From Summary: "A limited investigation of a 1/24-scale dynamically similar model of the Navy Bureau of Aeronautics DR-77 design was conducted in Langley tank no. 2 to determine the calm-water take-off and the rough-water landing characteristics of the design with particular regard to the take-off resistance and the landing accelerations. During the take-off tests, resistance, trim, and rise were measured and photographs were taken to study spray. During the landing tests, motion-picture records and normal-acceleration records were obtained."

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Flight-test measurements, related analytical studies, and corresponding pilots' opinions of the speed stability of tandem-rotor helicopter are presented. An undesirable instability, evidenced by rearward stick motion with increasing forward speed at constant power, is indicated to be caused by variations with speed of the front-rotor downwash at the rear rotor. An analytical expression for predicting changes in speed stability caused by changes in rotor geometry is derived and constants for use with the analytical expression are presented in chart form. Means for improving stability with speed are studied both analytically and experimentally. The test results also give some information as to the flow conditions at the rear rotor.

In this report, a brief discussion is given for each of the following activities under study during this period: xenon generator; C{sup 12} cross sections; critical mass problems (for process vessels in Bldg. 231); neutron beam catcher design; neutron diffraction spectrometer; beta spectrometer; hollow slug program; instrumentation; blackness corrections; exponential pile measurements with small slug size; critical lattice experiments; lattice theory; and radiation damage.