An experimental study of orifice coefficients, internal strut pressures, and loads on a small oleo-pneumatic shock strut

Author / Creator

Walls, James H., author

Available as

Online

Summary

Measurements of shock-strut internal pressures, telescoping velocity, and strut stroke were made during drop tests of a small oleo-pneumatic landing gear to determine the characteristics of the ori...

Measurements of shock-strut internal pressures, telescoping velocity, and strut stroke were made during drop tests of a small oleo-pneumatic landing gear to determine the characteristics of the orifice and to show the relationships between internal strut pressures and the overall loads developed by the strut. The range of shock-strut telescoping velocity available from the test data was between 1 and 7 feet per second and corresponded to a Reynolds number range of 9,500 to 66,500. The strut strokes available ranged between 1 and 7 inches and corresponded to approach-chamber lengths of 6.58 to 0.58 inches. Analysis of the data shows that variations in telescoping velocity and strut stroke result in relatively small changes in the orifice coefficient. Comparisons between strut forces determined from internal-pressure measurements and forces measured by an external dynamometer indicate that the strut forces can be accurately determined from the internal pressures times the appropriate areas. Comparison between time histories of strut force from internal-pressure measurements and force time histories from measurements of the telescoping velocity and strut stroke indicate that a close approximation of the strut forces during impact can be obtained when the orifice coefficient is assumed to be constant and the air-compression process to be isothermal.

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