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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.
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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; Reed, Warren D & Niles, Alfred S
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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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.
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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 & Collins, John H
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.
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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 & Marsh, E T
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.
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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 & Dutee, Francis J
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. & Clauser, F.
Description: None
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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, Milton & Clauser, Francis
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.
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Energy Loss, Velocity Distribution, and Temperature Distribution for a Baffled Cylinder Model

Energy Loss, Velocity Distribution, and Temperature Distribution for a Baffled Cylinder Model

Date: October 1, 1937
Creator: Brevoort, Maurice J
Description: A study has been made of the important principles involved in the operation of a baffle for an engine cylinder and shows that cooling can be improved by 20 percent by using a correctly designed baffle. Such a gain is as effective as a 65 percent increase in pressure drop across the standard baffle, which had a 1/4 inch clearance between baffle and fin tips.
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Flight tests of an airplane showing dependence of the maximum lift coefficient on the test conditions

Flight tests of an airplane showing dependence of the maximum lift coefficient on the test conditions

Date: November 1, 1937
Creator: Soule, H A & Hootman, James A
Description: Data are presented to show the extent to which the maximum lift coefficient and consequently the minimum speed of an airplane, determined by flight tests, may vary with test conditions. The data show that cl-max may vary as much as 14 percent, depending on the altitude and wing loading at which the tests were made, the position or motion of the propeller, and the rate at which the angle of attack is changing when the maximum lift coefficient is obtained. The variation of the maximum lift coefficient with these factors, which are under the control of the test engineer, shows the need of standardizing the test procedure. A further variation is shown with wing conditions as affected by weathering and vibration, factors that cannot be completely controlled.
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Free spinning wind-tunnel tests of a low-wing monoplane with systematic wings and tails

Free spinning wind-tunnel tests of a low-wing monoplane with systematic wings and tails

Date: December 1, 1937
Creator: Seidman, Oscar & Neihouse, A I
Description: None
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Free-spinning wind-tunnel tests of a low-wing monoplane with systemic changes in wings and tails

Free-spinning wind-tunnel tests of a low-wing monoplane with systemic changes in wings and tails

Date: August 1, 1937
Creator: Seidman, Oscar & Neihouse, A I
Description: A series of tests was made at the National Advisory Committee for Aeronautics (NACA) free-spinning tunnel to determine the effect of systematic changes in wing and tail arrangement upon steady-spinning and recovery characteristics of a conventional low-wing monoplane model for a basic loading condition. Eight wings and three tails, covering a wide range of aerodynamic characteristics, were independently ballasted so as to be interchangeable with no change in mass distribution. For each of the 24 wing-tail combinations, observations were made of steady spins for four control settings and of recoveries for five control manipulators. The results are presented in the form of charts comparing the spin characteristics. The results showed that, with a poor tail arrangement, wing plan form and tip shape had a considerable effect on the spinning characteristics.
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Full scale span load distribution on a tapered wing with split flaps of various spans

Full scale span load distribution on a tapered wing with split flaps of various spans

Date: February 1, 1937
Creator: Parsons, John F & Silverstein, Abe
Description: Pressure-distribution tests were conducted in the full-scale wind tunnel on a 2:1 tapered U.S.A. 45 airfoil equipped with 20 percent chord split trailing-edge flaps of various spans. A special installation was employed in the tests utilizing a half-span airfoil mounted vertically above a reflection plane. The airfoil has a constant chord center section and rounded tips and is tapered in thickness from 18 percent c at the root to 9 percent c at the tip. The aerodynamic characteristics, given by the usual dimension less coefficients, are presented graphically as functions of flap span and angle of attack as well as by semispan load diagrams. The results indicate, in general, that only a relatively small increase in the normal-force coefficient is to be expected by extending the flap span of an airfoil-flap combination, similar to the one tested, beyond 70 percent of the wing span.
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Full-scale wind-tunnel and flight test of a Fairchild 22 airplane equipped with a Zap flap and Zap ailerons

Full-scale wind-tunnel and flight test of a Fairchild 22 airplane equipped with a Zap flap and Zap ailerons

Date: March 1, 1937
Creator: Dearborn, C H & Soule, H A
Description: A wing equipped with a Zap flap and Zap ailerons was tested on a Fairchild 22 airplane in the full-scale wind tunnel and in flight to determine the effect of the flaps and ailerons on the performance and the control characteristics of the airplane. The flaps were 0.30 of the wing chord and 0.83 of the wing span. Two sets of ailerons having equal areas but different proportions were tested, one set being 0.56 of the semispan and 0.18 of the chord and the other set being 0.46 of the semispan and 0.22 of the chord. The wind-tunnel tests showed that, when the ailerons and horizontal tail surfaces were removed, the flaps increased the maximum lift coefficient from 1.48 to 2.39. In flight, the fully deflected flaps decreased the minimum speed from 48.2 to 38.8 miles per hour. The take-off and landing distances were both reduced by the flaps. The wind-tunnel tests showed the ailerons to increase the drag coefficient, at a lift coefficient and Reynolds Number corresponding to the high speed of the airplane, from 0.0432 to 0.0498 and 0.0514, the 0.46 semispan ailerons giving the highest drag. In the flight tests both sets of ailerons were found to ...
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Full-scale wind-tunnel and flight tests of a Fairchild 22 airplane equipped with external-airfoil flaps

Full-scale wind-tunnel and flight tests of a Fairchild 22 airplane equipped with external-airfoil flaps

Date: July 1, 1937
Creator: Reed, Warren D & Clay, William C
Description: Wind-tunnel and flight tests have been made of a Fairchild 22 airplane equipped with a wing having external-airfoil flaps that also perform the function of ailerons. Lift, drag, and pitching-moment coefficients of the airplane with several flap settings, and the rolling- and yawing-moment coefficients with the flaps deflected as ailerons were measured in the full-scale tunnel with the horizontal tail surfaces and propeller removed. The effect of the flaps on the low speed and on the take-off and landing characteristics, the effectiveness of flaps when used as ailerons, and the forces required to operate them as ailerons were determined in flight. The wind-tunnel tests showed that the flaps increased the maximum lift coefficient of the airplane from 1.51 with the flap in the minimum drag position to 2.12 with the flap in the minimum drag position to 2.12 with the flap deflected 30 degrees. In the flight tests the minimum speed decreased from 46.8 miles per hour with the flaps up to 41.3 miles per hour with the flaps deflected. The required take-off run to attain a height of 50 feet was reduced from 820 to 750 feet and the landing run from a height of 50 feet was reduced ...
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Fuselage-drag tests in the variable-density wind tunnel: streamline bodies of revolution, fineness ratio of 5

Fuselage-drag tests in the variable-density wind tunnel: streamline bodies of revolution, fineness ratio of 5

Date: September 1, 1937
Creator: Abbott, Ira H
Description: Results are presented of the drag tests of six bodies of revolution with systematically varying shapes and with a fineness ratio of 5. The forms were derived from source-sink distributions, and formulas are presented for the calculation of the pressure distribution of the forms. The tests were made in the N.A.C.A. variable-density tunnel over a range of values of Reynolds number from about 1,500,000 to 25,000,000. The results show that the bodies with the sharper noses and tails have the lowest drag coefficients, even when the drag coefficients are based on the two-thirds power of the volume. The data shows the most important single characteristic of the body form to be the tail angle, which must be fine to obtain low drag.
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Heat transfer from cylinders having closely spaced fins

Heat transfer from cylinders having closely spaced fins

Date: May 1, 1937
Creator: Biermann, Arnold E
Description: The heat-transfer coefficients have been determined for five steel cylinders having fins 1.22 inches wide and the spacing between the fins ranging from 0.022 to 0.131 inch. The cylinders were tested with and without baffles in a wind tunnel; they were also tested enclosed in jackets with the cooling air supplied by a blower. A maximum heat transfer was reached at a fin space of about 0.45 inch for the cylinders tested with each of the three methods of cooling investigated. The rise in temperature of the air passing between the fins and the change in flow pattern were found to be important factors limiting the heat transfer that may be obtained by decreasing the fin space. The use of baffles for directing the air around the cylinders with closely spaced fins proved very effective in increasing the over-all heat-transfer coefficient, provided that the spacing was not appreciably less than that for maximum heat transfer.
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Hydrodynamic tests in the N.A.C.A. tank of a model of the hull of the Short Calcutta flying boat

Hydrodynamic tests in the N.A.C.A. tank of a model of the hull of the Short Calcutta flying boat

Date: January 1, 1937
Creator: Ward, Kenneth E
Description: The hydrodynamic characteristics of a model of the hull of the Short Calcutta (N.A.C.A. Model 47) are presented in non-dimensional form. This model represents one of a series of hulls of successful foreign and domestic flying boats the characteristics of which are being obtained under similar test conditions in the N.A.C.A. tank. The take-off distance and time for a flying boat having the hull of the Calcutta are compared at two values of the gross load with the corresponding distances and times for the same flying boat having hulls of two representative American types, the Sikorsky S-40 and the N.A.C.A. 11-A. This comparison indicates that for hulls of the widely different forms compared, the differences in take-off time and distance are negligible.
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Increasing the strength of aluminum-alloy columns by prestressing

Increasing the strength of aluminum-alloy columns by prestressing

Date: January 1, 1937
Creator: Holt, M & Hartman, E C
Description: A series of tests was made in which the column strength of 17ST tubing was increased as much as 50 percent by prestressing the tubing to 40,000 pounds per square inch in compression under conditions of support that prevented column failure at this stress. This prestressing achieves it's beneficial effects entirely by improving the compressive properties of the material, principally the proportional limit.
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The lateral instability of deep rectangular beams

The lateral instability of deep rectangular beams

Date: May 1, 1937
Creator: Dumont, C & Hill, H N
Description: Experimental and analytical studies were made of solid and hollow deep rectangular beams to study their lateral instability under various conditions of loading and restraint. The tests were made on bars and tubes of 17ST aluminum alloy. Failure by lateral buckling occurred only in tests on the solid beams. It was found that, within the elastic range, the test results were in agreement with the classical theory for the lateral buckling of deep beams as given by Prandtl, Mitchell, and Timoshenko. The tests were extended to the inelastic range, where it was found that the substitution for Young's modulus of an average modulus of elasticity derived from the stress-strain curve made it possible to predict instability at high stresses.
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Maximum forces applied by pilots to wheel-type controls

Maximum forces applied by pilots to wheel-type controls

Date: November 1, 1937
Creator: Mcavoy, William H
Description: Measurements were made of the maximum push, pull, and tangential forces that could be applied to airplane wheel-type controls for a wide range of fore-and-aft positions of the wheel. The measurements were conducted with several sizes of wheels and several heights of the center of the wheel above the seat. Various one and two-hand grips with pilots both secure and free were studied for each of the two pilots used in the investigation.
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The measurement of air speed in airplanes

The measurement of air speed in airplanes

Date: January 1, 1937
Creator: Thompson, F L
Description: Various methods of measuring the air speed of airplanes are described. Particular emphasis is placed on the procedure required to obtain precise measurements of speed by the use of the suspended Pitot-static head or the suspended static head. Typical calibration curves for service installations of Pitot-static heads are shown and the relation between errors in air speed and corresponding errors in observed altitude for such installations is discussed. There is included a brief discussion of various speed-course methods of measuring speed.
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