Report presents the results of an investigation of full-scale nose-slot cowlings conducted in the NACA 20-foot wind tunnel to furnish information on the pressure drop available for cooling. Engine conductances from 0 to 0.12 and exit-slot conductances from 0 to 0.30 were covered. Two basic nose shapes were tested to determine the effect of the radius of curvature of the nose contour; the nose shape with the smaller radius of curvature gave the higher pressure drop across the engine. The best axial location of the slot for low-speed operation was found to be in the region of maximum negative pressure for the basic shape for the particular operating condition. The effect of the pressure operating condition on the available cooling pressure is shown.
A comprehensive investigation has been carried on with full-scale models in the NACA 20-foot wind tunnel, the general purpose of which is to furnish information in regard to the physical functioning of the composite propeller-nacelle unit under all conditions of take-off, taxiing, and normal flight. This report deals exclusively with the cowling characteristics under condition of normal flight and includes the results of tests of numerous combinations of more than a dozen nose cowlings, about a dozen skirts, two propellers, two sizes of nacelle, as well as various types of spinners and other devices.
"Tests were made of eight full-scale propellers of different shape at various tip speeds up to about 1,000 feet per second. The range of blade-angle settings investigated was from 10 degrees to 30 degrees at the 0.75 radius. The results indicate that a loss in propulsive efficiency occurred at tip speeds from 0.5 to 0.7 the velocity of sound for the take-off and climbing conditions" (p. 517).
It is shown that the lift distribution for a biplane with unequal chords may be calculated by the method developed in NACA Technical report no. 458 if corrections are made for the inequality in chord lengths. The method is applied to four cases in which the upper chord was greater than the lower and good agreement is obtained between observed and calculated lift coefficients.
"This report is the fourth of a series on systematic tests conducted which compares lateral control devices with particular reference to their effectiveness at high angles of attack. The present report covers tests with floating tip ailerons on rectangular Clark y wings. Ailerons of two profiles were tested - symmetrical and Clark y, both with adjustable trailing-edge flaps. Each form was tested at three hinge-axis locations, both with and without vertical end plates between the ailerons and the wing proper. The results from these tests are compared with the results from tests on a wing of the same over-all size equipped with average-sized ordinary ailerons" (p. 481).
This report presents the results of an investigation of the spinning characteristics of NY-1 naval training biplane. The results of flight tests and an analysis based on wind-tunnel test data are given and compared. The primary purpose of the investigation was the determination in flight of the effect of changes in mass distribution along the longitudinal axis, without change of mass quantity or centroid. Other effects were also investigated, such as those due to wing loading, center-of-gravity position, dihedral of wings, control setting, and the removal of a large portion of the fabric from the fin and rudder. The wind tunnel test results used in the numerical analysis were obtained in the 7 by 10 foot wind tunnel through an angle-of-attack.
"The results of an experimental investigation on the boundary-correction factor are presented in this report. The values of the boundary-correction factor from the theory, which at the present time is virtually completed, are given in the report for all conventional types of tunnels. With the isolation of certain disturbing effects, the experimental boundary-correction factor was found to be in satisfactory agreement with the theoretically predicted values, thus verifying the soundness and sufficiency of the theoretical analysis" (p. 79).
This report gives the results in the 20-foot propeller research tunnel of the National Advisory Committee for Aeronautics on the interference drag and propulsive efficiency of a nacelle-propeller combination located in 21 positions with reference to a thick wing. The lift, drag, and propulsive efficiency were obtained at several angles of attack for each of the 21 locations. A net efficiency was derived for determining the over-all effectiveness of each nacelle location. Best results were obtained with the propeller about 25 per cent of the chord directly ahead of the leading edge. A location immediately above or below the wing near the leading edge was very poor.
Three model wings, two with typical slotted ailerons and one with typical frise ailerons, have been tested as part of a general investigation on lateral control devices with particular reference to their effectiveness at high angles of attack, in the 7 by 10 foot wind tunnel of the National Advisory Committee for Aeronautics. Force tests, free-autorotation tests, and forced-rotation tests were made which show the effect of the various ailerons on the general performance of the wing, on the lateral controllability, and on the lateral stability, in general, rolling control at 20 degree angle of attack to plain ailerons of the same size. The adverse yawing moments obtained with the slotted and frise ailerons were, in most cases, slightly smaller than those obtained with plain ailerons of the same size and deflection. However, this improvement was small as compared to the improvement obtainable by the use of suitable differential movements with any of the ailerons, including the plain.
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