Getting Under Headway.
A bird, on first rising from the ground, or beginning its flight from
a tree, will flap its wings to get under headway. Here again we have
another illustration of the manner in which a flying machine gets under
headway—the motor imparts the force necessary to put the machine into
the air, but right here the similarity ceases. If the machine is to be
kept afloat the motor must be kept moving. A flying machine will not
sustain itself; it will not remain suspended in the air unless it is
under headway. This is because it is heavier than air, and gravity draws
it to the ground.
