A ram air turbine (RAT) is a small wind turbine that is installed in an aircraft to be used as a source of power during emergencies. These turbines are connected to an electrical generator or a hydraulic pump and use the airstream to generate power by ram pressure from the aircraft’s speed. More power is generated when the aircraft is operating at a higher speed and less is generated when operating at lower speeds.
Present-day aircraft will generally only use RATs in an emergency where both the primary and secondary power sources are lost. If this occurs, the RAT is used to power the aircraft’s crucial systems such as flight controls, instruments, and hydraulics. Some types of RATs will only produce hydraulic power, which is then used to power generators.
RATs are commonly used in military aircraft as this type of aircraft must be fully prepared for emergencies, including a complete loss of power. RATs are also used in civilian aircraft, in emergency situations, and sometimes to even power centrifugal pumps, which are used to pressurize the spray systems on crop-dusting aircraft. In the United States, using a RAT in crop-dusting aircraft is especially convenient, as it allows an FAA-certified engine and an aircraft’s power systems to operate without modification.
RAM air turbines are the core of an aircraft’s emergency power system and have even helped save 1,700 lives in 16 documented emergency situations. In the event of a power loss, the RAT deploys from the wing or fuselage and derives power from the airstream to help control and land the aircraft. All in all, RAM air turbines are both useful and crucial in the aviation world, and in operating safe aircraft.