jet engines

[rcawthr]

What fuel do jet engines use

[rojash]

Kerosene.

[rcawthr]

If it is kerosene how come it is so explosive?

[heathfield]

Its flash point is 38�C and its auto-ignition temperature is 210�C. If a fuel tank ruptures and the kerosene spills onto the hot engine or is ignited by sparks, the burning fuel heats the kerosene next to it, vapourising it, and igniting it in turn. Any of the fuel so heated to over 210� will ignite spontanously. Woosh!

[sarnieken]

Kerosene is used in commerical jet and turboprop engines. Naptha-type fuel is used in military applications and is rated according to its various points of ignition. These are JP numbers, similar to Octance numbers in road fuel. Jets like the Lockheed SR-71 Blackbird use JP-7 where commercial jets use lesser rated fuels.

On a side note, Naptha was one of the ingredients of the devestatingly effective Napalm bomb that was used heavily in Vietnam.

Hope this helps.
K

[rcawthr]

I don't know whether this is the correct teminology has kerosene got a higher calorific value than petrol.?

If it were heating oil there would be 28 second oil and 32 second oil what is the difference.

[heathfield]

Calories aren't really the measure for energy. It's Joules. Liquid fuels are rated in Joules per gram weight. Thus petrol is rated at 50 kJ/g, kerosene at 48kJ/g, Diesel at 45kJ/g.

'28 second oil' is kerosene AKA paraffin. '32 second oil' is gas oil, AKA diesel. The numbers are a measure of the viscosity, describing the time it takes the oil to drain from a calibrated standard vessel.

[Gef]

Sarnie is talking a load of mince.

[heathfield]

Gef - no he isn't. So why do you think so?

[blade']

Gef is now researching google very extensivley trying to back up his comments regarding Sarnie.. and has since realised he may in fact be wrong himself.

[Gef]

Actually blade I have been at work all day.

The best place to look for information on aviation fuels is wikipedia. The JP type fuels are kerosene based (naphtha based fuels are too volatile and hence too dangerous) and the numbering system bears no relation to the octane (note the spelling) numbers used for petrol/gasoline type fuels.

Also, heathfield, calorific value is the correct scientific term even though energy values are now usually quoted in joules.

[Gef]

(Sorry clicked submit by mistake)

For liquid fuels it makes more sense to quote the calorific value per unit volume rather than per unit mass.

The figures I found on Wikipedia were (in MJ / litre):

gasoline 34.6; diesel 38.7 and kerosene (Jet A) 33.

Hope this helps and sorry for the dumb response after too many glasses of wine last night.