“It must take a terrific blast of air to start these babies on their way,” Stan said, running his hand along one of the big torpedoes.
“Yes, it does,” Sutherland replied. “But the air doesn’t have to move it far. It just expels it from the tube, where there are trigger catches which trip switches here on the torpedo to set its own machinery going.”
“Wonderful piece of mechanism, aren’t they?” March mused.
“Yes, they’re really little submarines with an explosive charge instead of a crew,” the executive officer agreed. “And the TNT takes up only a small space, really. Half the length is compressed air to drive the torp. It’s got to move pretty fast, you know, to get to the target accurately. There’s about four hundred horsepower packed into that little fellow there—from compressed air, heated by an alcohol flame, blowing like fury against two trim little turbines turning the propellers.”
“The aiming devices must be very accurate,” Stan said.
“Wonderful!” Sutherland exclaimed. “You probably know there’s a little whirling gyroscope that keeps the torp on the course which can be set by the operator in advance of firing. Then there’s the compensating chamber and pendulum to keep it at its proper depth. It can’t very well get off course.”
“But don’t you have to aim chiefly with the sub itself, sir?” March asked. “I mean—doesn’t the sub have to be aimed right at the target for the torpedo to get there?”
“Not at all,” Sutherland replied. “The sub doesn’t have to be any closer than sixty degrees in facing its target. You set the proper course on the torpedo itself and the automatic devices put it on that course right away—and keep it there!”
“Then the important thing,” Stan said, “is for the skipper to get the course right, not necessarily to line up the sub with his target.”
“That’s right,” the older officer agreed. “The skipper must determine the course to his target and call it out. If he’s good, he gets his ship.”