"An investigation of the suitability of the N.A.C.A. Roots type aircraft engine supercharger to flight-operating conditions, as determined the effects of the use of the supercharger upon engine operation and airplane performance, is described in this report. Attention was concentrated on the operation of the engine-supercharger unit and on the improvement of climbing ability; some information concerning high speeds at altitude was obtained. The supercharger was found to be satisfactory under flight-operating conditions. Although two failures occurred during the tests, the causes of both were minor and have been eliminated" (p. 207).

From title page: "For some years the Bureau of Mines, in connection with its investigations relating to efficiency in the combustion of fuels, as been engaged in a study of smoke prevention. Popular support for such work is usually based upon the injurious effects of smoke on the human ssytem, and this paper is published as a contribution to the literature dealing with that subject."

The TE-1 is designed for the economical training of pilots and is a single seat parasol cantilever monoplane. It is nearly entirely made of wood, using a 40 HP. air-cooled Salmson A.D. 9 engine, and weighs 255 kg empty.

Summary of physiography and life zones and mammals of North Dakota.

The Bugle is a twin engine tractor biplane. It features two Jupiter engines and oleo-pneumatic landing gear. Its maximum speed is 120 MPH.

In compressorless Diesel engines and in explosion engines using fuels with high boiling points it is difficult to effect a good combustion of the fuel mixture. This report presents different methods for calculating the size and uniformity of fuel droplets and mixtures.

This report presents a theoretical treatment of the vaporization process of medium and heavy oils. The results of this investigation, which were mostly obtained from the lighter components of the heavy fuels, require a 10- or 16-fold vaporization in comparison with gasoline. We must attain a still finer degree of atomization, in order to include the heavier components.

This report examines the cause and effect of the energy conversion in airless-injection engines. In order to obtain a criterion for the chosen working method, it takes into consideration the time relations between the individual processes. Observations of the engine alone do not suffice to obtain the necessary basis for a critical analysis of the processes.

"The results of this test show that the dynamic scale has very little effect on the drag coefficient of a disk over a wide range of Reynolds Number. A comparison of these results with those of tests made on a series of disks at Göttingen University furnishes a good check on the method of testing in this tunnel" (p. 1).

With three 230 HP. engines and all metal construction, the Roland, Rohrbach VIII is a passenger aircraft with seating for two pilots and 10 passengers. Details of the components, characteristics, performance data, drawings, and photographs are provided.

Purchased for the British Air Ministry, the Southampton seaplane uses 2 Napier Lion engines and has a boat hull with outriggers mounted on the wings. It was designed as a military aircraft and can be easily converted to a bomber. A description of the design, flight characteristics, and photographs and blueprints are provided.

Note presenting the resistances of a series of three similar disks placed normal to the wind as determined in the atmospheric wind tunnel. The curves of drag coefficient plotted against Reynolds number for this tunnel show discrepancies between overlapping values which are to be attributed to the presence of the tunnel walls.

From Introduction: "The airplane designer often finds it necessary, in meeting the requirements of visibility, to remove area or to otherwise locally distort the plan or section of an airplane wing. This report, prepared for the Bureau of Aeronautics January 15, 1925, contains the experimental results of tests on six 5 by 30 inch N-20 wing models, cut out or distorted in different ways, which were conducted in the 8 by 8 foot wind tunnel of the Navy Aerodynamical Laboratory in Washington in 1924. The measured and derived results are given without correction for vl/v for wall effect and for standard air density, p=0.00237 slug per cubic foot."

A product of the Air Navigation Engineering Co., the Missel Thrush is a light airplane suitable for private ownership. It is a two seat tractor fuselage biplane with single I interplane struts designed by J. Bewsher.

It seems desirable to have some simple method for calculating quickly and with sufficient accuracy: 1) the correct position of the center of gravity; 2) the requisite tail-group dimensions; 3) and the course of the wing and tail-group moments. In out deductions, we will first replace the biplane (disregarding the effect of stagger, decalage and induced drag) by an equivalent monoplane, whose dimensions and position in space can be approximately determined in a simple manner.

Built by the 'Czecho-Slovakian' aircraft factory, AVIA, the B.H. 21, has a top speed of 250 MPH, and carries 120 kg of gasoline and 20 kg of oil, giving it a radius of action of 600-650 km. It is equipped with a Hispano-Suiza engine capable of 300 HP. Details of the design, structure, wings, stabilizer, fuselage, controls, fuel tanks, landing gear, tail, characteristics, performances, drawings, and photographs are provided.

The staff and construction of the Institute are described as well as a variety of experiments and researches being conducted there. The six sections of the laboratory are described, including the Section for Theoretical Researches, Section for Aerodynamic Researches, Windmill Section, Section for Engine-Propeller Groups, Section for Material Testing, and Section for Instrument Making. Special attention is given to the various wind tunnels and testing facilities present.

Memorandum describing warning or correcting devices based on the registering of two distinct factors, the air speed and the angle of attack. The authors of the report define the conditions for the flight of an airplane and then study the causes of stalled flight in the different cases where it can occur.

Report presenting an investigation to determine the effect of tubing length on the indicated pressure values as ascertained in the pressure distribution measurements on the PW-9. The purpose was to determine the percentage of error in the pressure readings which might be caused by various lengths of tubing between the pressure orifices and pressure cell at the manometer. The differences in head caused by variations in the length of tubing are small, the lowest recorded being zero, the highest 2.7 percent.

The task of removing the boundary layer by suction consists in producing, in place of the ordinary flow with the formation of vortices, another kind of flow in which the vortices are eliminated by drawing small quantities of fluid from certain points on the surface into the interior of the body. The experiments with a sphere, which constitute the subject of this report, were made early in the present year .

Report discussing a case study of a coal company in Western Pennsylvania to show how mining companies might decrease their timber bills.

The Hamlet is a three engine high wing monoplane of comparatively small size, fitted with three Bristol Lucifer series IV engines of 130 HP. each, and designed to carry a pilot and four passengers. Details of the layout, wings, slot and flap gear, fuselage, characteristics, performance, and drawings are provided.

"The influence of different orifices on the result of measuring the same pressure distributions is the subject of this note. A circular cylinder is exposed to an air stream perpendicular to its axis and its pressure distribution is repeatedly determined. The pressures measured on the downstream half of the cylinder do not change for the orifice sizes used in the tests" (p. 1).

Report on how to identify good gasoline and kerosene, written for the average citizen, with an explanation of purchaser and supplier relationships.