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flipdewaf
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New Breed Of Engines Needed?

Wed Nov 07, 2007 11:17 pm

Just been watching news night on the beeb with an article on oil nearly at $100/barrel and was thinking maybe we could all have a good go at throwing in ideas for engines to power aircraft that don't run on oil, i.e. a huge battery running electric motors for props. If you have any ideas please say them and please no bashing people too much and please dont make this a thread about weather we need to think about this or not, just imagine that oil has already run out and we do need it Big grin

Fred
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Boston92
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 2:31 am

The airlines have proven that the oil prices don't mean much by most posting large profits.
 
flipdewaf
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 3:12 am

BAH! Thats why i said you have to imagine that the oil has already run out, I know we don't need anything just yet.

Fred
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Starlionblue
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 4:02 am

Quoting Flipdewaf (Thread starter):
i.e. a huge battery running electric motors for props.

While electric motors are hugely efficient, they have two issues when it comes to aircraft.
- By weight, energy storage (batteries) is very inefficient compared to hydrocarbons.
- Electric motors don't scale up as well as turbines so you would need many, increasing costs.

I see hydrogen as one of the possible paths. The issue here is that while hydrogen is quite energetic by weight, it is not very efficient by volume. In other words, the fuel tanks are much bigger than for, say, jetfuel, for the same energy storage.


In the deeper future, we have lightships powered by ground based lasers super heating the air around them. Models have already flown. It's not without it's flaws but by keeping the fuel on the ground a lot of weight is saved, with consequent efficiency gains.


I definitely see blimps and rigid airships making a comeback for cargo. They are very efficient but slow.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tdscanuck
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 4:53 am

Quoting Flipdewaf (Thread starter):
Just been watching news night on the beeb with an article on oil nearly at $100/barrel and was thinking maybe we could all have a good go at throwing in ideas for engines to power aircraft that don't run on oil,

I think the first step, if we truly ran out of oil, would be to go to synthetic oil.

The energy density of current aircraft propulsion systems is very hard to beat. If we really ran out of oil (but, obviously, still have some form of energy supply) then the lowest cost option may well be to accept the energy cost of making synthetic oil and use that to run the airplane.

Tom.
 
2H4
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 5:03 am

Quoting Starlionblue (Reply 3):
The issue here is that while hydrogen is quite energetic by weight, it is not very efficient by volume. In other words, the fuel tanks are much bigger than for, say, jetfuel, for the same energy storage.

Hmmm....so we need lots of volume. BWB, anyone?



Quoting Starlionblue (Reply 3):
I definitely see blimps and rigid airships making a comeback for cargo. They are very efficient but slow.

How would blimps and airships negotiate weather? At what altitudes would they typically cruise?

2H4
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Starlionblue
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 7:28 am

Quoting 2H4 (Reply 5):
Quoting Starlionblue (Reply 3):
The issue here is that while hydrogen is quite energetic by weight, it is not very efficient by volume. In other words, the fuel tanks are much bigger than for, say, jetfuel, for the same energy storage.

Hmmm....so we need lots of volume. BWB, anyone?

Indeed.

Quoting 2H4 (Reply 5):
How would blimps and airships negotiate weather? At what altitudes would they typically cruise?

Well, rigid airships have been in service before. If the Germans had had easy access to helium they might still be in service today.

I'm guessing we're talking low altitude and stay away from bad weather. Much easier today with weather satellites than it was in the 30s. IIRC the USAAF (or was it just plain Army?) lost at least one of their airships to a storm, as did the Brits.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
flipdewaf
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 11:54 am

Quoting Starlionblue (Reply 3):

I see hydrogen as one of the possible paths. The issue here is that while hydrogen is quite energetic by weight, it is not very efficient by volume. In other words, the fuel tanks are much bigger than for, say, jetfuel, for the same energy storage.

I heard they was a way of storing hydrogen within a certain metal, between the molecules in the metal or something. I remember reading it in a Sunday times motoring article but i'm not sure how heavy this was but it was able to fuel the car for around 5kmiles.

Fred
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futurecaptain
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 3:17 pm

We need to go to the moon and start picking out the Hydrogen 3. That stuff, it seems, could power the planet.

Or unducted fans for now to save fuel, but the damn NIMBYS probably won't let that happen.
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Starlionblue
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 3:51 pm

Quoting Futurecaptain (Reply 8):
We need to go to the moon and start picking out the Hydrogen 3. That stuff, it seems, could power the planet.

Don't we need to figure out the nuclear fusion thing first?


Going off topic here:

Let's face it, aviation is pretty efficient. Weight concerns are such that airliners are at the cutting edge of efficiency. What sets me off is the sheer inefficiency of other things. Case in point: When I look at an air conditioner part of me wants to say "Wouldn't some more and better shaped cooling fins improve things? Why is that fan shaped like three vinyl records welded to a propshaft?"

There is a lot that can be done to improve "fuel burn" for the planet as a whole. Eking such improvements out of aviation is much trickier than eking them out of other things.

[Edited 2007-11-08 07:55:14]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
2H4
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 4:25 pm

Quoting Starlionblue (Reply 9):
There is a lot that can be done to improve "fuel burn" for the planet as a whole.

Indeed....and not just from a technological standpoint, but from a behavioral standpoint. Alternative transportation should be taken more seriously, lest people continue firing up their H2s and driving a block away to run an errand.

2H4
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BAE146QT
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RE: New Breed Of Engines Needed?

Thu Nov 08, 2007 4:55 pm

Use nuclear power stations to run compressors. These compressors compact ordinary air - almost down to degenerate matter - to fill tanks on board the airliner. Open the taps, and the air squirts out the back and pushes the airliner along.

Voila - one aircraft that is propelled in the same manner as a party balloon. Quiet* and environmentally sound.


Might have to wait for materials science to catch up before we can make tanks that strong though. And you'd probably want to be a couple of miles away when "refuelling".





* Unless for comic effect you decided to make it do that *THTHTHTHTHBBBBBB* noise that balloons make.
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Starlionblue
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RE: New Breed Of Engines Needed?

Fri Nov 09, 2007 1:01 am

Quoting BAe146QT (Reply 11):
Use nuclear power stations to run compressors. These compressors compact ordinary air - almost down to degenerate matter - to fill tanks on board the airliner. Open the taps, and the air squirts out the back and pushes the airliner along.

Or just invent The Squeezer. Big grin Huh? I hear you cry... John Varley (a great, great author) had this device in "Red Lightning" which created a massless bubble that could be altered in size. Basically you made a big bubble and then squeezed. Poke a hole in the bubble for a reaction drive. Make the bubble disappear for a bomb.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
speedracer1407
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RE: New Breed Of Engines Needed?

Fri Nov 09, 2007 2:30 am

Shame on you all. You're thinking too small. What we need is warp drive. There are plenty of technical manuals out there that explain the whole thing. It's all the greenies out there that are holding us back, worried about the "space time continuum," or whatever.
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tdscanuck
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RE: New Breed Of Engines Needed?

Fri Nov 09, 2007 3:06 am

Quoting Starlionblue (Reply 6):
IIRC the USAAF (or was it just plain Army?) lost at least one of their airships to a storm, as did the Brits.

It was the Navy. USS Macon:
http://en.wikipedia.org/wiki/USS_Macon_%28ZRS-5%29

Quoting Flipdewaf (Reply 7):
I heard they was a way of storing hydrogen within a certain metal, between the molecules in the metal or something. I remember reading it in a Sunday times motoring article but i'm not sure how heavy this was but it was able to fuel the car for around 5kmiles.

Metal hydrides. Energy density by volume is OK, but by weight it's pretty awful.

Tom.
 
Boeing7E7
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RE: New Breed Of Engines Needed?

Fri Nov 09, 2007 3:14 am

Engine efficiency and fuel blends will continue to improve over time, the key is to get everyone but aviation off the oil well until aviation engineering horizons reach a point where they don't need it either.
 
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Starlionblue
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RE: New Breed Of Engines Needed?

Fri Nov 09, 2007 3:39 am

Quoting Tdscanuck (Reply 14):
Quoting Starlionblue (Reply 6):
IIRC the USAAF (or was it just plain Army?) lost at least one of their airships to a storm, as did the Brits.

It was the Navy. USS Macon:
http://en.wikipedia.org/wiki/USS_Mac...-5%29

Oops.  ashamed 

Quoting Boeing7E7 (Reply 15):
Engine efficiency and fuel blends will continue to improve over time, the key is to get everyone but aviation off the oil well until aviation engineering horizons reach a point where they don't need it either.

Exactly. Aviation is so efficient and so hard to change compared to ships and cars it hardly seems like the right place to start.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
hypersonic
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RE: New Breed Of Engines Needed?

Wed May 28, 2008 4:16 pm

Aren't there ways yet to use Pure Water as the fuel source?

What is needed is some high temperature catalytic process to rapidly cleave the hydrogen from the Oxygen, that once separated, can then be recombined in a combustion chamber to produce thrust - similar to a rocket?

Electrolysis cleaves of courses, but is rather slow.

The trick of course is getting the closed loop catalyst separation -up to temperature- first, then it can bleed heat from the engine to keep the chemical process 'hot'.. but because its an aircraft & not a rocket trying to get into orbit, only relatively small amounts of fuel burn compared to a full blown rocket, will be required to make the requisite thrust for an aircraft.

Any thoughts?
 
nomadd22
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RE: New Breed Of Engines Needed?

Wed May 28, 2008 5:09 pm



Quoting Hypersonic (Reply 17):
Aren't there ways yet to use Pure Water as the fuel source?

What do you think you get when you combust hydrogen? Water. That's called a perpetual motion engine. Or, trying to get something for nothing. It doesn't work in life or physics.
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hypersonic
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RE: New Breed Of Engines Needed?

Wed May 28, 2008 6:09 pm



Quoting Nomadd22 (Reply 18):
Quoting Hypersonic (Reply 17):
Aren't there ways yet to use Pure Water as the fuel source?

What do you think you get when you combust hydrogen? Water. That's called a perpetual motion engine. Or, trying to get something for nothing. It doesn't work in life or physics.

HUH?? - No it's not - if you collected the water exhaust, then it would be a closed loop system maybe..., but Nothing i'm suggesting above violates the second law of thermodynamics.

There will be energy loss during the combustion stage for starters, energy loss from using whatever electrical battery power to initially heat up the catalyst system using microwaves or some other heating system etc etc, & the water would become depleated just like any fuel... Hardly perpetual energy? -  expressionless 
 
2H4
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RE: New Breed Of Engines Needed?

Wed May 28, 2008 6:15 pm



Quoting Hypersonic (Reply 19):

There will be energy loss during the combustion stage for starters, energy loss from using whatever electrical battery power to initially heat up the catalyst system using microwaves or some other heating system etc etc, & the water would become depleated just like any fuel... Hardly perpetual energy?

Steam engines would be a bit heavy for use in airliners, I think.  Wink

2H4
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hypersonic
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RE: New Breed Of Engines Needed?

Wed May 28, 2008 6:36 pm



Quoting 2H4 (Reply 20):


Steam engines would be a bit heavy for use in airliners, I think. Wink

2H4

How about this  Wink

http://images.google.co.uk/imgres?im...D1%26hl%3Den%26safe%3Doff%26sa%3DG

Toot Toot!!!
 
2H4
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RE: New Breed Of Engines Needed?

Wed May 28, 2008 6:39 pm



Quoting Hypersonic (Reply 21):
How about this

Man, that's cool. As I was examining the first photo, I was thinking to myself how cool it must have sounded. Then I read the article and saw that it was unusually quiet. Still, I'd love to hear it run.

2H4
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flipdewaf
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RE: New Breed Of Engines Needed?

Wed May 28, 2008 9:24 pm



Quoting Hypersonic (Reply 21):
How about this

Thats excellent! We'll have to start measuring SFC in Lumps/hr/lb

Fred
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tdscanuck
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RE: New Breed Of Engines Needed?

Sat Jun 07, 2008 3:33 am



Quoting Hypersonic (Reply 19):
HUH?? - No it's not - if you collected the water exhaust, then it would be a closed loop system maybe..., but Nothing i'm suggesting above violates the second law of thermodynamics.

You're suggesting starting with water, cracking it to hydrogen and oxygen, burning that to extract useful work (thrust), and ending up back with water.

That's a direct violation of the second law.

Tom.
 
futurecaptain
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RE: New Breed Of Engines Needed?

Sat Jun 07, 2008 4:01 am



Quoting Tdscanuck (Reply 24):
You're suggesting starting with water, cracking it to hydrogen and oxygen, burning that to extract useful work (thrust), and ending up back with water.

That's a direct violation of the second law.

No because it takes more power to separate the water than you can get back from burning the hydrogen. So energy is lost there. You wouldn't be limited by the amount of water you have but instead by the amount of electricity you have in the battery.

Now, if there was an outside way to charge the battery we can be on to something. Use solar power to keep the battery charged to keep the process of separating the water going could help.

Or heck, use wind power from the forward motion of the aircraft to turn a generator to charge the battery.
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wingscrubber
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RE: New Breed Of Engines Needed?

Sun Jun 08, 2008 1:41 am

Energy cannot be created nor destroyed, it merely changes form.
Any work you intend to extract from burning or bonding hydrogen and oxygen has to be first put in to seperate the atoms with electrolysis. You get out what you put in...

I once had a thought that you could have nuclear-fueled electroysis-hydrogen burning piston engines in cars... and then I realised I was adding an un-necessary step. Nuclear fuel drives ships and submarines just with electricity. Thermo-nuclear reactors are a bit big to carry around in cars and planes though.

I posted in another thread somewhere that I believe cryoplanes are the future... aircraft can carry hydrogen or liquid natural gas around in large cryogenic tanks when the kerosene and it's imitatations runs dry. Look up the Tu-155... it's dormant future technology I tell you.
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Alessandro
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RE: New Breed Of Engines Needed?

Wed Dec 10, 2008 4:29 pm

Perhaps blimps with Stirling engines would be a good idea?
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