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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1934

The effect of trim angle on the take-off performance

Data obtained at the N.A.C.A. tank from tests on the models of three flying-boat hulls - N.A.C.A. models 11-A, 16, and 22 - are used to demonstrate the effect of trim angle on water resistance. A specific example is taken, and data from Model 11-A are used to show that the trim angle giving the minimum water resistance will give minimum total air-plus-water resistance. Total-resistance curves for best trimmed angles and other angles are compared for the same example. The effect of wind on best trim angles and upon the take-off and run is shown by the working of an example. The possibility of using tank data on trim angles as aid in piloting is discussed, and an instrument for use in determining the trim angle of seaplanes is described. The importance of maintaining the best trim angle throughout the take-off is indicated.

Shoemaker, James M↗
NASA NTRS1938

The Aerodynamic Drag of Five Models of Side Floats N.A.C.A. Models 51-E, 51-F, 51-G, 51-H, 51-J

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.

House, R O↗
NASA NTRS1953

Estimation of Hydrodynamic Impact Loads and Pressure Distributions on Bodies Approximating Elliptical Cylinders with Special Reference to Water Landings of Helicopters

An approximate method for computing water loads and pressure distributions on lightly loaded elliptical cylinders during oblique water impacts is presented. The method is of special interest for the case of emergency water landings of helicopters. This method makes use of theory developed and checked for landing impacts of seaplanes having bottom cross sections of V and scalloped contours. An illustrative example is given to show typical results obtained from the use of the proposed method of computation. The accuracy of the approximate method was evaluated through comparison with limited experimental data for two-dimensional drops of a rigid circular cylinder at a trim of 0 degrees and a flight -path angle of 90 degrees. The applicability of the proposed formulas to the design of rigid hulls is indicated by the rough agreement obtained between the computed and experimental results. A detailed computational procedure is included as an appendix.

Schnitzer, Emanuel↗
NASA NTRS1926

The Supermarine "Southampton" seaplane : observation or bomber

Purchased for the British Air Ministry, the Southampton seaplane uses 2 Napier Lion engines and has a boat hull with outriggers mounted on the wings. It was designed as a military aircraft and can be easily converted to a bomber.

AIRPLANES - SUPERMARINE SOUTHAMPTON (BRIT )↗
NASA NTRS1927

Savoia seaplane S.55 : military or commercial

The S.55 is a two engine twin hull seaplane built by Societa Idrovolanti Alta Italia (Seaplane Company of Upper Italy). The S.55 (Santa Maria) is to be used for an around the world flight In 1927. It will have a useful load of 7,500 lbs. and a cruising speed of 100 MPH.

SAVOIA S 55 SEAPLANE (ITALY)↗
NASA NTRS1925

Schutte-Lanz airship projects after the war

The stressing of an airship depends on three nonuniformly distributed forces: air forces; the distribution of acceleration forces; and how the air pressure is distributed on the hull. This report examines the stresses and comes to conclusions on the size of airships.

AIRSHIPS - RIGID↗
NASA NTRS1926

Recent experiments with large seaplanes

This report covers the following aspects of large seaplane design and construction: heavy wing loading; propeller design; how the motion of the airplane is affected by increasing the dihedral angle; power plants; floats; and the hull.

SEAPLANES - DESIGN↗
NASA NTRS1927

Experiments on airfoils with trailing edge cut away

Airfoils with their trailing edge cut away are often found on aircraft, as the fins on the hulls of flying boats and the central section of the wings for affording better visibility. It was therefore of some interest to discover the effect of such cutaways on the lift and drag and on the position of the center of pressure. For this purpose, systematic experiments were performed on two different airfoils, a symmetrical airfoil and an airfoil of medium thickness, with successive shortenings of their chords.

AIRFOILS↗
NASA NTRS1924

The Aerodynamic Plane Table

This report gives the description and the use of a specially designed aerodynamic plane table. For the accurate and expeditious geometrical measurement of models in an aerodynamic laboratory, and for miscellaneous truing operations, there is frequent need for a specially equipped plan table. For example, one may have to measure truly to 0.001 inch the offsets of an airfoil at many parts of its surface. Or the offsets of a strut, airship hull, or other carefully formed figure may require exact calipering. Again, a complete airplane model may have to be adjusted for correct incidence at all parts of its surfaces or verified in those parts for conformance to specifications. Such work, if but occasional, may be done on a planing or milling machine; but if frequent, justifies the provision of a special table. For this reason it was found desirable in 1918 to make the table described in this report and to equip it with such gauges and measures as the work should require.

Zahm, A F↗
NASA NTRS1929

Water-Pressure Distribution on Seaplane Float

The investigation presented in this report was conducted for the purpose of determining the distribution and magnitude of water pressures likely to be experienced on seaplane hulls in service. It consisted of the development and construction of apparatus for recording water pressures lasting one one-hundredth second or longer and of flight tests to determine the water pressures on a UO-1 seaplane float under various conditions of taxiing, taking off, and landing. The apparatus developed was found to operate with satisfactory accuracy and is suitable for flight tests on other seaplanes. The tests on the UO-1 showed that maximum pressures of about 6.5 pounds per square inch occur at the step for the full width of the float bottom. Proceeding forward from the step the maximum pressures decrease in magnitude uniformly toward the bow, and the region of highest pressures narrows toward the keel. Immediately abaft the step the maximum pressures are very small, but increase in magnitude toward the stern and there once reached a value of about 5 pounds per square inch. (author)

Thompson, F L↗
NASA NTRS1930

Flow and Force Equations for a Body Revolving in a Fluid

Part I gives 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. Integration of the pressure supplies basic formulas for the zonal forces and moments on the revolving body. Part II, applying this steady-flow method, finds the velocity and pressure at all points of the flow inside and outside an ellipsoid and some of its limiting forms, and graphs those quantities for the latter forms. Part III finds the pressure, and thence the zonal force and moment, on hulls in plane curvilinear flight. Part IV derives general equations for the resultant fluid forces and moments on trisymmetrical bodies moving through a perfect fluid, and in some cases compares the moment values with those found for bodies moving in air. Part V furnishes ready formulas for potential coefficients and inertia coefficients for an ellipsoid and its limiting forms. Thence are derived tables giving numerical values of those coefficients for a comprehensive range of shapes.

Zahm, A F↗
NASA NTRS1930

Water Pressure Distribution on a Twin-Float Seaplane

This is the second of a series of investigations to determine water pressure distribution on various types of seaplane floats and hulls, and was conducted on a twin-float seaplane. It consisted of measuring water pressures and accelerations on a TS-1 seaplane during numerous landing and taxiing maneuvers at various speeds and angles. The results show that water pressures as great as 10 lbs. per sq. in.may occur at the step in various maneuvers and that pressures of approximately the same magnitude occur at the stern and near the bow in hard pancake landings with the stern way down. At the other parts of the float the pressures are less and are usually zero or slightly negative for some distance abaft the step. A maximum negative pressure of 0.87 lb. Per square inch was measured immediately abaft the step. The maximum positive pressures have a duration of approximately one-twentieth to one-hundredth second at any given location and are distributed over a very limited area at any particular instant.

Thompson, F L↗
NASA NTRS1936

Potential flow about elongated bodies of revolution

This report presents a method of solving the problem of axial and transverse potential flows around arbitrary elongated bodies of revolution. The solutions of Laplace's equation for the velocity potentials of the axial and transverse flows, the system of coordinates being an elliptic one in a meridian plane, are given. The theory is applied to a body of revolution obtained from a symmetrical Joukowsky profile, a shape resembling an airship hull. The pressure distribution and the transverse-force distribution are calculated and serve as examples of the procedure to be followed in the case of an actual airship. A section on the determination of inertia coefficients is also included in which the validity of some earlier work is questioned.

Kaplan, Carl↗
NASA NTRS1937

Pressure-Distribution Measurements at Large Angles of Pitch on Fins of Different Span-Chord Ratio on a 1/40-Scale Model of the U. S. Airship "Akron."

Report presents the results of pressure-distribution measurements on a 1/40-scale model of the U. S. Airship "Akron" conducted in the NACA 20-foot wind tunnel. The measurements were made on the starboard fin of each of four sets of horizontal tail surfaces, all of approximately the same area but differing in span-chord ratio, for five angles of pitch varying from 11.6 degrees to 34 degrees, for four elevator angles, and at air speeds ranging from 56 to 77 miles per hour. Pressures were also measured at 13 stations along the rear half of the port side of the hull at one elevator setting for the same five angles of pitch and at an air speed of approximately 91 miles per hour. The normal force on the fin and the moment of forces about the fin root were determined. The results indicate that, ignoring the effect on drag, it would be advantageous from structural considerations to use a fin of lower span-chord ratio than that used on the "Akron."

Mchugh, James G↗
NASA NTRS1940

The calculated effect of various hydrodynamic and aerodynamic factors on the take-off of a large flying boat

Report presents the results of an investigation made to determine the influence of various factors on the take-off performance of a hypothetical large flying boat by means of take-off calculations. The factors varied in the calculations were size of hull (load coefficient), wing setting, trim, deflection of flap, wing loading, aspect ratio, and parasite drag. The take-off times and distances were calculated to the stalling speeds and the performance above these speeds was separately studied to determine piloting technique for optimum take-off.

Olson, R E↗