"The hot-wire anemometer suggests itself as a promising method for measuring the fluctuating air velocities found in turbulent flow. The only obstacle is the presence of a lag due to the limited energy input which makes even a fairly small wire incapable of following rapid fluctuations with accuracy. This paper gives the theory of the lag and describes an experimental arrangement for compensating for the lag for frequencies up to 100 or more per second when the amplitude of the fluctuation is not too great. An experimental test of the accuracy of compensation and some results obtained with the apparatus in a wind-tunnel air stream are described. While the apparatus is very bulky in its present form, it is believed possible to develop a more portable arrangement" (p. 359).

Autostability is the watchword of this tandem monoplane. The tandem design causes a natural flat flight pattern and it can also land and take off from very short runways. Details of the form, wings, ailerons, fuselage, characteristics, performances, drawings, and photographs are provided.

This report provides a description of an automatic control mechanism that consists of an automatic elevator control, aileron control, and a rudder control. Each automatic control can be independently switched on or off.

The ignition temperature, ignition lag, and ignition strength of simple and homogeneous fuels in combustion air of small oxygen content differ from what they are in air of greater oxygen content. In the case of small oxygen content, these fuels behave as if mixed unevenly. In the case of air with a definite oxygen content, the simple fuels have two ignition points, between which ignition takes place within a certain temperature range. The phenomena are explained by pyrogenous decomposition, comparison of the individual heat quantities, and the effect of the walls.

The F180 was designed for reliable long distance travel in stages of 500, 1000, 1500 km, carrying loads of 2500, 2000, and 1500 kg respectively. At maximum load it can carry 20 passengers.

The present article, which constitutes a continuation of the work of Von Baumhauer and Konig, will therefore be restricted to the fluttering of the tail surfaces and especially to oscillations of the horizontal empennage. This will also illustrate the characteristics of all other phenomena of fluttering.

In order to determine the first part of the flight path a new method is described which requires only one photographic camera.

This report shows how the actual performance of an airplane varies with air temperature when the pressure is held constant. This leads to comparatively simple methods of reducing observed data to standard conditions. The new methods which may be considered exact for all practical purposes, have been used by the Navy Department for about a year, with very satisfactory results. The report also contains a brief historical review of the important papers which have been published on the subject of performance reduction, and traces the development of the standard atmosphere. (author).

Memorandum exploring the concept that if fire safety is not to be acquired at the expense of the functioning reliability of the engine, we must try to burn fuels which are less inflammable at their temperature of utilization. A definition of temperature of utilization is explored and some examples for various types of fuels are given.

This report describes in detail the new propeller research tunnel of the National Advisory Committee for Aeronautics at Langley Field, Va. This tunnel has an open jet air stream 20 feet in diameter in which velocities up to 110 M. P. H. Are obtained. Although the tunnel was built primarily to make possible accurate full-scale tests on aircraft propellers, it may also be used for making aerodynamic tests on full-size fuselages, landing gears, tail surfaces, and other aircraft parts, and on model wings of large size. (author).

"Experiments with a two-stroke-cycle, crank case scavenging engine. Effect of systematic variation of the height of the scavenge and exhaust ports on the scavenging, as determined by gas analysis. The best results were obtained under conditions differing from the usual ones" (p. 1).

Made for an Australian buyer, the Canberra is capable of carrying a payload of 1900 lbs. with a top speed of 126 M.P.H. At 105-110 M.P.H. it has a range of about 475 miles. It has a single Jupiter VI engine.

"This note describes a simple and inexpensive method for determining the deflection of propeller blades under operating loads. Both the centrifugal force and air force loads are applied statically as a number of concentrated loads by means of weights and wires. Two methods of attaching the wires to the propeller blades have been tested, both giving approximately the same deflections. The method is considered useful for studying the deflections of propellers of different shapes under various operating conditions" (p. 1).

"In order to study the effect of the fuselage, landing gear, and engine on the air flow through the propeller, a survey was made in the plane of the Sperry Messenger propeller with the propeller removed. The tests were made in the 20-foot air stream of the propeller research tunnel of the National Advisory Committee for Aeronautics at Langley Field, Virginia. The variation of the velocity with distance from the center in the propeller plane was found to be appreciable and well worth consideration in the design of propellers" (p. 1).

"The assumption is made that a skeleton or cutaway center section is desirable for forward vision and to determine the effect of such mutilation upon performance the following work was done. The airplane used was a Vought VE-7 and in addition to the cutaway center section a system of end plates or fins was installed. Various conditions and combinations were investigated in level flight and in climb" (p. 1).

"The drag of a Sperry Messenger airplane with the wings removed, and also the drag of its various component parts, was measured in the 20-foot air stream of the N.A.C.A. propeller research tunnel at air speeds from 50 to 100 m.p.h. It was found that the three-cylinder radial air-cooled engine nearly doubled the drag of the bare fuselage, and the drag of the landing gear was about the same as that of the fuselage and engine combined" (p. 1).

These tables are intended to provide a standard method and to facilitate the calculation of the quantity of "Standard Helium" in high pressure containers. The research data and the formulas used in the preparation of the tables were furnished by the Research Laboratory of Physical Chemistry, of the Massachusetts Institute of Technology.

Since lightness is desirable in airplane construction, greater stresses must be tolerated than in other kinds of construction. It is therefore necessary to have a more accurate knowledge of the greatest stresses that may occur and of the actual properties of the materials used. The Aeronautic Research Laboratories took the limit of elasticity as the basis of the strength calculations. Many tests were made of different steels, woods, aluminum alloys, and fabrics.

This paper is the second of a series of notes, each of which presents the complete results of pressure distribution tests made at Langley Field by the National Advisory Committee for Aeronautics, on wing and tail ribs of the VE-7 and TS airplanes for a particular maneuver of flight. The results for pull-ups are presented in the form of curves which show the variation of pressure distribution, total loads, normal acceleration and center of pressure with respect to time.

"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).

A special protractor was designed and built with a view towards supplying a simple, inexpensive, practical, portable instrument for making measurements to detect propeller warpage under practically all conditions, without the use of auxiliary equipment, and without having to remove the propeller from the airplane. A detailed description is given of the protractor. Techniques for measuring are described. Directions are given on how to use the protractor to set detachable blade-type propellers on an airplane.

We propose to make a study of the difficulties in using stressed coverings and their appropriate solutions. Fatigue and buckling are also discussed.

The purpose of the experiments was to determine the difference in the strength of steel tubes welded by different methods, as compared with one another and also with unwelded, unannealed tubes, including; moreover, a comparison of the results obtained by experienced and inexperienced welders.

This research was undertaken in connection with a general study of the application of the fuel injection engine to aircraft. The purpose of the investigation was to determine the effect of four important factors in the design of a centrifugal type automatic injection valve on the penetration, general shape, and distribution of oil sprays. The general method employed was to record the development of single sprays 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. Investigations were made concerning the effects on spray characteristics, of the helix angle of helical grooves, the ratio of the cross-sectional area of the orifice to that of the grooves, the ratio of orifice length to diameter, and the position of the seat. Maximum spray penetration was obtained with a ratio of orifice length to diameter of about 1.5. Slightly greater penetration was obtained with the seat directly before the orifice.