The marine turbine of a destroyer produces 5000 horsepower while rotating 25 thousand revolutions per minute (rpm). But the ship propellers work best while rotating as 180 rpm.
Were the gear to operate ideally, what would be the output torque?
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The marine turbine of a destroyer produces 5000 horsepower while rotating 25 thousand revolutions per minute (rpm). But the ship propellers work best while rotating as 180 rpm. Consequently the power of the turbine is passed through a reduction gear which changes its characteristics. The rotation rate is reduced and the torque of rotation is increased. These gear boxes are necessary but inefficient. Our sketch shows a reduction gear in operation.
a) Were the gear to operate ideally, what would be the output torque?
b) For the actual gear, calculate: i) the torque, ii) the heat rate and iii) the efficiency delivered to the prop shafts?
To maintain constant speed, an airliner sets engines to 85% power then tips the nose up 5 degrees.