Appendix A

Hydrogen Technology through World War II



[247] Hydrogen is the simplest element, a molecule of two atoms, a gas at normal conditions, colorless, odorless, nontoxic but asphyxiating, and non-corrosive but reactive. It occurs In many substances, the most common of which is water, and ranks ninth in abundance of the chemical elements on the earth. Active chemically, hydrogen exists free only in minute quantities. There is plenty of hydrogen in stars, and Jupiter is believed to be made up entirely of hydrogen in several forms under intense pressure.


Only helium is more difficult to liquefy than hydrogen. At atmospheric pressure, hydrogen boils at 20.3 K. It is the lightest element; its liquid density is 1/14 that of water.


Hydrogen ignites very easily and burns over a wider range of mixtures with air or oxygen than any other fuel. It releases more than twice as much energy on burning as gasoline on a mass basis, but because of its low density rates low on a volume basis. Hydrogen's low density and liquid temperature, coupled with other characteristics, are major obstacles to its more widespread use as a fuel.


The first experimental investigation of liquid hydrogen for flight propulsion in the United States began in 1945. It started at the same time that documents from Germany on technical details of jet aircraft and rockets became available. Nevertheless, research indicates that U.S. interest in hydrogen for aircraft and rockets was not directly linked to German work.


Hydrogen had interested scientists and engineers for centuries, and since its liquefaction at the end of the nineteenth, had been considered as a fuel by three rocket pioneers. Providing some background for a better understanding of post-World War II hydrogen developments in the United States is the purpose of this appendix.

Appendix A continues with the following:


Hydrogen through the Nineteenth Century Gaseous Hydrogen.


Rocket Pioneers.


Hydrogen Technology, 1900-1945.


Hydrogen as a Rocket Fuel.