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Old 02-15-2011, 04:07 PM   #6 (permalink)
Arragonis
The PRC.
 
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The passage involved is this :

Quote:
Later testing involved the use of an exhaust turbine which was a half-scale version of that used in the Whittle W.1 turbojet, the first British jet engine to fly. Unlike a conventional turbocharger the turbine was coupled to the engine's accessory driveshaft and acted as a power recovery device. It was thought that using the turbine would lower fuel consumption allowing the engine to be used in larger transport aircraft.
My reading of this is that it used a belt from a "turbine" (similar to a Turbo) to recover some power but not sure where the power went or how it was used although it seems to reduce fuel consumption somehow. Maybe it added a subtle jet to the aircraft or aided in turning the propeller. The latter seems likely as the next bit says

Quote:
This was confirmed during testing however failures due to severe overheating and drive shaft fractures were experienced.
Adding a belt to a turbo which has low inertia will increase the resistance of the turbo vs. exhaust pressure - so lag will increase. This is not an issue when you are piloting a propellor plane across the Atlantic - the engine will be running for 9+ hours at a constant speed. It is an issue when you need your turbo car to complete that overtake.

A key factor in a modern turbo car is responsiveness (i.e. reducing lag). Modern turbos have variable geometry to allow this to happen but its still not instant at low revs. Adding a belt will make this worse.

There is wasted energy in a turbo though. Most turbos make more boost than is required and this released. I've wondered about this being captured and then released at lower engine speeds to offset the lag effect.
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