Report discussing the results of testing conducted to determine the knock-limited performance of fuel blends containing 80 percent of S-2 reference fuel and 20 percent of several exploratory fuels. Butyl acetate, sec-butyl acetate, isopropyl acetate, sec-butyl alcohol, tert-butyl alcohol, isopropyl alcohol, cyclohexanol, methylcyclohexanol, isobutylcarbinol, sec-butylcarbinol, triethyl borate, and dimethylfuran were examined.

Report discusses the maximum lift coefficients for conventional and tailless airplanes in the gliding and landing conditions. Three areas are used to calculate the coefficients: wing area alone, wing area plus horizontal-tail area, and wing area plus horizontal- and vertical-tail areas.

Report discusses the results of testing to determine the maximum rates of control stick (elevator) motion and corresponding maximum stick forces that could be exerted based on experiments with several pilots. The main topics explored were the comparison of the maximum rates of push and pull, maximum rates of push and pull when a mental restriction was placed on the pilot, and maximum rates at which the pilot though he would apply the elevator control forces versus the actual application of forces. Information about experimental procedures and the rig the testing occurred on is included.

Report discusses an apparatus that may be used for indicating the formation of fatigue cracks or for following the progress of cracks. Details of the experiment and discussion of the way in which the deflection-crack area relationship may be used to monitor fatigue cracks are included.

"A model of a flying boat was tested to determine the landing characteristics when the depth of the step was reduced to zero by means of a retractable planing flap on the forebody" (p. 4). The results of stability and resistance testing are presented.

Report discusses the results of an investigation into the effectiveness of water injection into the combustion end zone of a spark-ignition engine cylinder for the suppression of knock. The injection angle was found to be very important for obtaining maximum results. The results of various angles and amounts of water were examined.

Report discusses the results of strength tests of several curved-sheet 24S-T aluminum alloy specimens stiffened longitudinally and transversely and loaded in shear. Curved-web beams and cylindrical shells were both examined in the tests. Results provided include the load at which the sheet began to show shear buckles, where the buckles occurred, and whether or not the failures involved rupture of the sheet.

Report discusses a method of replica creation and testing of the surface-finish variation of aircraft engine parts subject to wear. In this report, a positive replica is created, the surface is treated, the replica is tested to make sure the fidelity is high enough, and a series of ring-sticking tests are conducted on the replicas. A summary of the results of the testing is also included.

Report discusses the results of compressive testing of 24S-T aluminum-alloy sheet-stiffener panels with five ratios of stiffener thickness to sheet thickness. For each ratio, rivets of five different diameters were used to attach the stiffeners to the sheets. The compressive strengths were found to increase with an increase in the diameter of the rivets until the ratio of rivet diameter to over-all thickness reached a certain point.

Report discusses the results of testing water injection on a multicylinder aircraft engine and the potential fuel savings from the procedure. The speeds at which water injection for engine cooling is beneficial are illustrated and information about the manifold pressures and average rear spark-plug-gasket temperatures are also included.

Report discusses a method developed to estimate the quantities of internal coolants required to prevent overheating of the aircraft cylinder when oxygen boost is applied. The formula and calculations related to inlet-air pressure, added oxygen, added water, added nitrogen, and total fluid weight are detailed.

Report discusses an analysis and preliminary design of a control linkage that varies automatically with dynamic pressure. The advantages of the device, including greater lateral control than a fixed control linkage without additional aerodynamic balance, are detailed. The effect of variable linkage on lateral-control characteristics is also described.

"Formulas for the calculation of hinge-moment characteristics of an elevator with a spring tab have been developed in terms of basic aerodynamic parameters, spring stiffness, and airspeed. The formulas have been used in a study of the stick-force gradients on a pursuit airplane equipped with an elevator with a spring tab. Charts are presented showing the variation of stick-force gradient in accelerated flight over a large range of speed and the complete range of spring stiffness for various center-of-gravity locations, altitudes, and airplane sizes" (p. 1).

From Summary: "Local-instability tests of 24S-T aluminum-alloy formed Z- and channel-section columns were made in order to determine a length of test specimen that would avoid the increased strength associated with short lengths and also permit the occurrence of a convenient buckling pattern. The effect of column length on the critical compressive stress, on the average stress at maximum load, and on the number of half-waves of the buckling pattern is shown."

Report discusses the "effects of oil introduced into the combustion chamber and of oil-spray piston cooling on the knock-limited performance of aircraft engines" (from Summary). A CFR engine and Allison V-1710 cylinder were used to test the rate of oil consumption, knock, and knock-limited brake mean effective pressure.

Report discusses measurements of the relaxation time of steam and nitrogen due to their importance as turbine-working fluids. Additional calculations regarding different nozzle lengths are included.

"An electronic circuit for instantaneously indicating angular velocity and acceleration, both positive and negative, of rotating masses is described; readings are taken on electrical indicating meters. The indicator is described in terms of general application. A circuit diagram, calibration curves, and a mathematical analysis of the differentiation circuit are included" (p. 1).

Report discusses the results of testing of 10-inch 24S-T aluminum alloy shear panels with 1.5 inch holes with notched edges to determine if a notch decreases the strength of the panel and if reinforcements can overcome the negative effects of the notch. The notch did appear to increase the stress concentration around the holes, but the lack of applicability to real-world scenarios is discussed.

"Strength tests were made on two sets of beams having webs with large circular lightening holes. The main conclusion drawn from the tests is that allowable web stressed derived from pure shear tests and allowable flange stresses derived from compression tests cannot be applied in the design of beams without making corrections for interaction" (p. 1). Pure shear tests and beam tests were performed and the circumstances of failure were investigated.

Report discusses an investigation that was conducted to compare the strength and tightness of machine-countersunk flush-riveted joints assembled with NACA flush rivets and a type of commercial flush rivet. A comparison was also generated between the strength and tightness of counterpunched flush-riveted joints assembled with the same types of rivet. NACA's flush-riveted joints tended to be stronger and tighter than the commercial joints.

Report discusses the results of an investigation into the tightness, shear strength, tensile strength, and life under pulsating loads of hollow, hydraulically expanded rivets made of 17S-T aluminum alloy. The countersunk-head rivets with inserts had a much higher maximum load in shear than the modified-roundhead rivets, which did not have inserts.

Report describes a balanced-diaphragm device for measuring dynamometer torque of single-cylinder or multicylinder engines that was developed for laboratory use. Design variables are described, included desired torque-measuring device characteristics, diaphragm design, pilot valve, the torque-indicating instrument, the capacity range, ability of reversed operation, and double-acting operation. The accuracy is described as satisfactory and effects of other variables are negligible.

Report discusses measurements of gust size and intensity during the spring and summer of 1941 and 1942 under a variety of weather conditions and various altitudes up to 34,000 feet. Information about average gust-gradient distance, gust velocities, and gust frequency is included.

"The effects of changes in aileron rigging between 2 deg up and 2 deg down on the stick forces were determined from wind-tunnel data for a finite-span wing model. These effects were investigated for ailerons deflecting equally in both directions and linearly with stick deflection. Data were analyzed for a Frise, a sealed internally balanced, and a beveled-trailing-edge aileron" (p. 1).