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.

This research on the pressure variations in the injection system of the N.A.C.A. Spray Photography Equipment and on the effects of these variations on the motion of the timing valve stem was undertaken in connection with the study of fuel injection systems for high-speed oil engines. The methods of analysis of the pressure variations and the general equation for the motion of the spring-loaded stem for the timing valve are applicable to a spring-loaded automatic injection valve, and in general to all hydraulically operated valves. A sample calculation for a spring-loaded automatic injection valve is included.

"This report gives the results of the second portion of an investigation in the twenty-foot Propeller Research Tunnel of the National Advisory Committee for Aeronautics, on the cowling and cooling of a "Whirlwind" J-5 radial air-cooled engine. The first portion pertains to tests with a cabin fuselage. This report covers tests with several forms of cowling, including conventional types, individual fairings behind the cylinders, individual hoods over the over the cylinders, and the new N. A. C. A. complete cowling, all on an open cockpit fuselage. Drag tests were also made with a conventional engine nacelle, and with a nacelle having the new complete cowling" (p. 191).

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.

From Summary: "In Technical Report no. 247 of the National Advisory Committee for Aeronautics theoretical formulas are given from which was computed a table for the pressure of air on coming to rest from various speeds, such as those of aircraft and propeller blades. In that report, the table gave incompressible and adiabatic stop pressures of air for even-speed intervals in miles per hour and for some even-speed intervals in knots per hour. Table II of the present report extends the above-mentioned table by including the stop pressures of air for even-speed intervals in miles per hour, feet per-second, knots per hour, kilometers per hour, and meters per second."

From Introduction: "The increasing use of airplane wings equipped with ailerons and the importance of knowing the aerodynamic characteristics of tail units (empennages) provided with movable parts (rudders and elevators) impart some interest to the so-called "empirical profiles." For this purpose we thought best to employ the method proposed by Munk for the approximate theoretical study of thin, slightly curved profiles, assimilable, from an aerodynamic view-point, to their mean camber line."

"In the present paper I shall not consider the problem of the best arrangement of airplane and propeller, but only a simple method for designing a propeller for a given arrangement of airplane parts. The inflow to the propeller and hence the efficiency of the propeller is affected most by the fuselage. The effect of the wings and of the other parts lying in the propeller slip stream is much less and is also more difficult to determine" (p. 1-2).

This report tries to give a comprehensive survey of the most important propeller problems such as the shape of propellers and the effect of atmospheric conditions on propeller performance.

This report presents a brief survey of the uses of sheet-metal coverings in conjunction with the inner structure. A method of construction is presented as well as a discussion on the strength of sheet metal.

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.

The 127 is a cantilever monoplane without external bracing. It is designed to accompany and protect bombardment and observation aircraft. Descriptions of the airfoil, fuselage, power plant, landing gears, and armament are provided.

Part I of this paper covers the constructional design of metal flying-boat hulls and does not elaborate any further. Part II deals with the actual construction process of the hull.

As a rule, the actual lift distribution at the wing tips shows deviations from the theoretical distribution, so that an approximate evaluation of the distribution may be regarded as satisfactory. After a few brief remarks on the fundamentals of the exact computation, the method will be so presented that the lift distribution for deflected ailerons may be determined for other values of the parameter p from the results already obtained. Coefficients will then be given in the form of diagrams and numerical tables, from which the desired forces and moments can be easily obtained by substitution in the given equations.

An investigation on the cowling of radial air-cooled engines was conducted in the 20-foot Propeller Research Tunnel at Langley Field. Cooling and drag tests were made with each form of cowling. The propulsive efficiency was found to be practically the same with all forms of cowling.

The Goldfinch is equipped with the Bristol Jupiter Mark Vii engine. It is the all metal version of the Gloster Gamecock used by the R.A.F. A description of the construction, components, flying qualities, characteristics, drawings, and photographs are provided.

This report examines the take-off conditions of airplanes equipped with tractive propellers, and particularly the more difficult take-off of airplanes heavily loaded per unit of wing area (wing loading) or per unit of engine power (power loading).

"The results of an investigation to determine the pressures in the open cockpit of a Vought VE-7 airplane are given. The information has been considered valuable on account of its possible effect upon the operation of instruments, particularly altimeters, due to a variation from the true static pressure which is induced by the passage of the airplane through the air. The observed values are small and the effect upon instruments is inconsiderable" (p. 1).

The Villiers 24 C.A.N. 2 is a night pursuit sesquiplane equipped with the 450 HP direct-drive Lorraine 12 Eb engine. It is characterized by Handley Page slotted wings. Details of the construction, wings, flaps, controls, characteristics, performances, drawings, and photographs are provided.

"This report presents the results of an investigation undertaken in the 20-foot Propeller Research Tunnel at Langley Field on the cowling of radial air-cooled engines. A portion of the investigation has been completed, in which several forms and degrees of cowling were tested on Wright "Whirlwind" J-5 engine mounted in the nose of a cabin fuselage. The cowlings varied from the one extreme of an entirely exposed engine to the other in which the engine was entirely inclosed. Cooling tests were made and each cowling modified, if necessary, until the engine cooled approximately as satisfactorily as when it was entirely exposed" (p. 165).

The purpose of this report is to correlate, bring up to date, and put under a single cover all the information thought to be essential to an understanding of the formulas regarding bearing strength of wood under steel aircraft bolts and washers and other factors influencing fitting design.

The Ca 97 is constructed with wings half overhung, a large fuselage, all metal construction, and can be configured with 1 to 3 engines.

Tests were made to determine the effect of fillets between wings and fuselage on the drag and propulsive efficiency of a high-wing cabin monoplane. These tests were made in the 20-foot Propeller Research Tunnel of the National Advisory Committee for Aeronautics.

Evidences were found that neither gasification nor vaporization of the injected fuel occurs before ignition; also that the hydrogen coefficient has no significance. However the knowledge of the ignition point and of the "time lag" is important. After ignition, the combustion proceeds in a series of reactions, the last of which at least are now known.

The question of whether the fuel should be adapted to the engine or whether it is possible to improve equipment such as carburetors and engines so that as much of the crude oil as possible may be used without further transformation is examined in this report. Various ignition points and fuel mixtures are investigated in this regard.