It has been found not difficult to keep down the weight of framework
and supporting surfaces to about a pound per square foot. The most
common ratio of surface to total weight is about one to two: so that
the machinery and operator will require one square foot of surface
for each pound of their weight. On this basis, the smallest possible
man-carrying aeroplane would have a surface scarcely below 250 square
feet. Most biplanes have twice this surface: a thousand square feet
seems to be the limit without structural weakness. Some recent French
machines, designed for high speeds, show a greatly increased ratio
of weight to surface. The _Hanriot_, a monoplane with wings upwardly
inclined toward the outer edge, carries over 800 pounds on less than
300 square feet. The Farman monoplane of only 180 square feet sustains
over 600 pounds. The same aviator's racing biplane is stated to support
nearly 900 pounds on less than 400 square feet.
[Illustration: THE TELLIER TWO-SEAT SIX-CYLINDER MONOPLANE AT
THE PARIS SHOW
One of this type has been sold to the Russian Government
(From _Aircraft_)]
Motor weights can be brought down to about two pounds per horse-power,
but such extreme lightness is not always needed and may lead to
unreliability of operation. The effect of an accumulation of ice,
sleet, snow, rain, or dew might be serious in connection with flights
in high altitudes or during bad weather. After one of his last year's
flights at Étampes Mr. Farman is said to have descended with an extra
load of nearly 200 pounds on this account. With ample motor power,
great flexibility in weight sustention is made possible by varying the
inclination of the planes. In January of this year, Sommer at Douzy
carried six passengers in a large biplane on a cross-country flight:
and within the week afterward a monoplane operated by Le Martin flew
for five minutes with the aeronaut and seven passengers, at Pau. The
total weight lifted was about half a ton, and some of the passengers
must have been rather light. The two-passenger Fort Myer biplane of
the Wright brothers is understood to have carried about this total
weight. These records have, however, been surpassed since they were
noted. Bréguet, at Douai, in a deeply-arched biplane of new design,
carried eleven passengers, the total load being 2602 pounds, and that
of aeronaut and passengers alone 1390 pounds. The flight was a short
one, at low altitude; but the same aviator last year made a long flight
with five passengers, and carried a load of 1262 pounds at 62 miles per
hour. And as if in reply to this feat, Sommer carried a live load of
1436 pounds (13 passengers) for nearly a mile, a day or two later, at
Mouzon. One feels less certain than formerly, now, in the snap judgment
that the heavier-than-air machine will never develop the capacity for
heavy loads.
[Illustration: A MONOPLANE
(From _Aircraft_)]