rman aero
engine design, apart from the early Daimler and other pioneer makes.

At the outbreak of hostilities in 1914, thanks to subsidies to
contractors and prizes to aircraft pilots, the German aeroplane
industry was in a comparatively flourishing condition. There were about
twenty-two establishments making different types of heavier-than-air
machines, monoplane and biplane, engined for the most part with the
four-cylinder Argus or the six-cylinder Mercedes vertical type engines,
each of these being of 100 horse-power--it was not till war brought
increasing demands on aircraft that the limit of power began to rise.
Contemporary with the Argus and Mercedes were the Austro-Daimler,
Benz, and N.A.G., in vertical design, while as far as rotary types were
concerned there were two, the Oberursel and the Stahlhertz; of these the
former was by far the most promising, and it came to virtual monopoly
of the rotary-engined plane as soon as the war demand began. It was
practically a copy of the famous Gnome rotary, and thus deserves little
description.

Germany, from the outbreak of war, practically, concentrated on the
development of the Mercedes engine; and it is noteworthy that, with one
exception, increase of power corresponding with the increased demand
for power was attained without increasing the number of cylinders. The
various models ranged between 75 and 260 horse-power, the latter being
the most recent production of this type. The exception to the rule
was the eight-cylinder 240 horse-power, which was replaced by the 260
horse-power six-cylinder model, the latter being more reliable and but
very slightly heavier. Of the other engines, the 120 horsepower Argus
and the 160 and 225 horse-power Benz were the most used, the Oberursel
being very largely discarded after the Fokker monoplane had had its day,
and the N.A.G. and Austro-Daimler Daimler also falling to comparative
disuse. It may be said that the development of the Mercedes engine
contributed very largely to such success as was achieved in the war
period by German aircraft, and, in developing the engine, the builders
were careful to make alterations in such a way as to effect the least
possible change in the design of aeroplane to which they were to be
fitted. Thus the engine base of the 175 horse-power model coincided
precisely with that of the 150 horse-power model, and the 200 and 240
horse-power models retained the same base dimensions. It was estimated,
in