Hydyne

Hydyne is a mixture of 60% unsymmetrical dimethylhydrazine (UDMH) and 40% diethylenetriamine (DETA), developed in 1957 at Rocketdyne for use in liquid-fuel rockets. Hydyne was used as the fuel for the first stage of the Juno I rocket that launched Explorer 1, the first successful satellite launch conducted by the United States.

Mary Sherman Morgan, a chemical engineer at Rocketdyne's propulsion research thermodynamics unit and a leader in the development of Hydyne, first started work on the new compound early in 1956. The problem faced by Morgan and the company's chemical engineers was to replace the PGM-11 Redstone fuel (including 25% water and 75% ethyl alcohol) with a compound that would boost the rocket's performance enough to launch a small satellite into orbit. .

The Jupiter-C and Juno I rockets used the same first-stage engines as the missile, but needed more thrust due to the increased size of the payload/warhead. With the use of the newly developed Hydyne, composed of a blend of 60% unsymmetrical dimethylhydrazine (UDMH) and 40% diethylenetriamine (DETA), the Jupiter-C and Juno I engines gained a 12% increase in thrust and higher specific impulse. The resulting fuel was not only more powerful fuel than alcohol, but also more toxic. The first Hydyne-powered Redstone R&D flight took place on November 29, 1956. After the three Jupiter C and six Juno I launches including the launch of America's first satellite, Explorer I), Hydyne was discontinued in favor of higher performing fuels.

'Bagel' was the whimsical name suggested by Morgan, who engineered the Hydyne-LOX (Liquid OXygen) propellant combination used by North American Aviation in their early U.S. rocket designs of the incipient space race. Morgan was considered a rocketry pioneer as she was the only female technical analyst employed by NAA in Downey, California. Morgan suggested calling her new fuel invention 'Bagel', allowing the Redstone propellant combination to be then called 'Bagel and LOX' (a tongue in cheek reference to the brined salmon, Lox, which is served with cream cheese on bagels). Her suggested name for the new fuel was not accepted, and 'Hydyne' was chosen instead by the U.S. Army.

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