The problem of the transformation of numerical values expressed in one system of units into another set or system of units frequently arises in connection with aerodynamic problems. Report contains aerodynamic coefficients and conversion tables needed to facilitate such transformation. (author).
Report presents results of wind tunnel tests of cambered aerofoils and body-wing combinations used for biplanes. Aerodynamic characteristics including drag, lift-drift ratio and stability derivatives are given.
Report discusses the comparative continuous flow characteristics of single and double poppet valves. The experimental data presented affords a direct comparison of valves, single and in pairs of different sizes, tested in a cylinder designed in accordance with current practice in aviation engines.
Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.
Report presents stress analysis of individual components of an airplane. Normal and abnormal loads, sudden loads, simple stresses, indirect simple stresses, resultant unit stress, repetitive and equivalent stress, maximum steady load and stress are considered.
Certain parts of an airplane are subjected not only to the stresses imposed by the aerodynamic or flying load, but also to the initial stresses, caused by the tension in the stay and drift wires. Report describes a tensiometer that measures such stresses which is simple in construction, accurate, and easily and quickly operated even by inexperienced persons. Two sizes of the instrument are available. One is suitable for wires up to one-fourth inch in diameter and the other for wires from one-fourth to three-eights inch in diameter.
The object of this report is to present the results of a theoretical and experimental study of the effect, on the performance of air speed indicators, of the different atmospheric conditions experienced at various altitudes.
Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, Congressional report, summaries of the committee's activities and research accomplished, expenditures, problems, recommendations, and a compilation of technical reports produced.
Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, Congressional report, summaries of the committee's activities and research accomplished, expenditures, problems, recommendations and a compilation of technical reports produced.
Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, Congressional report, summaries of the committee's activities and research accomplished, expenditures, and problems.
Report discusses the theory of energy losses in wind tunnels, the application of the Drzewiecki theory of propeller design to wind tunnel propellers, and the efficiency and steadiness of flow in model tunnels of various types.
Among other factors which affect the horsepower of an airplane engine are the atmospheric pressure, and consequently the altitude at which the engine is working, and the compression ratio, or cylinder volume divided by clearance volume. The tests upon which this report is based were selected from a large number of runs made during the intercomparison of various gasolines to determine the variation of horsepower with altitude at three different compression ratios. The test results and conclusions are presented in this report.
The purposes of the experimental investigation on the performance of air propellers described in this report are as follows: (1) the development of a series of design factors and coefficients drawn from model forms distributed with some regularity over the field of air-propeller design and intended to furnish a basis of check with similar work done in other aerodynamic laboratories, and as a point of departure for the further study of special or individual types and forms; (2) the establishment of a series of experimental values derived from models and intended for later use as a basis for comparison with similar results drawn from certain selected full-sized forms and tested in free flight.
The Bureau of Standards undertook the investigation of airplane fabrics with the view of finding suitable substitutes for the linen fabrics, and it was decided that the fibers to be considered were cotton, ramie, silk, and hemp. Of these, the cotton fiber was the logical one to be given primary consideration. Report presents the suitability, tensibility and stretching properties of cotton fabric obtained by laboratory tests.
Report includes specifications for the use and production of instruments used in the navigation and operation of aircraft. Specifications are included for the following instruments: barometer or altimeter, compass, air speed meter, inclinometer, drift meter, tachometer, oil gauge, oil pressure gauge, gasoline gauge, gasoline flow indicator, distance indicator, barograph, angle of attack indicator, radiator temperature indicator, gasoline feed system pressure indicator, sextant, airplane director.
Report describes the principles of operation and characteristics of some of the instruments which have been devised or used to measure both low and high speeds of aeroplanes. Since the pitot tube is the instrument which has been most commonly used in the United States and Great Britain as a speedometer for aeroplanes, it is treated first and somewhat more fully than the others.
Part 1 gives details of models tested and methods of testing of the Eiffel 36 wing alone and the JN2 aircraft. Characteristics and performance curves for standard JN are included. Part 2 presents a statistical analysis of the following: lift and drag contributed by body and chassis tested without wings; lift and drag contributed by tail, tested without wings; the effect on lift and drift of interference between the wings of a biplane combination; lift and drag contributed by the addition of body, chassis, and tail to a biplane combination; total parasite resistance; effect of varying size of tail, keeping angle of setting constant; effect of varying length of body and size of tail at the same time, keeping constant moment of tail surface about the center of gravity; forces on the tail and the effects of downwash; effect of size and setting of tail on statical longitudinal stability effects of length of body on stability; the effects of the various elements of an airplane on longitudinal stability and the placing of the force vectors. Part 3 presents the fundamental principals of dynamical stability; computations of resistance derivatives; solution of the stability equation; dynamical stability of the Curtiss JN2; tabulation of resistance derivatives; discussion of the resistance derivatives; formation and solution of stability equations; physical conceptions of the resistance derivatives; elements contributing to damping and an investigation of low speed conditions. Part 4 includes a summary of the results of the statistical investigation and a summary of the results for dynamic stability.
Report presents the experimental results of fabrics used for balloons and aeroplanes. Tensile properties, surface roughness, skin friction, flammability, permeability, and water absorption were tested for different combinations of materials.
This report is descriptive of various methods used in the kiln drying of woods for airplanes and gives the results of physical tests on different types of woods after being dried by the various kiln-drying methods.
The purpose of this report is to give a simple treatment of the problem of calculating the final or limiting velocity of an object falling in vertical motion under gravity in a resisting medium. The equations of motion are easily set up and integrated when the density of the medium is constant and the resistance varies as the square of the velocity. The results show that the fundamental characteristics of the vertical motion under gravity in a resisting medium is the approach to a terminal or limiting velocity, whether the initial downward velocity is less or greater than the limiting velocity. This method can be used to calculate the terminal velocity of a bomb trajectory.
Report presents the results of an extensive experimental investigation of the performance of different types of carburetors as effecting the maintenance under all conditions of correct ratio between the weights of fuel and air. It also gives a description of the Bureau of Standards carburetor test plant, test equipment and measuring instruments used to determine the metering characteristics of carburetors.
Report discusses periodic stresses in gyroscopic bodies with applications to air screws caused by particle mass. Report concludes that all modern air screws obey the laws found for plane groups of particles. In particular the two-bladers exert on the shaft a rhythmic gyroscopic torque; the multibladers a steady one; both easily calculable for any given conditions of motion and mass distribution.
A report to the Weather Bureau, Washington DC, from the chairman of the Subcommittee on the Atmosphere in Relation to Aeronautics describing the activities accomplished and the proposal of work to be undertaken by the subcommittee.
Part 1 presents the results of a wind tunnel test of a biplane model with an 18 inch span. The lift, drift, and pitching moment were measured for a series of angles of incidence corresponding to the maximum possible changes of flight attitude. Only the discussion of symmetrical or longitudinal changes is given. From the observed rate of variation of the forces and pitching moment, it was possible to calculate the derivatives needed in the complete theory of longitudinal stability in still air. The damping of the pitching oscillation was also determined experimentally. Part 2 presents a theoretical method for determining the effects of gusts on aeroplanes in the following cases: (1) head-on gusts rising from 0 to j feet per second with various degrees of sharpness, (2) up gusts of the same type, (3) rotary gusts of the same type, (4) rear gusts and down gusts are included by merely changing the sign of j.
Report presents results that show that it is possible to furnish efficient terminal connections that would allow for repairs for aviation wires and cables and eliminate the use of acid solder and blow torch.
This investigation was conducted at the Bureau of Standards for the National Advisory Committee for Aeronautics. Brass has often been assumed superior to steel for spark plug shells because of its greater heat conductivity. The measurements described in this report prove the contrary, showing that the interior of a spark plug having a brass shell is from 50 degrees to 150 degrees c. (90 degrees to 270 degrees f.) hotter than that of a similar steel plug. Consistent results were obtained in both an aviation and a truck engine, and under conditions which eliminated all other sources of difference between the plugs. It is to be concluded that steel is to be preferred to brass for spark plug shells. This report embodies the results of measurements taken of electrodes and a comparison of brass and steel insulators of spark plugs while they were in actual operation. The data throw considerable light upon the problem of the proper control of temperatures in these parts.
Report presents a new method for solving linear equations developed by Bromwich, which is suited to determine the motion for any particular gust, when the machine started from equilibrium, without the trouble of determining the constants of integration in the complementary function. (author).
Report presents requirements of internal combustion engines suitable for aircraft. Topics include: (1) service requirements for aeronautic engines - power versus weight, reliability, and adaptability factors, (2) general characteristics of present aero engines, (3) aero engine processes and functions of parts versus power-weight ratio, reliability, and adaptability factors, and (4) general arrangement, form, proportions, and materials of aero parts - power-weight ratio, reliability, and adaptability.
The aerodynamical constants of an airplane necessary for the discussion of stability are partly observed and partly calculated. Among the calculated coefficients is n(p), which is the variation of yawing moment due to rolling. (author).