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A balanced diaphragm type of maximum cylinder pressure indicator: A balanced diaphragm type of maximum cylinder pressure indicator was designed to give results consistent with engine operating conditions. The apparatus consists of a pressure element, a source of controlled high pressure and a neon lamp circuit. The pressure element, which is very compact, permits location of the diaphragm within 1/8 inch of the combustion chamber walls without water cooling. The neon lamp circuit used for indicating contact between the diaphragm and support facilitates the use of the apparatus with multicylinder engines.
English Airplane Construction: English airplane construction is presented with a particular emphasis on metal construction techniques. Steel rib and fuselage construction are discussed as well as the use of duralumin in construction.
Experiments with a model water tunnel: This report describes a model water tunnel built in 1928 by the NACA to investigate the possibility of using water tunnels for aerodynamic investigations at large scales. The model tunnel is similar to an open-throat wind tunnel, but uses water for the working fluid.
The Fiat "TR.1" Training and Touring Airplane (Italian): A Two-Place High-Wing Monoplane: Circular presenting a description of the Fiat T.R.1 airplane, which has been created for training and long-distance touring. Information regarding the fuel tanks, aircraft design, controls, tail characteristics, and flight characteristics is provided.
The Handley Page Type 42 Commercial Airplane (British): A Metal Sesquiplane: Circular presenting a description of the Handley Page 42, which is an all-metal sesquiplane. Details are provided of the cockpit, wings, fuselage, tail, power plant, landing gear, controls, and flying qualities.
Riveting in Metal Airplane Construction Part 1 : Riveting Methods and Equipment in German Metal Airplane Construction: "Although all constructors in Germany use duralumin quite frequently, and prefer cold riveting exclusively for permanent (nondetachable) connections of individual structural components, their methods and equipment are very diversified. The differences are due to a great extent to the diversity of structural types and to the special shapes of the individual subassemblies. The results is that different manufacturers have developed totally different riveting methods, as well as entirely different working methods" (p. 1).
Riveting in Metal Airplane Construction Part 2: Riveting Methods and Equipment (Concluded), Strength of Riveted Joints in Duralumin: This report includes descriptive material on rivet inspection, types of rivets and sizes. Tabular data on shearing strength of rivets at failure, ultimate shear of various rivets, tensile tests of rivet plate, and tensile strength values of riveted joints are provided.
Riveting in Metal Airplane Construction Part 3: Strength of Riveted Joints in Duralumin (Continued), Test Installation and Arrangement: This report includes strength of riveted joints in duralumin, descriptions of test procedure and results of tests. Tabulated data includes: curshing strength by failure for various conditions, shearing strength of hole edge zone in direction of tearing, tearing strengths of plates weakened by rivet holes, and enlargement of holes at beginning of break.
Riveting in Metal Airplane Construction Part 4: Strength of Riveted Joints in Duralumin (Concluded), Comparative Tests With Riveted Joints: Tests were made to determine the crushing strength of a riveted joint, in order to define the difference in crushing stregth between a strictly bolted joint and a riveted joint. The object was to tabulate the crushing strength by failure on various plate thicknesses for a one-rivet double-shear riveted joint.
Maneuverability investigation of an F6C-4 fighting airplane: "In order to compare the relative maneuverability of two fighting airplanes and to accumulate additional data to assist in establishing a satisfactory criterion for the maneuverability of any airplane, the National Advisory Committee for Aeronautics has conducted maneuverability investigations on the F6C-3 (water-cooled engine) and the F6C-4 (air-cooled engine) airplanes. The investigation made on the F6C-3 airplane was reported in NACA-TR-369. This report contains the results of the investigation made on the F6C-4 airplane" (p. 475).
Coal-Mine Fatalities in November, 1930: Report issued by the U.S. Bureau of Mines on the fatalities of coal miners in November, 1930. The common causes of death, and the location of the mines that the fatalities occurred in are listed. This report includes tables.
Development of a Non-Autorotative Airplane Capable of Steep Landing: In the following we develop a non-autorotating monoplane wing. The conditions imposed on such a wing, aside from its freedom from autorotation,with respect to its polars and its construction, are taken into account as far as possible. It is indicated that the autorotation characteristics of a wing are dependent upon the speed of air flow as well as on the angle of yaw. This report postulates the knowledge of the behavior of certain conventional wings of different chords and cambers with respect to their air loads at large angles of attack.
The effectiveness of a double-stem injection valve in controlling combustion in a compression-ignition engine: An investigation was made to determine to what extent the rates of combustion in a compression-ignition engine can be controlled by varying the rates of fuel injection. The tests showed that the double-stem valve operated satisfactorily under all normal injection conditions; the rate of injection has a definite effect on the rate of combustion; the engine performance with the double-stem valve was inferior to that obtained with a single-stem valve; and the control of injection rates permitted by an injection valve of two stages of discharge is not sufficient to effect the desired rates of combustion.
Factors Influencing Flow of Natural Gas Through High-Pressure Transmission Lines: Report issued by the U.S. Bureau of Mines on the effects of different operating conditions on high-pressure natural gas pipelines. Analysis of past and current studies on natural gas transmission are presented. This report includes tables, graphs, and an illustration.
Goldstein's Solution of the Problem of the Aircraft Propeller With a Finite Number of Blades: This report examines the Betz theory on frictionless, lightly loaded propellers and Prandtl's addendum extended to moderately loaded propellers. The author then goes on to extend the discussion to Goldstein's solution for propellers with a finite number of blades.
The interference effects on an airfoil of a flat plate at mid-span position: "This report gives the results of an investigation of the mutual interference of an airfoil and a flat plate inserted at mid-span position. The tests were conducted in the Variable-Density Wind Tunnel of the National Advisory Committee for Aeronautics at a high value of the Reynolds Number. The interference effects of this combination were found to be small. Supplementary tests indicated that the use of fillets decreases both the lift and drag slightly. A bibliography of publication dealing with interference between wings and bodies, and with the effects of cut-outs and fillets is included" (p. 1).
Liquid Cooling of Aircraft Engines: This report presents a method for solving the problem of liquid cooling at high temperatures, which is an intermediate method between water and air cooling, by experiments on a test-stand and on an airplane. A utilizable cooling medium was found in ethylene glycol, which has only one disadvantage, namely, that of combustibility. The danger, however is very slight. It has one decided advantage, that it simultaneously serves as protection against freezing.
Mammals of New Mexico: Summary of the species of mammals native to New Mexico, including a map of the life zones, descriptions of the physiographic features, and lists of characteristic zone-marking plants, birds, mammals.
Method of Determining the Weights of the Most Important Simple Girders: "This paper presents a series of tables for the simple and more common types of girders, similar to the tables given in handbooks under the heading "Strength of Materials," for determining the moments, deflections, etc., of simple beams. Instead of the uniform cross section there assumed, the formulas given here apply only to girders of "uniform strength," i.e., it is assumed that a girder is so dimensioned that a given load subjects it to a uniform stress throughout its whole length. This principle is particularly applicable to very strong structures" (p. 1).
The Supermarine S.6.B. Racing Seaplane (British): A Low-Wing Twin-Float Monoplane: Circular presenting a description of the Supermarine S.6.B. racing seaplane, which was the winner of a seaplane contest. Information regarding the oil system, water system, fuel system, floats, and controls are provided.
Tests of N.A.C.A. airfoils in the variable density wind tunnel Series 44 and 64: This note is one of a series covering an investigation of a number of related airfoils. It presents the results obtained from tests in the N.A.C.A. Variable Density Wind Tunnel of two groups of six airfoils each. One group, the 44 series, has a maximum mean camber of 4 percent of the chord at a position 0.4 of the chord behind the leading edge and the other group, the 64 series, has a maximum mean camber of 6 percent of the chord at the same position. The members within each group differ only in maximum thickness, the maximum thickness/chord ratios being: 0.06, 0.09, 0.12, 0.15, 0.18, and 0.21. The results are analyzed with a view to indicating the variation of the aerodynamic characteristics with profile thickness for airfoils having a certain mean camber line form.
Wind Tunnel of the Bucharest Polytechnic Institute: This report describes the Bucharest wind tunnel and presents numerous photographs and diagrams. The wind tunnel is of the closed- circuit type, the return being symmetrical with respect t o the longitudinal axis of the tunnel. Th e tunnel is of the horizontal type with a diameter of 3. 2 m (10. 5-ft.) a t the beginning of the entrance cone, and 1.5 m ( 4,92 ft.) at the entrance to the test chamber. The latter, 2 m (6.56 ft.) long, may be either of the open-jet type or enclosed in a cylindrical housing.
Wind-Tunnel Research Comparing Lateral Control Devices, Particularly at High Angles of Attack 1: Ordinary Ailerons on Rectangular Wings: "This report is the first in a series in which it is intended to compare the relative merits of all ordinary and some special forms of ailerons and other lateral control devices in regard to their effect on lateral controllability, lateral stability, and airplane performance. The comparisons are based on wind-tunnel test data, all the control devices being fitted to model wings having the same span, area, and airfoil section, and being subjected to the same series of force and rotation tests. The results are given for five different aileron movements: one with equal up-and-down deflection, one with average and one with extreme differential motion, one with upward deflection only, and one with the ailerons arranged to float with respect to the wing" (p. 357).
Automatic Stability of Airplanes: It is endeavored in this report to give a full outline of the problem of airplane stability and to classify the proposed solutions systematically. Longitudinal stability, which can be studied separately, is considered first. The combination of lateral and directional stabilities, which cannot be separated, will be dealt with later.
Flight tests to determine the effect of a fixed auxiliary airfoil on the lift and drag of a parasol monoplane: Comparative flight tests were made with a small parasol monoplane in which the aerodynamic characteristics of the airplane were determined with the normal wing and with an auxiliary airfoil installed.
The Gaseous Explosive Reaction at Constant Pressure: Further Data on the Effect of Inert Gases: An investigation of gaseous explosive reactions is discussed in this report. Measurements were taken to calculate the maximum flame temperature attained and making correlations with existing thermal data on this reaction.
Meteorological Conditions During the Formation of Ice on Aircraft: These are the results of a number of records recently secured from autographic meteorological instruments mounted on airplanes at times when ice formed. Ice is found to collect on an airplane only when the airplane is in some form of visible moisture, such as cloud, fog, mist, rain. etc., and the air temperature is within certain critical limits. Described here are the characteristics of clear ice and rime ice and the specific types of hazards they present to airplanes and lighter than air vehicles.
The pressure distribution over a long elliptical wing tip on a biplane in flight: This note presents the results of flight pressure-distribution tests on the right upper wing panel of a Douglas M-3 airplane equipped with an elliptical tip of length equal to the wing chord. The results are given in such form that the load distribution for any normal-force coefficient within the usual range encountered in flight may easily be determined.
Photomicrographic studies of fuel sprays: A large number of photomicrographs of fuel sprays were taken for the purpose of studying the spray structure and the process of spray formation. They were taken at magnifying powers of 2.5, 3.25, and 10, using a spark discharge of very short duration for illumination. Several types and sizes of nozzles were investigated, different liquids were used, and a wide range of injection pressures was employed. The sprays were photographed as they were injected into a glass-walled chamber in which the air density was varied from 14 atmospheres to 0.0013 atmosphere.
The characteristics of 78 related airfoil sections from tests in the variable-density wind tunnel: An investigation of a large group of related airfoils was made in the NACA variable-density wind tunnel at a large value of the Reynolds number. The tests were made to provide data that may be directly employed for a rational choice of the most suitable airfoil section for a given application. The variation of the aerodynamic characteristics with variations in thickness and mean-line form were systematically studied. (author).
Charts for determining the pitching moment of tapered wings with sweepback and twist: From Summary: "This report presents a convenient method for calculating the pitching-moment characteristics of tapered wings with sweepback and twist. The method is based on the fact that the pitching-moment characteristics of a wing may be specified by giving the value of the pitching moment at zero lift and the location of the axis about which the axis is constant. Data for calculating these characteristics are presented by curves which apply to wings having a linear distribution of twist along the span and which cover a large range of aspect ratios. The curves are given for wings having straight taper and distorted elliptical plan forms. The characteristics of wings of other shapes may be determined by interpolation."
The D.H. 85 "Leopard Moth" Airplane (British): A Three-Seat Cabin High-Wing Monoplane: Circular describing the De Havilland "Leopard Moth", which is a three-seat cabin high-wing monoplane with a good cruising speed and fuel efficiency. Details of the components, controls, characteristics, performance, drawings, and photographs are provided.
The Dewoitine D.332 Commercial Airplane (French): A Three-Engine All-Metal Low-Wing Monoplane: Circular describing the Dewoitine D.332, which is a commercial three-engine all-metal low-wing monoplane form France. Details of the construction history, wing, fuselage, power plant, landing gear, characteristics, performance, drawings, and photographs are provided.
The Drag of Streamline Wires: "Preliminary results are given of drag tests of streamline wires. Full-size wires were tested over a wide range of speeds in the N.A.C.A. high speed tunnel. The results are thus directly applicable to full-scale problems and include any compressibility effects encountered at the higher speeds. The results show how protuberances may be employed on conventional streamline wires to reduce the drag, and also show how the conventional wires compare with others having sections more like strut or symmetrical airfoil sections" (p. 1).
The effect of spray strips on a model of the P3M-1 flying boat hull: This note presents the results of a series of tests made in the N.A.C.A. tank on a one-sixth full-size model of the hull and side floats of the Navy P3M-1 flying boat for the purpose of finding a method of reducing the amount of spray thrown into the propellers of this craft when taking off and landing. The model was tested without spray strips and with five different spray-strip arrangements. The best arrangement was an improvement over the bare hull with no spray strips, but the improvement was not sufficient to be satisfactory with the propellers in the designed position.
The Flight of an Autogiro at High Speed: This report presents a method for computing the flight performance of an autogiro at high speed, the velocity component along the blades being accounted for by calculation of the profile drag and the equation for zero torque.
Flight Tests on the Lateral Control of an Airplane having a Split Flap which Retracts Ahead of Conventional Ailerons, Special Report: "Since the recent more or less extensive adoption of high-lift flaps on airplane wings, the problem of providing satisfactory lateral control without sacrificing a part of the span of the flaps has become one of some importance. The difficulties have been largely a matter of obtaining satisfactory rolling moments with a smoothly graduated action, together with sufficiently small control forces throughout the entire speed range. As part of an investigation including several different lateral-control arrangements to be used with split flaps, the tests reported in this paper were made on one arrangement in which conventional ailerons of narrow chord are used, and a split flap is retracted into the under surface of the wing forward of the ailerons" (p. 1).
Practical Experiences With Lightning Discharges to Airplanes: The present report describes many cases of airplanes being struck by lightning and the measures that can be taken to minimize damage to them. The data indicates that the hazard to airplanes from lightning is overestimated and that dangers can be minimized by appropriate weather forecasts and training of the pilots.
The Reduction in Drag of a Forward-Sloping Windshield: "This paper gives results of a short investigation of the drag of a forward-sloping closed-cabin windshield. The drag of the windshield in both the original and a final modified form was determined from tests in the variable-density wind tunnel. The final form of the windshield was arrived at by modifying the original as the result of flow observations in the N.A.C.A. smoke tunnel. The investigation studied the utility of the N.A.C.A. smoke tunnel as applied to reducing the drag of objects for which the full dynamic scale could not be approached in the smoke tunnel, but designers should find the results of the flow observations and drag measurements of value" (p. 1).
Strength Tests of Thin-Walled Duralumin Cylinders in Pure Bending: "This report is the third of a series presenting the results of strengths tests on thin-walled cylinders and truncated cones of circular and elliptic section; it includes the results obtained from pure bending tests on 58 thin-walled duralumin cylinders of circular section with ends clamped to rigid bulkheads. The tests show that the stress on the extreme fiber at failure as calculated by the ordinary theory of bending is from 30 to 80 percent greater than the compressive stress at failure for thin-walled cylinders in compression. The tests also show that length/radius ratio has no consistent effect upon the bending strength and that the size of the wrinkles that form on the compression half of a cylinder in bending is approximately equal to the size of the wrinkles that form in the complete circumference of a cylinder of the same dimensions in compression" (p. 1).
Trend of Airplane Flight Characteristics: This report describes the development of airplane characteristics since the war and indicates the direction development should take in the immediate future. Some of the major topics include: the behavior of an airplane about its lateral, vertical, and longitudinal axes. Behavior at large angles of attack and landing characteristics are also included.
Working Charts for the Determination of Propeller Thrust at Various Air Speeds: A set of propeller performance charts, based on a torque speed coefficient has been constructed from full-sized metal propeller data obtained in the NACA propeller-research tunnel.
Effect of Viscosity on Fuel Leakage Between Lapped Plungers and Sleeves and on the Discharge From a Pump-Injection System: "Test data and analysis show that the rate of fuel leakage between a lapped plunger and sleeve varies directly with the density of the fuel, the diameter of the plunger, the pressure producing the leakage, and the cube of the mean clearance between the plunger and sleeve. The rate varies inversely as the length of the lapped fit and the viscosity of the fuel. With a mean clearance between the plunger and sleeve of 0.0001 inch the leakage amounts to approximately 0.2 percent of the fuel injected with gasoline and as low as 0.01 percent with diesel fuel oils" (p. 63).
Wing-Fuselage Interference, Tail Buffeting, and Air Flow About the Tail of a Low-Wing Monoplane: "This report presents the results of wind tunnel tests on a Mcdonnell Douglas airplane to determine the wing-fuselage interference of a low-wing monoplane. The tests included a study of tail buffeting and the air flow in the region of the tail. The airplane was tested with and without the propeller slipstream, both in the original condition and with several devices designed to reduce or eliminate tail buffeting. The devices used were wing-fuselage fillets, a NACA cowling, reflexed trailing edge of the wing, and stub auxiliary airfoils" (p. 143).
Aerodynamic Effects of a Split Flap on the Spinning Characteristics of a Monoplane Model: From Summary: "The investigation described in this report was made to determine the change in aerodynamic forces and moments produced by split flaps in a steady spin. The test were made with the spinning balance in the NACA 5-foot vertical wind tunnel. A low-wing monoplane model was tested with and without the split flaps in 12 spinning attitudes chosen to cover the probable spinning range. The results obtained indicate that the use of split flaps on an airplane is unlikely, in any case, to have much beneficial effect on a spin, and it might make the spin dangerous."
Air flow in a separating laminar boundary layer: Report discussing the speed distribution in a laminar boundary layer on the surface of an elliptic cylinder, of major and minor axes 11.78 and 3.98 inches, respectively, has been determined by means of a hot-wire anemometer. The direction of the impinging air stream was parallel to the major axis. Special attention was given to the region of separation and to the exact location of the point of separation. An approximate method, developed by K. Pohlhausen for computing the speed distribution, the thickness of the layer, and the point of separation, is described in detail; and speed-distribution curves calculated by this method are presented for comparison with experiment.
A complete tank test of the hull of the Sikorsky S-40 flying boat - American Clipper Class: The results of a complete test in the N.A.C.A. tank on a model of the hull of Sikorsky S-40 flying boat ('American Clipper') are reported. The test data are given in tables and curves. From these data non-dimensional coefficients are derived for use in take-off calculations and the take-off time and run for the S-40 are computed. The computed take-off time was obtained by the Sikorsky Aviation Corporation in performance tests of the actual craft.
Effect of Combustion-Chamber Shape on the Performance of a Prechamber Compression-Ignition Engine: "The effect on engine performance of variations in the shape of the prechamber, the shape and direction of the connecting passage, the chamber volume using a tangential passage, the injection system, and the direction of the fuel spray in the chamber was investigated using a 5 by 7 inch single-cylinder compression-ignition engine. The results show that the performance of this engine can be considerably improved by selecting the best combination of variables and incorporating them in a single design. The best combination as determined from these tests consisted of a disk-shaped chamber connected to the cylinder by means of a flared tangential passage" (p. 1).
The Effect of Weight and Drag on the Sinking Speed and Lift/Drag Ratio of Gliders: The most important factors in evaluating performance of gliders are minimum sinking speed and minimum gliding angle. To assure their optimum value the energy necessary for flight, that is, the energy of lift and friction must be kept very low, or in other words, weight and total drag which have a decisive effect on the sinking speed and on the gliding angle, must be kept to a minimum. How great the effect of a reduction of these two quantities will be shown in the following.
Tabulated Analyses of Texas Crude Oils: Report issued by the U.S. Bureau of Mines covering the crude oils from different regions of Texas. Analysis of the properties of each oil sample from the different regions of the state are presented. This report includes tables, and a map.

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