The C-5A Support Area Airfield Tests at Harper Lake

The site selection process and tests with a C-5A aircraft on unsurfaced soils are described. The work was performed as a part of the Category I/II flight-performance tests of the aircraft. Harper Lake, California, was selected as the test site. In-place soil tests were conducted and aircraft ground performance was measured during taxi, landing, and takeoff operations. Soil strength was adequate to support the aircraft; however, the friable, cracked soil condition made it difficult to determine effects of the aircraft on the soil or the effect of the austere airfield situation on the performance of the aircraft. For conditions encountered, the aircraft appeared to have little effect on changes in soil strength. Turning and braking of the aircraft imposed the most severe condition upon the soil. Invariant soil strength conditions do not permit conclusions to expected variation in aircraft ground roll distance during takeoff. Present ground flotation criteria developed from tests with other types of aircraft appear reasonable when extrapolated to the loading conditions imposed by the C-5A. (Author) DDC Form 55 not necessary for document request.