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An Experimental Investigation of Flow Conditions in the Vicinity of an NACA D(Sub S)-Type Cowling

Description: Data are presented of the flow conditions in the vicinity of an NACA D sub S -type cowling. Tests were made of a 1/2 scale-nacelle model at inlet-velocity ratios ranging from 0.23 to 1.02 and angles of attack from 6 deg to 10 deg. The velocity and direction of flow in the vertical plane of symmetry of the cowling were determined from orifices and tufts installed on a board aligned with the flow. Diagrams showing velocity ratio contours and lines of constant flow angles are given.
Date: August 1, 1946
Creator: Bryant, Rosemary P. & Boswinkle, Robert W.
Item Type: Report

Wind-Tunnel Tests of a 1/5-Scale Semispan Model of the Republic XF-12 Horizontal Tail Surface

Description: Wind-tunnel tests of a 1/5-scale semispan model of the Republic XF-12 horizontal tail surface equipped with an internally balanced elevator were conducted in the 6- by 6-foot test section of the Langley stability tunnel. The tests included measurements of the aerodynamic characteristics of the horizontal tail with and without a beveled trailing edge and also included measurements of the tab characteristics. The variation of the aerodynamic characteristics with boundary-layer conditions and leakage in the internal-balance chambers, measurements of the boundary-layer displacement thickness near the elevator hinge axis, and pressure distributions at the mean geometric chord were also obtained. The results showed that the hinge-moment characteristics of the elevator were critical to boundary-layer conditions and internal-balance leakage. Increasing the boundary-layer displacement thickness by use of roughness strips reduced the rate of change of elevator hinge moments with tab deflection by about 20 percent. The present horizontal tail appears to be unsatisfactory for longitudinal stability with power on, however, an increase in horizontal-tail lift effectiveness should correct this difficulty. The maneuvering stick force per unit acceleration will be extremely critical to minor variations of the elevator hinge moments if the elevator is linked directly to the stick.
Date: January 1, 1945
Creator: Denaci, H. G.
Item Type: Report

Wind-Tunnel Tests of a 1/6-Scale Model of Republic XF-12 Vertical Tail Incorporating a De-Icing Air Duct

Description: A 1/6-scale model of the Republic XF-12 vertical tail with stub fuselage, stub horizontal tail, and a de-icing air duct was tested in the Langley stability tunnel. The investigation consisted of a study of the effects of the duct, with and without air flow, on the aerodynamic characteristics of the model. The model tested was a revision of a model previously tested in the Langley stability tunnel. The revised model differed from the original model in that it incorporated a de-icing air duct, included a dorsal fin, and had a larger stub fuselage. A comparison of data obtained form tests of the original and revised models was made. The results of the investigation indicated that the air duct had very little effect on the aerodynamic characteristics of the model. A small change occurred in the variation of rudder hinge-moment coefficient with angle of attack but it is believed that this change can be corrected by a properly applied spring tab.
Date: January 1, 1945
Creator: MacLachlan, Robert & Miller, Sadie M.
Item Type: Report

Wind-Tunnel Tests of a 1/6-Scale Model of Republic XF-12 Vertical Tail with Stub Fuselage and Stub Horizontal Tail

Description: A 1/6-scale model of the Republic XF-12 vertical tail with stub fuselage and stub horizontal tail was tested in the Langley stability tunnel to determine the aerodynamic characteristics of the model, The investigation included a study of the effects of boundarylayer thickness, rudder area, and cover-plate alinement on the aerodynamic characteristics. Tuft studies were made in the vicinity of the junction of the vertical and stub horizontal tails. The results of the investigation indicated that the flow in the vicinity of the junction of the vertical and stub horizontal tails was only slightly improved by the addition of a fillet. An increase in boundary-layer thickness produced a slight decrease in rudder effectiveness. The increase in lift of the combined rudders over that of the upper rudder alone was not proportional at low deflections and was approximately proportional at high deflections to the increase in rudder area. When the balance-chamber cover plates were bowed out, the change in rudder hinge moment with rudder angle was less negative. The variation of the lift coefficient with angle of attack and the variation, at small values of angle of attack, of rudder hinge-noment coefficient with angle of attack was approximately the same for all model configurations tested. The upper rudder used in conjunction with a tab was found to satisfy the Army specifications regarding asymmetric power on a multiengine airplane.
Date: June 2, 1945
Creator: MacLachlan, Robert
Item Type: Report

Wind-Tunnel Tests of a Portion of a PV-2 Helicopter Rotor Blade

Description: A portion of a PV-2 helicopter rotor blade has been tested in the 6- by 6-foot test section of the Langley stability tunnel to determine if the aerodynamic characteristics were seriously affected by cross flow or fabric distortion. The outer portion of the blade was tested as a reflection plane model pivoted about the tunnel wall to obtain various angles of cross flow over the blade. Because the tunnel wall acts as a plane of sy~try, the measured aerodynamic characteristics correspond to those of an airfoil having various angles of sweepforward and sweepback. Tests were made with the vents on the lower surface open and also with the vents sealed and the internal pressure held at -20 inches of water producing an internal pressure coefficient of -1.059. The change in contour resulting from the range of internal pressures used had very little effect on the aerodynamic characteristics of the blade. The test methods were considered to simulate inadequately the flow conditions over the rotor blade because the effects of cross flow were limited to conditions corresponding to sweep of the blade. The results indicated that this type of cross flow had only minor effects on the aerodynamic characteristics of the blade. It is believed, therefore, that future tests to determine the effects on the aerodynamic characteristics of cross flow should utilize complete rotors.
Date: March 29, 1945
Creator: Kemp, William B., Jr.
Item Type: Report

Correlation Tests of the Ditching Behavior of an Army B-24D Airplane and a 1/16-Size Model

Description: Behaviors of both model and full-scale airplanes were ascertained by making visual observations, by recording time histories of decelerations, and by taking motion picture records of ditchings. Results are presented in form of sequence photographs and time-history curves for attitudes, vertical and horizontal displacements, and longitudinal decelerations. Time-history curves for attitudes and horizontal and vertical displacements for model and full-scale tests were in agreement; maximum longitudinal decelerations for both ditchings did not occur at same part of run; full-scale maximum deceleration was 50 percent greater.
Date: January 1, 1946
Creator: Jarvis, George A. & Fisher, Lloyd J.
Item Type: Report