As a result of Soviet experiments with a number of different devices for
destroying telephone and telegraph wire lines, the grappling iron was found to be
most effective. The plane used for the experiments was an IL-2 (Stormovik). It
was found that the breaking of wire in one span resulted in the destruction of
several adjacent spans.
Grappling irons, if not available, can be easily constructed in any field
workshop. If steel or iron rods are not obtainable, a grappling iron can be made
of four insulator knob supports (insulator hooks), .71 inch in diameter (figure 1). Four
hooks are welded together and formed into a grappling iron (figure 2). A
ring is made in the base. A .16- to .24-inch cable is then put through the ring and
spliced to form a strong loop. The other end of the cable is attached to the bomb
release lock of the airplane. This enables the pilot to drop the grappling iron on
the landing field when the mission is accomplished.
The mounting of the grappling iron on the plane is also very simple. The
cable is wound on a wooden block, from five to seven inches in diameter, and
about 12 inches long (figure 3). The block is tied to the fuselage; it is released
first, and then the pilot throws out the grappling iron. At 155 miles an hour, the
unwound cable forms an angle of 30° to 40° with the longitudinal axis of the
plane (figure 4) which is quite sufficient for the destruction of overhead wires.