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Wind-tunnel investigation of ground effect on wings with flaps

Wind-tunnel investigation of ground effect on wings with flaps

Date: May 1, 1939
Creator: Recant, Isidore G
Description: An investigation was conducted in the N.A.C.A. 7- by 10-foot wind tunnel to determine the effect of ground proximity on the aerodynamic characteristics of wings equipped with high-lift devices. A rectangular and a tapered wing were tested without flaps, with a split flap, and with a slotted flap. The ground was represented by a flat plate, completely spanning the tunnel and extending a considerable distance ahead and back of the model. The position of the plate was varied from one-half to three chord lengths below the wing. The results are presented in the form of curves of absolute coefficients, showing the effect of the ground on each wing arrangement. The effect of the ground on lift, drag, and pitching moment is discussed. An appendix gives equations for calculating tunnel-wall corrections to be applied to ground-effect tests conducted in rectangular tunnels when a plate is used to represent the ground. The tests indicated that the ground effect on wings with flaps is a marked decrease in drag, a decrease in diving moment, and a substantial reduction in maximum lift.
Contributing Partner: UNT Libraries Government Documents Department
Contribution to the theory of the heated duct radiator

Contribution to the theory of the heated duct radiator

Date: April 1, 1939
Creator: Winter, H
Description: A method is developed with no neglect of certain factors in mass flow of air and in the drag of the heated radiator, i.e., one under actual operating conditions, as compared with the corresponding values in the cold state, may be simply computed. Although a symmetrical duct radiator has been used to bring out the flow relations, the results apply equally as well to the unsymmetrical radiator shapes usual in airplane construction.
Contributing Partner: UNT Libraries Government Documents Department
High-Speed Tests of Radial-Engine Cowlings

High-Speed Tests of Radial-Engine Cowlings

Date: April 1, 1939
Creator: Robinson, Russell G. & Becker, John V.
Description: The drag characteristics of eight radial-engine cowlings have been determined over a wide speed range in the N.A.C.A. 8-foot high-speed wind tunnel. The pressure distribution over all cowlings was measured, to and above the speed of the compressibility burble, as an aid in interpreting the force tests. One-fifth-scale models of radial-engine cowlings on a wing-nacelle combination mere used in the tests.
Contributing Partner: UNT Libraries Government Documents Department
Intermittent-flow coefficients of a poppet valve

Intermittent-flow coefficients of a poppet valve

Date: April 1, 1939
Creator: Waldron, C D
Description: Flow coefficients were determined for the inlet valve of a modern air-cooled cylinder during operation of the valve. The cylinder head with valves was mounted on a large tank that could be evacuated. Operating the valve with a rotating cam allowed air to flow through the valve into the evacuated tank. The change of pressure in the tank was a measure of the amount of air flowing though the valve in a given number of cycles. The flow coefficients were determined from the pressure across the valve, the quantity of air flowing, and the valve-lift curve. Coefficients were measured with lifts of 0.1 to 0.6 inch and speeds of 130 to 1,200 r.p.m. The results obtained with intermittent flow were compared with the results of tests made with steady flow through this cylinder head. This comparison indicated that steady-flow coefficients can be used for intermittent flow.
Contributing Partner: UNT Libraries Government Documents Department
Investigations and tests in the towing basin at Guidonia

Investigations and tests in the towing basin at Guidonia

Date: April 1, 1939
Creator: Cremona, C
Description: The experimental methods at the Guidonia towing basin are discussed including specifications. Some of the components examined are the bridge towing carriage, side towing carriage, catapult installation, and dynamometer systems. Tests were performed on hulls and floats, as well as motor boats and torpedo shaped bodies. Theoretical investigations were also performed to determine pressure distributions on geometrically simple bodies, propagation of small wave motions, and planing and submerged surfaces.
Contributing Partner: UNT Libraries Government Documents Department
Propeller tests to determine the effect of number of blades at two typical solidities

Propeller tests to determine the effect of number of blades at two typical solidities

Date: April 1, 1939
Creator: Lesley, E P
Description: Propellers with equal total blade area, but with different numbers, were tested at Stanford University. The tests show generally that, for equal total blade area, propellers with the larger number of blades absorb the greater power and, provided hubs have equal drag, develop the higher efficiency. It is shown that the differences found are in agreement, qualitatively, with what might be predicted from simple blade-element theory.
Contributing Partner: UNT Libraries Government Documents Department
Tests of an N.A.C.A. 23012 Airfoil with a slotted deflector flap

Tests of an N.A.C.A. 23012 Airfoil with a slotted deflector flap

Date: April 1, 1939
Creator: House, R O
Description: Section aerodynamic characteristics of a large-chord N.A.C.A. 23012 airfoil with a slotted deflector flap were obtained in the N.A.C.A. 7- by 10-foot wind tunnel. The characteristics of an N.A.C.A. slotted flap and of a simple split flap are included for comparison. The slotted deflector flap was found to have a somewhat lower maximum lift coefficient and somewhat higher drag at high lift coefficients than the N.A.C.A. slotted flap. The high drag of the open slot with the deflector flap neutral indicates that the slot should be closed for this condition.
Contributing Partner: UNT Libraries Government Documents Department
Theory of automatic control of airplanes

Theory of automatic control of airplanes

Date: April 1, 1939
Creator: Weiss, Herbert K
Description: Methods of automatically controlling the airplane are reviewed. Equations for the controlled motion including inertia effects of the control are developed and methods of investigating the stability of the resulting fifth and higher order equations are presented. The equations for longitudinal and lateral motion with both ideal and non-ideal controls are developed in dimensionless form in terms of control parameters based on simple dynamic tests of the isolated control unit.
Contributing Partner: UNT Libraries Government Documents Department
Wind-tunnel investigation of effect of yaw on lateral-stability characteristics I : four N.A.C.A. 23012 wings of various plan forms with and without dihedral

Wind-tunnel investigation of effect of yaw on lateral-stability characteristics I : four N.A.C.A. 23012 wings of various plan forms with and without dihedral

Date: April 1, 1939
Creator: Bamber, M J & House, R O
Description: Four N.A.C.A. 23012 wings were tested at several angles of yaw in the N.A.C.A. 7- by 10-foot wind tunnel. All the wings have rounded tips and, in plan form, one is rectangular and the others are tapered 3:1 with various amounts of sweep. Each wing was tested with two amounts of dihedral and with partial-span split flaps. The coefficients of lift, drag, and pitching moment are given for all the models at zero yaw. The coefficients of rolling moment, yawing moment, and side force are given for the rectangular wing at all values of yaw tested. The rate of change in the coefficients with angle of yaw is given in convenient form for stability calculations.
Contributing Partner: UNT Libraries Government Documents Department
Wind-tunnel tests of several forms of fixed wing slot in combination with a slotted flap on an N.A.C.A. 23012 airfoil

Wind-tunnel tests of several forms of fixed wing slot in combination with a slotted flap on an N.A.C.A. 23012 airfoil

Date: April 1, 1939
Creator: Bamber, M J
Description: None
Contributing Partner: UNT Libraries Government Documents Department