than one full-scale SPS satellite. Because of the speculative nature of the benefits resulting from this salvage use, they are not quantified further. 4.4 Power Supply for Laser-Propelled Aircraft It has been proposed by researchers at the University of Washington and Lockheed Missiles and Space Company that space-based lasers be used to power aircraft on transoceanic flights. Conceptually, oceanic flights would be conducted by means of conventional kerosene-powered jet engines for takeoff and climb to altitude. Upon reaching altitude, at some point over the ocean, the kerosene combustors would be shut down and the aircraft provided energy from a laser beam originating in space. Energy in the laser beam would be intercepted by a laser receiver mounted on the top of the aircraft and used as thermal energy to power turbofan engines. Upon descent the laser power would be discontinued and the use of kerosene resumed. It seems reasonable to base projections of the demand for power by oceanic aircraft on the assumption that the number of oceanic flights beyond the year 2030 is equal to the current number of oceanic flights. It is furthermore reasonable to assume that all aircraft in the oceanic regions at that point in time will be comparable to current heavy aircraft such as the DC-10 and 747. Table 4.1 summarizes the current oceanic air traffic. There are presently about 3000 aircraft-hours spent in the oceanic sectors each day. The power requirements of a wide-bodied aircraft are typified by the 747 and DC-10. The 747 burns an average of about 24,000 pounds per hour of fuel at cruise and the DC-10 17,000 pounds per hour. These numbers correspond to power levels of 133.6 MW thermal and 94.6 MW thermal respectively. Thus the average energy * Hertzberg, Abraham, Kenneth Sun and Wayne Jones, Laser Aircraft, Astronautics and Aeronautics, March 1979, pp. 41-49.
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