Question 10Motor Plants - QMED

The correct answer is C) The engine speed is equal to the propeller shaft speed. In a direct drive main propulsion arrangement, the engine is directly coupled to the propeller shaft, without any gearing or other speed-changing mechanisms in between. This means that the engine speed and the propeller shaft speed are the same - they rotate at the same rate. The engine speed is not variable or different from the propeller shaft speed, as the other answer choices suggest. The other options are incorrect because they do not accurately describe the relationship between the engine and propeller shaft speeds in a direct drive system. Option A is incorrect because the engine-to-propeller shaft speed ratio is fixed, not variable. Options B and D are incorrect because the engine speed is equal to, not greater than or lower than, the propeller shaft speed.