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The additional-mass effect of plates as determined by experiments

Description: The apparent increase in the inertia properties of a body moving in a fluid medium has been called the additional-mass effect. This report presents a resume of test procedures and results of experimental determinations of the additional-mass effect of flat plates. In addition to data obtained from various foreign sources and from a NACA investigation in 1933, the results of tests recently conducted by the National Advisory Committee for Aeronautics are included.
Date: 1941
Creator: Gracey, William
Item Type: Report
Partner: UNT Libraries Government Documents Department

The aerodynamics of a wind-tunnel fan

Description: The vortex blade-element theory modified to apply to an axial fan working in a duct is reviewed. Thrust and power coefficients for a fan are identified with the corresponding coefficients for airplane propellers. The relation of pressure produced by the fan to the blade-element coefficients is developed. The distribution of axial velocity of fluid through a fan is assumed to be controlled by the fan itself. The radial distribution of tangential velocity imported by the fan to fluid moving through the fan is shown to be independent of the axial-velocity distribution. A nondimensional coefficient, designated the rotation constant, is introduced. This constant is based solely upon design information. The use of the rotation constant in simplifying the design of a fan for a specific operating condition is demonstrated. Based on the use of the rotation constant, a graphical method is outlined by which the performance of a given fan in a given wind tunnel may be predicted and by which the distributions of axial velocity of the fluid through the fan under various operating conditions may be established.
Date: August 1941
Creator: Corson, Blake W
Item Type: Report
Partner: UNT Libraries Government Documents Department

Air transport by gliders : some technical observations

Description: This short analysis may be useful in determining the real tactical possibilities of "glider trains" and in adopting the course to be followed in possible studies of these questions. In this analysis most prominent are: (a) the power required for the train in level flight; (b) its speed; (c) climb; and (d) the type of airplane best suited for towing as well as design requirements for transport gliders.
Date: June 1, 1941
Creator: Stepniewski, Wieslaw
Item Type: Report
Partner: UNT Libraries Government Documents Department

Analysis and prediction of longitudinal stability of airplanes

Description: An analysis has been made of the longitudinal stability characteristics of 15 airplanes as determined in flight. In the correlation of satisfactory and unsatisfactory characteristics with determined values, the derivative that expresses the ratio of static-restoring moments to elevator-control moments was found to represent most nearly the stability characteristics appreciated by the pilots. The analysis was extended to study the effects of various design features on the observed stability characteristics. Design charts and data are included that show the effects on longitudinal stability of relative positions of wing and tail, fuselage size and location, engine nacelles, and horizontal-tail arrangements.
Date: January 1, 1941
Creator: Gilruth, R R & White, M D
Item Type: Report
Partner: UNT Libraries Government Documents Department

Analysis of ground effect on the lifting airscrew

Description: A study is presented of ground effect as applied to the lifting airscrew of the type used in modern gyroplane and helicopters. The mathematical analysis of the problem has been verified by tests made of three rotor models in the presence of a large circular "ground plane." A method of approximating the decelerating effect during vertical approach to the ground has been devised. The results of the study are presented in the form of convenient charts.
Date: December 1941
Creator: Knight, Montgomery & Hegner, Ralph A
Item Type: Report
Partner: UNT Libraries Government Documents Department

An apparatus for measuring rates of discharge of a fuel-injection system

Description: A portable apparatus for rapidly determining rates of discharge of a fuel-injection system is described. Satisfactory operation of this apparatus with injection-pump speeds up to 2400 r.p.m was obtained. Rate-of-discharge tests were made with several cam-plunger-valve injection systems with long injection tubes. A check valve designed to reduce secondary discharges was tested. This check valve was operated with injection-pump speeds up to 2400 r.p.m without the occurrence of large secondary discharges.
Date: March 24, 1941
Creator: Dutee, Francis J
Item Type: Report
Partner: UNT Libraries Government Documents Department

Boundary layer removal by suction

Description: Flight-test data and wind-tunnel data on suction profiles are substantially in agreement. The lift values found in the model test can be actually flown and used as a basis for the design. To visualize the action of the suction, the flow conditions with and without suction on the upper surface were photographed; figures 12 to 15 are sections of the film.
Date: April 1, 1941
Creator: Schrenk, O
Item Type: Report
Partner: UNT Libraries Government Documents Department

Buckling tests on eccentrically loaded beam columns

Description: Formulas are obtained for computing the buckling load of rods eccentrically loaded at each end, the computation being extended in particular to the inelastic range. The test results are graphically presented on three sets of curves. Two of these, at least for the elastic range, are independent of the material tested. The third set, which is independent of the material, possesses greater clearness and is therefore used for comparing the test results with the theoretical.
Date: October 1, 1941
Creator: Cassens, J
Item Type: Report
Partner: UNT Libraries Government Documents Department

The calculation of span LCAD distributions of swept-back wings

Description: Span load distributions of swept-back wings have been calculated. The method used was to replace the wing with a bound vortex at the quarter-chord line and to calculate the downwash due to the system of bound and trailing vortices to conform at the three-quarter-chord line to the slope of the flat-plate wing surface. Results are given for constant-chord and 5:1 tapered plan forms, for sweep-back angles of 0 degrees, 30 degrees, and 45 degrees, and for aspect ratios of 3, 6, and 9. Some comments on the stalling of swept-back wings are included.
Date: December 1, 1941
Creator: Mutterperl, William
Item Type: Report
Partner: UNT Libraries Government Documents Department

Characteristics of NACA 4400R Series Rectangular and Tapered Airfoils, Including the Effect of Split Flaps

Description: At the request of the Bureau of Aeronautics, Navy Department, tests were made in the variable-density wind tunnel of a tapered wing of 3-10-18 plan form and based on the NACA 4400R series sections. The wing was also tested with 0.2 chord spit flaps, deflected 60 deg span ratios of 0.3, 0.5, 0.7 and 1.0 respectively. In order to get data from which to calculate the characteristics of the flapped wing, the investigation was extended to include tests of the four rectangular airfoils of the NACA 4400R series (4409R, 4412R, 4415R, and 4418R) with full-span 0.2 chord, trailing edge split flaps deflected 60 deg.
Date: January 1941
Creator: Greenberg, Harry
Item Type: Report
Partner: UNT Libraries Government Documents Department

Comparison of automatic control systems

Description: This report deals with a reciprocal comparison of an automatic pressure control, an automatic rpm control, an automatic temperature control, and an automatic directional control. It shows the difference between the "faultproof" regulator and the actual regulator which is subject to faults, and develops this difference as far as possible in a parallel manner with regard to the control systems under consideration. Such as analysis affords, particularly in its extension to the faults of the actual regulator, a deep insight into the mechanism of the regulator process.
Date: February 1, 1941
Creator: Oppelt, W
Item Type: Report
Partner: UNT Libraries Government Documents Department

Comparison of Intercooler Characteristics

Description: A method is presented of comparing the performance, weight, and general dimensional characteristics of inter-coolers. The performance and dimensional characteristics covered in the comparisons are cooling effectiveness, pressure drops and weight flows of the charge and cooling air, power losses, volume, frontal area, and width. A method of presenting intercooler data is described in which two types of charts are plotted; (1) A performance chart setting forth all the important characteristics of a given intercooler and (2) a replot of these characteristics for a number of intercoolers intended to assist in making a selection to satisfy a given set of installation conditions. The characteristics of commercial intercoolers obtained from manufacturers' data and of some computed designs are presented on this basis. A standard test procedure and instrumentation are suggested whereby comparable data may be obtained by different testing organizations.
Date: May 1, 1941
Creator: Reuter, J. George & Valerino, Michael F.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Comparison of Vee-Type and Conventional Tail Surfaces in Combination with Fuselage and Wing in the Variable-Density Tunnel

Description: The pitching and the yawing moments of a vee-type and a conventional type of tail surface were measured. The tests were made in the presence of a fuselage and a wing-fuselage combination in such a way as to determine the moments contributed by the tail surfaces. The results showed that the vee-type tail tested, with a dihedral angle of 35.3 deg, was about 71 percent as effective in pitch as the conventional tail and had a yawing-moment to pitching-moment ratio of 0.3. The conventional tail, the panels of which were all congruent to those of the vee-type tail, had a yawing-moment to pitching-moment ratio of 0.48. These ratios are in fair agreement with values calculated by methods shown in this and previous reports. The values of the measured moments were reduced from 15 to 25 percent of the calculated value by fuselage interference.
Date: July 1, 1941
Creator: Greenberg, Harry
Item Type: Report
Partner: UNT Libraries Government Documents Department

Compressibility Effects in Aeronautical Engineering

Description: Compressible-flow research, while a relatively new field in aeronautics, is very old, dating back almost to the development of the first firearm. Over the last hundred years, researches have been conducted in the ballistics field, but these results have been of practically no use in aeronautical engineering because the phenomena that have been studied have been the more or less steady supersonic condition of flow. Some work that has been done in connection with steam turbines, particularly nozzle studies, has been of value, In general, however, understanding of compressible-flow phenomena has been very incomplete and permitted no real basis for the solution of aeronautical engineering problems in which.the flow is likely to be unsteady because regions of both subsonic and supersonic speeds may occur. In the early phases of the development of the airplane, speeds were so low that the effects of compressibility could be justifiably ignored. During the last war and immediately after, however, propellers exhibited losses in efficiency as the tip speeds approached the speed of sound, and the first experiments of an aeronautical nature were therefore conducted with propellers. Results of these experiments indicated serious losses of efficiency, but aeronautical engineers were not seriously concerned at the time became it was generally possible. to design propellers with quite low tip. speeds. With the development of new engines having increased power and rotational speeds, however, the problems became of increasing importance.
Date: August 1, 1941
Creator: Stack, John
Item Type: Report
Partner: UNT Libraries Government Documents Department