Report presenting an investigation of a surge inhibitor that was able to cause a considerable gain in stable-airflow operating range over the range of equivalent impeller tip speeds tested. While the inhibitor was designed to triple the stable-airflow operating range, it increased it more than eight times its original value.

Memorandum presenting an investigation conducted in the 4- by 4-foot supersonic tunnel to determine the longitudinal stability and control characteristics of a model of a supersonic airplane configuration at Mach number 1.40. The model had a 40 degree sweptback wing with 10-percent-thick circular-arc sections normal to the quarter-chord line. The results indicated a high degree of longitudinal stability that was fairly constant throughout the trim-lift-coefficient range.

Report presenting testing to determine the effects of viscosity on the drag and base pressure characteristics of various bodies of revolution at a Mach number of 1.5. The models were tested with smooth surfaces and roughness to evaluate the effects of Reynolds number for both laminar and turbulent boundary layers. Results regarding the reduction of data, precision, effects of support interference, Schileren photographs, and theoretical calculations are provided.

Report presenting tests made in the 40- by 80-foot wind tunnel to evaluate the effects of wing modifications on the static longitudinal characteristics of a 35 degree swept-wing airplane. The wing modifications were designed to replace existing wing slats as low-speed high-lift devices. Results regarding the two-dimensional tests, full-scale tests, design of wing modification 1, test results of the airplane, and a comparison of test results with predictions are provided.

Report presenting the results of an investigation at transonic speeds by the wing-flow method of the longitudinal stability characteristics of a 42.8 degree sweptback supersonic airplane configuration. Lift, pitching-moment, and rolling-moment characteristics of the semispan model as well as stabilizer hinge moments and effective downwash at the tail were measured over a range of Mach numbers. The wing-flow data is compared to data for the same configuration from other research facilities.

The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from September 4, 1947 to September 5, 1947 are presented.

This report presents the results of an investigation undertaken to determine the feasibility of making glide landings in gusty air. Wind velocities were measured at several stations between the ground and a height of 51 feet, and flight tests were made to determine the actual influence of gusts on an airplane gliding close to the ground.