equipment added. As the load is increased so must the
surface area of the planes be increased. Just what this
increase in surface area should be is problematical as
experienced aviators disagree, but as a general proposition
it may be placed at from three to four times the area of
a 20-foot glider.[3]

[3] See Chapter XXV.

Some Practical Examples.

The Wrights used a biplane 41 feet in spread, and 6 1/2
ft. deep. This, for the two planes, gives a total surface
area of 538 square feet, inclusive of auxiliary planes.
This sustains the engine equipment, operator, etc., a total
weight officially announced at 1,070 pounds. It shows
a lifting capacity of about two pounds to the square
foot of plane surface, as against a lifting capacity of
about 1/2 pound per square foot of plane surface for the
20-foot glider. This same Wright machine is also reported
to have made a successful flight, carrying a total
load of 1,100 pounds, which would be over two pounds
for each square foot of surface area, which, with auxiliary
planes, is 538 square feet.

To attain the same results in a monoplane, the single
surface would have to be 60 feet in spread and 9 feet
deep. But, while this is the mathematical rule, Bleriot
has demonstrated that it does not always hold good.
On his record-breaking trip across the English channel,