useful load. The loading per square foot was, for biplanes, about 4-1/2,
and, for monoplanes, 6 lb.

On the outbreak of war, and until the end of 1914, of the ten types in
use--Avro, B.E., Bristol, Sopwith, Vickers, M. Farman, H. Farman,
Caudron, Morane, and Voisin--five were British and five were French and
all were fitted with French engines. The average horse-power was still
about 83, but the average maximum speed had risen to 74, and the minimum
had fallen to 41 miles per hour. The load averaged 609 lb.

A remarkable advance in machine and engine construction is shown by
referring to the tables for 1918. At the Armistice of the twelve
types--Avro, Bristol Fighter, Sopwith Snipe, S.E. 5a, de Havilland 4 and
9a, Vickers Vimy, Handley Page O/400 and V/1,500, Fairey Seaplane 3c, F.
2 A. and F. 5--all were British and, except the de Havilland 9a, which
had an American engine, were fitted with engines of British manufacture.
The F. 2 A., and F. 5, were twin-engined, while one, the Handley Page
V/1,500, was equipped with four engines. The average horse-power was per
engine, 344, and per machine, 516; the average maximum speed 111, and
the minimum 53-1/2 miles per hour, the climb to 6,500 feet was carried
out in 13 minutes and to 10,000 feet in 24 minutes with an average load,
including fuel for 5-1/2 hours, of 2,742 lb. The average ceiling was
15,500 feet; the loading per square foot about 8 lb.

The years following the Armistice have witnessed the conversion of
military machines and the development of new designs for commercial
purposes. In 1921 there were thirteen types fitted with British engines:
Avro, Bristol, de Havilland 4, 16 and 18, Vickers Vimy, Handley Page
O/400 and W. 8, B.A.T., Westland, Fairey, Supermarine and Vickers
Amphibians. No British machine had a foreign engine. The Vickers Vimy,
Handley Page O/400 and W. 8, which had a passenger-carrying capacity of
15, were twin-engined. The average horse-power was per engine, 387, and
per machine, 474; the average maximum speed 114, and the minimum 49,
miles per hour. With an average load of 2,467 lb., including fuel for
4-1/2 hours, 19 minutes was required for a climb to 10,000 feet. The
average loading per square foot was about 13 lb., and the average
ceiling 15,793 feet.

Before the war, in addition to the Royal Aircraft Factory, there were
only eight firms engaged, on a very small scale, in the manufacture of
aircraft in England, and an aero engine indust