Part II : 1950-1957
Other Interests in Hydrogen
 During the last quarter of 1955 and concurrent with Garrett's Air Force contract, two other events occurred to broaden interest in hydrogen for aircraft.
In October, the Fuels and Propulsion Panel of the USAF Scientific Advisory Board met and considered superfuels and reconnaissance vehicles.* On superfuels, the panel noted that hydrogen was one of three main lines of attack. It was most anxious to see engine studies and preliminary aircraft design studies directed towards application of hydrogen for aircraft propulsion. Further studies by the NACA since the March meeting continued to show excellent combustion characteristics of hydrogen. The panel believed that power plant development using hydrogen would encounter minimum difficulties, but an aircraft to use low-density fuel would require substantial redesign. Also noted was a need to study the possible adaptation of hydrogen to current aircraft or missiles.63
Anticipating the panel's conclusions, the Air Force included $4.5 million in the FY 1957 budget request for development related to hydrogen, a substantial increase over the $1 million of the previous year.
In November, Wright Field issued a technical note, "Cycle Performance of Some Selected Engine Configurations Using Liquid Hydrogen Fuel," in which Robert P. Carmichael analyzed nine engine systems using hydrogen as a coolant and a turbine working fluid as well as a fuel.64
 He also compared the performance of these engines with a conventional turbojet. Among his conclusions: some of the hydrogen engines gave superior performance compared to conventional turbojets; precooling the incoming air with liquid hydrogen increased the mass flow through the engine; both precooling and use of hydrogen turbines increased combustion pressure and permitted operation at higher altitudes with smaller combustors than conventional jets using hydrocarbon fuels.
Carmichael's analysis was distributed to nine major aircraft engine manufacturers and seven airframe manufacturers, causing Garrett to complain that their proprietary rights had been violated (pp.136-37).** In spite of the complexity of some of the hydrogen engines, the note must have stirred up considerable interest in hydrogen within the aeronautical community.
** The allegation is
questionable in view of Wright Fieldís long background in
turborockets and research on hydrogen. The official response to
Garrett indicated that no proprietary data had been used in the
Carmichael report and that engine cycles in general are not