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The aerodynamic characteristics of six commonly used Airfoils over a large range of positive and negative angles of attack

Description: This paper presents the results of tests of six commonly used airfoils: the CYH, the N-22, the C-72, the Boeing 106, and the Gottingen 398. The lifts, drags, and pitching moments of the airfoils were measured through a large range of positive and negative angles of attack. The tests were made in the variable density wind tunnel of the National Advisory Committee for Aeronautics at a large Boeing 106, and the Gottingen 398 airfoils, the negative maximum lift coefficients were found to be approximately half the positive; but for the M-6 and the CYH, which have less effective values were, respectively, 0.8 and 0.6 of the positive values.
Date: November 1931
Creator: Anderson, Raymond F
Partner: UNT Libraries Government Documents Department

The aerodynamic characteristics of three tapered airfoils tested in the variable density wind tunnel

Description: This report contains the lift, drag, and moment characteristics of tapered Clark Y, Gottingen 393, and USA 45 airfoils as obtained from tests made in the Variable Density Wind Tunnel of the NACA. The results are given at both low and high Reynolds Numbers to show scale effect and to provide data for use in airplane design.
Date: February 1931
Creator: Anderson, Raymond F
Partner: UNT Libraries Government Documents Department

The aerodynamic drag of five models of side floats N.A.C.A. Models 51-E, 51-F, 51-G, 51-H, 51-J

Description: The drag of five models of side floats was measured in the N.A.C.A. 7- by 10-foot wind tunnel. The most promising method of reducing the drag of floats indicated by these tests is lowering the angle at which the floats are rigged. The addition of a step to a float does not always increase the drag in the flying range, floats with steps sometimes having lower drag than similar floats without steps. Making the bow chine no higher than necessary might result in a reduction in air drag because of the lower angle of pitch of the chines. Since side floats are used formally to obtain lateral stability when the seaplane is operating on the water at slow speeds or at rest, greater consideration can be given to factors affecting aerodynamic drag than is possible for other types of floats and hulls.
Date: December 1938
Creator: House, R O
Partner: UNT Libraries Government Documents Department

The aerodynamic drag of flying-boat hull model as measured in the NACA 20-foot wind tunnel I.

Description: Measurements of aerodynamic drag were made in the 20-foot wind tunnel on a representative group of 11 flying-boat hull models. Four of the models were modified to investigate the effect of variations in over-all height, contours of deck, depth of step, angle of afterbody keel, and the addition of spray strips and windshields. The results of these tests, which cover a pitch-angle range from -5 to 10 degrees, are presented in a form suitable for use in performance calculations and for design purposes.
Date: April 1935
Creator: Hartman, Edwin P
Partner: UNT Libraries Government Documents Department

The aerodynamic effect of a retractable landing gear

Description: Tests were conducted in the N.A.C.A. full scale wind tunnel at the request of the Army Air Corps to determine the effect of retractable landing gear openings in the bottom surface of a wing upon the characteristics of a Lockheed Altair airplane. The tests were extended to include the determination of the lift and drag characteristics throughout the angle-of-attack range with the landing gear both retracted and extended. Covering the wheel openings in the wing with sheet metal when the wheels were extended reduced the drag only 2 percent at a lift coefficient of 1.0, which was assumed for the take-off condition. Therefore, the wheel openings in the bottom side of the wing have a negligible effect upon the take-off of the airplane. Retracting the landing gear reduced the minimum drag of the complete airplane 50 percent.
Date: March 1933
Creator: Defrance, Smith J
Partner: UNT Libraries Government Documents Department

Aerodynamic effects of a split flap on the spinning characteristics of a monoplane model

Description: The investigation described in this report was made to determine the change in aerodynamic forces and moments produced by split flaps in a steady spin. The test were made with the spinning balance in the NACA 5-foot vertical wind tunnel. A low-wing monoplane model was tested with and without the split flaps in 12 spinning attitudes chosen to cover the probable spinning range. The changes in coefficients produced by adding the split flaps are given for longitudinal force, normal force, and rolling and yawing moments about body axes. The results obtained indicate that the use of split flaps on an airplane is unlikely, in any case, to have much beneficial effect on a spin, and it might make the spin dangerous. The change in the spin will depend upon the aerodynamic and inertia characteristics of the particular airplane. A dangerous condition is most likely to be attained with airplanes which are statically stable in yaw in the spinning attitude and which have large weights distributed along wings.
Date: December 1934
Creator: Bamber, M J
Partner: UNT Libraries Government Documents Department

The aerodynamic forces and moments on a spinning model of the F4B-2 airplane as measured by the spinning balance

Description: The aerodynamic forces and moments on a 1/12-scale model of the F4B-2 airplane were measured with the spinning balance in nine spinning attitudes with three sets of tail surfaces, namely, F4B-2 surfaces; F4B-4 fin and rudder with rectangular stabilizer; and with all tail surfaces removed. In one of these attitudes measurements were made to determine the effect upon the forces and moments of independent and of simultaneous displacement of the rudder and elevator for two of the sets of tail surfaces. Additional measurements were made for a comparison of model and full-scale data for six attitudes that were determined from flight tests with various control settings. The characteristics were found to vary in the usual manner with angle of attack and sideslip. The F4B-2 surfaces were quite ineffective as a source of yawing moments. The F4B-4 fin and F4B-2 stabilizer gave a greater damping yawing moment when controls were against the spin than did the F4B-2 surfaces but otherwise there was little difference. Substitution of a rectangular stabilizer for the F4B-2 stabilizer made no appreciable difference in the coefficient. Further comparisons with other airplane types are necessary before final conclusions can be drawn as to the relations between model and full-scale spin measurements.
Date: February 1935
Creator: Bamber, M J & Zimmerman, C H
Partner: UNT Libraries Government Documents Department

Aerodynamic rolling and yawing moments produced by floating wing-tip ailerons, as measured by spinning balance

Description: The investigation described in this report was made to determine the effectiveness of floating wing-tip ailerons as an airplane control in the spin. In these tests the ailerons, not being balanced, were set parallel to the axis of rotation, which is probably very nearly the attitude that balanced floating ailerons would assume in a spin. The tests were made with the spinning balance in the N.A.C.A. 5-foot vertical tunnel. The model was tested with and without the ailerons in 12 spinning attitudes chosen to cover the probable spinning range. Rolling- and yawing-moment coefficients are given as measured for the model with and without the ailerons, and computed values are given for the ailerons alone. The addition of floating wing-tip ailerons to the model doubled the rolling-moment coefficient and increased the yawing-moment coefficient by 0.05 and more. Both moments were in a sense to oppose the spin.
Date: March 1934
Creator: Bamber, Millard J
Partner: UNT Libraries Government Documents Department

Aerodynamic tests of a low aspect ratio tapered wing with various flaps, for use on tailless airplanes

Description: Wind tunnel tests were made of a model wing having an aspect ratio of 3 and a tapered plan form with a straight trailing edge. The model had the Clark Y airfoil section throughout it's entire span and had no washout, depending on a trailing-edge flap for longitudinal balance and control. The flap had a constant chord and was divided into four equal portions along the span. The tests were made with the entire flap deflected to obtain longitudinal control and balance, and also with the inner portions deflected alone, and with the outer portions deflected alone. It was found that the simple wing with no washout or change of basic section along the span has aerodynamic characteristics well suited for use on tailless airplanes. A higher lift coefficient was obtained with the full-span flap deflected as a unit to give longitudinal balance than was obtained with either the inner or the outer portions of the flap deflected.
Date: June 1933
Creator: Weick, Fred E. & Sanders, Robert
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
Partner: UNT Libraries Government Documents Department

Analysis and model tests of autogiro jump take-off

Description: An analysis is made of the autogiro jump take-off, in which the kinetic energy of the rotor turning at excess speed is used to effect a vertical take-off. By the use of suitable approximations, the differential equation of motion of the rotor during this maneuver is reduced to a form that can be solved. Only the vertical jump was studied; the effect of a forward motion during the jump is discussed briefly. The results of model tests of the jump take-off have been incorporated in the paper and used to establish the relative accuracy of the results predicted from the analysis. Good agreement between calculation and experiment was obtained by making justifiable allowances.
Date: October 1, 1936
Creator: Wheatley, John B & Bioletti, Carlton
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
Partner: UNT Libraries Government Documents Department

An application of the von Karman-Millikan laminar boundary-layer theory and comparison with experiment

Description: The von Karman-Millikan theory of laminar boundary layers presented in NACA Technical Report No. 504 is applied to the laminar boundary layer about an elliptic cylinder on which boundary-layer and pressure-distribution measurements were made. An outline of the procedure of the von Karman-Millikan method is given. Good agreement is obtained between the calculated and experimental results, indicating that the method may be applied generally to the laminar boundary layer about any body provided that an experimentally determined pressure distribution is available. It appears that for all Reynolds Number above 24,000 the separation point for the elliptic cylinder should occur at a constant distance behind the point of minimum pressure, provided that the boundary layer does not become turbulent.
Date: October 1935
Creator: Von Doenhoff, Albert E
Partner: UNT Libraries Government Documents Department

An approximate spin design criterion for monoplanes

Description: A quantitative criterion of merit has been needed to assist airplane designers to incorporate satisfactory spinning characteristics into new designs. An approximate empirical criterion, based on the projected side area and the mass distribution of the airplane, has been formulated in a recent British report. In the present paper, the British results have been analyzed and applied to American designs. A simpler design criterion based solely on the type and the dimensions of the tail, has been developed: it is useful in a rapid estimation of whether a new design is likely to comply with the minimum requirements for safety in spinning.
Date: June 1, 1939
Creator: Donlan, Charles J & Seidman, Oscar
Partner: UNT Libraries Government Documents Department

A balanced diaphragm type of maximum cylinder pressure indicator

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.
Date: December 1, 1930
Creator: Spanogle, J A & Collins, John H , Jr
Partner: UNT Libraries Government Documents Department

Basic requirements of fuel-injection nozzles for quiescent combustion chambers

Description: This report presents test results obtained during an investigation of the performance of a single-cylinder, high-speed, compression-ignition test engine when using multiple-orifice fuel-injection valve nozzles in which the number and the direction of the orifices were varied independently.
Date: June 1, 1931
Creator: Spanogle, J A & Foster, H H
Partner: UNT Libraries Government Documents Department

The behavior of thin-will monocoque cylinders under torsional vibration

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.
Date: August 1, 1937
Creator: Pekelsma, Robert E
Partner: UNT Libraries Government Documents Department

Bending stresses due to torsion in cantilever box beams

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.
Date: June 1, 1935
Creator: Kuhn, Paul
Partner: UNT Libraries Government Documents Department

Bending tests of circular cylinders of corrugated aluminum-alloy sheet

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.
Date: March 1, 1937
Creator: Buckwalter, John C.; Reed, Warren D. & Niles, Alfred S.
Partner: UNT Libraries Government Documents Department