Will we see a return to Propeller planes?

[Hookah Smoking Caterpiller]

When Oil runs out and most cars run on biofuel will we see a return to Propeller engines, as they run on normal petrol, rather than jet planes which require aviation fuel finer than normal petrol.

Or is this all bollocks?

[Simetrical]

Jet engines don't require any particular kind of energy source, in principle. They could run just as well on biofuel if they were designed for it. There's no magical property of jet engines that absolutely requires some particular type of fuel. Nor of propellers that allows them to use more types. Both basically just require fuel to do work, standard heat engines. Any kind of heat source can potentially be used.

Of course, the assumption that we're definitely moving to biofuel at any time in the near future is unwarranted. We could be going to hydrogen fuel, liquefied coal, or even batteries, who knows.

[Death Merchant]

The reason why planes use aviation fuel (kerosine) is the fact that it is lighter than diesiel and other petroleum and also produces a higher yield of energy when it combusts giving the jet engine more thrust

As said a jet engine could be designed to run on other sources of energy although batteries (too heavy) and hydrogen (fuel cost too high) look in their infancy one issue would be however petrol and diesiel freezing at high altitude so the tanks would have to be kept warm somehow

[Sphere]

I don't think that is quite correct. IIRC jet engines require fuel with longer heavier carbon chains, closer to diesel (kerosene is "heavier" than gasoline). This is because they require the fuel to undergo extreme compression without igniting. Propeller engines, or at least high performance ones, need a very light fuel.

[Sphere]

Wiki confirms my memory. Jet fuel is indeed "heavier" or less refined than gasoline.

Jet A-1: Between 8 and 16 carbon numbers
Gasoline: Between 5 and 12

[Simetrical]

I doubt those are strict requirements. Designing the engine for different fuel would almost certainly work, it would just be less optimal. It might result in a change in the type of engine used, I don't know. I'm not an engineer, I'm a mathematician.

[Syron]

Why on earth would you want planes to run on the same fuel we use in cars and therefore hugely drive up the demand (and hence prices) for lighter fuels?

The fact that planes run on Kerosine is a relative advantage as there is little to no other demand for it.

You see, crude is refined in the refinary into a variety of "grades" depending on melting points (and therefore chain size). It doesn't require anymore processing to produce kerosine than it does to produce Petroleum.

[Hookah Smoking Caterpiller]

so I guess this is an overall 'NO' then, oh well, I was looking forward to planes looking good again and the UK reactivating all their Spitfires and Hurricanes.

[Sphere]

You see, crude is refined in the refinary into a variety of "grades" depending on melting points (and therefore chain size). It doesn't require anymore processing to produce kerosine than it does to produce Petroleum.

That is the simplistic version. The demand for gasoline has changed the process. Many of the heavy fuels are "cracked" down the the 5-12 carbon chains that make up gasoline because there is an enormous demand for gas (or petroleum if you are a heathen).

so I guess this is an overall 'NO' then, oh well, I was looking forward to planes looking good again and the UK reactivating all their Spitfires and Hurricanes

Not so fast, I am pretty sure piston engined planes are more fuel efficient than jets. All the new military transport planes use piston engines. Also, ethanol is a great fuel for high performance engines, I would not be surprised if piston plane engines could run on 80-100% ethanol efficiently. The reason jets are dominant is due to their superior top speed, not because they are more efficient. I would have to crack open my fluid dynamics textbook to give you a better explanation as to why propellers cant match jets in terms of speed.

[Syron]

That is the simplistic version. The demand for gasoline has changed the process. Many of the heavy fuels are "cracked" down the the 5-12 carbon chains that make up gasoline because there is an enormous demand for gas (or petroleum if you are a heathen being correct ).

Of course it's a simplifed version! I would have to write a few books to explain it all.

The point is there is no advantage for planes to run on Petoleum because it is not like Kerosine is hard to obtain.

[Sphere]

The point is there is no advantage for planes to run on Petoleum because it is not like Kerosine is hard to obtain.

I can't argue with you. It would make much more sense to have mostly diesel cars, and less demand for gas because that is how mother nature stratifies its carbon chains, but alas that is not the way things are.

And petro may be correct, but it still makes you a heathen.

[Oglethorpe1983]

No...No we wont.. Becuase propellers planes simply cannot reach or maintain the speeds, altitudes, and distences that jet planes can. This means they are unsuited for military applications in the 21st C. And as for commerical purposes there are two things that matter speed and cost. passenger liners want speed, commerical freight want cost (but speed is a plus too) in both places propeller planes are at a disadvantage...

While were at it though..why not bring back Zepplins...field with Hydrogen and everyone aboard get a free thermite suit to wear, and there a special smoking room on board for that sense of luxury.....

[Hookah Smoking Caterpiller]

No...No we wont.. Becuase propellers planes simply cannot reach or maintain the speeds, altitudes, and distences that jet planes can. This means they are unsuited for military applications in the 21st C. And as for commerical purposes there are two things that matter speed and cost. passenger liners want speed, commerical freight want cost (but speed is a plus too) in both places propeller planes are at a disadvantage...

While were at it though..why not bring back Zepplins...field with Hydrogen and everyone aboard get a free thermite suit to wear, and there a special smoking room on board for that sense of luxury.....

What about contra-rotating propellers like those on the Soviet Tu-35 'Bear', these reach 'Jet like' speeds, could ones with triple contra-propellers be used?

There has been increasing discussions within the avaiaton industry about the return of Zeppelins and airships...

[The Sixth Wizard]

Whatever happens, everything starts in the military. I think if the military forces of the world go green it will be much easier for the rest of the world to follow suit.

[Kanaric]

The soviets had a jet in the 80s that ran on liquid hydrogen. I'm sure once hydrogen fuel becomes common that might be what jet engines turn to if it is any cheaper.


http://en.wikipedia.org/wiki/Tupolev_Tu-154

It is a commercial jet as well.

[christof139]

Yes, turbo-props are and have been in use for short flights for decades, and more advanced and fuel efficient props may be developed, and for moving air freight the slower prop planes would still be efficent and fast.

Problem with Zeps is mainly the weather as they could get knocked out of the sky by severe weather and ripped from their mooring. A big study on this was done in the USA some years ago, maybe 1970s or 1980s, I forget. However, Zeps travelling at only 40mph or so would be efficient to move mainly local and regional freight and to be used for passengers to fly in if they had the time to do so at slower speeds.

Chris


Chris

[chris_uk_83]

The main problem with propellers is that they work by shoving air backwards. This in turn causes the aircraft to move forwards as per Newton's third law of motion. At high altitudes, the air is much less dense, meaning that you can't get as good a shove from it.

Jet engines also use air in their operation, but they are much better suited to working at altitude. I'm afraid I don't know enough about jet engines to explain why though.

[vizi]

If you want to go bombing around in prop jets join the Weather service and fly into hurricanes.



I am serious btw. But I agree with most of what is said by the other posters.

[Simetrical]

The main problem with propellers is that they work by shoving air backwards. This in turn causes the aircraft to move forwards as per Newton's third law of motion. At high altitudes, the air is much less dense, meaning that you can't get as good a shove from it.

Jet engines also use air in their operation, but they are much better suited to working at altitude. I'm afraid I don't know enough about jet engines to explain why though.

A cursory look at Wikipedia suggests that jet engines work basically like rockets, by expelling some gas at high-ish speed.

[christof139]

The main problem with propellers is that they work by shoving air backwards. This in turn causes the aircraft to move forwards as per Newton's third law of motion. At high altitudes, the air is much less dense, meaning that you can't get as good a shove from it.

Jet engines also use air in their operation, but they are much better suited to working at altitude. I'm afraid I don't know enough about jet engines to explain why though.

There are and have been pusher-props rather than puller-props, but that is mainly due to where the props are placed on a plane I do believe.

Many prop planes, including large ones, have quite efficient engines.

Chris