Position Fixing in Aircraft During Long Distance Flights Over the Sea

Air navigation has so far been only by dead reckoning; with long distance flights overseas such methods are no longer adequate.—Methods of position fixing by astronomical observations.—Difficulties of taking sights in the air.— Visibility of the horizon.—Cloud horizons.—“Dip.”—The Baker Air Sextant.— Gravity controlled vertical for sight taking.Difficulties of working out the observations in the air.—The navigation machine.—Curves of constant altitude and constant position angle.—The equations of their mercator projections.—The radii of curvature.—Error of declination treated as a correction to altitude.—Special slide rule.—Star curves.—Chronometers for air work.—Practical construction of altitude and position angle curves.—Checks upon the accuracy.Run between sights.—Theoretical case.

Aero-Engine Efficiencies

By the efficiency of a petrol engine, one usually understands the thermal efficiency, or the ratio of the heat returned as work on the crank shaft, to the heat energy in the fuel. This efficiency is vitally important in an aero engine intended for long-distance work, since it directly affects the weight of fuel to be carried.The necessity for a high thermal efficiency on the B.H.P. almost of necessity involves that of a high mechanical efficiency, that is it requires that the losses due to mechanical friction and to pumping losses shall be small.But an engine may have a high thermal efficiency and yet have a comparatively low brake mean effective pressure. It may, owing to too small a valve area or to poor design of the induction system, only be able to draw a small weight charge into the cylinder, although it may use this very efficiently once it is in the cylinder.

Calculation of Stresses in Aeroplane Wing Spars

The following method of calculating the stresses in the spars of an aeroplane wing is essentially a simplification in form of the method given in the paper “Some Contributions to the Theory of Engineering Structures, with special reference to the Problem of the Aeroplane,” by Messrs. H. Booth and H. Bolas, issued by the Air Department of the Admiralty in April, 1915.