"This document contains reproductions of technical papers on some of the most recent research results on aircraft loads, flutter, and structures from the NACA laboratories. These papers were presented by members of the staff of the NACA laboratories at the Conference held at the Langley Aeronautical Laboratory March 5, 6, and 7, 1957. The primary purpose of this Conference was to convey to contractors of the military services and others concerned with the design of aircraft these recent research results and to provide those attending an opportunity to discuss the results" (p. 6).

Report describing an investigation 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. Results regarding ignition, acceleration, altitude operational limits, combustion efficiency, and pressure loss are provided.

From Introduction: "Range in more or less steady level flight depends directly on aerodynamic lift-drag ratio at high supersonic speeds, just as it does at lower speeds. This result follows from the classical Breguet range equation in the case of powered flight, and it may be easily deduced from the equations of motion for unpowered or gliding flight (see refs. 1 and 2)."

Report presenting an investigation of three cone-cylinder bodies to obtain boundary-layer-transition data at very low ratios of wall to local stream temperature. Surface finishes at several levels of roughness height were tested. Results regarding the smooth body and rough bodies are provided.

Memorandum presenting wind tunnel tests performed on a family of missiles. This paper summarizes some of the performance and stability and control characteristics of the missiles.

Report presenting an investigation to obtain the pressure distribution over a sharp-nose body of revolution with a circular-arc profile and fineness ratio 6 at transonic speeds using the NACA wing-flow method. Results regarding the variation of pressure coefficient with Mach number, pressure distributions along the body axis, pressure drag, and effects of interference and horizontal gradient are provided.

Report presenting an investigation in the high-speed 7- by 10-foot tunnel through a range of Mach numbers to determine the effects of external-store fineness ratio, store shape, store chordwise position, pylon thickness, pylon length, and pylon sweep angle on the aerodynamic characteristics of a number of underwing pylon-suspended external stores in combination with a 45 degree sweptback semispan wing and fuselage.

Report summarizing several experimental tail-pipe-burner investigations to indicate the effects of tail-pipe-burner design variables on the performance and operating characteristics. Most of the configurations were investigated over a wide range of altitudes and flight Mach numbers. The results indicate the desirable design features of a tail-pipe burner that will operate with high combustion efficiency and exhaust-gas temperature up to an altitude of approximately 50,000 feet.

From Summary: "Experimental force, moment, and center-of-pressure variations for a large number of bodies of revolution have been compared with the calculated characteristics based on the approximate theory developed in NACA-RM-A9I26. The bodies varied in fineness ratio from 4.5 to 21.1, from blunt unboattailed bodies to airship hulls, and the experimental results are given for widely varying Mach number ranges of angle of attack. It is shown that the lift and drag characteristics are fairly accurately predicted by the theory but that the actual center of pressure is more rearward than the theory indicates."

Preliminary results at high speeds indicate lower bearing temperatures, less internal bearing wear, and greater reliability of the conventional, cage-type cylindrical roller bearings than of either full-complement or special cageless roller bearings of the types investigated, although the latter bearing types have been operated successfully to DN values of 1.0 X 10 superscript 6.

"The over-all performance of a 16-stage axial-flow compressor was determined with various stator-blade resettings and a reduction in solidity of the rotor blades in the last three stages. It was shown that little control over the sudden change in slope of the surge-limit line at intermediate speeds was obtained with the blade modifications attempted, except that some change in speed at which the change in slope occurred could be effected by stator-blade resettings" (p. 1).

An analysis is made of the factors affecting the weight-flow rate per unit frontal area of centrifugal compressors with axial-flow vaned diffusers preceded by mixed-flow vaneless sections. It is shown that, for specified inlet conditions to the impeller and vaned diffuser, the weight-flow rate is increased at the expense of pressure ratio and vice versa. Charts are presented to help the designer make a satisfactory compromise between weight-flow rate and pressure ratio. Some conclusions of the investigation are : (1) Prewhirl is of negligible value in centrifugal compressors designed for high weight-flow rates.

A finite-difference method previously presented for computing elastic stresses in rotating disks is extended to include the computation of the disk stresses when plastic flow and creep are considered. A finite-difference method is employed to eliminate numerical integration and to permit nontechnical personnel to make the calculations with a minimum of engineering supervision. Illustrative examples are included to facilitate explanation of the procedure by carrying out the computations on a typical gas-turbine disk through a complete running cycle. The results of the numerical examples presented indicate that plastic flow markedly alters the elastic-stress distribution.

Report presenting a comparison of three hypervelocity vehicles: a ballistic rocket, a skip rocket, and a rocket glider. Range efficiency, automatic heating, and problems of glide rockets are explored.

Report presenting an investigation to evaluate the external-store drag reductions obtainable by application of Baldwin's moment-of-area rule. Several wing-body combinations were investigated with and without four typical air-to-air missiles. Results regarding the total-drag measurements, wave-drag components, and effectiveness of moment-of-area rule for reducing the drag of the external-store installations are provided.

A variational theorem is presented for a body undergoing creep. Solutions to problems of the creep behavior of plates, columns, beams, and shells can be obtained by means of the direct methods of the calculus of variations in conjunction with the stated theorem. The application of the theorem is illustrated for plates and columns by the solution of two sample problems.

Memorandum presenting an investigation to define the relationships between the extent of laminar flow and such variables as surface smoothness, wall temperature, pressure gradient, and Mach number. The purpose of this particular paper is to review briefly the results that have been obtained from research.

"The information on the propeller-cowling-nacelle combinations, presented in Technical Reports nos. 592, 593, and 596 and in Technical Note 620, is applied to the practical design of NACA cowlings. The main emphasis is placed on the method of obtaining the dimensions of the cowling; consequently, the physical functioning of each part of the cowling is treated very briefly. A practical method of designing cowlings and some examples are presented" (p. 383).

Memorandum presenting an investigation of the performance of a five-stage transonic research compressor with distorted inlet flow. Both overall performance and individual blade-row performance results over a range of compressor speeds and equivalent weight flows were obtained with three circumferential inlet flow-distortion patterns covering annular extents of 60, 120, and 180 degrees. Results regarding compressor-inlet conditions and overall performance and individual blade-row performance are provided.

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 August 16, 1947 to August 20, 1947 are presented.

Memorandum presenting an investigation of a double-ramp cascade inlet at Mach number 3.05 in order to determine the penalties associated with decreasing the length of inlets by means of cascades. Total-pressure recovery and profile distortion of the cascade inlet were compared with a similar single-passage inlet that captured the same mass flow.

"Tests of a 1/20-scale model of the Fleetwings XBTK-1 airplane have been performed in the Langley 15-foot free-spinning tunnel to determine the trim tendencies of the airplane at attitudes above the stall. The results of the tests indicated that the model would trim longitudinally only in the normal range of angles of attack and that the yaw trim tendencies for such longitudinal trim conditions were normal. Although wide oscillations in yaw were noted for some conditions, they occurred at angles of attack larger than those indicated as possible for longitudinal trim and spin equilibrium" (p. 1).

"A supplementary investigation has been conducted in the Langley 20-foot free-spinning tunnel on a l/24-scale model of the Grumman F11F-1 airplane to determine the spin and recovery characteristics with alternate nose configurations, the production version and the elongated APS-67 version, with and without empty and full wing tanks. When spins were obtained with either alternate nose configuration, they were oscillatory and recovery characteristics were considered unsatisfactory on the basis of the fact that very slow recoveries were indicated to be possible. The simultaneous extension of canards near the nose of the model with rudder reversal was effective in rapidly terminating the spin" (p. 1).

From Summary: "Force characteristics determined from tank tests of a 1/5.78 scale model of a hydro-ski-wheel combination for the Grumman JRF-5 airplane are presented. The model was tested in both the submerged and planing conditions over a range of trim, speed, and load sufficiently large to represent the most probable full-size conditions."