Theoretical - airplanes without conventional fuel.

[weemadando]

OK - imagine for a moment that we've done the peak oil thing and there is flatly no more conventional petrochemicals.

What viable methods of air travel are there which don't rely on petrochemicals?

Is there aviation grade biofuel - I could look, this up, but it's a sub-question really.

And what alternatives are there? Could we see a return of the nuclear powered aircraft with electrically powered propellers?

[Junghalli]

A ramjet is one possibility: its only fuel is hydrogen. Though you'd need some other kind of engine to get it up to Mach .5.

[Lambda 00]

ramjets use hydrocarbon fuel, scramjets however, might be what you're thinking about. I don't know

[Hawkwings]

Nuclear powered ramjet would work, but the only problem (besides safety) is that ramjets need a lot of speed. So at low speed it could operate a turbofan.

See here: http://bbs.stardestroyer.net/viewtopic.php?t=114583

[Broomstick]

What viable methods of air travel are there which don't rely on petrochemicals?

Define "viable" - what sort of aviation are you talking about? The A-380, Alaska bush plane cargo carriers, air medical evacuation...? "aviation" is a pretty big subject.

Is there aviation grade biofuel - I could look, this up, but it's a sub-question really.

Yeah. There are viable diesel airplane engines that run on anything you can burn in any other diesel engine, including biodiesel. If I recall, the very first diesel engine was run on peanut oil. Here is a wiki on diesel aircraft engines with links to manufacturers.

The Embraer EMB 202 Ipanema with the ethanol fuel option is being utilized in Brazil for agricultural purposes and, as we know, ethanol can be produced from biological sources.

In the 1930's someone actually managed to convert a Travelair airplane to steam power. Yes, it actually flew.

And, of course, there is the "steampunk" zepplin - using steam to power the propulsion system on a zepplin utilizing gas for lift. I don't know if anyone ever built one, but it wouldn't surprise me if someone had as there is no reason it wouldn't work.

There was the Me 163 Komet which ran on hydrazine, methanol, and hydrogen peroxide - is hydrazine a petrochemical? Anyhow - it's not gasoline or diesel fuel.

I see no reason to go nuclear - although that's not to say it couldn't be done as yet another alternative. Nuclear, however, has the problem of weight from shielding vs. irradiating cargo/passengers/bystanders.

I guess my point here is that we already have flown alternative-fuel aircraft. For the most part development stalled due to the availability and/or cost of petrol type fuels and engines, but given sufficient incentive it wouldn't surprise me to see refinements.

[Shroom Man 777]

You could have a solar powered aircraft in the form of a zeppelin with the dorsal side of its "blimp" coated in solar cells!

[weemadando]

What viable methods of air travel are there which don't rely on petrochemicals?

Define "viable" - what sort of aviation are you talking about? The A-380, Alaska bush plane cargo carriers, air medical evacuation...? "aviation" is a pretty big subject.

Really, the whole variety - I know that most small plane roles can easily be converted/replaced.

But international aviation, air forces etc - that's going to be a whole other story.

[Lord of the Abyss]

As I recall, theoretical work has been done on powering aircraft from the ground via microwave or laser, which would get around the weight problem of using nuclear power for airplanes. Just keep those heavy radioactives and shielding on the ground. On the other hand, as far as I know, theory is as far as it's gotten.

[Broomstick]

Some time back I had a discussion with a jumbo jet pilot (he has flown both passenger airline and cargo) regarding jet engines. Jets of that sort run on what is, essentially, a fancy form of kerosene. I asked about alternative fuels and he had a reasonable argument that modern jet turbines could run on diesel fuel such as biodiesel, but less efficiently. I don't have a record of the conversation nor am I capable of either proving or disproving that statement. If true, however, that indicates that it would continue to be possible to fly the biggest jets post-peak-oil, but it would require more fuel per mile and be less efficient. Which seems to be a common theme with p-p-o fuel solutions.

I've heard zepplins proposed as a solution, but that tends to ignore that helium is a finite resource so long as we are essentially confined to planet Earth. You certainly can use hydrogen, which can be obtained through chemical processes and is actually a more efficient lift gas than helium, but there is the fire hazard problem. It's not insurmountable - the Graf Zepplin flew for years without incident using hydrogen for lift - but the risk is greater than when using helium.

Bottom line, though, p-p-o transportation of any sort is going to get more expensive, slower, or both. If we had only 1/10 as many people in the world as we do at present most of these problems would not be problems - there would be sufficient petroleum to meet demand for longer, softening the landing; and there would be less demand for agricultural products thereby lowering the cost of both biofuel and food. Aviation isn't going to go away, but how much we use it and how will certainly change.

[FSTargetDrone]

There was the Me 163 Komet which ran on hydrazine, methanol, and hydrogen peroxide -

The Me 163 also had a tendency to explode on landing. Not to mention that the fuel was of course horrendously dangerous to handle--you didn't want to be around any spills of the stuff without extensive bodily protection.

is hydrazine a petrochemical? Anyhow - it's not gasoline or diesel fuel.

Some quick info:

Hydrazine (N2H4) found early use as a fuel, but it was quickly replaced by UDMH. It is still used as a monopropellant for satellite station-keeping motors. Hydrazine marketed for rocket propellant contains a minimum of 97 per cent N2H4, the other constituent being primarily water. Hydrazine is a clear, water-white, hygroscopic liquid. The solid is white. Hydrazine a toxic, flammable caustic liquid and a strong reducing agent. Its odour is similar that of ammonia, though less strong. It is slightly soluble in ammonia and methyl-amine. It is soluble in water, methanol, ethanol, UDMH, and ethylenediamine. Hydrazine is manufactured by the Raschig process, which involves the oxidation of ammonia to chloramine, either indirectly with aqueous sodium hypochlorite or directly with chlorine, and subsequent reaction of chloramine with excess ammonia. Raw materials include caustic, ammonia, and chlorine; these are high-tonnage, heavy chemicals. The cost of anhydrous hydrazine in drum quantities in 1959 was $ 7.00 per kg. The projected price, based on large-scale commercial production, was expected to be $ 1.00 per kg. Due to environmental regulations, by 1990 NASA was paying $ 17.00 per kg.

[Broomstick]

There was the Me 163 Komet which ran on hydrazine, methanol, and hydrogen peroxide -

The Me 163 also had a tendency to explode on landing.

Also on engine start up, take-off, while maneuvering, during refueling, sitting in the hot sun too long on the flight line...

Actually, they had a disturbing tendency to explode for no discernible reason whatsovever.

[FSTargetDrone]

The Me 163 also had a tendency to explode on landing.

Also on engine start up, take-off, while maneuvering, during refueling, sitting in the hot sun too long on the flight line...

Actually, they had a disturbing tendency to explode for no discernible reason whatsovever.[/quote]

Otherwise, it was perfectly safe.

[FSTargetDrone]

Damnation, sorry for the quote foul-up. I've only been posting here since 2004...

Also on engine start up, take-off, while maneuvering, during refueling, sitting in the hot sun too long on the flight line...

Actually, they had a disturbing tendency to explode for no discernible reason whatsovever.

[Broomstick]

Ha ha "perfectly safe"...

Wouldn't get me to ride on one, that's for damn sure!

Can anyone else think of a power source we've missed? Other than human powered - while it's been done it is more of a stunt than anything practical.

[CaptainChewbacca]

Ha ha "perfectly safe"...

Wouldn't get me to ride on one, that's for damn sure!

Can anyone else think of a power source we've missed? Other than human powered - while it's been done it is more of a stunt than anything practical.

I've always thought the commercial aircraft version of Project Pluto would be terrifyingly awesome to behold. Of course, it'd kill everyone it flew over.

[Sikon]

The Fischer-Tropsch process can produce various types of synthetic liquid fuel from syngas, including jet fuel and aviation gasoline (a mixture with octane: C8H18, etc).

Syngas is a mixture primarily of carbon monoxide and hydrogen, which can be produced with any carbon and energy feedstock from coal (CTL) to natural gas (NGL) to biomass, instead of oil.

(It's even possible to make an aircraft indirectly nuclear-powered without a reactor onboard, through nuclear-powered fuel synthesis on the ground with CO2 as the carbon feedstock for the FT process, although that is in the realm of unfunded proposals today, unlike the other methods that are currently implemented).

Many past threads have discussed the Fischer-Tropsch process with more details, references, etc. In varying implementations, mostly but not solely with natural gas feedstock at the moment, it is the foundation of the 20% of the current liquid fuel supply that comes from sources other than crude oil, a percentage increasing year by year.

In 2006, the U.S. Air Force tested a synthetic fuel blend from Syntroleum in a B-52 bomber. It functions the same as the standard fuel, working in the same aircraft and same aircraft engines. The USAF is scheduled to certify all its aircraft on synthetic fuel by 2011, as part of an Assured Fuel Initiative program for half of its fuel consumption to be obtained from such by 2016.

[raptor3x]

OK - imagine for a moment that we've done the peak oil thing and there is flatly no more conventional petrochemicals.

What viable methods of air travel are there which don't rely on petrochemicals?

Is there aviation grade biofuel - I could look, this up, but it's a sub-question really.

And what alternatives are there? Could we see a return of the nuclear powered aircraft with electrically powered propellers?

Gas-turbine engines really aren't that picky. You can take just about any turbofan engine out there, modify the combustor slightly and it'll run just fine on hydrogen or ethanol. Depends on your fuel-air ratio you might have issues with turbine durability but the engine will run.

[FSTargetDrone]

Ha ha "perfectly safe"...

Wouldn't get me to ride on one, that's for damn sure!

Actually, someone made a glide-only replica some years ago, and flew it!

Mr. Josef Kurz from Germany has built his own glider replica of the Me 163B, and is currently flying it! In 1944-1945 Josef Kurz was in training for Me 163B service, but the end of the war prevented him from flying the real thing. What better to do than build your own one, then? Construction was started in 1994, and first flight was made at 18 June 1996. It is flown from the airfield at Ziegenhain. Flying characteristics are extraordinary according to the builder. Mr. Kurz is planning to put a 100 hp engine in his replica, in order to have self-starting capability.

The shape of the original is definitely well captured in this replica. The trouble-prone skid appears to be replaced by a single wheel, with a white skid painted on. The tail wheel is completely faired in, which is different from the original. The rear-view windows are omitted. The color scheme is possibly an attempt to make it look like Me 163B V41, that was painted all red for the first combat mission in May 1944. All in all a remarkable piece of work, and it must be a huge thrill to see this glider whizzing by at speed!

[Sea Skimmer]

What viable methods of air travel are there which don't rely on petrochemicals?

We’ll run out of oil long before finding or making natural gas becomes impossible, basic designs for gas powered jets have been around for a long time, you just have to make them way bulkier to accommodate the fuel tanks. I’ve got a chart somewhere showing basic designs by Tupolev to replace its entire existing airliner lineup with designs adapted for LNG fuel.

Is there aviation grade biofuel - I could look, this up, but it's a sub-question really.

Yes, and the USAF has already flown a B-52 with the stuff and many other aircraft. Its now working on adapting biofuel to supersonic engines. Funny enough I also just now saw this on the BBC, a 747 flew across the Atlantic using nut oil for fuel.
http://news.bbc.co.uk/2/hi/uk_news/7261214.stm

And what alternatives are there? Could we see a return of the nuclear powered aircraft with electrically powered propellers?

As much as I might wish for it, god no. That will never ever happen. Among the many reasons why this is so, its infeasible to build a nuclear powered aircraft which has full shielding on the reactor, the reactors actually flown in real life only had forward shields to protect the plane crew. That which means whenever the thing is on the ground you’d need a multiple mile exclusion zone around it. Making the transition from cooling via 500mph slipstream to cooling with some kind of ground equipment would also be absurdly dangerous with a high energy reactor that could actually power a large aircraft. You can’t really throttle back power until you’ve already landed… I suppose if a plane melted down on the runway we could just pave a new runway over the top of it.

[fusion]

Induced gamma emission

That is something we could use...
link
So, yes it is something that we can use...

[weemadando]

Thank you Richard Branson for flying a 747 w/ biofuel today.

That all said - I want ramjet powered hydrogen filled zeppelins. NOW!

[Ted C]

Is there aviation grade biofuel - I could look, this up, but it's a sub-question really.

If I was hearing the news on the radio correctly this morning, a plane made a transatlantic flight on biofuel, so yes.

[weemadando]

Is there aviation grade biofuel - I could look, this up, but it's a sub-question really.

If I was hearing the news on the radio correctly this morning, a plane made a transatlantic flight on biofuel, so yes.

I brought this up in the post above yours.

It was only a hop from London to Amsterdam and it was a 747 w/ one engine running on a closed circuit so that if it had any issues, the rest would operate fine.

[wjs7744]

I've always thought that H2 zeppelins were a good idea, and we would probably still be using them if not for morons who claim that they tend to explode. After all, anyone who passed high school chemistry knows that elementary pure hydrogen doesn't actually do so.

I always understood that they could take much heavier loads that aerofoil craft, but were also slower. Have I got this right? By the way, do any of you engineer types have any numbers for the useful lift they produce?

[Broomstick]

The useful lift of a zeppelin depends on the quantity, and to a lesser extent, the type of lift gas with hydrogen being a better lifter than helium. A really, really big zeppelin can carry huge loads for relatively little fuel, but even a one-man airship is HUGE by the standards of most vehicles.

If I recall correctly, 80 mph was about the top speed for the old school zepps, around 130 kph.

With H2 fire is a real risk - but then, we use other flammable fuels and items on a daily basis, this is manageable.