You limited your search to:

  Partner: UNT Libraries Government Documents Department
 Serial/Series Title: NACA Special Report
 Collection: Technical Report Archive and Image Library
The Effect of Surface Irregularities on Wing Drag. II - Lap Joints, 2, Lap Joints

The Effect of Surface Irregularities on Wing Drag. II - Lap Joints, 2, Lap Joints

Date: February 1, 1938
Creator: Hood, Manley J.
Description: Tests have been made in the NACA 8-foot high-speed wind tunnel of the drag caused by four types of lap joint. The tests were made on an airfoil of NACA 23012 section and 5-foot chord and covered in a range of speeds from 80 to 500 miles per hour and lift coefficients from 0 to 0.30. The increases in profile drag caused by representative arrangements of laps varied from 4 to 9%. When there were protruding rivet heads on the surface, the addition of laps increased the drag only slightly. Laps on the forward part of a wing increased the drag considerably more than those farther back.
Contributing Partner: UNT Libraries Government Documents Department
Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report

Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report

Date: May 1, 1940
Creator: McHugh, James G.
Description: Adjustable cowling flaps, an adjustable-length cowling skirt, and a bottom opening with adjustable flap were tested as means of controlling the rate of cooling-air flow through an air-cooled radial-engine cowling. The devices were tested in the NACA 20-foot tunnel on a model wing-nacelle-propeller combination, through an airspeed range of 20 to 80 miles per hour, and with the propeller blade angle set 23 degrees at 0.75 of the tip radius. The resistance of the engine to air flow through the cowling was simulated by a perforated plate. The results indicated that the adjustable cowling flap and the bottom opening with adjustable flap were about equally effective on the basis of pressure drop obtainable and that both were more effective means of increasing the pressure drop through the cowling than the adjustable-length skirt. At conditions of equal cooling-air flow, the net efficiency obtained with the adjustable cowling flaps and the adjustable-length cowling skirt was about 1% greater than the net efficiency obtained with the bottom opening with adjustable flap.
Contributing Partner: UNT Libraries Government Documents Department
Notes on New French Commercial Airplanes

Notes on New French Commercial Airplanes

Date: April 4, 1935
Creator: unknown
Description: This document discusses the types of commercial planes ordered by Air France. Characteristics of the Wibault 670, the Dewoitine D.620, Bloch 300, and the Potez 620 airplanes are included. Pictures and diagrams of these aircraft are also included.
Contributing Partner: UNT Libraries Government Documents Department
Estimated Effect of Ring Cowl on the Climb and Ceiling of an Airplane, Special Report

Estimated Effect of Ring Cowl on the Climb and Ceiling of an Airplane, Special Report

Date: June 1, 1931
Creator: Louden, F. A.
Description: Although the application of a ring cowl to an airplane with an air-cooled engine increases the maximum L/D and the high speed to an appreciable extent, the performance in climb and ceiling is not increased as much as one would expect without analyzing the conditions. When a ring cowl is installed on an airplane, the propeller is set at a higher pitch to allow the engine to turn its rated r.p.m. at the increased high speed. V/nD is increased and the propeller efficiency at high speed is increased slightly. The ratio of r.p.m. at climbing speed, V(sub c) , to the r.p.m. at maximum speed, V (sub m) is dependent upon the ratio of V(sub c) to V(sub m). The increase in V(sub c) for all airplane with ring cowl i s not as great as the increase in V(sub m), so that the ratio V(sub c)/V(sub m) is less than for the airplane without ring. Consequently the r.p.m. and full throttle thrust power available are less at V(sub c) for the airplane with ring cowl and in spite of the increase in L/D due to the installation of the ring, the excess thrust power available for climbing is not ...
Contributing Partner: UNT Libraries Government Documents Department
Definition of Method of Measurement of Supporting and Control Surface Areas, Special Report

Definition of Method of Measurement of Supporting and Control Surface Areas, Special Report

Date: May 1, 1931
Creator: unknown
Description: Definitions of methods of measurements of supporting and control surface areas are presented. Methods for measuring the supporting surface, i.e., the wing area, and the control surfaces, i.e., the horizontal tail area, the vertical tail area, and the trailing control surface areas are defined. Illustrations of each of the areas are included.
Contributing Partner: UNT Libraries Government Documents Department
The Effect of Surface Irregularities on Wing Drag. I. Rivets and Spot Welds, 1, Rivets and Spot Welds

The Effect of Surface Irregularities on Wing Drag. I. Rivets and Spot Welds, 1, Rivets and Spot Welds

Date: February 1, 1938
Creator: Hood, Manley J.
Description: Tests have been conducted in the NACA 8-foot high-speed wind tunnel to determine the effect of exposed rivet heads and spot welds on wing drag. Most of the tests were made with an airfoil of 5-foot chord. The air speed was varied from 80 to 500 miles per hour and the lift coefficient from 0 to 0.30. The increases in the drag of the 5-foot airfoil varied from 6%, due to countersunk rivets, to 27%, due to 3/32-inch brazier-head rivets, with the rivets in a representative arrangement. The drag increases caused by protruding rivet heads were roughly proportional to the height of the heads. With the front row of rivets well forward, changes in spanwise pitch had negligible effects on drag unless the pitch was more than 2.5% of the chord. Data are presented for evaluating the drag reduction attained by removing rivets from the forward part of the wing surface; for example, it is shown that over 70% of the rivet drag is caused by the rivets on the forward 30% of the airfoil in a typical case.
Contributing Partner: UNT Libraries Government Documents Department
Method of Determining the Weights of the Most Important Simple Girders

Method of Determining the Weights of the Most Important Simple Girders

Date: December 1, 1931
Creator: Cassens, J.
Description: This paper presents a series of tables for the simple and more common types of girders, similar to the tables given in handbooks under the heading "Strength of Materials," for determining the moments, deflections, etc., of simple beams. Instead of the uniform cross section there assumed, the formulas given here apply only to girders of "uniform strength," i.e., it is assumed that a girder is so dimensioned that a given load subjects it to a uniform stress throughout its whole length. This principle is particularly applicable to very strong structures. Girders of uniform strength are the lightest girders conceivable, because any girder, all of whose members are stressed to the limit, can not be surpassed by a lighter girder, if the two girders have the same form. The weight G of a member of length l, cross section F and specific gravity gamma is: G = Flgamma.
Contributing Partner: UNT Libraries Government Documents Department
Relative Efficiencies and Design Charts for Various Engine-Propeller Combinations, Special Report

Relative Efficiencies and Design Charts for Various Engine-Propeller Combinations, Special Report

Date: September 1, 1936
Creator: Biermann, David
Description: The relative efficiencies of various engine-propeller combinations were the subject of a study that covered the important flight conditions, particularly the take-off. Design charts that graphically correlate the various propeller parameters were prepared to facilitate the solution of problems and also to c1arify the conception of the relationships of the various engine-propeller design factors. It is shown that, among the many methods for improving the take-off thrust, the use of high-pitch, large-diameter controllable propellers turning at low rotational speeds is probably the most generally promising. With such a combination the take-off thrust may be further increased, at the expense of a small loss in cruising efficiency, by compromise designs wherein the pitch setting is slightly reduced and the diameter is further increased. The degree of compromise necessary to accomplish the maximum possible take-off improvement depends on such design factors as overspeeding and overboosting at take-off as well as depending on the design altitude. Both overspeeding and designing for altitude operation have the same effect on the take-off thrust as compromising in that the propulsive efficiency is increased thereby; boosting the engine, however, has the reverse effect on the propulsive efficiency, although the brake horsepower is increased.
Contributing Partner: UNT Libraries Government Documents Department
Mechanical Properties of Flush-Riveted Joints

Mechanical Properties of Flush-Riveted Joints

Date: January 1, 1940
Creator: Bruggeman, Wm. C. & Roop, Frederick C.
Description: The strength of representative types of flush-riveted joints has been determined by testing 865 single-shearing, double-shearing, and tensile specimens representing 7 types of rivet and 18 types of joint. The results, presented in graphic form, show the stress at failure, type of failure, and d/t ratio. In general, 'dimpled' joints were appreciably stronger than countersunk or protruding-head joints, but their strength was greatly influenced by constructional details. The optimum d/t ratios have been determined for the several kinds of joints. Photomacrographs of each type show constructional details and, in several instances, cracks in the sheet.
Contributing Partner: UNT Libraries Government Documents Department
Performance Characteristics of an Aircraft Engine with Exhaust Turbine Supercharger, Special Report

Performance Characteristics of an Aircraft Engine with Exhaust Turbine Supercharger, Special Report

Date: May 1, 1941
Creator: Lester, E. M. & Paulson, V. A.
Description: The Pratt and Whitney Aircraft company and the Naval Aircraft Factory of the United States Navy cooperated in a laboratory and flight program of tests on an exhaust turbine supercharger. Two series of dynamometer tests of the engine super-charger combination were completed under simulated altitude conditions. One series of hot gas-chamber tests was conducted by the manufacturer of the supercharger. Flight demonstrations of the supercharger installed in a twin-engine flying boat were terminated by failure of the turbine wheels. The analysis of the results indicated that a two-stage supercharger with the first-stage exhaust turbine driven will deliver rated power for a given indicated power to a higher altitude, will operate more efficiently, and will require simpler controls than a similar engine with the first stage of the supercharger driven from the crankshaft through multispeed gears.
Contributing Partner: UNT Libraries Government Documents Department