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  Partner: UNT Libraries Government Documents Department
 Decade: 1930-1939
 Serial/Series Title: NACA Technical Notes
 Collection: Technical Report Archive and Image Library
The behavior of thin-will monocoque cylinders under torsional vibration

The behavior of thin-will monocoque cylinders under torsional vibration

Date: August 1, 1937
Creator: Pekelsma, Robert E
Description: Curves of forced frequency against amplitude are presented for the conditions where the forced frequency is both increased and decreased into the resonant range. On the basis of these curves it is shown that the practical resonance frequency is the point where wrinkling first occurs and that the resonance frequency will be subject to considerable travel once permanent wrinkles appear in the vibrating shell. The decreasing mode of striking resonance is found to be by far the most destructive condition.
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Bending stresses due to torsion in cantilever box beams

Bending stresses due to torsion in cantilever box beams

Date: June 1, 1935
Creator: Kuhn, Paul
Description: The paper beings with a brief discussion on the origin of the bending stresses in cantilever box beams under torsion. A critical survey of existing theory is followed by a summary of design formulas; this summary is based on the most complete solution published but omits all refinements considered unnecessary at the present state of development. Strain-gage tests made by NACA to obtained some experimental verification of the formulas are described next. Finally, the formulas are applied to a series of box beams previously static-tested by the U.S. Army Air Corps; the results show that the bending stresses due to torsion are responsible to a large extent for the free-edge type of failure frequently experienced in these tests.
Contributing Partner: UNT Libraries Government Documents Department
Bending tests of circular cylinders of corrugated aluminum-alloy sheet

Bending tests of circular cylinders of corrugated aluminum-alloy sheet

Date: March 1, 1937
Creator: Buckwalter, John C
Description: Bending tests were made of two circular cylinders of corrugated aluminum-alloy sheet. In each test failure occurred by bending of the corrugations in a plane normal to the skin. It was found, after analysis of the effect of short end bays, that the computed stress on the extreme fiber of a corrugated cylinder is in excess of that for a flat panel of the same basic pattern and panel length tested as a pin-ended column. It is concluded that this increased strength was due to the effects of curvature of the pitch line. It is also concluded from the tests that light bulkheads closely spaced strengthen corrugated cylinders very materially.
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Boosted performance of a compression-ignition engine with a displaced piston

Boosted performance of a compression-ignition engine with a displaced piston

Date: May 1, 1936
Creator: Moore, Charles S
Description: Performance tests were made using a rectangular displacer arranged so that the combustion air was forced through equal passages at either end of the displacer into the vertical-disk combustion chamber of a single-cylinder, four-stroke-cycle compression-ignition test engine. After making tests to determine optimum displacer height, shape, and fuel-spray arrangement, engine-performance tests were made at 1,500 and 2,000 r.p.m. for a range of boost pressures from 0 to 20 inches of mercury and for maximum cylinder pressures up to 1,150 pounds per square inch. The engine operation for boosted conditions was very smooth, there being no combustion shock even at the highest maximum cylinder pressures. Indicated mean effective pressures of 240 pounds per square inch for fuel consumptions of 0.39 pound per horsepower-hour have been readily reproduced during routine testing at 2,000 r.p.m. at a boost pressure of 20 inches of mercury.
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The calculated effect of trailing-edge flaps on the take-off of flying boats

The calculated effect of trailing-edge flaps on the take-off of flying boats

Date: November 1, 1934
Creator: Parkinson, J E
Description: The results of take-off calculations are given for an application of simple trailing-edge flaps to two hypothetical flying boats, one having medium wing and power loading and consequently considerable excess of thrust over total resistance during the take-off run, the other having high wing and power loading and a very low excess thrust. For these seaplanes the effect of downward flap settings was: (1) to increase the total resistance below the stalling speed, (2) to decrease the get-away speed, (3) to improve the take-off performance of the seaplane having considerable excess thrust, and (4) to hinder the take-off of the seaplane having low excess thrust. It is indicated that flaps would allow a decrease in the high angles of wing setting necessary with most seaplanes, provided that the excess thrust is not too low.
Contributing Partner: UNT Libraries Government Documents Department
Calculated effect of various types of flap on take-off over obstacles

Calculated effect of various types of flap on take-off over obstacles

Date: May 1, 1936
Creator: Wetmore, J W
Description: In order to determine whether or not flaps could be expected to have any beneficial effect on take-off performance, the distances required to take off and climb to an altitude of 50 feet were calculated for hypothetical airplanes, corresponding to relatively high-speed types and equipped with several types of flap. The types considered are the Fowler wing, the Hall wing, the split flap, the balanced split flap, the plain flap, and the external-airfoil flap. The results indicate that substantial reductions in take-off distance are possible through the use of flaps, provided that the proper flap angle corresponding to a given set of conditions is used. The best flap angle for taking off varies inversely as power loading and, to a much smaller extent, varies inversely with wing loading. Apparently, the best take-off characteristics are provided by the type of device in which the flap forms an extension to the main wing as in the case of the Fowler wing and the external-airfoil flap.
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Calculation of horsepower available : appendix to estimation of the variation of thrust horsepower with air speed

Calculation of horsepower available : appendix to estimation of the variation of thrust horsepower with air speed

Date: July 1, 1934
Creator: Ober, Shatswell
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Calculations of the effect of wing twist on the air forces acting on a monoplane wing

Calculations of the effect of wing twist on the air forces acting on a monoplane wing

Date: January 1, 1935
Creator: Datwyler, G
Description: A method is presented for calculating the aerodynamic forces on a moncylane wing, taking into account the elastic twisting of the wing due to these forces. The lift distribution along the span is calculated by the formulas of Amstutz as a function of the geometrical characteristics of the wing and of the twist at stations 60 and 90 percent of the semispan. The twist for a given lift distribution is calculated by means of influence lines. As a numerical example, the forces on a Swiss military D.2V airplane are calculated. Comparisons with the strip method and with the ordinary stress-analysis method are also given.
Contributing Partner: UNT Libraries Government Documents Department
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.
Contributing Partner: UNT Libraries Government Documents Department
Carbon-monoxide indicators for aircraft

Carbon-monoxide indicators for aircraft

Date: July 1, 1936
Creator: Womack, S H J
Description: Several improvements that have been made on commercially available carbon-monoxide indicators to make them more suitable for aircraft use are described. These improvements include an automatic flow regulator, which permits the use of a simplified instrument on aircraft where a source of suction is available, and a more reliable alarm attachment. A field method for testing instruments on standard samples of carbon monoxide is described. Performance data and instructions in operation and maintenance are given.
Contributing Partner: UNT Libraries Government Documents Department