Which engine configuration has the compressor and power section mounted on a common driveshaft?

Which engine configuration has the compressor and power section mounted on a common driveshaft?

• A. Direct Shaft Turbine
• B. Dual Rotor
• C. Feathering Axis
• D. Disk Area

Answer: (A)

The main idea here is how the engine’s drive system connects the compressor and the power section. When those two parts are mounted on a common driveshaft, they are mechanically tied together on one shaft, so the same shaft both drives the compressor and carries the power-turbine that provides output torque. This is known as a direct shaft turbine (a single-spool arrangement). This arrangement is straightforward and compact because there’s no separate, independent power-turbine shaft to decouple rotor speed from engine speed. However, it also means rotor speed is tightly linked to engine speed, with less flexibility to optimize each part independently. The other options don’t describe this setup: a dual-rotor configuration uses two separate shafts, feathering axis relates to blade pitch control rather than drivetrain, and disk area concerns the rotor disk, not engine shafting.

The main idea here is how the engine’s drive system connects the compressor and the power section. When those two parts are mounted on a common driveshaft, they are mechanically tied together on one shaft, so the same shaft both drives the compressor and carries the power-turbine that provides output torque. This is known as a direct shaft turbine (a single-spool arrangement).

This arrangement is straightforward and compact because there’s no separate, independent power-turbine shaft to decouple rotor speed from engine speed. However, it also means rotor speed is tightly linked to engine speed, with less flexibility to optimize each part independently.

The other options don’t describe this setup: a dual-rotor configuration uses two separate shafts, feathering axis relates to blade pitch control rather than drivetrain, and disk area concerns the rotor disk, not engine shafting.