Report presenting a discussion of a number of the problems that most frequently arise with airfoils on helicopters. A reference list of published reports on airfoil section characteristics which are useful in regards to these helicopter problems is also included.

Report presenting free-flight investigations conducted on four 16-inch-diameter ramjet units to determine the performance at high subsonic and supersonic velocities. Data for evaluating the performance were obtained from radio-telemetering and radar-tracking equipment. Results regarding combustion performance, diffuser total-pressure recovery, thrust coefficient, and external drag coefficient are provided.

From Summary: "The pressure drops through electrically heated Inconel tubes with length-diameter ratios of 29.25, 58.50, 87.75, and 117.00 have been measured at entrance Mach numbers from approximately 0.12 to the value at which choking occurred. The heat-input rate was varied from zero to the highest values allowable without damaging the tubes. Experimental data and a number of computed variables are presented in tabular form."

From Summary: "Ogive-cylindrical fuselages of fineness ratio 11 have been flight-tested with and without stabilizing fins. Base-pressure measurements over a range of free-stream Mach numbers from 0.7 to 1.3 indicated that the fins reduced the base drag. A rear-support sting similar to those used in wind tunnels was tested with one of the fuselages and found to reduce base suction by 40 percent at subsonic speeds, but to have little effect at Mach numbers above 1.15."

Report presenting an investigation of the effect of Reynolds number and the addition of leading-edge roughness on the aerodynamic characteristics of wings with aspect ratio 1, 2, and 3, a rectangular plan form, square-cut wing tips, and NACA 0012 airfoil sections. Results regarding lift and moment, lift-curve slope, and maximum lift are provided.

Report presenting an investigation in the 4- by 4-foot supersonic pressure tunnel to determine the effects of body contouring as specified by the transonic drag-rise area rule on the aerodynamic characteristics of a delta wing-body combination at Mach numbers of 1.41 and 2.01. Body contouring reduced zero-lift drag of a delta wing-body combination from that of a basic wing-body combination without contouring by 18 percent at Mach number 1.41 and 6 percent at Mach number 2.01. Results regarding the characteristics at zero lift and characteristics for the lifting condition are provided.

Memorandum presenting an investigation of modifications to an indented body which was originally designed on the basis of the transonic drag-rise rule to determine the effects on the aerodynamic characteristics of a 45 degree sweptback-wing-body combination. The investigation covered a range of Mach numbers and angles of attack. Results regarding lift, drag for the nonlifting case, drag for the lifting case, maximum lift-to-drag ratios, and pitching moment are provided.

"A single-stage axial fan was built and tested in the shop of the propeller-research tunnel of the NACA. The fan comprised a simple 24-blade rotor having a diameter of 21 inches and a solidity of 0.86 and a set of 37 contravanes having a solidity of 1.33. The rotor was driven by a 25-horsepower motor capable of rotating at a speed of 3600 r.p.m. The fan was tested for volume, pressure, and efficiency over a range of delivery pressures and volumes for a wide range of contravane and blade-angle settings" (p. 49).

From Summary: "A simplified lifting-surface theory is applied to the problem of evaluating span loading due to flap deflection for arbitrary wing plan forms. With the resulting procedure, the effects of flap deflection on the span loading and associated aerodynamic characteristics can be easily computed for any wing which is symmetrical about the root chord and which has a straight quarter-chord line over the wing semispan. The effects of compressibility and spanwise variation of section lift-curve slope are taken into account by the procedure. The method presented can also be used to calculate the downwash in the vertical center of the wake of a wing which has arbitrary spanwise loading."

From Summary: "The results of the basic flutter theory originally devised in 1934 and published as NACA Technical Report no. 496 are presented in a simpler and more complete form convenient for further studies. The paper attempts to facilitate the judgement of flutter problems by a systematic survey of the theoretical effects of the various parameters. A large number of experiments were conducted on cantilever wings, with and without ailerons, in the NACA high-speed wind tunnel for the purpose of verifying the theory and to study its adaptability to three-dimensional problems."

From Summary :"An investigation was conducted with a single combustor from a J47 turbojet engine using weathered aviation gasoline and several spark-plug modifications to determine altitude ignition, acceleration, and steady state operating characteristics. Satisfactory ignition was obtained with two modifications of the original opposite-polarity spark plug up to and including an altitude of 40,003 feet at conditions simulating equilibrium windmilling of the engine at a flight speed of 400 miles per hour. At a simulated altitude of 30,000 feet, satisfactory ignition was obtained over a range of simulated engine speeds."

"An investigation was made to determine the static longitudinal and lateral stability and control characteristics of a 1/6-scale model of the revised Republic XF-84H airplane with and without the propeller operating. The model had a 40 degree swept wing of aspect ratio 3.45 and was equipped with a thin, three-blade supersonic-type propeller. Modifications incorporated in the revised model included a raised horizontal tail, increased rudder size, wing fences at 65 percent semispan, and a modified wing leading edge outboard of the fences" (p. 1).