In Partnership With

August 1, 1918

Determination of Permeability of Balloon Fabrics*

Conventional Propeller Calculations

News of the Fortnight

3031

Determination of Permeability of Balloon Fabrics*

1—Introduction One of the most essential characteristics of a balloon envelope is that it shall be gas tight, or nearly so. Therefore the determination of the permeability of balloon fabrics to hydrogen, which is the gas used in the modern dirigible and kite balloons, is of first importance in determining their suitability for balloon construction.

2021

Conventional Propeller Calculations

Under war conditions, when there is lack of time for extensive propeller trials and experimental work, we must be able to predict the performance of a propeller as to the horsepower absorbed at given airplane and engine speeds and as to its efficiency under these conditions.

3839

News of the Fortnight

Bristol Production Discontinued When Archer A. Landon, Chief of the Production Division, Bureau of Aircraft Production, was in Buffalo, N. Y., last week, he ordered the discontinuance of the manufacture of Bristol fighting planes. Later he prepared the following statement for publication : “Early last year it was decided, when the demand for twoseated fighters was great, to put into production at the Curtiss Co. an adaptation facsimile of the Bristol fighter, an English battle plane, fitted to a 12-cylinder Liberty motor.
2627

The De Haviland-iv Biplane*

This large airplane employed for long distance reconnaissance and for bomb dropping, is chiefly built by the Aircraft Manufacturing Co., Ltd. (England). The different machines show minor differences in construction and outfitting according to the time of construction.
3435

The Roland D.ii Biplane*

This single-seater pursuit biplane made its first appearance on the Western front in March, 1917, and is still being used to some extent by the enemy, particularly on the Eastern sectors. A description of this machine, therefore, appears to be of timely interest.
3637

Skilled Workmen May Be Retained

3839

Digest of the Foreign Aeronautical Press

New Type of Observation Balloon—A new type of observation balloon has just been produced in Italy to the designs of Signor Prassone, director of the Italian Army Aircraft Works, and Major Avorio, chief of the Aerostatic Section of the Italian army.
3637

Cost of the Air Mail Service

The first tabulated report on the operation and maintenance of the air mail service has just been released by Otto Praeger, second assistant postmaster-general, and is printed in the accompanying tables. The report covers the period from the start of the service, on May 15, to the end of that month.
3637

Aeronautical Patents

July 151918 August 151918