Two low-acceleration transonic-flutter vehicles were launched and flown. The first carried two test wings, one of which fluttered at M = 0.92 at a frequency of 61.4 cycles per second. The reference flutter speed determined from two-dimensional theory for an unswept wing in incompressible flow is conservative when compared to the experimental flutter speed. The second vehicle carried two test wings, one of which failed at M = 0.71 because of low-frequency divergent oscillation. Since this failure was not caused by conventional flexure-torsion flutter, no comparison with a reference flutter speed can be made.

Report presenting an investigation in the stability tunnel to determine the combined effect of wing and wing-body interference on the contribution of an x-tail configuration to the low-speed rolling-stability derivatives of an airplane model with an unswept midwing and to indicate the change due to roll in the local flow angularity at a number of stations across the tail surfaces for one-half of the x-tail. Results regarding the static longitudinal characteristics, steady-roll characteristics, and angularity measurements are provided.

Report presenting an investigation in the 300 mph 7- by 10-foot tunnel to determine the chordwise and spanwise load distribution on a thin 60 degree delta-wing-fuselage model equipped with double slotted and extended double slotted flaps. The effects of a canard on the loads of the wing with the extended double slotted flaps are also determined.

This report describes the redesigned variable-density wind tunnel of the National Advisory Committee for Aeronautics; it supersedes a previous report that described the original tunnel. The operation of the balance and the method of testing are explained and the method of correcting and presenting airfoil data is described. A summary of the formulas for predicting the characteristics of finite wings from the airfoil section data as they are usually presented is also given.

Report presenting results of a flight investigation of a radar fire-control system installed in a fighter airplane. Some of the factors included in the radar evaluation are "noise" of the steering dot, lack of target-attitude information, and sensitivity and linearity of the display.

"Theoretically derived charts showing the profile-drag-thrust ratio are presented for helicopter rotors operating in forward flight and having hinged rectangular blades with a linear twist of 0 degree, 8 degrees, and 16 degrees. The charts, showing the profile-drag characteristics of the rotor for various combinations of pitch angle, ratio of thrust coefficient to solidity, and a parameter representing shaft power input, are presented for tip-speed ratios ranging from 0.05 to 0.50. Also presented in chart form are the ratio of thrust coefficient to solidity as a function of angles of attack, as a function of inflow ratio and collective pitch, and as a function of power and thrust coefficients" (p. 1).

From Summary: "The equations relating the wing and tail loads are derived for a unit elevator displacement. These equations are then converted into a nondimensional form and charts are given by which the wing- and tail-load-increment variation may be determined under dynamic conditions for any type of elevator motion and for various degrees of airplane stability. In order to illustrate the use of the charts, several examples are included in which the wing and tail loads are evaluated for a number of types of elevator motion. Methods are given for determining the necessary derivatives from results of wind-tunnel tests when such tests are available."

A summary is given of the background and present status of the pure-planing theory for rectangular flat plates and v-bottom surfaces. The equations reviewed are compared with experiment. In order to extend the range of available planing data, the principal planing characteristics for models having sharp bottom surfaces having constant angles of dead rise of 20 degrees and 40 degrees. Planing data were also obtained for flat-plate surfaces with very slightly rounded chines for which decreased lift and drag coefficients are obtained.

"Tests were made of a 1/18-scale dynamically similar model of the Lockheed Constellation airplane to investigate its ditching characteristics and proper ditching technique. Scale-strength bottoms were used to reproduce probable damage to the fuselage. The model was landed in calm water at the Langley tank no. 2 monorail. Various landing attitudes, speeds, and fuselage configuration were simulated" (p. 1).

From Summary: "An investigation has been conducted in the NACA Cleveland altitude wind tunnel to evaluate the operational characteristics of a 3000-pound-thrust axial-flow turbojet engine over a range of simulated altitudes from 2000 to 50,000 feet and simulated flight Mach numbers from 0 to 1.04 throughout the operable range of engine speeds. Operational characteristics investigated include engine operating range, acceleration, deceleration, starting, altitude and flight-Mach-number compensation of the fuel-control system, and operation of the lubrication system at high and low ambient-air temperatures."

Memorandum presenting an airborne missile simulator used to represent visually the predicted flight behavior of the Navy XASM-N-7 Bullpup air-to-surface missile, which is guided along the line of sight to the target by bang-bang radio signals controlled by the pilot of the launch airplane. Quantitative response measurements showed that the simulator gave a good representation of the trajectory and control characteristics predicted for the Bullpup missile, and the simulation appeared plausible to the pilots.