FYI:
Ram air turbine
https://en.wikipedia.org/wiki/Ram_air_turbine
Quote:
A ram air turbine (commonly known by the acronym RAT) is a small turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed of the aircraft.
With the exception of crop dusters (see below), modern aircraft only use RATs in an emergency—in case of the loss of both primary and auxiliary power sources the RAT will power vital systems (flight controls, linked hydraulics and also flight-critical instrumentation). Some RATs produce only hydraulic power, which is in turn used to power electrical generators. In some early aircraft (including airships), small RATs were permanently mounted and operated a small electrical generator or fuel pump.
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From the same link:
Quote:
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An Me 163B Komet, showing its nose-mount ram-air turbine.
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Again the same link as sourced:
Quote:
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Many modern types of commercial airliners are equipped with RATs. In the 1960s the Vickers VC10 was one of the first types of airliner equipped with a RAT. The Airbus A380 has the largest RAT propeller in the world at 1.63 metres (5.3 ft) in diameter, but around 80 centimetres (2.6 ft) is more common. A typical large RAT on a commercial aircraft can be capable of producing, depending on the generator, from 5 to 70 kW. Smaller, low airspeed models may generate as little as 400 watts.
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https://www.flickr.com/photos/bernd2011/7759518858
Airbus A380
http://a380flightdeck.tumblr.com/pos...am-air-turbine
Quote:
Ram air turbine (RAT).
A ram air turbine (commonly known by the acronym RAT) is a small turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed of the aircraft.
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An engineer would have to do the math for me, but I suspect for cars direct to the engine is going to be most efficient.
However, maybe if you are far from the main power source as with a train car or a caboose, and have a power requirement while underway, then it might make sense. Then again, train cars have wheels and axles, which could be mechanically/parasitically drawn upon for generator power, right?