Ram air turbine

In normal conditions the RAT is retracted into the fuselage (or wing), and is deployed manually or automatically following complete loss of power.

RATs are common in military aircraft, which must be capable of surviving sudden and complete loss of power.

Some free-fall nuclear weapons, such as the British Yellow Sun and Red Beard, used RATs to power radar altimeters and firing circuits; these were a more reliable alternative to batteries.

As many as five AN/ALQ-99 systems with built in ram air turbines can be mounted on a Boeing EA-18G Growler, with two under each wing and one under the fuselage of the aircraft.

A typical large RAT on a commercial aircraft can be capable of producing 5 to 70 kW, depending on the generator.

RATs have also been used to power centrifugal pumps to pressurize the spray systems on aircraft that are used as crop dusters to deliver liquid agents to cropland.