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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Investigation of sonic boom generated by thin, nonlifting, rectangular wings

A theory is described for predicting sonic boom pressure signatures emitted by nonlifting rectangular wings. Comparisons are made with previous (Whitham) theory and with experimentally determined near field signatures. Although both theories agree with experiment for low aspect ratio wings, Whitman's theory seriously overpredicts signature length for high aspect ratio wings. No experiments were conducted in the far field, but the two theories predict nearly identical results in this region.

Davis, S. S.↗
NASA NTRS1971

An experimental study of the strength and stability of thin monocoque shells with reinforced and unreinforced rectangular cutouts

Axial compression tests were run on eleven thin-walled aluminum cylinders having rectangular cutouts. Various types of reinforcement were used around the cutouts, and some tests were run with no reinforcement. The test results are compared with the cylinder buckling loads prior to installation of the cutouts (obtained without damaging the cylinder by using a buckle-capture technique), and correlated with computer-predicted failure loads. The latter were based on the use of the STAGS computer program. For thin cylinders such as these, the test and computer-based analysis shows that for small to moderate size cutouts, reinforcement of the cutout is of no benefit unless the cylinder is of extremely high (geometrical) quality. For cylinder quality and cutout size where reinforcement is beneficial, the relative merits of the various reinforcement configurations are discussed, and an empirical basis for design is proposed.

Holmes, A. M. C.↗
NASA NTRS1972

Peak axial-velocity decay with multi-element rectangular and triangular nozzles

The aircraft noise created by the impingement of engine exhaust jet of STOL aircraft with externally blown flaps is discussed. It was determined that the jet-flap interaction noise can be lowered by reducing the impinging velocity of the jet. The reduction must occur at a specific distance from the flap to be effective. The peak axial-velocity decay obtained with rectangular and triangular single element mixer nozzles is presented. Equations are developed for estimating the peak axial velocity decay curves for a wide range of nozzle configurations.

Groesbeck, D. E.↗