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AFTER outlining the fundamental physical background for the release of atomic energy, the author shows that the high concentration of energy and the high cost and relative scarcity of atomic fuels mark them for use where there is a high premium on performance, rather than on direct cost per unit of power. This makes atomic energy attractive for aircraft propulsion, where it could combine high performance with large payload and long range. Chief obstacles in design of an atomic aircraft engine are development of light-weight shielding against deadly radiations; adequate cans to retain radioactive fission products; a pile capable of operating at high temperature and high thermal stresses; and a safe, flexible control mechanism.

THE trend of large, fast airplane designs is toward greater flexibility and more rapid application of landing and flight loads. With this combination of conditions, the inertia forces associated with the elastic distortions of the structure can not be ignored. In turn, the elastic forces are changed so that a rigid-body load analysis becomes inadequate and dynamic load analysis is necessary and of significant advantage in promoting efficient structural design. If the history of the exciting forces is known, a dynamic analysis is feasible by the methods described here. These methods require careful application to account successfully for the complex distortions of the airplane structure. The responses are calculated by a classical linearized solution; these are then employed in the determination of loads. An example of the dynamic bending moments in an airplane hull during a water landing and another example of the dynamic shears in an airplane wing traversing a gust are given.

THE practical aerodynamic problems encountered in designing aircraft for flight in the transonic range are discussed here. Raising the effective critical Mach number of an airplane is shown to be a more efficient method of increasing speed than either an increase in engine power or a decrease in parasite drag. Aerodynamic problems of both low and high speed, which result from designing for high speed, are discussed. It is concluded that the aerodynamic problems connected with the design of high-speed aircraft are fairly well defined but that further experimental and theoretical research is required to solve these problems and establish design details. In particular, further correlation between wind tunnel and flight tests is needed in order to arrive at practical engineering solutions to the problems encountered in designing transonic aircraft. For this paper, Mr. Van Every was awarded the 1948 Wright Brothers Medal by the Society of Automotive Engineers.

WE should be designing superchargers for better overall efficiency, according to Mr. Pigott, because the effect on engine capacity is pronounced, and gets to be more so at higher boost pressures. Mr. Pigott shows also that supercharger performance can be rather well predicted without trying out a variety of blowers in expensive engine setups. He sees no reason to suppose that the newer adiabatic rotaries can be considerably improved as they are further developed. He adds that the Roots type has seen considerable development and will be at the end of its string when boost pressures exceed 7 or 8 psi, which they are certain to do in the future.