rudder. The curtains at the ends
were intended to give lateral stability, which was further ensured by
setting the wings slightly inclined upwards from the centre, so that
when seen from the front they formed a wide V. This feature is still
to be found in many aeroplanes to-day and has come to be known as the
'dihedral.' The motor was at first of 24 horse-power, for which later a
50 horse-power Antoinette engine was substituted; whilst a three-wheeled
undercarriage was provided, so that the machine could start without
external mechanical aid. The machine was constructed of bamboo and
steel, the weight being as low as 352 lbs. The span was 40 feet, the
length being 33 feet, with a total surface of main planes of 860 square
feet. It will thus be seen--for comparison with the Wright machine--that
the weight per horse-power (with the 50 horse-power engine) was only 7
lbs., while the wing loading was equally low at 1/2 lb. per square foot.

The main features of the Santos-Dumont machine were the box-kite form of
construction, with a dihedral angle on the main planes, and the forward
elevator which could be moved in any direction and therefore acted in
the same way as the rudder at the rear of the Wright biplane. It had a
single propeller revolving in the centre behind the wings and was fitted
with an undercarriage incorporated in the machine.

The other chief French experimenters at this period were the Voisin
Freres, whose first two machines--identical in form--were sold to
Delagrange and H. Farman, which has sometimes caused confusion, the two
purchasers being credited with the design they bought. The Voisins, like
the Wrights, based their designs largely on the experimental work of
Lilienthal, Langley, Chanute, and others, though they also carried out
tests on the lifting properties of aerofoils in a wind tunnel of their
own. Their first machines, like those of Santos-Dumont, showed the
effects of experimenting with box-kites, some of which they had built
for M. Ernest Archdeacon in 1904. In their case the machine, which was
again a biplane, had, like both the others previously mentioned, an
elevator in front--though in this case of monoplane form--and, as in
the Wright, a rudder was fitted in rear of the main planes. The Voisins,
however, fitted a fixed biplane horizontal 'tail'--in an effort to
obtain a measure of automatic longitudinal stability--between the two
surfaces of which the single rudder worked. For lateral s