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  Partner: UNT Libraries Government Documents Department
 Decade: 1930-1939
 Year: 1937
 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.
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.
Contributing Partner: UNT Libraries Government Documents Department
Charts expressing the time, velocity, and altitude relations for an airplane diving in a standard atmosphere

Charts expressing the time, velocity, and altitude relations for an airplane diving in a standard atmosphere

Date: April 1, 1937
Creator: Pearson, H A
Description: In this report charts are given showing the relation between time, velocities, and altitude for airplanes having various terminal velocities diving in a standard atmosphere. The range of starting altitudes is from 8,000 to 32,000 feet, and the terminal velocities vary from 150 to 550 miles per hour. A comparison is made between an experimental case and the results obtained from the charts. Examples pointing out the use of the charts are included.
Contributing Partner: UNT Libraries Government Documents Department
Compression-ignition engine performance at altitudes and at various air pressures and temperatures

Compression-ignition engine performance at altitudes and at various air pressures and temperatures

Date: November 1, 1937
Creator: Moore, Charles S
Description: Engine test results are presented for simulated altitude conditions. A displaced-piston combustion chamber on a 5- by 7-inch single cylinder compression-ignition engine operating at 2,000 r.p.m. was used. Inlet air temperature equivalent to standard altitudes up to 14,000 feet were obtained. Comparison between performance at altitude of the unsupercharged compression-ignition engine compared favorably with the carburetor engine. Analysis of the results for which the inlet air temperature, inlet air pressure, and inlet and exhaust pressure were varied indicates that engine performance cannot be reliably corrected on the basis of inlet air density or weight of air charge. Engine power increases with inlet air pressure and decreases with inlet air temperatures very nearly as straight line relations over a wide range of air-fuel ratios. Correction factors are given.
Contributing Partner: UNT Libraries Government Documents Department
Considerations affecting the additional weight required in mass balance of ailerons

Considerations affecting the additional weight required in mass balance of ailerons

Date: August 1, 1937
Creator: Diehl, W S
Description: This paper is essentially a consideration of mass balance of ailerons from a preliminary design standpoint, in which the extra weight of the mass counterbalance is the most important phase of the problem. Equations are developed for the required balance weight for a simple aileron and this weight is correlated with the mass-balance coefficient. It is concluded the location of the c.g. of the basic aileron is of paramount importance and that complete mass balance imposes no great weight penalty if the aileron is designed to have its c.g. inherently near to the hinge axis.
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Discharge characteristics of a double injection-valve single-pump injection system

Discharge characteristics of a double injection-valve single-pump injection system

Date: May 1, 1937
Creator: Lee, Dana W
Description: The discharge characteristics of two similar injection valves operated by a single-cylinder fuel-injection pump were determined with an apparatus that measured the quantity of fuel discharged from each valve during every 0.5 degrees of pump rotation. It was found that similar discharges took place from the two valves at all pump speeds when the valve-opening pressures, the nozzle-orifice diameters, and the injection-tube lengths were the same for both valves. Under these conditions, the effects of changing the pump speed, the pump throttle setting, or the nozzle orifice diameter were very similar to those occurring with a single-injection valve. By a proper selection of discharge-orifice areas and valve-opening pressures it was possible to obtain a great many combinations of discharge quantities, discharge rates, and injection timings for the two valves. A series of tests using injection tubes of unequal lengths for the two valves showed that under these conditions the injection timing and the fuel quantity discharged from each valve varies widely and erratically with changes in the pump speed.
Contributing Partner: UNT Libraries Government Documents Department
Effect of air-entry angle on performance of a 2-stroke-cycle compression-ignition engine

Effect of air-entry angle on performance of a 2-stroke-cycle compression-ignition engine

Date: August 1, 1937
Creator: Earle, Sherod L
Description: An investigation was made to determine the effect of variations in the horizontal and vertical air-entry angles on the performance characteristics of a single-cylinder 2-stroke-cycle compression-ignition test engine. Performance data were obtained over a wide range of engine speed, scavenging pressure, fuel quantity, and injection advance angle with the optimum guide vanes. Friction and blower-power curves are included for calculating the indicated and net performances. The optimum horizontal air-entry angle was found to be 60 degrees from the radial and the optimum vertical angle to be zero, under which conditions a maximum power output of 77 gross brake horsepower for a specific fuel consumption of 0.52 pound per brake horsepower-hour was obtained at 1,800 r.p.m. and 16-1/2 inches of Hg scavenging pressure. The corresponding specific output was 0.65 gross brake horsepower per cubic inch of piston displacement. Tests revealed that the optimum scavenging pressure increased linearly with engine speed. The brake mean effective pressure increased uniformly with air quantity per cycle for any given vane angle and was independent of engine speed and scavenging pressure.
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The effect of curvature on the transition from laminar to turbulent boundary layer

The effect of curvature on the transition from laminar to turbulent boundary layer

Date: September 1, 1937
Creator: Clauser, M.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The effect of curvature on the transition from laminar to turbulent boundary layer

The effect of curvature on the transition from laminar to turbulent boundary layer

Date: September 1, 1937
Creator: Clauser, Milton
Description: In the flow over the upper surface of a wing, a discrepancy between the predicted and actual point of transition from laminar to turbulent boundary layer was found. This effect may be due to the comparatively small radius of curvature of the upper surface of the wing. Tests were undertaken to investigate this effect. As far as the authors know, the present investigation is the first to show that curvature has a pronounced effect on the transition of the boundary layer from the laminar to the turbulent state. It appears that three important results have been obtained thus far. First, the experimental points for the convex and concave side of the sheet are consistent with each other and, with the experimental accuracy involved, lie on the same curve. Second, this curve can be approximated by a straight line. Third, the order of magnitude of the variation is such that the curvature ordinarily used on the upper surface of an airplane wing might double the critical Reynolds number.
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Empirical corrections to the span load distribution at the tip

Empirical corrections to the span load distribution at the tip

Date: August 1, 1937
Creator: Pearson, H A
Description: An analysis of existing pressure-distribution data was made to determine the variation of the tip loading with wing plan form. A series of empirical tip corrections was derived that may be added to theoretical curves in certain cases to obtain a closer approach to the actual loading at the tip. The analysis indicated that the need for a tip correction decreases as either the aspect ratio or the wing taper is increased. In general, it may be said that, for wings of conventional aspect ratio, corrections to the theoretical span load curves are necessary only if the wing is tapered less than 2:1 and has a blunt tip. If the tip is well rounded in plan form, no correction appears necessary even for a wing with no taper.
Contributing Partner: UNT Libraries Government Documents Department
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