Memorandum presenting an experimental investigation in which liquid hydrogen was used as a heat sink for turbine-cooling in a high-temperature turbojet engine. Several problems were revealed which will require special attention in future work. The primary issue was pressure surging in the fuel system, which presented a problem in flow measurement and control.

"The similarity rules for linearized compressible flow theory (Gothert's rule and its supersonic counterpart) are extended to second order. It is shown that any second-order subsonic flow can be related to "nearly incompressible" flow past the same body, which can be calculated by the Janzen-Rayleigh method" (p. 925).

Report presenting a theoretical investigation to determine the static and dynamic characteristics of a control-surface actuator and missile combination, with primary consideration given to the minimization of the effects of Mach number and altitude.The results indicate that the type of actuator studied in combination with a missile might replace a gain-adjusted acceleration control system. Results regarding the control-system static characteristics, control-system dynamic characteristics, comparison of torposervo and position-servo actuation, and some suggestions for further research are provided.

A pneumatic proportional-plus -integral shock-positioning control unit was investigated for controlling a ram-jet engine at a flight Mach number of 2.5 and altitudes of 50,000 to 65,000 feet. A satisfactory of attack, the control action was marginal for the same control settings used at zero angle of attack.

From Introduction: "The use of automatic controls to reduce the tendency for rolling divergence has been investigated in references 2 and 3. These studies have considered the effect of artificial changes in certain stability derivatives on the rolling divergence, and have shown that increased damping in pitch may be quite effective in reducing the divergent tendency. In the present report, a different type of automatic control is investigated."

Report presenting force-test data showing the effects of change in leading-edge radius on the low-speed longitudinal stability of a 6-percent-thick 45 degree sweptback wing of aspect ratio 3 for several ranges of Mach and Reynolds numbers. The results indicated that as the airfoil sections were thinned at the nose, separation effects occurred at lower values of lift coefficient.

Report presenting flight measurements of the horizontal-tail loads on the Douglas X-3 research airplane during wind-up turns, pull-ups, and stabilizer pulses over a range of altitudes and Mach numbers.

Good internal performance over a wide range of flight conditions can be obtained with either a plug nozzle or a variable ejector nozzle that can provide a divergent shroud at high pressure ratios. For both the ejector and the plug nozzle, external flow can sometimes cause serious drag losses and, for some plug-nozzle installations, external flow can cause serious internal performance losses. Plug-nozzle cooling and design of the secondary-air-flow systems for ejectors were also considered .