Memorandum presenting an investigation of the problems associated with the design of a low-pressure-loss, short afterburner for sea-level thrust augmentation in a static, sea-level test stand. Results regarding diffuser pressure losses, afterburner pressure losses, and afterburner performance are provided.

Report presenting the results of a preliminary investigation of a scale model of a convertible-type airplane in the full-scale tunnel. The maximum lift and stalling characteristics of several configurations, the longitudinal stability characteristics, and the effectiveness of the control surfaces with the propellers removed are provided. Results regarding the propulsive characteristics, and effect of propeller operation on the lift and static thrust of the model propellers are also provided.

Report presenting a wind-tunnel investigation through a speed range from Mach number 0.30 to 0.90 to determine the lateral-control characteristics of a 20-percent-chord by 39-percent-semispan aileron and a 60-percent-semispan stepped spoilers on a semispan-wing model with aspect ratio of 3.06 with 51.3 degrees sweepback of the wing leading edge. The aileron rolling effectiveness decreased as the Mach number increased, while the spoiler rolling-moment effectiveness decreased with Mach number.

Report presenting an investigation of combustion occurring downstream of various turbulence promoters in a 20-inch length of a 1 7/8-inch inside-diameter, water-jacketed tubing using premixed vaporized fuel and air. Among the turbulence promoters investigated were flat plates perforated with 1/8-inch diameter holes, 1/4-inch diameter holes, and a single large hole to give 12.4, 17.2, and 21.5 percent open area respectively.

In the determination of the performance of an air-cooled turbine, the cooling-air-flow characteristics between the root and the tip of the blades must be evaluated. The methods, which must be verified and the unknown functions evaluated, that are expected to permit the determination of pressure, temperature, and velocity through the blade cooling-air passages from specific investigation are presented.

Report presenting five fuels of boiling temperatures and several hydrocarbon types in a jet-propulsion annular combustor to determine the effect of fuel boiling temperature and paraffinic and aromatic hydrocarbon types on combustion efficiency and altitude operational limit. At the severe inlet-air condition, the highest combustion efficiencies were obtained with the paraffinic and aromatic fuels with low boiling temperatures were found to vary from 30 to 58 percent.

"Tests have been made at high speeds to determine the drag of models, simulating propeller shanks, in the form of a circular cylinder and three airfoils, the NACA 16-025, the NACA 16-040, and the NACA 16-040 with the rear 25 percent chord cut off. All the models had a maximum thickness of 4 1/2 inches to conform with average propeller-shank dimensions and a span of 20 1/4 inches. For the tests the models were supported perpendicular to the lower surface of the wing of an XP-51 airplane (p. 277).

From Summary: "The boundary-layer velocity profiles in the tip region of an axial-flow compressor downstream of the guide vanes and downstream of the rotor were measured by use of total-pressure and claw-type yaw probes. These velocities were resolved into two components: one along the streamline of the flow outside the boundary layer, and the other perpendicular to it. The affinity among all profiles was thus demonstrated with the boundary-layer thickness and the deflection of the boundary layer at the wall as the generalizing parameters. By use of these results and the momentum-integral equations, boundary-layer characteristics on the walls of an axial-flow compressor were qualitatively evaluated."

"A theoretical investigation has been made of the Saint-Venant torsion of certain composite bars. These bars are composed of two materials -- one material in the form of a thin-walled cylindrical shell and the other material in the form of a core which fills the interior of the shell and is bonded to it. An approximate boundary-value problem is formulated on assumptions similar to those of the theory of torsion of hollow thin-walled shells (Bredt theory)" (p. 771).

Report presenting an investigation of the problems associated with the design of a low-pressure-loss, short afterburner for sea-level thrust augmentation in a static, sea-level test stand using the power section of a 5970-pound-thrust, axial-flow turbojet engine. The various portions of the afterburner and procedures used to test it are described. Results regarding diffuser pressure losses, afterburner pressure losses, and afterburner performance are provided.

"The importance of atomizing and mixing liquid oxygen and heptane was studied in a 200-pound-thrust rocket engine. Ten injector elements were used with both steel and transparent chambers. Characteristic velocity was measured over a range of mixture ratios. Combustion gas-flow and luminosity patterns within the chamber were obtained by photographic methods" (p. 1).

"An investigation was made at the Langley landing-loads track to obtain data on the coefficient of friction during wheel spin-up. A landing gear was tested at horizontal velocities ranging from 0 to 180 feet per second together with vertical velocities of 7.0 and 9.3 feet per second. The results indicate the effect of forward speed and tire inflation pressure on the coefficient of friction" (p. 1).

An experimental investigation was carried out to determine the boundary-layer transition characteristics of bodies of revolution with flat and nearly flat faces. Shadowgraphs indicated that the boundary layer remained laminar on the front faces and was turbulent only on the sides. The tests also yielded information on the total drag coefficients and static longitudinal stability of the models.

This report is the sixth of a series giving wind tunnel tests results on the interference drag and propulsive efficiency of nacelle-propeller-wing combinations. The present report gives the results of tests of a radial-engine nacelle with pusher propeller in 17 positions with reference to a Clark Y wing; tests of the same nacelle and propeller in three positions with reference to a thick wing; and tests of a body and pusher propeller with the thick wing, simulating the case of a propeller driven by an extension shaft from an engine within the wing. Some preliminary tests were made on pusher nacelles alone.

From Summary: "The present paper is a continuation of the general study of flutter published in NACA reports nos. 496 and 685. The paper is mainly devoted to flutter in three degrees of freedom (bending, torsion, and aileron) for which a number of selected cases have been calculated and presented in graphical form. The results are analyzed and discussed with regard to the effects of structural damping, of fractional-span ailerons, and of mass-balancing. The analysis shows that more emphasis should be put on the effect of structural damping and less on mass-balancing."