Wernher von Braun, Novelist
Half a century ago, the rocket scientist tried his hand at fiction.
- By airspacemag.com
- Air & Space magazine, January 2007
(Page 2 of 6)
The power plants in particular had been designed to be independent of the atmosphere, except for cooling, for it had been thought unwise to rely upon burning any fuel in the relatively low oxygen concentration of the Martian atmosphere. Supercharging, similar to that used in aircraft engines for high altitudes, might have been effective, but Holt’s judgment was that this would be a questionable expedient in view of the refusal of the spectroscope operators on Lunetta to commit themselves.
The caterpillars, therefore, were driven by two propellants, concentrated hydrogen peroxide, as used in the reaction pistols, and common fuel oil. The hydrogen peroxide was first dissociated into water vapor and oxygen in a catalyzing chamber. This mixture evolved steam at high temperature by the energy of dissociation. Into it was injected a metered quantity of fuel oil, which promptly burned in the oxygen portion of the mixture. A row of successive nozzles injected water into the flame, thus producing steam of moderate heat, only slightly contaminated by carbon dioxide and carbon monoxide from the combustion of the oil.
The flow of this steam could be regulated by throttling the admission of its three constituents. It turned a turbine which provided power for the caterpillar.
The steam was condensed in a low-pressure condenser, cooled by a blower, after passing through the turbine. The carbon dioxide and carbon monoxide remained in the vapor phase and were drawn off and expelled by a second and smaller blower, while the water in liquid phase was recirculated from the condenser to the combustion chamber. The water loss of the system, therefore, was limited to the portions affected by dissociation of the peroxide and the combustion of the oil, by being ejected into the atmosphere as withdrawn from circulation.
The efficiency of this system was quite high in view of the necessity for providing artificially the oxygen which an ordinary engine would extract from the atmosphere, and considering that this oxygen formed part of the propellants and so tankage had to be provided for it. In order to conserve supplies, the cruising speed of the land vehicles was restricted to 13 mph.
The tracks of the caterpillars extended across their whole lower surface and their twelve foot length in order to diminish their surface loading and give maximum traction on the softest ground. In the weak Martian gravity, the vehicles weighted but 28% of their terrestrial tonnage. This reduced the danger of becoming mired, but it also diminished the traction to the same extent. Thus the maximum obtainable length tended to prevent non-propulsive “churning” of the tracks.
Directional control was obtained by braking one or the other of the tracks, their low ground pressures permitting this despite their great width.
The power plant was located between the tracks, and above it was an elongated cylindrical body which could be pressurized and which provided space for passengers and lading. Forward it had two large, oval windows through which the driver might view the ground, and several circular ports along the sides for the passengers. Two hemispherical, plastic gun turrets stood above the forward and after ends of the cylinder. Just behind it, mounted on the framework of the strange vehicle, was a small crane such as is used on wrecking tow cars. From the crane’s jib to the forward end of the cylinder ran the radio antenna which was to aid communication via the radio bombs.