So far as
the aeroplane is concerned it is somewhat at a disadvantage as
compared with the airship, as the latter is able to hover over a
position, and, if a spring-gun is employed to impart an initial
velocity to the missile, there is a greater probability of the
projectile striking the target provided it has been well-aimed.
But even then other conditions are likely to arise, such as
air-currents, which may swing the missile to one side of the
objective. Consequently adequate allowance has to be made for
windage, which is a very difficult factor to calculate from
aloft.
Bomb-dropping from an aeroplane is even more difficult. If for
instance the aeroplane is speeding along at 60 miles an hour, the
bomb when released will have a speed in the horizontal plane of
60 miles an hour, because momentarily it is travelling at the
speed of the aeroplane. Consequently the shell will describe a
curved trajectory, somewhat similar to that shown in Fig. 7.
On the other hand, if the aeroplane is travelling slowly, say at
20 miles an hour, the curve of the trajectory will be flatter,
and if a head wind be prevailing it may even be swept backwards
somewhat after it has lost its forward momentum, and describe a
trajectory similar to that in Fig.
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