Found this name from "Britain´s war machine" by David Edgerton and some info from the net: "The idea of the Helmover was that it ran for much of the time on or just under the surface (with a snort to provide air to the engine), under radio control from the aircraft which had dropped it (which would fly figure-of-eights at a safe distance above and behind it). On approach to the target it would be directed to submerge, the Meteor engine continuing to run via compressed air bottles. One problem was that it could not be guided when submerged. Speed was 40 knots (surfaced or submerged) range 50 miles on the surface, three miles submerged. It carried exactly one ton of explosives, which should have been enough to deal with any ship. For use against ships in harbours protected by booms, they were experimenting with a nose shaped to ride up over such obstacles. It was indeed sized to be carried in a Lancaster bomb-bay. There was a proposed ship-launched version which was much longer to provide more volume for fuel and oxygen cylinders. This measured 49'9" long and weighed 20,900 lb. Ranges were 150 miles surfaced, 8 miles submerged. I've no idea how they would have controlled that (perhaps a spotter plane) but it makes the 24" Long Lance look like a little toy..." Tony Williams O what a Big One! Air dropped Lancaster 38 inch T - The Great Planes and warbirds Community Wonder if anyone can give more info or a picture....