Aviation Fuels

[SinUnNombre]

I dunno about methane as far as its volume goes.  I do know that both hydrogen and methane tend to have some pretty undesirable materials effects.  Methane, if I recall correctly, as used in air racers has to be flushed out of the plane's engine and fuel system at the end of each flight lest it corrode everything through.

Madoc

I'm not sure if this has been answered already, cause I haven't read every post yet, just skimmed. But anyway, the main reason for this is that methane will collect water out of the atmosphere, and when its burned, that water is left behind to corrode the engine, fuel system, etc. This can happen with any alcohol-based fuel as well. Straight alcohol, ethanol, methanol, etc. At least I think that's how I read it.

Jon


EDIT: Hobbes already answered this. See, I told you I just skimmed through.

[GTX]

Hi folks,

Interesting addition to this thread - here's what the USAF is doing on this front.

Regards,

Greg

[MartG]

While in the personal transportation arena, experiments in alternative fuelled vehicles is underway....

[ysi_maniac]

I am thinking about mix powered planes, Ryan Fireball/DarkShark and so.

Can different engines share the same fuel ?

I assume that turbo prop and turbojet can.
But piston (gasoline) and turbojet? I assume they cannot.

... and piston diesel and turbojet? I am not sure but I think I read that M1 Abrams uses the same diesel fuel of other armour. Am I wrong?

Thanks a lot,
Carlos.

[Archibald]

But piston (gasoline) and turbojet? I assume they cannot.

yep, Boeing KC-97s had separates tanks for their jets and pistons engines.  

[B777LR]

What fuel did Me-262s run on?

[Archibald]

What fuel did Me-262s run on?

I think the 262 had "ordinary" jet fuel (albeit synthetic). Coal-based fuels only worked in ramjets or pulsejets (if I remember well).  

[Hobbes]

... and piston diesel and turbojet? I am not sure but I think I read that M1 Abrams uses the same diesel fuel of other armour. Am I wrong?

AIR, gas turbines can burn almost anything, including diesel. Piston engines are choosier about their fuel.  

[Mossie]

Rocket engines can't be run on the same fuel as other engines, as it's the reaction of the fuels to another component, rather than their combustion that creates thrust.  In fact, the design of a rocket has to be very specific to the fuel your using, swapping fuels from one type to another would be either useless or potentially disastrous.  Mixed jet/rocket aircraft like the Saro SR.177 had to carry two seperate fuel supplys.

You can run some engines on different fuels.  Diesel engines will run on vegetable oil, believe it or not, with no conversion.  You have to add something though, can't remember what.  Stinks to high-heaven though, got picked up by a taxi once who was very proud that he didn't have to pay fuel duty, bet he didn't get many customers ring him more than once though!

[The Rat]

I know for a fact that at least some jet engines can run quite well on low octane (80/87) avgas. One of my first days ramp ratting at Buttonville we had a visiting Gazelle helicopter ask for a top-up and I told him we didn't have jet fuel (A few months later we did). "No problem" he replied, "80 octane is fine." In it went, up he went, and several more times in fact, before we had an MU-2 based there and jet fuel became a regular commodity. Whether it could be done all the time is something I'm not sure about though, but maybe Evan could help us here?

[elmayerle]

Well, you can run turbines on av-gas, provided their controls are set up for it (one of the wonders of FADEC is that it makes adjusting for different fuels far, far easier).  Now, I think I'd prefer running more 100LL to 80/87 in a turbine engine (I don't like the idea of the extra lead in my turbine's combustor, almost as bad as some of the high-sulfur fuels encountered some places).  I'm not sure you could run an aircraft turbine on regular diesel fuel, but there might be an acceptable blend that both could burn.  Actually, I always thought that to be one of the real advantages of the SCORE (Stratified Charge Omnivorous Rotary Engine) engine, full multi-fuel capability, smoothness of a turbine, and fuel economy more like a piston engine but either there were other drawbacks I'm not familiar with or there are other reasons this kind of engine hasn't been adopted.

[Jennings]

Yes, theoretically gas turbines can run on almost any fuel.  Just don't tell your maintenance guys if you run diesel oil in your PT-6 however.  They'll not be a happy lot.  Life expectancy of injector nozzles, burner liners, and turbine blades will be seriously affected if jet fuel isn't burned consistently.

J

[Hobbes]

Rocket engines can't be run on the same fuel as other engines, as it's the reaction of the fuels to another component, rather than their combustion that creates thrust.  In fact, the design of a rocket has to be very specific to the fuel your using, swapping fuels from one type to another would be either useless or potentially disastrous.

Well, yes and no. Chemical rockets do use combustion to create thrust.
You can build a rocket that runs on e.g. kerosene; in fact, the first stage of the Saturn V did just that. If you use kerosene, the other 'half' of the fuel is liquid oxygen. The Spectre and other engines used by the British ran on a mix of HTP (hydrogen peroxide) and kerosene.
You're correct that rocket engines are fuel-specific, mainly because the combustion chamber needs to be designed for the fuel used.  

[ysi_maniac]

So ...
I want to build an aircraft powered by a piston engine and a turbojet, using the same fuel for both.
What is the best option for piston engine: petrol/gasoline or diesel?

[Hobbes]

Depends on the time frame. Diesel engines used to have too low a power/weight ratio to be usable in aircraft. That's getting better these days, but you're probably still better off with a petrol engine.