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 Collection: National Advisory Committee for Aeronautics Collection
Flow and Force Equations for a Body Revolving in a Fluid

Flow and Force Equations for a Body Revolving in a Fluid

Date: December 1, 1979
Creator: Zahm, A. F.
Description: A general method for finding the steady flow velocity relative to a body in plane curvilinear motion, whence the pressure is found by Bernoulli's energy principle is described. Integration of the pressure supplies basic formulas for the zonal forces and moments on the revolving body. The application of the steady flow method for calculating the velocity and pressure at all points of the flow inside and outside an ellipsoid and some of its limiting forms is presented and graphs those quantities for the latter forms. In some useful cases experimental pressures are plotted for comparison with theoretical. The pressure, and thence the zonal force and moment, on hulls in plane curvilinear flight are calculated. General equations for the resultant fluid forces and moments on trisymmetrical bodies moving through a perfect fluid are derived. Formulas for potential coefficients and inertia coefficients for an ellipsoid and its limiting forms are presented.
Contributing Partner: UNT Libraries Government Documents Department
The Inertia Coefficients of an Airship in a Frictionless Fluid

The Inertia Coefficients of an Airship in a Frictionless Fluid

Date: December 1, 1979
Creator: Bateman, H.
Description: The apparent inertia of an airship hull is examined. The exact solution of the aerodynamical problem is studied for hulls of various shapes with special attention given to the case of an ellipsoidal hull. So that the results for the ellipsoidal hull may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction of motion by means of a formula involving a coefficient kappa which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio. The case of rotation of an airship hull is investigated and a coefficient is defined with the same advantages as the corresponding coefficient for rectilinear motion.
Contributing Partner: UNT Libraries Government Documents Department
Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors

Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors

Date: October 1, 1951
Creator: Castles, Walter, Jr. & Gray, Robin B.
Description: The empirical relation between the induced velocity, thrust, and rate of vertical descent of a helicopter rotor was calculated from wind tunnel force tests on four model rotors by the application of blade-element theory to the measured values of the thrust, torque, blade angle, and equivalent free-stream rate of descent. The model tests covered the useful range of C(sub t)/sigma(sub e) (where C(sub t) is the thrust coefficient and sigma(sub e) is the effective solidity) and the range of vertical descent from hovering to descent velocities slightly greater than those for autorotation. The three bladed models, each of which had an effective solidity of 0.05 and NACA 0015 blade airfoil sections, were as follows: (1) constant-chord, untwisted blades of 3-ft radius; (2) untwisted blades of 3-ft radius having a 3/1 taper; (3) constant-chord blades of 3-ft radius having a linear twist of 12 degrees (washout) from axis of rotation to tip; and (4) constant-chord, untwisted blades of 2-ft radius. Because of the incorporation of a correction for blade dynamic twist and the use of a method of measuring the approximate equivalent free-stream velocity, it is believed that the data obtained from this program are more applicable to free-flight calculations than ...
Contributing Partner: UNT Libraries Government Documents Department
Development of a supersonic area rule and an application to the design of a wing-body combination having high lift-to-drag ratios

Development of a supersonic area rule and an application to the design of a wing-body combination having high lift-to-drag ratios

Date: January 1, 1953
Creator: Fischetti, T. L. & Whitcomb, R. T.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Evolution of the helicopter

Evolution of the helicopter

Date: March 1, 1923
Creator: Balaban, K.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Wing pressure distributions over the lift range of the convair xf-92a delta-wing airplane at subsonic and transonic speeds

Wing pressure distributions over the lift range of the convair xf-92a delta-wing airplane at subsonic and transonic speeds

Date: November 30, 1955
Creator: Jordan, G. H. & Keener, E. R.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Determination of rate, area, and distribution of impingement of waterdrops on various airfoils from trajectories obtained on the differential analyzer

Determination of rate, area, and distribution of impingement of waterdrops on various airfoils from trajectories obtained on the differential analyzer

Date: February 16, 1949
Creator: Guibert, A. G.; Janssen, E. & Robbins, W. M.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Moments of cambered round bodies

Moments of cambered round bodies

Date: August 1, 1949
Creator: Kempf, Gunther
Description: Results are presented for the moments and position of force centers of a series of cambered round bodies derived from a torpedo-like body of revolution. The effects of placing fins on the rear of the body of revolution are also included.
Contributing Partner: UNT Libraries Government Documents Department
Compilation and Analysis of US Turbojet and Ram-Jet Engine Characteristics

Compilation and Analysis of US Turbojet and Ram-Jet Engine Characteristics

Date: November 27, 1956
Creator: Cesaro, R. S. & Walker, C. L.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The factors that determine the minimum speed of an airplane

The factors that determine the minimum speed of an airplane

Date: March 1, 1921
Creator: Norton, F H
Description: The author argues that because of a general misunderstanding of the principles of flight at low speed, there are a large number of airplanes that could be made to fly several miles per hour slower than at present by making slight modifications. In order to show how greatly the wing section affects the minimum speed, curves are plotted against various loadings. The disposition of wings on the airplane slightly affects the lift coefficient, and a few such cases are discussed. Another factor that has an effect on minimum speed is the extra lift exerted by the slip stream on the wings. Also discussed are procedures to be followed by the pilot, especially with regard to stick movements during low speed flight. Also covered are stalling, yaw, rolling moments, lateral control, and the effectiveness of ailerons and rudders.
Contributing Partner: UNT Libraries Government Documents Department
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