Reaction Motors: 75th Anniversary

Reaction Motors: 75th Anniversary of a Pioneering American Rocket Company

On December 18, 1941, 11 days after Pearl Harbor, four young members of the American Rocket Society (ARS)—James Wyld, John Shesta, H. Franklin Pierce, and Lovell Lawrence Jr.—officially incorporated Reaction Motors, Inc. (RMI), in New Jersey. The timing was no coincidence: it was one of many patriotic actions Americans took after suddenly finding themselves fighting a war. RMI, which was created to offer assisted-take-off rockets to the military aviation branches, was the first successful American company devoted to liquid-propellant rocketry. In its 31-year lifespan, it developed rocket engines of noteworthy importance, especially for pioneering X-planes. 

Science fiction writers and space enthusiasts in the New York City area had founded the American Interplanetary Society in 1930. They experimented with liquid-propellant rockets largely in imitation of the amateur group in Berlin, Germany. In the mid-1930s, the Society changed its name to the American Rocket Society, which sounded less crackpot, although even the word “rocket” was in disrepute in America because of pulp science fiction featuring heroes like Buck Rogers. Over time, younger, technically trained members, including RMI’s founders, took over what was still a New York-area club. They dropped the focus on rocket flights and concentrated on developing small motors. One of their creations was the ARS Test Stand No. 2, now in the Museum.

Beginning in 1938, Wyld invented a “regeneratively cooled” liquid-propellant rocket motor, meaning that the fuel was circulated in a cooling jacket around the engine before being injected into the combustion chamber to be burned with the oxidizer. That helped solve one critical problem: stopping the hot combustion gases from melting the engine. Others had experimented with this idea, and the German rocket team that developed the V-2 missile had incorporated the principle, unbeknownst to Wyld. But his was the first practical regeneratively cooled engine in the United States. It provided the starting point for the tiny company to make offers to the military right after incorporation. (See: Wyld Regeneratively Cooled Rocket Motor No. 1 and No. 2)

At first RMI staff consisted entirely of the four men working out of a rented store in Pompton Lakes, northern New Jersey. In January 1943, they moved to a much larger building not far away, a former speakeasy in Pompton Plains. Thanks to RMI's contact with the Navy Bureau of Aeronautics just before Pearl Harbor, the Navy funded experimental “jet-assisted take-off” (JATO) motors throughout the war. RMI raised the power of their engines from 100 pounds of thrust to several thousands. But liquid-propellant JATOs were complicated and required fueling, so none of the company’s engines were deployed. Instead, Navy and the Army Air Forces used solid-propellant engines  made by Aerojet in California, which was formed only three months after RMI.

It was during the early Cold War years that Reaction Motors reached the height of its influence. Its four-chamber, 6,000 lb. thrust engine (6000C-4, later called the XLR-11) powered the Bell X-1 rocket plane when Chuck Yeager broke the sound barrier in October 1947. That motor also propelled the Douglas D-558-2 Skyrocket aircraft that first exceeded Mach 2. The Viking sounding rocket that flew up to about 241 kilometers (150 miles) high in the early 1950s also had an RMI engine. The company’s largest and most elaborate project was the 57,000 lb. thrust, liquid oxygen/anhydrous ammonia XLR-99 for the X-15 hypersonic rocket plane. It proved to be technically challenging, so early X-15 test flights used two XLR-11s, one above the other.

In 1958, RMI became Reaction Motors Division of Thiokol Chemical Corporation, which specialized in large solid-propellant rocket motors. But RMD struggled to compete against the big California rocket companies like Rocketdyne. Reaction Motors was still in densely populated New Jersey and restricted in its ability to test loud and dangerous engines. It focused mostly on smaller, liquid-fuel propulsion systems for tactical missiles and spacecraft. For example, they made the little vernier engines on the Surveyor lunar lander that brought the spacecraft down gently on the Moon after the big retrorocket was discarded. Thiokol closed RMD in 1972 due to declining business, as the space race faded and the military was cut back. It was the end of one of the world’s most important early rocket-engine manufacturers.

Michael J. Neufeld is a senior curator in the Space History Department of the National Air and Space Museum and is responsible for rocket artifacts to 1945. Frank H. Winter is the retired curator for rocketry in the Museum. He published Pioneering American Rocketry: The Reaction Motors, Inc. (RMI) Story, 1941-1972 (American Astronautical Society, 2015) with the late Frederick I. Ordway, III, who worked at RMI in the 1950s. Winter is currently writing a shorter, more accessible RMI history for the American Institute of Aeronautics and Astronautics. He recently published  "Jimmy Wyld, the Young Genius Who Jump-Started the U.S. Rocket."