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Calculation of Centrally Loaded Thin-Walled Columns Above the Buckling Limit

Description: When thin-walled columns formed from flanged sheet, such as used in airplane construction, are subjected to axial load, their behavior at failure varies according to the slenderness ratio. On long columns the axis deflects laterally while the cross section form is maintained; buckling results. The respective breaking load in the elastic range is computed by Euler's formula and for the plastic range by the Engesser- Karman formula. Its magnitude is essentially dependent upon the length. On intermediate length columns, especially where open sections are concerned, the cross section is distorted while the cross section form is preserved; twisting failure results. The buckling load in twisting is calculated according to Wagner and Kappus. On short columns the straight walls of low-bending resistance that form the column are deflected at the same time that the cross section form changes - buckling occurs without immediate failure. Then the buckling load of the total section computable from the buckling loads of the section walls is not the ultimate load; quite often, especially on thin-walled sections, it lies considerably higher and is secured by tests. Both loads, the buckling and the ultimate load are only in a small measure dependent upon length. The present report is an attempt to theoretically investigate the behavior of such short, thin-walled columns above the buckling load with the conventional calculating methods.
Date: April 1945
Creator: Reinitzhuber, F.
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 tb 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 f11ght. Another advantage of the springy tab is that it might be used to provide almost any desired variation of elevator stick force with speed by adjusting the tab hinge-moment characteristics and the variation of spring moment with tab deflection. Unlike the bungee and the bobweight, the springy tab would provide stick-free static stability without requiring a pull force to hold the stick back while taxying. A device similar to the springy tab may be used on the rudder or ailerons to eliminate undesirable trim-force variations with speed.
Date: February 1, 1946
Creator: Hunter, Paul A. & Reeder, John P.
Partner: UNT Libraries Government Documents Department

Flight tests of a glider model towed by twin parallel towlines

Description: From Summary: "The stability characteristics of a glider towed by twin parallel towlines have been studied in the NACA free-flight tunnel. A preliminary theoretical analysis of the stability of a glider restrained from yawing was followed by an experimental investigation of the stability of a model towed from fixed tunnel points in such a way as to simulate tow in level flight. The results of the tests confirm the theoretical analysis and indicate that a pilotless, stable, towed-glider system is possible when twin parallel towcables are used."
Date: April 1943
Creator: Pitkin, Marvin & McKinney, Marion O., Jr.
Partner: UNT Libraries Government Documents Department

A numerical procedure for designing cascade blades with prescribed velocity distribution in incompressible potential flow

Description: Report presenting a step-by-step numerical procedure based on conformal-mapping theory for the design of a cascade of airfoils with a prescribed dimensionless-velocity distribution in incompressible potential flow. It includes a set of tables to serve as a guide in computation. A comparison of several different types of airfoil design are included to examine the reliability of the procedure.
Date: June 1950
Creator: Hansen, Arthur G. & Yohner, Peggy L.
Partner: UNT Libraries Government Documents Department

Investigation of two-stage counterrotating compressor I : design and over-all performance of transonic first compressor stage

Description: Report presenting a highly loaded transonic rotor which was designed, built, and tested as part of a two-stage counterrotating-compressor research program. The design conditions were chosen to explore the upper limits of loading and Mach number for the transonic unit. The complete rotor design procedure is presented as well as the recorded stall traces and techniques for obtaining the data.
Date: May 22, 1956
Creator: Wilcox, Ward W. & Wright, Linwood C.
Partner: UNT Libraries Government Documents Department

Effectiveness at transonic speeds of flap-type ailerons for several spanwise locations on a 4-percent-thick sweptback-wing-fuselage model with and without tails

Description: Report presenting a transonic investigation in the 16-foot transonic tunnel to determine the effects of spanwise location of a flap-type aileron on the lateral characteristics of a 4-percent-thick sweptback-wing-fuselage model. Results regarding the effect of aileron spanwise position on roll and lift effectiveness, tail effects, and effect of spanwise aileron position on complete model rolling-moment characteristics are provided.
Date: February 26, 1957
Creator: Hieser, Gerald & Whitcomb, Charles F.
Partner: UNT Libraries Government Documents Department

NACA Conference on Aircraft Structures

Description: This document contains reproductions of technical papers on some of the most recent research results on aircraft structures from the NACA Laboratories. These papers were presented by members of the staff of the NACA Laboratories at the NACA conference held at the Langley Aeronautical Laboratory March 7, 1951. The purpose of this conference was to convey to those involved in the study of aircraft structures these recent research results and to provide those attending an opportunity for discussion of these results. The papers in this document are in the same form in which they were presented at the conference so that distribution of them might be prompt. The original presentation and this record are considered as complimentary to, rather than as substitute for, the Committee?s system of complete and formal reports.
Date: March 7, 1951
Partner: UNT Libraries Government Documents Department

Preliminary analysis of a nuclear-powered supersonic airplane using ramjet engines

Description: Report presenting performance estimates for a family of airplanes designed to cruise at Mach number 4.25 and using General Electric AC-210 ramjet engines. The airplane was designed to carry a payload of 10,000 pounds and use a crew of one. Results regarding the shield weight, engine weight, number of engines, and nozzle-velocity coefficient are provided.
Date: April 11, 1958
Creator: Weber, Richard J. & Connolley, Donald J.
Partner: UNT Libraries Government Documents Department

The problem of the helicopter

Description: Report discussing some of the issues regarding the design and operation of helicopters and the theoretical basis behind them. Some particular issues covered include propeller blade design, helicopters in forced descent, horizontal travel, and stability and control.
Date: May 1920
Creator: Warner, E. P.
Partner: UNT Libraries Government Documents Department

A load factor formula

Description: The ultimate test of a load factor formula is experience. The chief advantages of a semi rational formula over arbitrary factors are that it fairs in between points of experience and it differentiates according to variables within a type. Structural failure of an airplane apparently safe according to the formula would call for a specific change in the formula. The best class of airplanes with which to check a load factor formula seems to be those which have experienced structural failure. Table I comprises a list of the airplanes which have experienced failure in flight traceable to the wing structure. The load factor by formula is observed to be greater than the designed strength in each case, without a single exception. Table II comprises the load factor by formula with the designed strength of a number of well-known service types. The formula indicates that by far the majority of these have ample structural strength. One case considered here in deriving a suitable formula is that of a heavy load carrier of large size and practically no reserve power.
Date: August 1927
Creator: Miller, Roy G.
Partner: UNT Libraries Government Documents Department

Low-speed aileron effectiveness as determined by force tests and visual-flow observations on a 52 degree sweptback wing with and without chord-extensions

Description: The results of an investigation of the effects of leading-edge chord-extensions and extensible leading-edge flaps on the low-speed aileron characteristics of a 52 degrees sweptback wing with circular-arc airfoil sections are presented. A description and illustrations of the vortex flow as it passes over the wing are included. The investigation was conducted at Reynolds numbers of 5.5 times 10(exp 6) and 1.3 times 10(exp 6) and corresponding Mach numbers of 0.11 and 0.065 for an angle-of-attack range of 0 degrees through stall.
Date: April 29, 1953
Creator: Cancro, Patrick A.
Partner: UNT Libraries Government Documents Department

A low-speed investigation of an annular transonic air inlet

Description: Low-speed wind-tunnel tests were conducted as preliminary steps in the study of fuselage-air-inlet arrangements believed suitable for use at transonic speeds. The forward part of the model consisted of an NACA 1-85-050 cowling located at the base of the long protruding fuselage nose designed to maintain substream surface velocities everywhere ahead of the entrance and thereby to avoid or minimize adverse boundary-layer-shock interaction effects up to low supersonic speeds. Pressure-recovery and surface-pressure measurements are presented for the model with three fuselage nose shapes for ranges of angle of attack and inlet-velocity ratio useful for high-speed flight.
Date: April 1952
Creator: Nichols, Mark R. & Rinkoski, Donald W.
Partner: UNT Libraries Government Documents Department

Flow and force characteristics of 2-percent-thick airfoils at transonic speeds

Description: From Summary: "A two-dimensional investigation utilizing pressure-distribution measurements and schileren photographs has been made of the flow and force characteristics of slab-sided airfoils of 2-percent thickness at transonic Mach numbers. The airfoils had various combinations of elliptically shaped leading and trailing edges from a fineness ratio of 0 to 10. The aerodynamic characteristics and an analysis of the flow past the models are presented."
Date: January 18, 1955
Creator: Lindsey, Walter F. & Landrum, Emma Jean
Partner: UNT Libraries Government Documents Department

Lift, drag, and static longitudinal stability characteristics of four airplane-like configurations at Mach numbers from 3.00 to 6.28

Description: Report presenting lift, drag, and pitching-moment coefficients, lift-drag ratios, and center-of-pressure positions for four airplane-like configurations determined from tests at a range of Mach numbers and angles of attack. The wings and nose shapes were modified for each of the configurations.
Date: April 25, 1955
Creator: Neice, Stanford E.; Wong, Thomas J. & Hermach, Charles A.
Partner: UNT Libraries Government Documents Department

A preliminary investigation of the static stability characteristics of four airplane-like configurations at Mach numbers from 3.00 to 6.28

Description: Report presenting side-force and directional-stability characteristics of four airplane-like configurations determined at a range of Mach numbers and angles of sideslip at zero angle of attack. Two configurations had trapezoidal wing and tail surfaces and two had triangular wing and tail surfaces. The directional stability of the configurations generally decreased with increasing Mach number.
Date: March 26, 1956
Creator: Wong, Thomas J. & Gloria, Hermilo R.
Partner: UNT Libraries Government Documents Department

Fuselage stress analysis

Description: Report analyzes the stresses in a fuselage of the built-up type in which the shear is taken by diagonal bracing wires. Tests are conducted for landing, flying, and thrust loads.
Date: 1920
Creator: Warner, Edward P. & Miller, Roy G.
Partner: UNT Libraries Government Documents Department

On the elementary relation between pitch, slip, and propulsive efficiency

Description: The author examines the current theory on the importance of reducing slip in airplane propellers. The author feels an exaggerated importance is attached to this supposition and feels that the increase in friction by an increase in propeller area or number of revolutions can't be discounted.
Date: 1920
Creator: Froude, W.
Partner: UNT Libraries Government Documents Department

Recent research on the creep of airframe components

Description: Report presenting the results of research on the creep of airframe components at elevated temperatures. Experimental lifetime data from creep tests of stainless-steel plates and aluminum-alloy unstiffened circular cylinders are presented and compared with results predicted from isochronous stress-strain curves.
Date: July 1957
Creator: Mathauser, Eldon E.; Berkovits, Avraham & Stein, Bland A.
Partner: UNT Libraries Government Documents Department

Effect of combustion-chamber shape on the performance of a prechamber compression-ignition engine

Description: The effect on engine performance of variations in the shape of the prechamber, the shape and direction of the connecting passage, the chamber volume using a tangential passage, the injection system, and the direction od the fuel spray in the chamber was investigated using a 5 by 7 inch single-cylinder compression-ignition engine. The results show that the performance of this engine can be considerably improved by selecting the best combination of variables and incorporating them in a single design. The best combination as determined from these tests consisted of a disk-shaped chamber connected to the cylinder by means of a flared tangential passage. The fuel was injected through a single-orifice nozzle directed normal to the air swirl and in the same plane. At an engine speed of 1,500 r.p.m. and with the theoretical fuel quantity for no excess air, the engine developed a brake mean effective pressure of 115 pounds per square inch with a fuel consumption of 0.49 pound per brake horsepower-hour and an explosion pressure of 820 pounds per square inch. A brake mean effective pressure of 100 pounds per square inch with a brake-fuel consumption of 0.44 pound per horsepower-hour at 1,500 r.p.m. was obtained.
Date: December 1934
Creator: Moore, C. S. & Collins, J. H., Jr.
Partner: UNT Libraries Government Documents Department

Drag investigation of some fin configurations for booster rockets at Mach numbers between 0.5 and 1.4

Description: Report discussing testing to obtain data on booster drag estimates and to investigate the drag of various booster fin configurations. Several tie-rod-braced fin assemblies were investigated with various types and arrangement of tie rods as well as a cantilever fin assembly. The cantilever fin assembly was found to have roughly the same drag coefficients as the most efficient tie-rod-braced assembly.
Date: November 21, 1950
Creator: McFall, John C., Jr.
Partner: UNT Libraries Government Documents Department

Drag or negative traction of geared-down supporting propellers in the downward vertical glide of a helicopter

Description: Discussed here are computations of drag or negative traction of geared down supporting propellers in the downward vertical glide of a helicopter. By means of Frounde's Theory, the maximum value of the drag of a windmill is calculated. For wooden propellers, the author finds that the difference between the drag and the weight is proportional to the number of blades and is larger for propellers of small diameter; thus it is 25 kg. for a six blade propeller with a diameter of 2 m. 50. The author notes that if we are to adopt large propellers, we must have recourse to a different method of construction, resulting in large dimension propellers much lighter than those made of wood. In discussing insufficient drag, the author notes that the question of the drag of geared down supporting propellers can only be decided by experiment.
Date: September 1920
Creator: Toussaint, A.
Partner: UNT Libraries Government Documents Department