ARS Engine No. 4, like its predecessors, was mounted in the nose, rather than the tail, of the rocket. The engine featured a single combustion chamber and four nozzles. The nozzles directed the jet gases to the rear and slightly away from the top of the gasoline tank on which the engine was mounted. The rocket powered by this engine was tested on September 9, 1934. It rose several hundred feet, at which point one of the nozzles burned out, bringing the flight to a close. In 1938, ARS member James Wyld suggested a cooling system whereby propellants circulate through a jacket surrounding the combustion chamber. Engines using this system are termed “regeneratively cooled.” The first Wyld rocket motor tested developed 41 kilograms (90 pounds) of thrust for 13½ seconds. It proved so successful that Wyld and other members of the ARS founded Reaction Motors, Inc., to produce and sell rocket engines based on this design. The performance of motors developed by the ARS prior to World War II was measured on a test stand with built-in fuel and oxidizer tanks and bottled nitrogen gas. The engine was mounted on a carriage, and connected to the stand’s propellant tanks by flexible metal hoses. Thrust was indicated on a pressure gauge. The stand was first used in 1938. All American Rocket Society artifacts are from G. E. Pendray and the American Institute of Aeronautics and Astronautics. H-1 Engine [Illustration: 51. A two-stage Saturn 1B rocket powered by H-1 engine cluster lifts off carrying Skylab 4 astronauts, November 16, 1973.] The H-1 liquid-propellant rocket engine was an outgrowth of the LR-79 which served as the basic power plant for the USAF Thor missile. The H-1 was used in the 8-engine cluster of the first stage of the Saturn 1 and 1B launch vehicles. The H-1 burns liquid oxygen and a grade of aviation kerosene to produce a total thrust of 92,986 kilograms (205,000 pounds). Each engine functions as an independent unit, with its own combustion chamber and turbopump, but fuel is drawn from common tanks. The Saturn 1B was first launched on February 26, 1966, and most recently on July 15, 1975, in the launch of the U.S. crew of the Apollo-Soyuz Test Project. It was developed by Rocketdyne, a division of North American Rockwell Corporation. The engine on exhibit is from the National Aeronautics and Space Administration. RL-10 Engine [Illustration: 52. RL-10 engines used to power Centaur launch vehicle.]