This is the heart of an Auxiliary Power Unit once fitted in a Vulcan Bomber. Its main purpose was to provide the aircraft's electrical needs whilst on the ground and prior to starting the main engines but it could also be used in flight, in an emergency, as the back-up electrical source. The Vulcan was perhaps the forerunner for the current "Fly by Wire" system as it's duplicated set of control surfaces were all electrically operated.
This is my little bit of history which is currently undergoing some TLC and although its airborne days are over, it will run again - much to the delight of my neighbors within a 3 mile radius.
The 30 KVA alternator is powered by a 60 horsepower, single shaft, gas turbine engine which has much historical ancestry and was built by the Rover Car Company, with this particular unit constructed around 1967.
This is the same basic engine that was used in Rover’s “JET 1” gas turbine powered car which was road tested at the Silverstone race track in Northampton back in 1950. http://news.bbc.co.uk/onthisday/hi/dates/stories/march/8/newsid_2516000/2516271.stm
The rest of the mighty Vulcan may now have gone for scrap but this little apu, at least, will remain functional and live on for another generation at least.