SUBMARINE JET PROPULSION

Korero (AEWS), Volume 2, Issue 20, 9 October 1944, Page 17

SUBMARINE JET PROPULSION

Recent comments on the antiquity of jet propulsion remind a correspondent of the Manchester Guardian Weekly that although the idea may be comparatively new for air-borne traffic it is as old as the hills —if not older—where under-water locomotion is concerned. The cuttlefish and its kin have used it for untold ages. It is not commonly known that many fishes can travel at high speed with tail and fins quite motionless by means of jets of water expelled forcibly from the gill slits. Frank W. Lane, the naturalist, states that an examination of some three hundred swift-moving fishes revealed the fact that two hundred and seventy of them had gill slits placed in the exact position for the most efficient use of jet propulsion. In addition, the jets of water have the added advantage of creating what is known as “ induced streamlining ” along the body of the fish while it is in motion. When a fish wishes to apply the emergency brakes it simply puts its jet propulsion mechanism into reverse gear, sucking in water through the gill slits and ejecting it rapidly from the mouth.