Transactions of the Society of Automotive Engineers Volume 15, No. 1

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 Excerpt: ... Radius of Gjroition Fio. 4--Comparison Of Euler's Formula With Johnson's Mula For Different Elastic Limits For of elasticity of the material used, the strength of the material not entering into the equation. Many tests have shown that the modulus of elasticity of steel is practically unaffected by heat-treatment, in addition to varying but little with great differences in the chemical composition. Thus, for example, a strut of heat-treated alloy-steel tubing will cripple at practically the same load as a strut of the same dimensions but of annealed low-carbon steel, providing (a) that the slenderness ratio is sufficiently high to justify the use of Euler's formula, and (6) that the ends are designed to transmit the loads without local failure. Fig. 4 shows the graph of Euler's formula, together with the graphs of Johnson's formula for various elastic limits, corresponding to different steels, and illustrates very plainly that nothing is gained by the use of high-strength steel where the length divided by the least radius of gyration exceeds about 100. MAINTAINING AIRPLANE ENGINE POWER AT GREAT ALTITUDES By Lieut-col V E Clark,1 USA Following the 1917 recommendation of the Boiling Airplane Mission that great energy be devoted to the development of means to maintain a high proportion of the power of airplane engines at great altitudes, some very creditable work was done. A recent flight test at 20,000-ft. altitude indicates a resultant marked increase in airplane performance. Interest in this development should be extended. The purpose of the paper is to indicate the possibilities and limitations of increasing airplane speed by introducing means to maintain high engine power at great altitudes. The DeHaviland-Four is selected as being an airplane typical of ...