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Effect of Normal Pressure on the Critical Shear Stress of Curved Sheet

Description: "In order to determine the critical stresses caused by an outward acting pressure on the upper surface of a wing due to the difference in internal and external pressures, torsional tests were made on two curved-sheet specimens subjected to an outward acting normal pressure. Results show that an outward acting normal pressure appreciable raises the critical shear stress for an unstiffened curved sheet; the absolute increase in critical shear stress is slightly greater for a 30 in. rib spacing than for a 10 in. rib spacing" (p. 1).
Date: January 1943
Creator: Rafel, Norman
Partner: UNT Libraries Government Documents Department

The Effect of Piston-Head Temperature on Knock-Limited Power

Description: To determine the effect of piston-head temperature on knock-limited power, tests were made in a supercharged CFR engine over a range of fuel-air ratios from 0.055 to 0.120, using S-3 reference fuel, AN-F-28, Amendment-2, aviation gasoline, and AN-F-28 plus 2 percent xylidines by weight. Tests were run at a compression ratio of 7.0 with inlet-air temperatures of 150 F and 250 F and at a compression ratio of 8.0 with an inlet-air temperature of 250 F. All other engine conditions were held constant.
Date: July 1944
Creator: Imming, Harry S.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Entrance-Region Heat-Transfer Coefficients

Description: "Experimental results of tests made at the Langley Memorial Aeronautical Laboratory are presented to show how heat-transfer coefficients can be increased by a method utilizing the high rate of heat transfer known to exist on any heat-transfer surface in the region adjacent to the edge on which the cooling or heating fluid impinges. The results show that, for the same pressure drop, the average surface heat-transfer.coefficient can be increased 50 to 100 percent when a cooling surface having a length of four inches in the direction of fluid flow is cut to form twenty fins with a length of 0.2 inch in the direction of fluid flow and the fins are sharpened and staggered in the air stream" (p. 1).
Date: November 1943
Creator: Joyner, Upshur T.
Partner: UNT Libraries Government Documents Department

An Experimental Investigation of the Effect of Propellers Used as Aerodynamic Brakes on Stability and Control

Description: "Tests were made of a model representative of a single-engine tractor-type airplane for the purpose of determining the stability and control effects of a propeller used as an aerodynamic brake. The tests were made with single-and dual-rotation propellers to show the effect of type of propeller rotation, and with positive thrust to provide basic data with which to compare the effects of negative thrust. Four configurations of the model were used to give the effects of tilting the propeller thrust axis down 5 deg., raising the horizontal tail, and combining both tilt and raised tail" (p. 1).
Date: July 1945
Creator: Stevens, Victor I.; McCullough, George B. & Hanson, Frederick H.
Partner: UNT Libraries Government Documents Department

Flight Measurements to Determine Effect of a Spring-Loaded Tab on Longitudinal Stability of an Airplane

Description: "In conjunction with a program of research on the general problem of stability of airplanes in the climbing condition, tests have been made of a spring-loaded tab, which is referred to as a "springy tab," installed on the elevator of a low-wing scout bomber. The tab was arranged to deflect upward with decrease in speed which caused an increase in the pull force required to trim at low speeds and thereby increased the stick-free static longitudinal stability of the airplane. It was found that the springy tab would increase the stick-free stability in all flight conditions, would reduce the danger of inadvertent stalling because of the definite pull force required to stall the airplane with power on, would reduce the effect of center-of-gravity position on stick-free static stability, and would have little effect on the elevator stick forces in accelerated flght" (p. 1).
Date: February 1946
Creator: Hunter, Paul A. & Reeder, John P.
Partner: UNT Libraries Government Documents Department

Flight Investigation of Wing-Gun Fairings on a Fighter Type Airplane

Description: Description is given of flight tests conducted on gun fairings, designed to correct the detrimental effects of the projecting and submerged wing guns on an F4F-3 fighter. It was found that the installation of unfaired guns on a clean wing resulted in a premature stall that increased the stalling speed in the carrier-approach and landing conditions of flight by suitably fairing the guns, it was possible to reduce the stalling speeds to values approaching very nearly the clean-wing values.
Date: October 1941
Creator: Nissen, J. M. & White, M. D.
Partner: UNT Libraries Government Documents Department

Flight Tests of Various Tail Modifications on the Brewster XSBA-1 Airplane 2: Measurements of Flying Qualities with Tail Configuration Number Two

Description: Several tail modifications of the Brewster XSBA-1 scout-bomber were investigated and results compared. Modifications consisted of variation of the chord of the elevator and rudder while the total area of the surfaces is kept constant and variations of the total area of the vertical tail surface. Configuration number 2 reduced trim changes by 50 percent and reduced average elevator control force gradient from 30 to 27 pounds/g. Stick travel required to stall in maneuver was 4.6 inches.
Date: December 1943
Creator: Phillips, W. H. & Crane, H. L.
Partner: UNT Libraries Government Documents Department

Flight Tests of the Lateral Control Characteristics of an F6F-3 Airplane Equipped with Spring-Tab Ailerons

Description: Tests were made to determine whether spring-tab ailerons tended to oscillate or flutter in speed ranges up to 400 mph. Flight tests showed spring-tab ailerons had desirable light stick forces and no tendency to overbalance. No flutter tendencies were indicated up to 400 mph, and any oscillations following abrupt control deflections were heavily damped.
Date: April 1945
Creator: Williams, Walter C.
Partner: UNT Libraries Government Documents Department

The Longitudinal Stability of Flying Boats as Determined by Tests of Models in the NACA Tank 2: Effect of Variations in Form of Hull on Longitudinal Stability

Description: Data taken from tests at constant speed to establish trim limits of stability, tests at accelerated speeds to determine stable limits of center of gravity shift, and tests at decelerated speeds to obtain landing characteristics of several model hull forms were used to establish hull design effect on longitudinal stability of porpoising. Results show a reduction of dead rise angle as being the only investigated factor reducing low trim limit. Various methods of reducing afterbody interference increased upper trim limit.
Date: November 1942
Creator: Truscott, Starr & Olson, Roland E.
Partner: UNT Libraries Government Documents Department

Principles of Moment Distribution Applied to Stability of Structures Composed of Bars or Plates

Description: Principles of the cross method of moment distribution, which have previously been applied to the stability of structures composed of bars under axial load, are applied to the stability of structures composed of long plates under longitudinal load.
Date: November 1943
Creator: Lundquist, Eugene E.; Stowell, Elbridge Z. & Schuette, Evan H.
Partner: UNT Libraries Government Documents Department

A Solution of the Direct and Inverse Potential Problems for Arbitrary Cascades of Airfoils

Description: Methods are given of determining the potential flow plast an arbitrary cascade of airfoils and the inverse problem of determining an airfoil having a prescribed velocity distribution in cascade. Results indicated that Cartesian mapping function method may be satisfactorily extended to include cascades. Numerical calculation for computing cascades by Cartesian mapping function method is considerably greater than for single airfoils but much less than hitherto required for cascades.
Date: December 1944
Creator: Mutterperl, William
Partner: UNT Libraries Government Documents Department

Numerical Evaluation by Harmonic Analysis of the (Epsilon)-Function of the Theodorsen Arbitrary-Airfoil Potential Theory

Description: Finite trigonometric series is fitted by harmonic analysis as an approximation function to the psi function of the Theodorsen arbitrary-airfoil potential theory. By harmonic synthesis, the corresponding conjugate trigonometric series is used as an approximation to the epsilon function. A set of coefficients of particularly simple form is obtained algebraically for direct calculation of the epsilon values from the corresponding set of psi values.
Date: September 1945
Creator: Naiman, Irven
Partner: UNT Libraries Government Documents Department

Operating Temperatures of a Sodium-Cooled Exhaust Valve as Measured by a Thermocouple

Description: "A thermocouple was installed in the crown of a sodium-cooled exhaust valve. The valve was then tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 F was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 rpm" (p. 1).
Date: December 1943
Creator: Sanders, J. C.; Wilsted, H. D. & Mulcahy, B. A.
Partner: UNT Libraries Government Documents Department

Preliminary Report on Laminar-Flow Airfoils and New Methods Adopted for Airfoil and Boundary-Layer Investigations

Description: "Recent developments in airfoil-testing methods and fundamental air-flow investigations, as applied to airfoils, are discussed. Preliminary test results, obtained under conditions relatively free from stream turbulence and other disturbances, are presented. Suitable airfoils and airfoil-design principles were developed to take advantage of the unusually extensive laminar boundary layers that may be maintained under the improved testing conditions" (p. 1).
Date: June 1939
Creator: Jacobs, Eastman N.
Partner: UNT Libraries Government Documents Department

Some Notes on the Determination of the Stick-Free Neutral Point from Wind-Tunnel Data

Description: "Two graphical methods are presented for determining the stick-free neutral point, and they are extensions of the methods commonly used to determine the stick-free neutral point. A mathematical formula for computing the stick-free neutral point is also given. These methods may be applied to determine approximately the increase in tail size necessary to shift the neutral point (stick fixed or free) to any desired location on an airplane having inadequate longitudinal stability" (p. 1).
Date: February 1944
Creator: Schuldenfrei, Marvin
Partner: UNT Libraries Government Documents Department