Type F Depth Charge (UK)
The British Type F Depth Charge was a small depth charges designed from scratch to be fired by a pneumatic gun. It is described in the Annual Report of the Torpedo School, 1915.
The charge was a club-like, streamlined charge suitable for use by bomb-throwers (guns worked by compressed CO2). Metal stabilizing fins were affixed to the back to help it fly efficiently.
A 1 pound initiator of Tetryl would set off 70 pounds of T.N.T. at 50 feet under action of a hydrostatic trigger. Vernon calculated that the danger radius was 25 feet. It was under trial in October 1915, and these were nearly completion by early December. The guns, firing on a fixed elevation on a turntable and trained by a hand spike, could throw the bomb up to 500 yards horizontally. Lower ranges were achieved by lower firing pressures, read off a gauge.
Similar to the Type D depth charge, a special primary safety gear in series with the main trigger, prevented initiation in water shallower than 10 feet.
- Annual Report of the Torpedo School, 1915. Plate 87.
- Annual Report of the Torpedo School, 1915. pp. 164-5, 174, Plates 73, 87.