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Rate of heat transfer from finned metal surfaces

Description: The object was to evaluate the factors which control the rate of heat transfer to a moving current of air from finned metal surfaces similar to those used on aircraft engine cylinders. The object was to establish data which will enable the finning of cooling surfaces to be designed to suit the particular needs of any specific application. Most of the work was done on flat copper specimens 6 inches square, upon which were mounted copper fins with spacings varying from 1/2 inch to 1/12 inch. All fins were 1 inch deep, 6 inches long, and .020 inch thick. The results of the investigation are given in the form of curves included here. In general, it was found that for specimens of this kind, the effectiveness of a given fin does not decrease very rapidly until its distance from adjacent fins has been reduced to 1/9 or 1/10 of an inch. A formula for the heat transfer from a flat surface without fins was developed, and an approximate formula for the finned specimens is suggested.
Date: January 1, 1930
Creator: Taylor, G Fayette & Rehbock, A
Item Type: Report
Partner: UNT Libraries Government Documents Department

Comparative performance obtained with XF7C-1 airplane using several different engine cowlings

Description: Discussed here are problems with the use of cowlings with radial air cooled engines. An XF7C-1 airplane, equipped with service cowling and with narrow ring, wide ring, and exhaust collector ring cowlings over the service cowling, was used. For these four cowling conditions, the rate of climb and high speed performance were determined, the cylinder conditions were measured, and pictures to show visibility were taken. The level flight performance obtained with an engine speed of 1900 r.p.m. for the service type, the narrow ring, the wide ring, and the exhaust collector ring was 144.4, 146.6, 152.8, and 155 mph, respectively. The rate of climb was practically the same for each type tested. The visibility was not materially impaired by the use of the wide or the narrow cowlings. With the narrow ring and exhaust collector ring cowlings there was an increase in cylinder temperature. However, this increase was not enough to affect the performance of the engine. The use of an exhaust collector ring incorporated into the cowling is practical where the problem of visibility does not enter.
Date: February 1, 1930
Creator: Schey, Oscar W.; Johnson, Ernest & Gough, Melvin N.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Test of an adjustable pitch model propeller at four blade settings

Description: This note describes tests of an adjustable blade metal model propeller, both in a free wind stream and in combination with a model fuselage, at four settings of the blades. The model propeller is designed for a uniform nominal pitch/diameter ratio of .7 and the blade settings used correspond to nominal pitch/diameter ratios of .5, .7, .9, and 1.1 at the .6 radius. The tests show that propellers of this type may be considerably changed in setting from the designed pitch angles and yet give excellent performance. The efficiency realized and power absorbed when blades are set at other than the designed angle, are little different than would be obtained from a propeller with uniform pitch equal to the mean pitch of the propeller under test.
Date: February 1, 1930
Creator: Lesley, E P
Item Type: Report
Partner: UNT Libraries Government Documents Department

The effect of wing tip floating ailerons on the autorotation of a monoplane wing model

Description: The preliminary tests described here were made to determine the extent to which wing tip floating ailerons might be effective in reducing airplane spinning tendencies. The tests showed that initial spinning tendencies and rates of stable spinning could doubtless be reduced by the use of tip floating ailerons on an airplane. It also appears to be desirable to reduce to a minimum the interference between wing and aileron. This would serve to maintain uniformity of action at all angles of attack and enable calculation of the aileron characteristics.
Date: March 1, 1930
Creator: Knight, Montgomery & Wenzinger, Carl J.
Item Type: Report
Partner: UNT Libraries Government Documents Department

The structure and properties of parachute cloths

Description: The requisite properties of a parachute cloth are discussed and the methods for measuring these properties described. In addition to the structural analysis of the cloths, the properties measured were weight, breaking strength, tear resistance, elasticity, and air permeability. Thirty-six silk cloths of domestic manufacture, not previously used in parachute construction are compared with some silk cloths of foreign manufacture. These foreign cloths were ones proven by trial and extended use to be suitable materials for parachute construction. Contrary to the belief that domestic woven cloths were not suitable materials for parachute construction, it is shown that many domestic silk cloths are satisfactory and in some respects superior to the foreign products. Based on a comparative study of all the cloths, specifications are drawn for the manufacture of silk parachute cloth.
Date: March 1, 1930
Creator: Mcnicholas, H J & Hedrick, F
Item Type: Report
Partner: UNT Libraries Government Documents Department

Pressure distribution on the tail surfaces of a PW-9 pursuit airplane in flight

Description: Presented here are pressure distribution data obtained from the tail surfaces of a PW-9 in a number of flight maneuvers. The results given are part of those obtained in an extensive investigation of the pressure distribution over all of the lifting and control surfaces of this airplane. The results are given in tabular and curve form and are discussed briefly with respect to their comparison with existing tail surface design specifications. It is recommended that tail load design loadings should be revised upwards. This is particularly true of leading edge loads, which should be at least doubled for thick sections.
Date: April 1, 1930
Creator: Rhode, Richard V
Item Type: Report
Partner: UNT Libraries Government Documents Department

Full scale drag tests on various parts of Fairchild (FC-2W2) cabin monoplane

Description: The drag due to the various parts of a Fairchild (FC-2W2) cabin monoplane was measured at air speeds varying from 50 to 100 m.p.h., in the Twenty-Foot Propeller Research Tunnel of the National Advisory Committee for Aeronautics. It was found that the largest drag was due to the radial air-cooled engine. The measured drag due to the landing gear was also large, being about 4/5 of that due to the engine. Substituting Musselman type wheels for the standard wheels caused no change in the drag due to the landing gear. A small decrease in drag was effected by adding a turtle back to the airplane fuselage.
Date: May 1, 1930
Creator: Hernstein, William H , Jr
Item Type: Report
Partner: UNT Libraries Government Documents Department

Refrigerated wind tunnel tests on surface coatings for preventing ice formation

Description: This investigation was conducted to determine the effectiveness of various surface coatings as a means for preventing ice formations on aircraft in flight. The substances used as coatings for these tests are divided into two groups: compounds soluble in water, and those which are insoluble in water. It was found that certain soluble compounds were apparently effective in preventing the formation of ice on an airfoil model, while all insoluble compounds which were tested were found to be ineffective.
Date: May 1, 1930
Creator: Knight, Montgomery & Clay, William C
Item Type: Report
Partner: UNT Libraries Government Documents Department

Some effects of air and fuel oil temperatures on spray penetration and dispersion

Description: Presented here are experimental results obtained from a brief investigation of the appearance, penetration, and dispersion of oil sprays injected into a chamber of highly heated air at atmospheric pressure. The development of single sprays injected into a chamber containing air at room temperature and at high temperature was recorded by spray photography equipment. A comparison of spray records showed that with the air at the higher temperature, the spray assumed the appearance of thin, transparent cloud, the greatest part of which rapidly disappeared from view. With the chamber air at room temperature, a compact spray with an opaque core was obtained. Measurements of the records showed a decrease in penetration and an increase in the dispersion of the spray injected into the heated air. No ignition of the fuel injected was observed or recorded until the spray particles came in contact with the much hotter walls of the chamber about 0.3 second after the start of injection.
Date: May 1, 1930
Creator: Gelalles, A. G.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Calibration and lag of a Friez type cup anemometer

Description: Tests on a Friez type cup anemometer have been made in the variable density wind tunnel of the Langley Memorial Aeronautical Laboratory to calibrate the instrument and to determine its suitability for velocity measurements of wind gusts. The instrument was calibrated against a Pitot-static tube placed directly above the anemometer at air densities corresponding to sea level, and to an altitude of approximately 6000 feet. Air-speed acceleration tests were made to determine the lag in the instrument reading. The calibration results indicate that there should be an altitude correction. It is concluded that the cup anemometer is too sluggish for velocity measurements of wind gusts.
Date: June 1, 1930
Creator: Pinkerton, Robert M
Item Type: Report
Partner: UNT Libraries Government Documents Department

Identification of aircraft by Rockwell test

Description: A large number of tests were made on tubes of 1025 and 4130X steel, in various diameters and wall thicknesses, and after diverse heat treatments. The Rockwell B scale was employed, as being the best suited to the ranges of hardness encountered. Only satisfactory chrome molybdenum tubes were found to show a hardness in excess of 90-B after normalizing. The method therefore provided the desired means of identification of chrome molybdenum steel. It is a qualitative test only. The conditions of a satisfactory test are as follows. 1) The tubing must be normalized. 2) It must be clean inside and out at the point where the test is to be made. 3) The tube must be held in correct alignment with the penetrator and must not move during the test. 4) For thin-walled tubes, the anvil must extend within the tube so as to support the wall.
Date: June 1, 1930
Creator: Knerr, Horace
Item Type: Report
Partner: UNT Libraries Government Documents Department

Identification of Aircraft Tubing by Rockwell Test

Description: Seamless steel tubing is today the principal material of construction for aircraft. The commercial grade of tubing containing about 0.10 to 0.20% carbon at first used is being superseded by two grades which are approved by the army and navy, and which are also becoming standard for commercial airplanes.
Date: June 1, 1930
Creator: Knerr, Horace C.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Performance of a high-speed compression-ignition engine using multiple orifice fuel injection nozzles

Description: This report presents test results obtained at the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics during an investigation to determine the relative performance of a single-cylinder, high-speed, compression-ignition engine when using fuel injection valve nozzles with different numbers, sizes, and directions of round orifices. A spring-loaded, automatic injection valve was used, centrally located at the top of a vertical disk-type combustion chamber formed between horizontally opposed inlet and exhaust valves of a 5 inch by 7 inch engine.
Date: June 1, 1930
Creator: Spanogle, J A & Foster, H H
Item Type: Report
Partner: UNT Libraries Government Documents Department

Strength in shear of the thin curved sheets of Alclad

Description: This note is on an investigation made to obtain information on the strength of thin curved sheets of Alclad in shear. Designers may utilize this material as a strength member as well as for a covering for the wings and fuselages. A reduction may then be made in the size of the internal strength members. These experiments were undertaken with the object of securing the maximum value from the metal in this respect. The point at which buckling occurs is of primary importance. The buckling shear of a curved thin plate was determined mathematically and also experimentally. The following formula was obtained mathematically: s=K E t/r in which s is the unit shear, K is a constant, E is the modulus of elasticity, t is the thickness of the material, and r is the radius of curvature. The value of K as determined by the experiments was found to be .075. This formula applies only when s is within the elastic limit of the material. The breaking point of the material was obtained in most of the tests as a matter of information and the results are included in this report. The effect of the supporting ribs was determined by varying the number used.
Date: June 1, 1930
Creator: Smith, George Michael
Item Type: Report
Partner: UNT Libraries Government Documents Department

The prevention of the ice hazard on airplanes

Description: A review of various methods to prevent ice formation and adhesion to aircraft surfaces is given. It was concluded that the adhesion of ice to a surface may be reduced somewhat by the application of certain waxes and varnishes. In the experiments described, the varnishes containing calcium stearate and calcium oleate gave the best results. In wind tunnel tests, the adhesion was further reduced by the application of these waxes and varnishes to a thin, heat insulating layer of rubber. The adhesion of ice is greatly reduced when the surface consists of a vehicle which carries an oil in sufficient quantity so that the surface of the vehicle is self lubricating. Ice may be removed from wings, struts, wires and other parts of an airplane during flight by the inflation of properly constructed pneumatic rubber members, providing that these members have been previously treated with a suitable low adhesion oil.
Date: July 1, 1930
Creator: Geer, William C & Scott, Merit
Item Type: Report
Partner: UNT Libraries Government Documents Department

Span load distribution on two monoplanes wing models as affected by twist and sweepback

Description: The results presented in this note show the effect of twist and sweepback on the span load distribution over two monoplane wing models. The tests were made in the Atmospheric Wind Tunnel of the Langley Memorial Aeronautical Laboratory. The data are taken from the results of an investigation dealing primarily with lateral stability. As presented, they are suitable as an aid in the structural design of certain monoplane wings.
Date: July 1, 1930
Creator: Knight, Montgomery & Noyes, Richard W
Item Type: Report
Partner: UNT Libraries Government Documents Department

Pressure distribution over a Douglas wing tip on a biplane in flight

Description: This note presents the results obtained in pressure distribution tests on the right upper wing panel and tip of a Douglas M-3 airplane in flight. These tests are a part of a more extensive investigation of the effect of changes in tip shape on the load distribution, the tip reported herein being the first of a series of tip shapes being tested. The results are given in tables and curves in such form that the load distribution for any conditions may be determined easily. Tests were made at Langley Field by the NACA in the spring of 1930.
Date: August 1, 1930
Creator: Rhode, Richard V. & Lundquist, Eugene E.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Simplified aerodynamic analysis of the cyclogiro rotating wing system

Description: A simplified aerodynamic theory of the cyclogiro rotating wing is presented herein. In addition, examples have been calculated showing the effect on the rotor characteristics of varying the design parameters of the rotor. A performance prediction, on the basis of the theory here developed, is appended, showing the performance to be expected of a machine employing this system of sustentation. The aerodynamic principles of the cyclogiro are sound; hovering flight, vertical climb, and a reasonable forward speed may be obtained with a normal expenditure of power. Auto rotation in a gliding descent is available in the event of a power-plant failure.
Date: August 1, 1930
Creator: Wheatley, John B
Item Type: Report
Partner: UNT Libraries Government Documents Department

Alterations and tests of the "Farnboro" engine indicator

Description: The 'Farnboro' electric indicator was tested as received from the manufacturers, and modifications made to the instrument to improve its operation. The original design of disk valve was altered so as to reduce the mass, travel, and seat area. Changes were made to the recording mechanism, which included a new method of locating the top center position on the record. The effect of friction on the motion of the pointer while taking motoring and power cards was eliminated by providing a means of putting pressure lines on the record. The modified indicator gives a complete record of the average cyclic variation in pressure per crank degree for any set of engine operating conditions which can be held constant for the period of time required to build up the composite card. The value of the record for accurate quantitative measurement is still questioned, although the maximum indicated pressure recorded on the motoring and power cards checks the readings of the balanced diaphragm type of maximum cylinder pressure indicator.
Date: September 1930
Creator: Collins, John H , Jr
Item Type: Report
Partner: UNT Libraries Government Documents Department

An investigation of airplane landing speeds

Description: This paper describes an investigation on airplane landing speeds which was made to determine the applicability of accepted aerodynamic theory to the prediction of this particular performance characteristic. The experimental work consisted in measuring the landing speed of several monoplanes by a new photographic method. The results of these tests supplemented by available information regarding biplanes were compared with predictions made with basic aerodynamic theory. The prediction makes use of the fundamental relation between wing loading, lift coefficient, and speed of level flight, and the effects of aspect ratio and proximity to the ground on lift curve slope.
Date: September 1, 1930
Creator: Ridley, Kenneth F
Item Type: Report
Partner: UNT Libraries Government Documents Department

An accurate method of measuring the moments of inertia of airplanes

Description: This note contains a description of an improved apparatus and procedure used by the NACA for determining the moments of inertia of airplanes. The method used, based on the pendulum theory, is similar to that previously used, but a recent investigation of its accuracy has resulted in the improvements described herein. The error, when using the new apparatus and procedure, has been found to be of the order of 1 per cent.
Date: October 1930
Creator: Miller, M P
Item Type: Report
Partner: UNT Libraries Government Documents Department

Analytical determination of the load on a trailing edge flap

Description: This report presents a theoretical analysis of the lift on a trailing edge flap. An analytical expression has been derived which enables the computation of the flap load coefficient. The theoretical results seem to show a fair agreement with the meager experimental results which are available.
Date: October 1930
Creator: Pinkerton, Robert M
Item Type: Report
Partner: UNT Libraries Government Documents Department

Effect of orifice length-diameter ratio on spray characteristics

Description: The effect of variations of orifice length to diameter ratio on spray characteristics was determined for a 0.014-inch and a 0.040-inch orifice for ratio of 0.5 to 4.0. The nozzles containing the orifices were mounted in an injection valve and tested with a plan stem and with a helically grooved stem. The injection pressure was varied from 4000 to 8000 pounds per square inch. The air density into which the fuel was sprayed was varied from the density obtained with a pressure of 60 pounds per square inch to the density obtained with a pressure of 250 pounds per square inch at room temperature. The tests showed that increasing the orifice length to diameter ratio with a plain stem in the injection valve causes the spray tip penetration first to decrease, reaching a minimum between a ratio of 1.5 and 2.5, and then to increase, reaching a maximum at a ratio greater than 3.5. The spray cone angle showed little change with variation of the ratio. With a helically grooved stem and small ratio of orifice area to groove area, the penetration at first shows little tendency towards a minimum; but as the time of injection is increased to 0.004 second, the penetration becomes a minimum at a ratio between 0.5 and 2.0.
Date: October 1, 1930
Creator: Gellales, A G
Item Type: Report
Partner: UNT Libraries Government Documents Department