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  Partner: UNT Libraries Government Documents Department
 Decade: 1930-1939
 Year: 1930
 Serial/Series Title: NACA Technical Notes
 Collection: Technical Report Archive and Image Library
An accurate method of measuring the moments of inertia of airplanes

An accurate method of measuring the moments of inertia of airplanes

Date: October 1, 1930
Creator: Miller, M P
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.
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Alterations and tests of the "Farnboro" engine indicator

Alterations and tests of the "Farnboro" engine indicator

Date: September 1, 1930
Creator: Collins, John H , Jr
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.
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Analytical determination of the load on a trailing edge flap

Analytical determination of the load on a trailing edge flap

Date: October 1, 1930
Creator: Pinkerton, Robert M
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.
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A balanced diaphragm type of maximum cylinder pressure indicator

A balanced diaphragm type of maximum cylinder pressure indicator

Date: December 1, 1930
Creator: Spanogle, J A
Description: A balanced diaphragm type of maximum cylinder pressure indicator was designed to give results consistent with engine operating conditions. The apparatus consists of a pressure element, a source of controlled high pressure and a neon lamp circuit. The pressure element, which is very compact, permits location of the diaphragm within 1/8 inch of the combustion chamber walls without water cooling. The neon lamp circuit used for indicating contact between the diaphragm and support facilitates the use of the apparatus with multicylinder engines.
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Calibration and lag of a Friez type cup anemometer

Calibration and lag of a Friez type cup anemometer

Date: June 1, 1930
Creator: Pinkerton, Robert M
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.
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Comparative performance obtained with XF7C-1 airplane using several different engine cowlings

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

Date: February 1, 1930
Creator: Schey, Oscar W
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.
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Effect of orifice length-diameter ratio on spray characteristics

Effect of orifice length-diameter ratio on spray characteristics

Date: October 1, 1930
Creator: Gellales, A G
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 ...
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Effect of the angular position of the section of a ring cowling on the high speed of an XF7C-1 airplane

Effect of the angular position of the section of a ring cowling on the high speed of an XF7C-1 airplane

Date: November 1, 1930
Creator: Gough, Melvin N
Description: The tests herein reported were conducted by the NACA to determine the effect of the angular position of the section of a ring cowling on the speed of an airplane having a radial air-cooled engine.
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The effect of wing tip floating ailerons on the autorotation of a monoplane wing model

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

Date: March 1, 1930
Creator: Knight, Montgomery
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.
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Experiments with a model water tunnel

Experiments with a model water tunnel

Date: December 1, 1930
Creator: Jacobs, Eastman N
Description: This report describes a model water tunnel built in 1928 by the NACA to investigate the possibility of using water tunnels for aerodynamic investigations at large scales. The model tunnel is similar to an open-throat wind tunnel, but uses water for the working fluid.
Contributing Partner: UNT Libraries Government Documents Department
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