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Glues Used in Airplane Parts
This report was prepared for the National Advisory Committee for Aeronautics and presents the results of investigations conducted by the Forest Products Laboratory of the United States Forest Service on the manufacture, preparation, application, testing and physical properties of the different types of glues used in wood airplane parts.
A Résumé of the Advances in Theoretical Aeronautics Made by Max M. Munk
"In order to apply profitably the mathematical methods of hydrodynamics to aeronautical problems, it is necessary to make simplifications in the physical conditions of the latter. In a valuable paper presented by Dr. Max M. Munk, of the National Advisory Committee for Aeronautics, Washington, to the Delft Conference in April, 1924, these necessary simplifying assumptions are discussed in detail. It is the purpose of the present paper to present in as simple a manner as possible some of the interesting results obtained by Dr. Munk's methods" (p. 93).
Preliminary experiments to determine scale and slip-stream effects on a 1/24th size model of a JN4H biplane
This work was undertaken to obtain results on a small model of a complete airplane which might be used for comparison with corresponding tests made in full flight. Somewhat similar tests have been previously made at various other laboratories; but as certain discrepancies exist between corresponding tests in different tunnels, it has been deemed advisable to obtain a direct comparison for this particular installation. The present work covers tests on a one-twenty-fourth scale model at speeds varying from 6.7 m/sec. (15 m.p.h.) to 40.2 m/sec, (90 m.p.h.). A slip stream correction has been obtained by the use of a small belt-driven propeller mounted in front of the model, and force coefficients thus obtained are compared with the measurements of the same forces made in full flight on a geometrically similar airplane. This report gives lift, drag, and longitudinal moment values obtained in tests of a particularly accurate model over a wide range of speeds. A measure of the slip stream corrections on lift and drag forces was obtained by the use of a power-driven model propeller. Measurements were also made of forces and longitudinal moments for all angles from 0 degree to 360 degrees.
The resistance of spheres in wind tunnels and in air
From Summary: "A satisfactory confirmation of Reynolds law has been accomplished, the effect of means of support determined, the range of experiment greatly extended by work in the new variable density wind tunnel, and the effects of turbulence investigated by work in the tunnels and by towing and dropping tests in free air. It is concluded that the erratic nature of most of the previous work is due to support interference and differing turbulence conditions. While the question of support has been investigated thoroughly, a systematic and comprehensive study of the effects of scale and quality of turbulence will be necessary to complete the problem, as this phase was given only general treatment."
The Distribution of Lift Over Wing Tips and Ailerons
"This investigation was carried out in the 5-foot wind tunnel of the Langley Memorial Aeronautical Laboratory for the purpose of obtaining more complete information on the distribution of lift between the ends of wing spars, the stresses in ailerons, and the general subject of airflow near the tip of a wing. It includes one series of tests on four models without ailerons, having square, elliptical, and raked tips respectively, and a second series of positively and negatively raked wings with ailerons adjusted to different settings. The results show that negatively raked tips give a more uniform distribution of air pressure than any of the other three arrangements, because the tip vortex does not disturb the flow at the trailing edge" (p. 105).
The Decay of a Simple Eddy
The principal result obtained in this report is a generalization of Taylor's formula for a simple eddy. The discussion of the properties of the eddy indicates that there is a slight analogy between the theory of eddies in a viscous fluid and the quantum theory of radiation. Another exact solution of the equations of motion of viscous fluid yields a result which reminds one of the well-known condition for instability in the case of a horizontally stratified atmosphere.
Diagrams of Airplane Stability
In this report a study is made of the effect on longitudinal and lateral oscillations of an airplane of simultaneous variations in two resistance derivatives while the remainder of the derivatives are constant. The results are represented by diagrams in which the two variable resistance derivatives are used as coordinates, and curves are plotted along which the modulus of decay of a long oscillation has a constant value. The same type of analysis is also carried out for the stability of the parachute.
The Inertia Coefficients of an Airship in a Frictionless Fluid
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 Inertial Coefficients of an Airship in a Frictionless Fluid
This report deals with the investigation of the apparent inertia of an airship hull. The exact solution of the aerodynamical problem has been studied for hulls of various shapes and special attention has been given to the case of an ellipsoidal hull. In order that the results for this last case 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 motion by means of a formula involving a coefficient K 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 7.
Stability of the Parachute and Helicopter
This report deals with an extension of the theory of stability in oscillation to the case of aircraft following a vertical trajectory, and particularly to the oscillations of parachutes.
Differential Pressures on a Pitot-Venturi and a Pitot-Static Nozzle Over 360 Degrees Pitch and Yaw
"Measurements of the differential pressures on two navy air-speed nozzles, consisting of a Zahm type Pitot-Venturi tube and a SQ-16 two-pronged Pitot-static tube, in a tunnel air stream of fixed speed at various angles of pitch and yaw between 0 degrees and plus or minus 180 degrees. This shows for a range over -20 degrees to +20 degrees pitch and yaw, indicated air speeds varying very slightly over 2 per cent for the Zahm type and a maximum of about 5 per cent for the SQ-16 type from the calibrated speed at 0 degree. For both types of air-speed nozzle the indicated air speed increases slightly as the tubes are pitched or yawed several degrees from their normal 0 degrees altitude, attains a maximum around plus or minus 15 degrees to 25 degrees, declines rapidly therefrom as plus or minus 40 degrees is passed, to zero in the vicinity of plus or minus 70 degrees to 100 degrees, and thence fluctuates irregular from thereabouts to plus or minus 180 degrees" (p. 223).
Some factors affecting the reproducibility of penetration and the cut-off of oil sprays for fuel-injection engines
This investigation was undertaken at the Langley Memorial Aeronautical Laboratory in connection with a general research on fuel-injection for aircraft. The purpose of the investigation was to determine the factors controlling the reproducibility of spray penetration and secondary discharges after cut-off. The development of single sprays from automatic injection valves was recorded by means of special high-speed photographic apparatus capable of taking 25 consecutive pictures of the moving spray at a rate of 4,000 per second. The effect of two types of injection valves, injection-valve tube length, initial pressure in the injection-valve tube, speed of the injection control mechanism, and time of spray cut-off, on the reproducibility of spray penetration, and on secondary discharges were investigated. It was found that neither type of injection valve materially affected spray reproducibility. The initial pressure in the injection-valve tube controlled the reproducibility of spray penetrations. An increase in the initial pressure or in the length of the injection-valve tube slightly increased the spray penetration within the limits of this investigation. The speed of the injection-control mechanism did not affect the penetration. Analysis of the results indicates that secondary discharges were caused in this apparatus by pressure waves initiated by the rapid opening of the cut-off valve. The secondary discharges were eliminated in this investigation by increasing the length of the injection-valve tube. (author).
The N.A.C.A. photographic apparatus for studying fuel sprays from oil engine injection valves and test results from several researches
"Apparatus for recording photographically the start, growth, and cut-off of oil sprays from injection valves has been developed at the Langley Memorial Aeronautical Laboratory. The apparatus consists of a high-tension transformer by means of which a bank of condensers is charged to a high voltage. The controlled discharge of these condensers in sequence, at a rate of several thousand per second, produces electric sparks of sufficient intensity to illuminate the moving spray for photographing. The sprays are injected from various types of valves into a chamber containing gases at pressures up to 600 pounds per square inch" (p. 361).
Astronomical Methods in Aerial Navigation
The astronomical method of determining position is universally used in marine navigation and may also be of service in aerial navigation. The practical application of the method, however, must be modified and adapted to conform to the requirements of aviation. Much of this work of adaptation has already been accomplished, but being scattered through various technical journals in a number of languages, is not readily available. This report is for the purpose of collecting under one cover such previous work as appears to be of value to the aerial navigator, comparing instruments and methods, indicating the best practice, and suggesting future developments.
The Corrosion of Magnesium and of the Magnesium Aluminum Alloys Containing Manganese
"The extensive use of magnesium and its alloys in aircraft has been seriously handicapped by the uncertainties surrounding their resistance to corrosion. This problem has been given intense study by the American Magnesium Corporation and at the request of the Subcommittee on Materials for Aircraft of the National Advisory Committee for Aeronautics this report was prepared on the corrosion of magnesium" (p. 419).
Pressure distribution over airfoils at high speeds
This report deals with the pressure distribution over airfoils at high speeds, and describes an extension of an investigation of the aerodynamic characteristics of certain airfoils which was presented in NACA Technical Report no. 207. The results presented in report no. 207 have been confirmed and extended to higher speeds through a more extensive and systematic series of tests. Observations were also made of the air flow near the surface of the airfoils, and the large changes in lift coefficients were shown to be associated with a sudden breaking away of the flow from the upper surface. The tests were made on models of 1-inch chord and comparison with the earlier measurements on models of 3-inch chord shows that the sudden change in the lift coefficient is due to compressibility and not to a change in the Reynolds number. The Reynolds number still has a large effect, however, on the drag coefficient. The pressure distribution observations furnish the propeller designer with data on the load distribution at high speeds, and also give a better picture of the air-flow changes.
Aerodynamic characteristics of airfoils at high speeds
From Summary: "This report deals with an experimental investigation of the aerodynamical characteristics of airfoils at high speeds. Lift, drag, and center of pressure measurements were made on six airfoils of the type used by the air service in propeller design, at speeds ranging from 550 to 1,000 feet per second. The results show a definite limit to the speed at which airfoils may efficiently be used to produce lift, the lift coefficient decreasing and the drag coefficient increasing as the speed approaches the speed of sound. The change in lift coefficient is large for thick airfoil sections (camber ratio 0.14 to 0.20) and for high angles of attack. The change is not marked for thin sections (camber ratio 0.10) at low angles of attack, for the speed range employed. At high speeds the center of pressure moves back toward the trailing edge of the airfoil as the speed increases. The results indicate that the use of tip speeds approaching the speed of sound for propellers of customary design involves a serious loss in efficiency."
Electrical characteristics of spark generators for automotive ignition
From Summary: "This paper reports the results of an extensive program of measurements on 11 ignition systems differing widely in type. The results serve primarily to give representative data on the electric and magnetic constants of such systems, and on the secondary voltage produced by them under various conditions of speed, timing, shunting resistance, etc. They also serve to confirm certain of the theoretical formulas which have been proposed to connect the performance of such systems with their electrical constants, and to indicate the extent to which certain simplified model circuits duplicate the performance of the actual apparatus."
Tables for calibrating altimeters and computing altitudes based on the standard atmosphere
From Summary: "During 1925 the assumption of an isothermal atmosphere which was in general use as the standard for the calibration of altimeters in the United States was replaced by a standard atmosphere which assumes an altitude-temperature relation closely corresponding to the average of upper air observations at latitude 40 degrees in this country. The same standard atmosphere had already been adopted somewhat earlier in the United States as the aircraft performance standard. National Advisory Committee for Aeronautics Technical Reports nos. 147 and 218 give necessary constants, tables, and information. However, neither of these reports includes all of the tables required for the computation of actual altitudes nor those readily suitable for use in calibrating altimeters, since the altitude intervals for which data are given are not sufficiently small."
Pressure element of constant logarithmic stiffness for temperature compensated altimeter
From Summary: "The usual type of altimeter contains a pressure element, the deflections of which are approximately proportional to pressure changes. An evenly divided altitude scale is secured by using a mechanism between the pressure element and pointer which gives the required motion of the pointer. A temperature-compensated altimeter was constructed at the Bureau of Standards for the Bureau of Aeronautics of the Navy Department which contained a manually operated device for controlling the multiplication of the mechanism to the extent necessary for temperature compensation. The introduction of this device made it difficult to adjust the multiplying mechanism to fit an evenly divided altitude scale. To meet this difficulty a pressure element was designed and constructed which gave deflections which were proportional to altitude; that is, to the logarithm of the pressure."
Jet Propulsion for Airplanes
This report is a description of a method of propelling airplanes by the reaction of jet propulsion. Air is compressed and mixed with fuel in a combustion chamber, where the mixture burns at constant pressure. The combustion products issue through a nozzle, and the reaction of that of the motor-driven air screw. The computations are outlined and the results given by tables and curves.
Bending moments, envelope, and cable stresses in non-rigid airships
This report describes the theory of calculating the principal stresses in the envelope of a nonrigid airship used by the Bureau of Aeronautics, United States Navy. The principal stresses are due to the gas pressure and the unequal distribution of weight and buoyancy, and the concentrated loads from the car suspension cables. The second part of the report deals with the variations of tensions in the car suspension cables of any type of airship, with special reference to the rigid type, due to the propeller thrust or the inclination of the airship longitudinally.
Forces on airships in gusts
In this report it is shown that determining the instantaneous angle of pitch, the acceleration of the gust is as important as its maximum velocity or yaw. Hitherto it has been assumed that the conditions encountered in gusts could be approximately represented by considering the airship to be at an instantaneous angle of yaw or pitch (according to whether the gust is horizontal or vertical), the instantaneous angle being tan to the (-1) power (v/v), where v is the component of the velocity of the gust at right angles to the longitudinal axis of the ship, and v is the speed of the ship. An expression is derived for this instantaneous angle in terms of the speed and certain aerodynamic characteristics of the airship, and of the maximum velocity and the acceleration of the gust, and the application of the expression to the determination of the forces on the ship is illustrated by numerical examples.
The torsional strength of wings
This report describes a simple method for calculating the position of the elastic axis of a wing structure having any number of spars. It is shown that strong drag bracing near the top and bottom of a wing greatly increases the torsional strength. An analytical procedure for finding the contribution of the drag bracing to the torsional strength and stiffness is described, based upon the principle of least work, and involving only one unknown quantity. A coefficient for comparing the torsional rigidity of different wings is derived in this report.
Wind Tunnel Studies in Aerodynamic Phenomena at High Speed
A great amount of research and experimental work has been done and fair success obtained in an effort to place airplane and propeller design upon an empirical basis. However, one can not fail to be impressed by the apparent lack of data available toward establishing flow phenomena upon a rational basis, such that they may be interpreted in terms of the laws of physics. With this end in view it was the object of the authors to design a wind tunnel differing from the usual type especially in regard to large power and speed of flow.
A study of taking off and landing an airplane
"This report covers the results of an investigation carried on at the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics for the purpose of discussing the various methods of effecting the take-off and the landing of an airplane, and to make a direct analysis of the control movements, the accelerations, and air speeds during these the maneuvers. The recording instruments developed at the laboratory were used in this test and the records obtained by them were made the basis for a comparative study of the two extreme methods of taking off (the tail-high and tail-low methods) and of various types of landings. The records should be of considerable value to a student pilot in enabling him to visualize the movements of the controls and the consequent effect upon the air speed and acceleration" (p. 555)
A Comparison of the Take-Off and Landing Characteristics of a Number of Service Airplane
"This investigation, which is a continuation of Technical Report 154, follows very closely the earlier methods and covers a number of service airplanes, whereas the previous report covered but one, the JN-4H. In addition to the air speed, acceleration, and control positions as given in report no. 154, information is here given regarding the distance run and the ground speed for the various airplanes during the two maneuvers" (p. 457).
Damping Coefficients Due to Tail Surfaces in Aircraft
"The object of the investigation described in this report was to compare the damping coefficients of an airfoil as calculated from a knowledge of the static characteristics of the section with those obtained experimentally with an oscillation. The damping coefficients as obtained, according to the conventional notation, can be considered either as due to pitching or as due to yawing, the oscillation in these experiments being so arranged that the surfaces oscillate about a vertical axis. This is in reality the case when the influence is yawing about the standard Z-axis, but it can also be considered as a pitching motion when the model is so rigged that its standard Y-axis becomes vertical" (p. 118).
A Study of Airplane Ranges and Useful Loads
This report is an analysis of the maximum flight radii of typical large airplanes and a discussion of the way in which the possible length of flight is affected by the change of weight by consumption of fuel during the flight.
Investigation of Slipstream Velocity
"These experiments were made at the request of the Bureau of Aeronautics, Navy Department, to investigate the velocity of the air in the slipstream in horizontal and climbing flight to determine the form of expression giving the slipstream velocity in terms of the airspeed of the airplane. The method used consisted in flying the airplane both on a level course and in climb at full throttle and measuring the slipstream velocity at seven points in the slipstream for the whole speed range of the airplane in both conditions. In general the results show that for both condition, horizontal and climbing flights, the slipstream velocity v subscript 3 and airspeed v can be represented by straight lines and consequently the equations are of the form: v subscript s = mv+b where m and b are constant" (p. 199).
Pressure Distribution Over a Wing and Tail Rib of a VE-7 and of a TS Airplane in Flight
"This investigation was made to determine the pressure distribution over a rib of the wing and over a rib of the horizontal tail surface of an airplane in flight and to obtain information as to the time correlation of the loads occurring on these ribs. Two airplanes, VE-7 and TS, were selected in order to obtain the information for a thin and a thick wing section. In each case the pressure distribution was recorded for the full range of angle of attack in level flight and throughout violent maneuvers" (p. 79).
Pressure Distribution on the C-7 Airship
This investigation was made for the purpose of determining the aerodynamic pressure distribution encountered on a "C" class airship in flight. It was conducted in two parts: (a) tests on the tail surfaces in which the pressures at 201 points were measured and (b) tests on the envelope in which 190 points were used, both tests being made under as nearly identical flight conditions as possible, so that the results could be combined and the pressure distribution over the entire airship obtained.
Determination of Turning Characteristics of an Airship by Means of a Camera Obscura
This investigation was carried out by the National Advisory Committee at Langley Field for the purpose of determining the adaptability of the camera obscura to the securing of turning characteristics of airships, and also of obtaining some of those characteristics of the C-7 airship. The method consisted in flying the airship in circling flight over a camera obscura and photographing it at known time intervals. The results show that the method used is highly satisfactory and that for the particular maneuver employed the turning diameter is 1,240 feet, corresponding to a turning coefficient of 6.4, and that the position of zero angle of yaw is at the nose of the airship.
An Investigation of the Aerodynamic Characteristics of an Airplane Equipped with Several Different Sets of Wings
This investigation was conducted by the National Advisory Committee for Aeronautics at Langley Field, Va., at the request of the Army Air Corps, for the purpose of comparing the full scale lift and drag characteristics of an airplane equipped with several sets of wings of commonly used airfoil sections. A Sperry Messenger Airplane with wings of R.A.F.-15, U.S.A.-5, U.S.A.-27, and Gottingen 387 airfoil sections was flown and the lift and drag characteristics of the airplane with each set of wings were determined by means of glide tests. The results are presented in tabular and curve form.
Characteristics of Five Propellers in Flight
"This investigation was made for the purpose of determining the characteristics of five full-scale propellers in flight. The equipment consisted of five propellers in conjunction with a VE-7 airplane and a Wright E-2 engine. The propellers were of the same diameter and aspect ratio. Four of them differed uniformly in thickness and pitch and the fifth propeller was identical with one of the other four with exception of a change of the airfoil section" (p. 267).
Characteristics of a boat type seaplane during take-off
This report, on the planing and get-away characteristics of the F-5-L, gives the results of the second of a series of take-off tests on three different seaplanes conducted by the National Advisory Committee for Aeronautics at the suggestion of the Bureau of Aeronautics, Navy Department. The single-float seaplane was the first tested and the twin-float seaplane is to be the third. The characteristics of the boat type were found to be similar to the single float, the main difference being the increased sluggishness and relatively larger planing resistance of the larger seaplane. At a water speed of 15 miles per hour the seaplane trims aft to about 12 degrees and remains in this angular position while plowing. At 2.25 miles per hour the planing stage is started and the planing angle is immediately lowered to about 10 degrees. As the velocity increases the longitudinal control becomes more effective but over control will produce instability. At the get-away the range of angle of attack is 19 degrees to 11 degrees with velocities from the stalling speed through about 25 per cent of the speed range.
Characteristics of a single float seaplane during take-off
At the request of the Bureau of Aeronautics, Navy Department, the National Advisory Committee for Aeronautics at Langley Field is investigating the get-away characteristics of an N-9H, a DT-2, and an F-5l, as representing, respectively, a single float, a double float, and a boat type of seaplane. This report covers the investigation conducted on the N-9H. The results show that a single float seaplane trims aft in taking off. Until a planing condition is reached the angle of attack is about 15 degrees and is only slightly affected by controls. When planing it seeks a lower angle, but is controllable through a widening range, until at the take-off it is possible to obtain angles of 8 degrees to 15 degrees with corresponding speeds of 53 to 41 M. P. H. or about 40 per cent of the speed range. The point of greatest resistance occurs at about the highest angle of a pontoon planing angle of 9 1/2 degrees and at a water speed of 24 M. P. H.
Characteristics of a twin-float seaplane during take-off
This report presents the results of an investigation of the planing and get-away characteristics of three representative types of seaplanes, namely, single float, boat, and twin float. The experiments carried out on the single float and boat types have been reported on previously. This report covers the investigation conducted on the twin-float seaplane, the DT-2, and includes as an appendix, a brief summary of the results obtained on all three tests. At low-water speeds, 20 to 30 miles per hour, the seaplane trims by the stern and has a high resistance. Above these speeds the longitudinal control becomes increasingly effective until, with corresponding speeds of 56 to 46 miles per hour. It was further determined that an increase in the load caused little if any change in the water speed at which the maximum angle and resistance occurred, but that it did produce an increase in the maximum angle.
Flight tests on U.S.S. Los Angeles Part 1: full scale pressure distribution investigation
The primary purpose of this investigation was to obtain simultaneous data on the loads and stress experience in flight by the U. S. S. Los Angeles which could be used in rigid airship structure design. A secondary object of the investigation was to determine the turning and drag characteristics of the airship. The aerodynamic loading was obtained by measuring the pressure at 95 locations on the tail surfaces, 54 on the hull, and 5 on the passenger car. These measurements were made during a series of maneuvers consisting of turns and reversals in smooth air and during a cruise in rough air which was just short of squall proportions.
Speed and deceleration trials of U.S.S. Los Angeles
From Summary: "The trials reported in this report were instigated by the Bureau of Aeronautics of the Navy Department for the purpose of determining accurately the speed and resistance of the U. S. S. "Los Angeles" with and without water recovery apparatus, and to clear up the apparent discrepancies between the speed attained in service and in the original trials in Germany. The trials proved very conclusively that the water recovery apparatus increases the resistance about 20 per cent, which is serious, and shows the importance of developing a type of recovery having less resistance. Between the American and the German speed trials without water recovery there remains an unexplained discrepancy of nearly 6 per cent in speed at a given rate of engine revolutions."
The altitude laboratory for the test of aircraft engines
Report presents descriptions, schematics, and photographs of the altitude laboratory for the testing of aircraft engines constructed at the Bureau of Standards for the National Advisory Committee for Aeronautics.
Synopsis of Aeronautic Radiator Investigations for Years 1917 and 1918
Extensive series of experiments have been conducted at the Bureau of Standards to determine the properties of cooling radiator cores manufactured for airplanes and to develop improvements in design. The analysis of the problem on which this work was based, and consequently the experimental method employed, is different from that commonly used. Instead of attempting to test complete radiators, either full size or in model, uniform sections representing different types of core construction have been tested and an analysis of the results made with a view to determining independently the various factors which influence its performance. This report describes referenced method of analysis in predicting the performance of radiators designed for aeronautic use.
A high-speed engine pressure indicator of the balanced diaphragm type
This report describes a pressure-measuring device especially adapted for use in mapping indicator diagrams of high-speed internal combustion engines. The cards are obtained by a point-to-point method giving the average of a large number of engine cycles. The principle involved is the balancing of the engine cylinder pressure against a measured pressure on the opposite side of the metal a diaphragm of negligible stiffness.
Comparison of hecter fuel with export aviation gasoline
Among the fuels which will operate at compression ratios up to at least 8.0 without preignition or "pinking" is hecter fuel, whence a careful determination of its performance is of importance. For the test data presented in this report the hecter fuel used was a mixture of 30 per cent benzol and 70 per cent cyclohexane, having a low freezing point, and distilling from first drop to 90 per cent at nearly a constant temperature, about 20 degrees c. below the average distillation temperature ("mean volatility") of the x gasoline (export grade). The results of these experiments show that the power developed by hecter fuel is the same as that developed by export aviation gasoline at about 1,800 r.p.m. at all altitudes. At lower speeds differences in the power developed by the fuels become evident. Comparisons at ground level were omitted to avoid any possibility of damaging the engine by operating with open throttle on gasoline at so high a compression. The fuel consumption per unit power based on weight, not volume, averaged more than 10 per cent greater with hecter than with x gasoline. The thermal efficiency of the engine when using hecter is less than when using gasoline, particularly at higher speeds. A generalization of the difference for all altitudes and speeds being 8 per cent. A general deduction from these facts is that more hecter is exhausted unburnt. Hecter can withstand high compression pressures and temperature without preignition. (author).
Results of Tests on Radiators for Aircraft Engines
Part 1 is to present the results of tests on 56 types of core in a form convenient for use in the study of the performance of and possible improvements in existing designs. Working rules are given by which the data contained in the report may be used, and the most obvious conclusions as to the behavior of cores are summarized. Part 2 presents the results of tests made to determine the pressure necessary to produce water flows up to 50 gallons per minute through an 8-inch square section of radiator core. These data are of special value in evaluating the hydraulic head against which the circulating pump is required to operate.
Power Characteristics of Fuels for Aircraft Engines
Report presents the summation of results obtained in the testing of fuels of various compositions and characteristics in the altitude laboratory. The data upon which this report is based has had an important influence upon the writing of specifications for the various grades of aviation fuels.
The application of propeller test data to design and performance calculations
From Summary: "This report is a study of a test data on a family of Durand's propellers (nos. 3, 7, 11, 82, 113, 139), which is fairly representative of conventional design. The test data are so plotted that the proper pitch and diameters for any given set of conditions are readily obtained. The same data are plotted in other forms which may be used for calculating performance when the ratio of pitch to diameter is known. These new plots supply a means for calculating the performance, at any altitude, of airplanes equipped with normal or supercharged engines."
Charts for graphical estimation of airplane performance
This report contains a series of charts which were developed in order to simplify the estimation of airplane performance. Charts are given for estimating propeller diameter and efficiency, maximum speed, initial rate of climb, absolute ceiling, service ceiling, climb in 10 minutes, time to climb to any altitude, maximum speed at any altitude, and endurance. A majority of these charts are based on the equations given in NACA Technical Report no. 173. Plots of pressure and density against altitude in standard air are also given for convenience. It must be understood that the charts giving propeller diameter, maximum speed, initial rate of climb, absolute ceiling, and speeds at altitudes are approximations subject to considerable error under certain conditions. These particular charts should not be used as a substitute for detailed calculations when accuracy is required, as, for example, in military proposals. (author).
The effect of flight path inclination on airplane velocity
This report was prepared at the request of the National Advisory Committee for Aeronautics in order to supply a systematic study of the relations between the flight velocity V and its horizontal component V subscript H, in power glides. Curves of V and V subscript H plotted against the inclination of the flight path 0 are given, together with curves which show the maximum values of V subscript H and the corresponding values of 0. Curves are also given showing the effect of small departures from the horizontal in high speed performance testing.
Engine performance and the determination of absolute ceiling
From Summary: "This report contains a brief study of the variation of engine power with temperature and pressure. The variation of propeller efficiency in standard atmosphere is obtained from the general efficiency curve which is developed in NACA report no. 168. The variation of both power available and power required are then determined and curves plotted, so that the absolute ceiling may be read directly from any known sea-level value of the ratio of power available to power required."
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