"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).

"This report combines the wind tunnel results of tests on four control surface models made in the two wind tunnels of the Navy Aerodynamic Laboratory, Washington Navy Yard, during the years of 1922 and 1924, and submitted for publication to the National Advisory Committee for Aeronautics May 7, 1927. The purpose of the tests was to compare, first, the lifts and the aerodynamic efficiencies of the control surfaces from which their relative effectiveness as tail planes could be determined; then the elevator hinge moments upon which their relative ease of operation depended. The lift and drag forces on the control surface models were obtained for various stabilizer angles and elevator settings in the 8 by 8 foot tunnel by the writer in 1922; the corresponding hinge moments were found in the 4 by 4 foot tunnel by Mr. R. M. Bear in 1924" (p. 429).

In this report is described an experimental method which the writer has evolved for dealing with air-cooled engines, and some of the data obtained by its means. Methods of temperature measurement and cooling are provided.

Provides instructions for bridge-grafting to save fruit trees that have been damaged by rodents or disease.

In the closer investigation of the results obtained from a wing model with a rotary cylinder mounted in its leading edge (NACA TM's 307 and 354), the velocity distribution in the vicinity of the surface of the model was determined by a hot-wire anemometer. The results confirmed the belief that the rotary cylinder had considerable effect on the air flow, but demonstrated the fact that the direct influence of the cylinder is confined to a very thin layer in immediate proximity to the surface.

The Fiat C.R. 20 has an all metal frame covered with fireproof fabric, except for the area near the engines, which is covered in duraluminum. It is armed with 4 machine guns and is capable of 280 KPH.

A guide to fitting and alteration of commercial sewing patterns and finished clothing for women.

Ignition-chamber engines and their fuel injection systems are investigated. Specific details are provided for fuel-injection nozzles and fuel pumps are provided.

Societe Provencale de Constructions Aeronautiques, builder of the "Meteore 63" has constructed a three engine (biplane) seaplane which has met conditions for a seaworthy certificate of the first class. A description of the design, hull, tail, power plant, characteristics, performances, drawings, and photographs are provided.

"One of the most striking phenomena which accompany the flow of fluids such as air and water about bodies, is that of changes in character. This phenomena is still very little understood. We will first discuss the nature of these changes and then show that pure theory leads to a multiplicity of characters of flow, among which we will endeavor to indicate those bearing some analogy to experimental results" (p. 1).

Designed by Engineer Brunet, the 3C2 is an all metal monoplane with two engines and provision for six machine guns and 12 10 Kg. bombs. A description of the design, components, characteristics, flying qualities, drawings, and photographs are provided.

Circular presenting a description of the Avia B.H. 11, which is a two-seat, low-wing monoplane with a plywood fuselage. The report describes the structural details and flight performance and provides blueprints and photographs of the aircraft.