Hello,
I have recently aquired a book called"Jet Engines" by Klaus Hunecke ISBN 0-7603-0459-9 and it says this about fuels :-
Aircraft have a broad operating envelope extending from normal ambient conditions at take-off and landing to very low atmospheric pressures and temperatures at cruising altitutes. In order to do this job, fuel requirements are as follows :-
The book goes on to describe each aspect in detail eg when the sulphur content of the fuel burns, it creates sulphur dioxide which combines with water to form sulphuric acid which is corrosive and therefore the sulphur content in fuel must not exceed 0.4%
Anyway nuff said about those aspects, the book furthers says that all turbine fuels are refinery products from crude oil, which
differ mainly in freezing point, volatility and flashpoint.
As an example low volatility is required in high performance military aircraft, which climb rapidly to altitude, but must not suffer fuel loss from low ambient pressure evaporation. These aircraft use JP-4.
Aircraft operating on aircraft carriers use JP-5 where a higher flashpoint of 60 deg C was called for.
High supersonic mach number aircraft(SR-71) require fuel that are thermally stable(meaning the fuel can absorb heat without producing carbon deposits in the heat exchanger or fuel nozzles) This is important because they use fuel to cool parts of the airframe heated by friction. JP-6 & JP-7 was the standard developed for these aircraft.
In civil aviation, Jet A1 is used witha freezing point of -50 deg C. This is mainly for long haul subsonic transport aircraft.
Am I brainy or what
