1,423 Matching Results

Search Results

A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

Description: Report describing the effects of an area of roughness on the velocity and turbulence measurements of an airfoil. It details the effects of the size, location, and height of the roughness on the Reynolds number. From Summary: "An investigation was made in the Langley low-turbulence pressure tunnel to determine the effect of size and location of a sandpaper type of roughness on the Reynolds number for transition."
Date: 1958
Creator: Horton, Elmer A. & von Doenhoff, Albert E.
Partner: UNT Libraries Government Documents Department

The effect of cowling on cylinder temperatures and performance of a Wright J-5 engine

Description: This report presents the results of tests conducted to determine the effect of different amounts and kinds of cowling on the performance and cylinder temperatures of a standard Wright J-5 engine. These tests were conducted in conjunction with drag and propeller tests in which the same cowlings were used. Four different cowlings were investigated varying from the one extreme of no cowling on the engine to the other extreme of the engine completely cowled and the cooling air flowing inside the cowling through an opening in the nose and out through an annular opening at the rear of the engine. Each cowling was tested at air speeds of approximately 60, 80, and 100 miles per hour.
Date: May 2, 1929
Creator: Schey, Oscar W. & Biermann, Arnold E.
Partner: UNT Libraries Government Documents Department

Supplies and production of aircraft woods

Description: The purpose of this report is to present in brief form such information as is available regarding the supplies of the kinds of wood that have been used or seem likely to become important in the construction of airplanes, and the amount of lumber of each species normally put on the market each year. A general statement is given of the uses to which each kind of wood is or may be put.
Date: 1920
Creator: Sparhawk, W. N.
Partner: UNT Libraries Government Documents Department

Nomenclature for Aeronautics

Description: The nomenclature for aeronautics presented in this Report No. 474 is a revision of the last previous report on this subject (i.e., Report no. 240.) This report is published for the purpose of encouraging greater uniformity and precision in the use of terms relating to aeronautics, both in official documents of the Government and in commercial publications. Terms in general use in other branches of engineering have been included only where they have some special significance in aeronautics, or form an integral part of its terminology.
Date: 1939
Partner: UNT Libraries Government Documents Department

A Theoretical Investigation of Longitudinal Stability of Airplanes with Free Controls Including Effect of Friction in Control System

Description: The relation between the elevator hinge moment parameters and the control forces for changes in forward speed and in maneuvers is shown for several values of static stability and elevator mass balance. The stability of the short period oscillations is shown as a series of boundaries giving the limits of the stable regions in terms of the elevator hinge moment parameters. The effects of static stability, elevator moment of inertia, elevator mass unbalance, and airplane density are also considered. Dynamic instability is likely to occur if there is mass unbalance of the elevator control system combined with a small restoring tendency (high aerodynamic balance). This instability can be prevented by a rearrangement of the unbalancing weights which, however, involves an increase of the amount of weight necessary. It can also be prevented by the addition of viscous friction to the elevator control system provided the airplane center of gravity is not behind a certain critical position. For high values of the density parameter, which correspond to high altitudes of flight, the addition of moderate amounts of viscous friction may be destabilizing even when the airplane is statically stable. In this case, increasing the viscous friction makes the oscillation stable again. The condition in which viscous friction causes dynamic instability of a statically stable airplane is limited to a definite range of hinge moment parameters. It is shown that, when viscous friction causes increasing oscillations, solid friction will produce steady oscillations having an amplitude proportional to the amount of friction.
Date: January 1, 1944
Creator: Greenberg, Harry & Sternfield, Leonard
Partner: UNT Libraries Government Documents Department

The Lagrangian Multiplier Method of Finding Upper and Lower Limits to Critical Stresses of Clamped Plates

Description: The theory of Lagrangian multipliers is applied to the problem of finding both upper and lower limits to the true compressive buckling stress of a clamped rectangular plate. The upper and lower limits thus bracket the truss, which cannot be exactly found by the differential-equation approach. The procedure for obtaining the upper limit, which is believed to be new, presents certain advantages over the classical Raleigh-Rite method of finding upper limits. The theory of the lower-limit procedure has been given by Trefftz but, in the present application, the method differs from that of Trefftz in a way that makes it inherently more quickly convergent. It is expected that in other buckling problems and in some vibration problems problems the Lagrangian multiplier method finding upper and lower limits may be advantageously applied to the calculation of buckling stresses and natural frequencies.
Date: January 1, 1946
Creator: Hu, Pai C. & Budiansky, Bernard
Partner: UNT Libraries Government Documents Department

Performance of B. M. W. 185-Horsepower Airplane Engine

Description: "This report deals with the results of a test made upon a B. M. W. Engine in the altitude chamber of the Bureau of Standards, where controlled conditions of temperature and pressure can be made to simulate those of the desired altitude. A remarkably low value of fuel consumption - 041 per B. H. P. hour - is obtained at 1,200 revolutions per minute at an air density of 0.064 pound per cubic foot and a brake thermal efficiency of 33 per cent and an indicated efficiency of 37 per cent at the above speed and density. In spite of the fact that the carburetor adjustment does not permit the air-fuel ratio of maximum economy to be obtained at air densities lower than 0.064, the economy is superior to most engines tested thus far, even at a density lower than 0.064, the economies superior to most engines tested thus far, even at a density (0.03) corresponding to an altitude of 25,000 feet" (p. 1).
Date: 1922
Creator: Sparrow, S. W.
Partner: UNT Libraries Government Documents Department

The Kiln Drying of Wood for Airplanes

Description: This report is descriptive of various methods used in the kiln drying of woods for airplanes and gives the results of physical tests on different types of woods after being dried by the various kiln-drying methods.
Date: 1919
Creator: Tiemann, Harry D.
Partner: UNT Libraries Government Documents Department

Diaphragms for Aeronautic Instruments

Description: This investigation was carried out at the request of the National Advisory Committee for Aeronautics and comprises an outline of historical developments and theoretical principles, together with a discussion of expedients for making the most effective use of existing diaphragms actuated by the hydrostatic pressure form an essential element of a great variety instruments for aeronautic and other technical purposes. The various physical data needed as a foundation for rational methods of diaphragm design have not, however, been available hitherto except in the most fragmentary form.
Date: 1923
Creator: Hersey, M. D.
Partner: UNT Libraries Government Documents Department

Lifting-Surface-Theory Aspect-Ratio Corrections to the Lift and Hinge-Moment Parameters for Full-Span Elevators on Horizontal Tail Surfaces

Description: A limited number of lifting-surface-theory solutions for wings with chordwise loadings resulting from angle of attack, parabolic-ac camber, and flap deflection are now available. These solutions were studied with the purpose of determining methods of extrapolating the results in such a way that they could be used to determine lifting-surface-theory values of the aspect-ratio corrections to the lift and hinge-moment parameters for both angle-of-attack and flap-deflection-type loading that could be used to predict the characteristics of horizontal tail surfaces from section data with sufficient accuracy for engineering purposes. Such a method was devised for horizontal tail surfaces with full-span elevators. In spite of the fact that the theory involved is rather complex, the method is simple to apply and may be applied without any knowledge of lifting-surface theory. A comparison of experimental finite-span and section value and of the estimated values of the lift and hinge-moment parameters for three horizontal tail surfaces was made to provide an experimental verification of the method suggested. (author).
Date: January 1, 1948
Creator: Crandall, Stewart M. & Swanson, Robert S.
Partner: UNT Libraries Government Documents Department

A Method of Estimating the Knock Rating of Hydrocarbon Fuel Blend

Description: The usefulness of the knock ratings of pure hydrocarbon compounds would be increased if some reliable method of calculating the knock ratings of fuel blends was known. The purpose of this study was to investigate the possibility of developing a method of predicting the knock ratings of fuel blends.
Date: January 1, 1943
Creator: Sanders, Newell D.
Partner: UNT Libraries Government Documents Department

The Measurement of Fuel-Air Ratio by Analysis for the Oxidized Exhaust Gas

Description: "An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy fuel Specification No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene" (p. 1).
Date: 1943
Creator: Gerrish, Harold C. & Meem, J. Lawrence, Jr.
Partner: UNT Libraries Government Documents Department

Icing-Protection Requirements for Reciprocating-Engine Induction Systems

Description: Report presenting an investigation of the icing of aircraft-engine induction systems. Criterions for safe operation and for the design of new induction system are established through the investigation. The results were obtained from laboratory investigations of carburetor-supercharger combinations, wind-tunnel investigations of air scoops, multicylinder-engine studies, and flight investigations.
Date: 1950
Creator: Coles, Willard D.; Rollin, Vern G. & Mulholland, Donald R.
Partner: UNT Libraries Government Documents Department

Comparison of high-speed operating characteristics of size 215 cylindrical-roller bearings as determined in turbojet engine and in laboratory test rig

Description: A comparison of the operating characteristics of 75-millimeter-bore (size 215) cylindrical-roller one-piece inner-race-riding cage-type bearings was made by means of a laboratory test rig and a turbojet engine. Cooling correlation parameters were determined by means of dimensional analysis, and the generalized results for both the inner- and the outer-race bearing operating temperatures are computed for the laboratory test rig and the turbojet engine. A method is given that enables the designer to predict the inner- and outer-race turbine roller-bearing temperatures from single curves, regardless of variations in speed, load, oil flow, oil inlet temperature, oil inlet viscosity, oil-jet diameter, or any combination of these parameters.
Date: 1952
Creator: Macks, E. Fred & Nemeth, Zolton N.
Partner: UNT Libraries Government Documents Department

Ice Prevention on Aircraft by Means of Engine Exhaust Heat and a Technical Study of Heat Transmission From a Clark Y Airfoil

Description: "This investigation was conducted to study the practicability of employing heat as a means of preventing the formation of ice on airplane wings. The report relates essentially to technical problems regarding the extraction of heat from the exhaust gases and its proper distribution over the exposed surfaces. In this connection a separate study has been made to determine the variation of the coefficient of heat transmission along the chord of a Clark Y airfoil. Experiments on ice prevention both in the laboratory and in flight show conclusively that it is necessary to heat only the front portion of the wing surface to effect complete prevention" (p. 3).
Date: June 12, 1931
Creator: Theodorsen, Theodore & Clay, William C.
Partner: UNT Libraries Government Documents Department

Flight determination of drag of normal-shock nose inlets with various cowling profiles at Mach numbers from 0.9 to 1.5

Description: External-drag data are presented for normal-shock nose inlets with NACA 1-series, parabolic, and conic cowling profiles. The tests were made at an angle of attack of 0 degrees by using rocket-propelled models in free flight at Mach numbers from 0.9 to 1.5. The Reynolds number based on body maximum diameter varied from 2.5 x 10 sup 6 to 5.5 x 10 sup 6. At maximum flow rate, the inlet models had about the same external drag at a Mach number of approximately 1.1, but at higher Mach numbers the sharp-lip conic cowling had the least drag. Blunting or beveling the lip of the conic cowling while keeping the fineness ratio constant resulted in drag coefficients slightly higher than for the sharp-lip conic cowling at maximum flow rate. At a mass-flow ratio of about 0.8, the conic cowlings with sharp, blunt, or beveled lips and the parabolic cowling all gave about the same drag. The higher drag of the NACA 1-49-300 cowling, compared with the blunt-lip conic cowling, is associated with the greater fullness back of the inlet.
Date: September 8, 1953
Creator: Sears, R. I.; Merlet, C. F. & Putland, L. W.
Partner: UNT Libraries Government Documents Department

Flight measurements of the dynamic longitudinal stability of several airplanes and a correlation of the measurements with pilots' observations of handling characteristics

Description: The dynamic longitudinal stability characteristics of eight airplanes as defined by the period and damping of the longitudinal oscillations were measured in flight to determine the degree of stability that may be expected in conventional airplanes. An attempt was made to correlate the measured stability with pilots' opinions of the general handling characteristics of the airplanes in order to obtain an indication of the most desirable degree of dynamic stability. The results of the measurements show that the period of oscillation increases with speed. At low speeds a range of periods from 11 to 23 seconds was recorded for the different airplanes. At high speeds the periods ranged from 23 to 64 seconds. The damping showed no definite trend with speed.
Date: July 15, 1936
Creator: Soulé, Hartley A.
Partner: UNT Libraries Government Documents Department

Full-scale wind-tunnel tests of a propeller with the diameter changed by cutting off the blade tips

Description: Tests were conducted in order to determine how the characteristics of a propeller are affected by cutting off the tips. The diameter of a standard 10-foot metal propeller was changed successively to 9 feet 6 inches, 9 feet 0 inches, 8 feet 6 inches, and 8 feet 0 inches. Each propeller thus formed was tested at four pitch settings using an open cockpit fuselage and a D-12 engine. A small loss in propulsive efficiency is indicated. Examples are given showing the application of the results to practical problems.
Date: December 10, 1929
Creator: Wood, Donald H.
Partner: UNT Libraries Government Documents Department

Tests of nacelle-propeller combinations in various positions with reference to wings 2: thick wing - various radial-engine cowlings - tractor propeller

Description: This report is the second of a series giving the results obtained in the 20-foot wind tunnel of the National Advisory Committee for Aeronautics on the interference drag and propulsive efficiency of nacelle-propeller-wing combinations. The first report gave the results of the test of a N.A.C.A. cowled air-cooled engine nacelle located in 21 positions with reference to a thick wing. The present report gives results of tests of a normal engine nacelle with several types of cowling and fairings in four of the positions with reference to the same wing. (author).
Date: May 12, 1932
Creator: Wood, Donald H.
Partner: UNT Libraries Government Documents Department

Tests of large airfoils in the propeller research tunnel, including two with corrugated surfaces

Description: This report gives the results of the tests of seven 2 by 12 foot airfoils (Clark Y, smooth and corrugated, Gottingen 398, N.A.C.A. M-6, and N.A.C.A. 84). The tests were made in the propeller research tunnel of the National Advisory Committee for Aeronautics at Reynolds numbers up to 2,000,000. The Clark Y airfoil was tested with three degrees of surface smoothness. Corrugating the surface causes a flattening of the lift curve at the burble point and an increase in drag at small flying angles.
Date: May 24, 1929
Creator: Wood, Donald H.
Partner: UNT Libraries Government Documents Department