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Revision of the Pocket Gophers of the Genus Thomomys

Description: Describes habits, predators, morphology, sexual variation, pelages, and distribution of pocket gophers. Describes genera and group relations. Describes, lists locations and distribution, and provides a key for species and subspecies.
Date: November 15, 1915
Creator: Bailey, Vernon
open access

Theory of an Airplane Encountering Gusts, 3

Description: Report presents a new method for solving linear equations developed by Bromwich, which is suited to determine the motion for any particular gust, when the machine started from equilibrium, without the trouble of determining the constants of integration in the complementary function. (author).
Date: October 15, 1918
Creator: Wilson, Edwin Bidwell
open access

Aircraft Accidents: Method of Analysis

Description: From Introduction Purpose and Organization: "This report on a method of analysis of aircraft accidents has been prepared by a special committee on the nomenclature, subdivision, and classification of aircraft accidents organized by the National Advisory Committee for Aeronautics in response to a request dated February 18, 1928, from the Air Coordination Committee consisting of the Assistant Secretaries for Aeronautics in the Departments of War, Navy, and Commerce."
Date: August 15, 1928
Creator: Special Committee on the Nomenclature, Subdivision, and Classification of Aircraft Accidents
open access

An Extended Theory of Thin Airfoils and Its Application to the Biplane Problem

Description: "The report presents a new treatment, due essentially to von Karman, of the problem of the thin airfoil. The standard formulae for the angle of zero lift and zero moment are first developed and the analysis is then extended to give the effect of disturbing or interference velocities, corresponding to an arbitrary potential flow, which are superimposed on a normal rectilinear flow over the airfoil. An approximate method is presented for obtaining the velocities induced by a 2-dimensional airfoil at a point some distance away" (p. 637).
Date: March 15, 1930
Creator: Millikan, Clark B.
open access

Elastic Instability of Members Having Sections Common in Aircraft Construction

Description: "Two fundamental problems of elastic stability are discussed in this report. In part one formulas are given for calculating the critical stress at which a thin, outstanding flange of a compression member will either wrinkle into several waves or form into a single half wave and twist the member about its longitudinal axis. In part two the lateral buckling of beams is discussed" (p. 373).
Date: October 15, 1930
Creator: Trayer, George W. & March, H. W.
open access

Pressure distribution tests on a series of Clark Y biplane cellules with special reference to stability

Description: "The pressure distribution data discussed in this report represents the results of part of an investigation conducted on the factors affecting the aerodynamic safety of airplanes. The present tests were made on semispan, circular-tipped Clark Y airfoil models mounted in the conventional manner on a separation plane. Pressure readings were made simultaneously at all test orifices at each of 20 angles of attack between -8 degrees and +90 degrees. The results of the tests on each wing arrangement are compared on the bases of maximum normal force coefficient, lateral stability at a low rate of roll, and relative longitudinal stability. Tabular data are also presented giving the center of pressure location of each wing" (p. 315).
Date: October 15, 1931
Creator: Noyes, Richard W.
open access

Measurement of the Differential and Total Thrust and Torque of Six Full-Scale Adjustable-Pitch Propellers

Description: "Force measurements giving total thrust and torque, and propeller slip stream surveys giving differential thrust and torque were simultaneously made on each of six full-scale propellers in the 20-foot propeller-research tunnel of the National Advisory Committee for Aeronautics. They were adjustable-pitch metal propellers 9.5 feet in diameter; three had modified Clark Y blade sections and three had modified RAF-6 blade sections. This report gives the differential thrust and torque and the variation caused by changing the propeller tip speed and the pitch setting" (p. 437).
Date: April 15, 1932
Creator: Stickle, George W.
open access

Rates of fuel discharge as affected by the design of fuel-injection systems for internal-combustion engines

Description: Using the method of weighing fuel collected in a receiver during a definite interval of the injection period, rates of discharge were determined, and the effects noted, when various changes were made in a fuel-injection system. The injection system consisted primarily of a by-pass controlled fuel pump and an automatic injection valve. The variables of the system studied were the pump speed, pump-throttle setting, discharge-orifice diameter, injection-valve opening and closing pressures, and injection-tube length and diameter.
Date: May 15, 1932
Creator: Gelalles, A. G. & Marsh, E. T.
open access

Photomicrographic studies of fuel sprays

Description: A large number of photomicrographs of fuel sprays were taken for the purpose of studying the spray structure and the process of spray formation. They were taken at magnifying powers of 2.5, 3.25, and 10, using a spark discharge of very short duration for illumination. Several types and sizes of nozzles were investigated, different liquids were used, and a wide range of injection pressures was employed. The sprays were photographed as they were injected into a glass-walled chamber in which the air density was varied from 14 atmospheres to 0.0013 atmosphere.
Date: December 15, 1932
Creator: Lee, Dana W. & Spencer, Robert C.
open access

Relative loading on biplane wings

Description: Recent improvements in stress analysis methods have made it necessary to revise and to extend the loading curves to cover all conditions of flight. This report is concerned with a study of existing biplane data by combining the experimental and theoretical data to derive a series of curves from which the lift curves of the individual wings of a biplane may be obtained.
Date: February 15, 1933
Creator: Diehl, Walter S.
open access

The Effect of Spray Strips on the Take-Off Performance of a Model of a Flying-Boat Hull

Description: "The effect on the take-off performance of a model of the hull of a typical flying boat, Navy PH-1, of fitting spray strips of four different widths, each at three different angles, was determined by model tests in the NACA Tank. Spray strips of widths up to 3 percent of the beam improve the general performance at speeds near the hump and reduce the spray thrown. A downward angle of 30 degrees to 45 degrees in the neighborhood of the step seems most favorable for the reduction of the spray" (p. 523).
Date: June 15, 1934
Creator: Truscott, Starr
open access

Some effects of injection advance angle, engine-jacket temperature, and speed on combustion in a compression-ignition engine

Description: "An optical indicator and a high-speed motion-picture camera capable of operating at the rate of 2,000 frames per second were used to record simultaneously the pressure development and the flame formation in the combustion chamber of the NACA combustion apparatus. Tests were made at engine speeds of 570 and 1,500 r.p.m. The engine-jacket temperature was varied from 100 degrees to 300 degrees F. And the injection advance angle from 13 degrees after top center to 120 degrees before top center. The results show that the course of the combustion is largely controlled by the temperature and pressure of the air in the chamber from the time the fuel is injected until the time at which combustion starts and by the ignition lag" (p. 343).
Date: January 15, 1935
Creator: Rothrock, A. M. & Waldron, C. D.
open access

Hydrogen as an auxiliary fuel in compression-ignition engines

Description: From Summary: "An investigation was made to determine whether a sufficient amount of hydrogen could be efficiently burned in a compression-ignition engine to compensate for the increase of lift of an airship due to the consumption of the fuel oil. The performance of a single-cylinder four-stroke-cycle compression-ignition engine operating on fuel oil alone was compared with its performance when various quantities of hydrogen were inducted with the inlet air. Engine-performance data, indicator cards, and exhaust-gas samples were obtained for each change in engine-operating conditions."
Date: April 15, 1935
Creator: Gerrish, Harold C. & Foster, Hampton H.
open access

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.
open access

Electrical thermometers for aircraft

Description: Electrical thermometers commonly used on aircraft are the thermoelectric type for measuring engine-cylinder temperatures, the resistance type for measuring air temperatures, and the superheat meters of thermoelectric and resistance types for use on airships. These instruments are described and their advantages and disadvantages enumerated. Methods of testing these instruments and the performance to be expected from each are discussed. The field testing of engine-cylinder thermometers is treated in detail.
Date: December 15, 1936
Creator: Peterson, John B. & Womack, S. H. J.
open access

Model Study of the Outlet Structures for the Wappapello Dam

Description: This memorandum constitutes a final report of the study performed at the U. S. Waterways Experiment Station on a model of the outlet works for the Wappapello Dam The model was built undistorted to the linear scale ratio, model-to-prototype, of 1 to 25. The general purpose of the model study was to check the hydraulic characteristics of all elements in the design of the outlet works, and to develop means of correcting any uneconomic, unsafe, or undesirable conditions.
Date: August 15, 1938
Creator: Waterways Experiment Station (U.S.)
open access

A study of air flow in an engine cylinder

Description: A 4-stroke-cycle test engine was equipped with a glass cylinder and the air movements within it were studied while the engine was being motored. Different types of air flow were produced by using shrouded intake valves in various arrangements and by altering the shape of the intake-air passage in the cylinder head. The air movements were made visible by mixing feathers with the entering air, and high-speed motion pictures were taken of them so that the air currents might be studied in detail and their velocities measured. Motion pictures were also taken of gasoline sprays injected into the cylinder on the intake stroke. The photographs showed that: a wide variety of induced air movements could be created in the cylinder; the movements always persisted throughout the compression stroke; and the only type of movement that persisted until the end of the cycle was rotation about the cylinder axis.
Date: September 15, 1938
Creator: Lee, Dana W.
open access

The unsteady lift of a wing of finite aspect ratio

Description: "Unsteady-lift functions for wings of finite aspect ratio have been calculated by correcting the aerodynamic inertia and the angle of attack of the infinite wing. The calculations are based on the operational method. The starting lift of the finite wing is found to be only slightly less than that of the infinite wing; whereas the final lift may be considerably less" (p. 1).
Date: June 15, 1939
Creator: Jones, Robert T.
open access

Correlation of Cooling Data From an Air-Cooled Cylinder and Several Multicylinder Engines

Description: "The theory of engine-cylinder cooling developed in a previous report was further substantiated by data obtained on a cylinder from a Wright R-1820-G engine. Equations are presented for the average head and barrel temperatures of this cylinder as functions of the engine and the cooling conditions. These equations are utilized to calculate the variation in cylinder temperature with altitude for level flight and climb" (p. 59).
Date: August 15, 1939
Creator: Pinkel, Benjamin & Ellerbrock, Herman H., Jr.
open access

Effect of fuel-air ratio, inlet temperature, and exhaust pressure on detonation

Description: From Summary: "An accurate determination of the end-gas condition was attempted by applying a refined method of analysis to experimental results. The results are compared with those obtained in Technical Report no. 655. The experimental technique employed afforded excellent control over the engine variables and unusual cyclic reproducibility. This, in conjunction with the new analysis, made possible the determination of the state of the end-gas at any instant to a fair degree of precision. Results showed that for any given maximum pressure the maximum permissible end-gas temperature increased as the fuel-air ratio was increased. The tendency to detonate was slightly reduced by an increase in residual gas content resulting from an increase in exhaust backpressure with inlet pressure constant."
Date: November 15, 1939
Creator: Taylor, E. S.; Leary, W. A. & Diver, J. R.
open access

Summary report on the induction of water to the inlet air as a means of internal cooling in aircraft-engine cylinders

Description: Report presenting investigations of a full-scale air-cooled aircraft-engine cylinder of 202-cubic-inch displacement to determine the effects of internal cooling by water induction on the maximum permissible power and output of an internal-combustion engine. Results regarding the maximum permissible engine performance, engine temperatures, and constant inlet-air pressure investigations are provided.
Date: August 15, 1942
Creator: Rothrock, Addison M. & Jones, Anthony W.
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