Part II : 1950-1957
Suntan Technology and Equipment
 What was learned with the Suntan project? The technology of liquid hydrogen was advanced in several ways. There is concurrently a revival of interest in hydrogen-fueled aircraft. As before, however, their potential value is controversial. NASA held a special conference on hydrogen-fueled aircraft in 1973 and has sponsored industry design studies of both subsonic and supersonic configurations. Although no specific development has started, NASA continues to sponsor research applicable to hydrogen-fueled aircraft.
On the other hand, Kelly Johnson, who turned back to petroleum fuels and designed the highly successful SR-71, remains disenchanted with liquid hydrogen. In 1974, he summed up his view: "Today, there is regenerated interest in liquid hydrogen for aircraft propulsion, but considering all phases of the problem, I do not think we will have such aircraft in the foreseeable future."54 Seaberg, who managed design study contracts with Boeing, Convair, and North American Aviation as part of the Suntan effort in 1957, agrees with Johnson's 1974 assessment.55 The essence of technological progress, however, is the conversion of the impossible to the possible, so the case for hydrogen-fueled aircraft remains open.
Although Suntan technology and equipment have yet to find application in aircraft, they soon found application in rocket propulsion. In 1958, the Suntan management team began searching for ways to use the technology their project had generated, as well as equipment like the boost pump and the hydrogen liquefaction plants. One result was a proposal to use liquid hydrogen in a rocket engine for the rapidly developing space program. Like a phoenix rising from the ashes, the technology and equipment of Suntan would indeed play a major role in the space program of the 1960s. To learn how this occurred, we must next consider several other developments that were running concurrently with Suntan-activities at Pratt & Whitney, General Dynamics, North American Aviation, NACA, and the Department of Defense.