One of the signs accompanying the buzz bomb. It reads
A Propeller Fuse
The small propeller unit on the tip of the
V-1 operated a cleverly designed mechanism that instructed the flying bomb when
it was over its target.
When the V-1 was in flight, the air stream would turn the propeller. As the
propeller turned, it operated a mechanism that counted the number of times the
propeller had rotated. The mechanism was set prior to firing by the launching
crew, based on careful calculations to determine the estimated number of
rotations the propeller would make prior to reaching the target.
When the prescribed number of propeller rotations was reached, the counter
would send a signal to the V-1's auto-pilot commanding the control surfaces to
send the flying bomb into a steep dive towards it target.
The V-1's final death dive was unintentionally silent. One of the only
engineering errors built into the V-1 occurred when it began its final dive.
Negative 'G' forces experienced by the craft during the initial part of the
dive starved the engine of fuel, shutting it off. Instead of diving into its
target under full power - which would have caused considerably more damage -
the flying bomb returned to Earth in a silent, unpowered, but still deadly