What is a RAM engine in aircraft?
A ramjet is a variant of an air breathing jet engine that does not include a rotary compressor; rather, it uses the engine’s forward motion to compress the incoming air. A ramjet cannot function at zero airspeed and therefore cannot be used to power an aircraft in all phases of flight. A variable geometry ramjet provides thrust over a wider range of velocities, but is much heavier. The maximum value of specific impulse is 4000 seconds. The ramjet was invented by Rene Lorin of France in 1913.
Does the Dreamliner have a RAM air turbine?
The ram air turbine (rat) is a backup power source installed on many modern aircraft, including the boeing 787. It deploys automatically or manually during a complete loss of electrical or hydraulic power, generating power from the airstream to operate essential flight systems. Rat systems in different aircraft models airbus rats are typically designed to provide both hydraulic and electrical power. They are integrated with one of the hydraulic systems and will drive an emergency generator.