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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.

SINCE “mass production” cannot be defined, our problem is to design for any specific quantity. To determine the suitability of the design for the quantity, a cost criterion is proposed. An examination of cost factors and the distribution of costs at various quantities shows the relative importance of each, so that our production design effort may be better directed. The principles of design producibility are shown to be directed toward minimizing our tooling and manufacturing problem. A detailed study of the material and assembly problems attempts to set forth the more exacting requirements of new design trends. A set of principles is set forth as a guide for more realistic production design effort. The principles emphasize the necessity for staying within the design, material, tooling, and manufacturing limitations of any organization, in other words, employ only “sure-fire design” practices.

A REVIEW of fatigue information as it applies to life expectancy calculations for aircraft is presented here. The author shows that the number of factors and the lack of data, as well as of a definite theory, make it impossible to do more than make a reasonable guess of life expectancy. He concludes that repeated load tests still [ILLEGIBLE] to be the most satisfactory method of [ILLEGIBLE] a safe life expectancy.

The paper discusses the general lubrication problems associated with operation of high-output aircraft engines. Since the paper is concerned with two types of aircraft engines, namely, turbine and reciprocating, a natural division into two parts is made. Part I deals with the problems of turbine engines, and part II deals with the problems of reciprocating engines. In part I it is indicated that the choice of a lubricant is very difficult for the turbine engine particularly, because of the wide temperature range (from -67°F to approximately 400° F). Two solutions to the problem of proper choice of a lubricant are discussed, namely (1) the use of supplemental lubricants, and (2) the use of additive lubricants. Data are presented on supplemental lubricants including the various oxides of iron, molybdenum disulfide and graphite.

THIS survey of psychological research in the field of reading aircraft and other instruments shows that the majority of serious errors cannot be eliminated by mere improvements in visibility, such as could be obtained by increases in size or illumination. Rather, it is said, we must find methods of indication that actually simplify the interpretational processes interposed between the seeing of an instrument and the making of an appropriate control action. For instance, it appears that most errors in the reading of such instruments as the altimeter can be eliminated by the use of a single-pointer instrument with a counter to indicate the number of revolutions of the pointer.

A realistic appraisal of the problem shows, the author says, that space travel is not just around the corner. He points out that we will most certainly have to await the development of high-velocity rockets with very low weights, which will be difficult to attain. Space travel will come, he feels, by the gradual process of developing better sounding rockets, longer-range rocket missiles, and eventually satellite vehicles. These last will be the first embryonic space vehicles. Only when this experience lies behind us does he believe that we will be in a position to consider the construction of a full-fledged spaceship capable of leaving the gravitational dominance of the earth.

A THOROUGH study of the problem has convinced the authors that preignition causes more aircraft-engine failures than detonation does. It has also brought them to the conclusion that the spark plug is the most common cause of this phenomenon, the combustion-chamber deposits the second cause, and the exhaust valve the least common cause.

TESTS conducted on a full-scale aircraft engine show that satisfactory engine operation can be obtained at warmed-up conditions with low-volatility fuels of the safety type. The engine used in the tests was modified for direct cylinder fuel injection, as fuels of this type are not sufficently volatile to be satisfactorily vaporized by means of a carburetor induction system. Knock-limited performance, specific fuel consumption, and oil dilution characteristics were studied in these tests.