Turbo-compound engine

The turbine is usually mechanically connected to the crankshaft, as on the Wright R-3350 Duplex-Cyclone, but electric and hydraulic power recovery systems have been investigated as well.

A conventional gas turbine is fed high-pressure, high-velocity air, extracts energy from it, and leaves as a lower-pressure, slower-moving stream.

Another World War II introduction was the use of the Meredith effect to recover heat from the radiator system to provide additional thrust.

[3] Blowdown turbines became relatively common features in the late- and post-war era, especially for engines designed for long overwater flights.

[6][7] The exhaust restriction imparted by the three blowdown turbines used on the Wright R-3350 is equal to a well-designed jet stack system used on a conventional radial engine, while recovering about 550 hp (410 kW) at METO (maximum continuous except for take-off) power.

It was realized in many cases the power produced by the simple turbine was approaching that of the enormously complex and maintenance-intensive piston engine to which it was attached.