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Squawk7777
16th Dec 2001, 22:27
Anybody know what the differences between Jet A, A-1, Jet B or Military JP-4, JP-5 and JP-8 are?

Don't remember that I have taken fuel types in my ground school classes ...
:D

4g_handicap
16th Dec 2001, 23:24
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 :-
clorific value must be high

combustion must be efficient under all conditions

engine start & inflight re-light must be easily possible

fuel & combustion products must not cause above-average engine deterioration

must possess sufficient lubrication properties for moving parts(eg engine pump)

must be easy to store, handle & pump, in particular at low airport temperatures


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 :D :D :D

Cardinal
17th Dec 2001, 08:19
An excellent thread on the topic can be found here: <a href="http://www.pprune.org/cgibin/ultimatebb.cgi?ubb=get_topic&f=3&t=002115" target="_blank">http://www.pprune.org/cgibin/ultimatebb.cgi?ubb=get_topic&f=3&t=002115</a> It started with Conquest fuel heaters but the tail end content is exactly what you're looking for. And the really handy stuff I'll paste here:

JET A/JET A1
Kerosene 100%
Napthalene 0.04%

JET B/JP-4
Kerosene 35-65%
Napthalene 35-65%
Benzene 0.1-0.4%

See the MSDSheets:

<a href="http://www.hess.com/about/msds/JetA_0325_clr.pdf" target="_blank">http://www.hess.com/about/msds/JetA_0325_clr.pdf</A>
<a href="http://www.hess.com/about/msds/Jp4_9947_clr.pdf" target="_blank">http://www.hess.com/about/msds/Jp4_9947_clr.pdf</A>
<a href="http://www.hess.com/about/msds/JP5_9942_clr.pdf" target="_blank">http://www.hess.com/about/msds/JP5_9942_clr.pdf</A>
<a href="http://www.hess.com/about/msds/JP8_HOV_4088_clr.pdf" target="_blank">http://www.hess.com/about/msds/JP8_HOV_4088_clr.pdf</A>

There, now the links should work.

[ 21 December 2001: Message edited by: Cardinal ]

[ 21 December 2001: Message edited by: Cardinal ]

[ 21 December 2001: Message edited by: Cardinal ]

[ 21 December 2001: Message edited by: Cardinal ]</p>

Flash2001
21st Dec 2001, 03:10
There's not very much napthalene in JP-4. JP-4 is a jet fuel first used by the military and was originally a very wide cut in the petroleum distillation process containing everything from lighter napthas to middle kerosenes. Now it may be a bit different.

Napthalene is better known as moth balls!

Prof2MDA
22nd Dec 2001, 10:30
On a related topic, does anyone have info on the comparison of volatility and/or vaporization rate of avgas to autogas? What are the additives in each and how do they compare?