: 150 mph
Max cruising speed: 135 mph
Min sinking speed: 2.93 ft/sec
Best glide ratio: 28:1
Take-off run to 50 ft: 950 ft
Range with max fuel: 900 miles