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A SET of feeler elevators or “feelevators” added to regular spring-tab elevators can lessen the effect of airspeed on the ratio of stick force to airplane normal acceleration. The author develops an equation for computing the stick force per g of normal acceleration with a spring-tab and feelevator arrangement, and applies the equation to a large, high-speed fighter. Plotted results show that, with the feelevator, the stick force required at high speeds to move the elevator is great enough so that the pilot will not accidentally set the elevators for dangerously large accelerations. Yet at low speeds, a reasonably small stick force is enough to control the elevators.

PRESENTED here is a detailed discussion of the measurement requirements of general fluid flow; the design and operational problems of temperature, pressure, and miscellaneous measuring devices; and the development and calibration of various instruments. The complications which distorted and unsteady flow add to the instrument problem are described. The authors analyze temperature probes to show how their accuracy is affected by radiation, conduction, and gas velocity. A design chart indicates-for various temperature-velocity combinations-which of these sources of error is most serious and what materials are most satisfactory for probes.

THE effects of the combustion process and detonation on internal coolants are presented here, as well as the effect of these coolants, in turn, on engine performance. Some of the conclusions reached by the author are: 1. The difference between knocking and non-knocking fuels is one of degree; most fuels show evidence of pressure differentials during the combustion process, even though audible knock is not present. 2. Complete vaporization of the internal coolant is probably not secured until combustion is under way. 3. Water suppresses detonation by slowing down the combustion time and by cooling the end portion of the charge with water vapor contained in the end portion. Alcohol follows the same pattern when added to rich mixtures; for lean mixtures the higher antiknock qualities of the alcohol introduce a new factor.

THIS report of a survey of hydraulic packings, especially O-ring seals, covers friction studies, torsional strength tests, plasticizer development, a study of rubbers, molding technique, and spiral failure. The Institute is reported to be planning to conduct research work along the lines of cycling tests and studies of stress aging, compounding, and backup rings.

WHEN V-tails are applied to conventional airplanes, appreciable reductions in airplane drag, tail surface area, and weight are achieved, according to the author. He also states that improvements in flying qualities are possible. These conclusions are based on several years' wind tunnel testing, as well as flight tests on one twin-engine airplane and one single-engine airplane.