Types of Fuel

[Perlmudder]

So what is the difference between the type of fuel run in an airplane and the type of fuel run in a turbine cat? Aren't the turbines pretty similar? Does a plane run "jet" fuel while a turbine cat runs diesel fuel or regular gasoline?

Sort of confused about this whole thing...

 

[ZBODaytona]

Well I am making an assumption..but I think it has to do with the fact that Jet A is desined to operate at altitude. I am pretty sure gasoline will not work in a turbine... Also avgas is a little different than regular gas as well.

 

[cigdaze]

Most turbines will burn some form of kerosine. JET-A is nothing more than a specialized grade of kerosine, the primary difference is the qualification which makes it suitable for operation in aircraft with stated flash point, self-ignition point, and freeze point. It had little to do with altitude, max thrust (and power) occurs at sea level (as is the case with most internal combustion engines).

 

[Tom A.]

Don't know the exact fuel differences but turbines run on kerosene based fuels. Jet fuel is a higher refined form of kerosene and diesel fuel is kerosene based. My understanding is that the marine turbines can run on any of these depending on their set up.

 

[Tom A.]

Beat me to it Cig

 

[cigdaze]

Just barely.

 

[Chris]

I'm going to assume by the word "airplane" he means jet/turbine powered.

They use essentially the same base stock. Theyre are different formulations dependent upon use and purpose. Most turbofan and turboprop aircraft run on Jet A. Jet A differs from Diesel in that it is being burned at high altitudes and subsequently needs different additives to perform in those low-oxygen conditions. Marinized turbines are typically modified to use Diesel, mostly in the fuel delivery and metering system.

Jet fuel has many differing charachteristics. It needs to pour at very low temperatures, but it also does not need to have the same lubricity as Diesel fuel as it doesn't have the same pumping and injector issues.

 

[ZBODaytona]

when i was thinking altitude i was thinking the freezing points and what nots.like chris just said. but i knew you guys would give us the whole truth...and i am assuming i am right that regular old gasoline will not run in them...right???? to big of difference in flashpoint right????

 

[Chris]

A turbine can be made to run on damn near any flammable liquid, with proper fuel system modifications. There are many 3rd world countries operating turbine-powered electrical generation facilities that install multifuel systems simply because of fuel supply stability.

And, an M1 Abrams tank will run on Diesel, any jet fuel, gasoline, alcohol, perfume, scotch or Sterno. Literally.

Keep in mind a turbine is mechanically a much simpler device. You're only managing two things- shaft speed and EGT. It's a simple task to alter the fuel deivery to accommodate those needs.

 

[cigdaze]

when i was thinking altitude i was thinking the freezing points and what nots.like chris just said. but i knew you guys would give us the whole truth...and i am assuming i am right that regular old gasoline will not run in them...right???? to big of difference in flashpoint right????

Correct. But only by design and mainly because the majority of turbines are adapted from the aviation industry. Not to say that you can't design a turbine to operate on different fuels, but because there's little-to-no availability, or demand. Chrysler designed and built a turbine car back in the 60's or 70's which could run satisfactorily on leaded gasoline, kerosine or diesel; so has the military for APUs and the like.

 

[Davidmnc]

Ok, here I go jumping in were I have no business at all, but I have always wondered. How affciant are these engines, and how easy are they to control the power? It just seems like the throttle response is very different from an internal combustion engine. What are the real advantages to a turbine over an internal combustion in a power boat.


Sorry if I sound stupid, but you guys should be used to that by now.

 

[cigdaze]

Extremely efficient. That's their biggest advantage. Their power-to-weight ratio is unsurpassed. The other major advantage is relatively little maintenance per operating hour (no reciprocating parts - only rotating). Yes, throttling will be different; the response is much slower and they resist change in angular velocity more so than their reciprocating counterparts - but therein lies another advantage, the risk of over-speed is mitigated because rpm spikes are more subtle while launching.

By the way, turbines and reciprocating piston engines are both internal combustion engines.

 

[Sean H]

Extremely efficient. That's their biggest advantage. Their power-to-weight ratio is unsurpassed. The other major advantage is relatively little maintenance per operating hour (no reciprocating parts - only rotating). Yes, throttling will be different; the response is much slower and they resist change in angular velocity more so than their reciprocating counterparts - but therein lies another advantage, the risk of over-speed is mitigated because rpm spikes are more subtle while launching.

By the way, turbines and reciprocating piston engines are both internal combustion engines.

I am not sure I would classify them as effecient. They burn a dramatically more amount of fuel than a comparable piston engine in a powerboat enviroment. Not to mention while idling and docking you are almost burning the same amount of fuel as running hard.

 

[cigdaze]

It's all relative. Ya, they guzzle dramatically more fuel, but they're also outputting dramatically more power.
A typical reciprocating engine reaches approximately 25-35% efficiency, while a typical turbine achieves about 65% power output with regards to the chemical potential input. HP for HP, they are much more efficient. Naturally, when outputting 3000+ horsepower they're going to be thirsty.

Good point on the idling, though.

 

[Sean H]

in the 1500 piston vs 1850 turbine, the turbine takes nearly double the fuel. when bud had their t-55 boat, it burned 4 times more fuel to make twice the power of the sterlings.

we were docked next to geico (and down wind) at biloxi when they burnt 106 gallons idiling for an hour or so between heat races... nothing like ear plugs and stinking of jet A for a hour.

 

[Chris]

I can tell you that in power generation, the turbine delivers more output per pound of fuel than anything else.

 

[Coolerman]

in the 1500 piston vs 1850 turbine, the turbine takes nearly double the fuel. when bud had their t-55 boat, it burned 4 times more fuel to make twice the power of the sterlings.

we were docked next to geico (and down wind) at biloxi when they burnt 106 gallons idiling for an hour or so between heat races... nothing like ear plugs and stinking of jet A for a hour.

a 3000hp piston engine would burn more than 4 times the fuel of a 1500hp piston engine though....

 

[Sean H]

a 3000hp piston engine would burn more than 4 times the fuel of a 1500hp piston engine though....

very true, but the outright speed of the boats changes little... so which is truly more efficient?

turbines in the powerboat world don't get to use their advantage due to the docking/idiling/part throttle/milling fuel consumption is so high. The turbines have to start a race (or even a poker run) with much more fuel than a similiar speed piston boat does.

 

[phragle]

correct me if I'm wrong...but the turbines are more reliable and live a lot longer with less hassles than 1075's and 1500's, they may use more fuel but they run evey weekend.. if you use the boat a lot, your going into 1075's twice a year if nothing goes wrong... motors in the shop don't get you to the islands.

 

[Sean H]

correct me if I'm wrong...but the turbines are more reliable and live a lot longer with less hassles than 1075's and 1500's, they may use more fuel but they run evey weekend.. if you use the boat a lot, your going into 1075's twice a year if nothing goes wrong... motors in the shop don't get you to the islands.

they get pulled, inspected, worked on or just break down alot for all their reliablity everybody preaches about...

just in the last 3 races i have been to, i have seen no less than 3 turbines come out and a couple more break during the race... and there are only 3 turbine boats running races...

is it always a turbine issue? probably not, but broke down is broke down.