Like the Goodyear blimp. Only for everything.
May 23, 2011 3:45 PM   Subscribe

IF, tomorrow, the world switched to blimps from jets for all but emergency travel, how much fuel would we save?

I'm reading an alternate history book where the development of the airplane happens but, for the most part, the world sticks with blimps. It's a slower, more comfortable world. Similar to the days of ship and rail travel. There's a few repeated mentions about the waste of fuel for "aeroplanes." I'm not one for chemistry or physics, but would there be a significant net fuel savings if the world went Blimp tomorrow?
posted by rileyray3000 to Society & Culture (18 answers total) 2 users marked this as a favorite
Given the reduced speed I imagine that any fuel savings would be offset by increased automobile gas consumption?
posted by ian1977 at 3:50 PM on May 23, 2011 [1 favorite]

is your metric kilos of fuel consumed per km traveled (or pounds per mile), or total global fuel consumption?

I suspect that blimps do better in straight kg/km efficiency, but you'd also need to take into account that in this world there would be a lot *less* travel/transport going on... both business and recreational travel these days largely depend on it being fast...
posted by russm at 3:55 PM on May 23, 2011

Modern airplanes travel high enough up in the atmosphere that the air is very thin and has significantly less drag. Blimps can't do that. Blimps also are much less aerodynamic, and they are at the mercy of the prevailing wind currents, i.e. they get buffeted around a lot so you have to spend a lot of time and fuel getting back on course. All in all I'd say modern airplanes are at least an order of magnitude more fuel efficient.
posted by Rhomboid at 4:01 PM on May 23, 2011 [1 favorite]

Blimps tend to move around 35 miles an hour, more or less. Maybe up in the 50s or so if the wind is with you and you're burning more fuel. Most commercial airliners cruise around 550 mph, give or take. So wouldn't it make more sense to take high speed trains everywhere except when crossing the oceans? Or just drive? Major international flights over water are a fairly small proportion of the overall air transport market overall.

So if this happened, there would be very little reason for the blimps to be flying at all, and so the question really just becomes: what if all domestic flights were replaced by high speed trains? I'm not sure that question can really be answered (where do you get the power for the trains?), but that's basically what it comes down to.
posted by zachlipton at 4:08 PM on May 23, 2011 [1 favorite]

As I understand it peak helium is no less a problem than peak oil, and potentially worse (even without a massive worldwide blimp industry). Which makes it a little hard to examine this hypothetical -- the fuel savings would probably be offset by wiping out our hydrogen reserves. I guess we could always go with hydrogen.

Also, at least in the early days, trans-atlantic blimp crossings took something like 58 hours in several legs, according to wikipedia. (The hindenberg were ~4 days.) It would be really hard to just switch to that from where we are now.
posted by advil at 4:21 PM on May 23, 2011 [1 favorite]

oops, wiping out our helium reserves
posted by advil at 4:21 PM on May 23, 2011 [1 favorite]

The Hindenburg travelled at 76MPH, got 2.65MPG, and carried 70 people (note that by using modern seat spacing, you could likely triple that, though I don't know if you'd still have enough lift, so although I'll use 70 for my calculations below, it probably looks better than that).

A Boeing 747 travels at 567MPH, gets 0.125MPG, and carries up to 600 passengers (though designed for only 350).

That puts the blimp at 185 people-miles per gallon, and the 747 at 75 people-miles per gallon. So we have a base increase in fuel efficiency of 2.5x for using blimps instead of jets. Not too bad...

And it gets better: Jets have an absolutely minimum airspeed, and thus an absolute minimum rate of fuel burn; Blimps have no such constraint. For that reason, and the large surface area of a blimp, no reason exists why we couldn't have a 100% solar-powered blimp, effectively consuming no fuel.

That said, zachlipton hit the nail on the head - People fly in jets because they can cross the Atlantic in 5-7 hours. A pleasant zeppelin-cruise might appeal to (some) holiday-goers, but business travelers (whom I've heard - Though don't have numbers handy, so someone feel free to correct me - Make up over 90% of domestic passenger air travel) would have nothing to do with it.
posted by pla at 4:28 PM on May 23, 2011 [4 favorites]

pla, your analysis is backwards. more people-miles per gallon is better.
posted by GuyZero at 4:33 PM on May 23, 2011

Also, blimps require a volume of lighter-than-air gas to remain airborne, and this supply must be topped up from time to time. For practical reasons and because of certain past events, we tend to use helium for this purpose, especially with passengers on board. Helium is incredibly abundant in the universe, but it's not at all easy to extract. Our helium supply tends to come from helium extracted from natural gas, and natural gas extraction tends to require a great deal of energy. If we did this, we'd probably run out of helium reserves fairly quickly and would have to go through a pretty expensive process to quickly try to come up with some more, which would burn a ton of fuel.
posted by zachlipton at 4:48 PM on May 23, 2011

Modern airplanes travel high enough up in the atmosphere that the air is very thin and has significantly less drag.

Besides that, this allows modern jet airplanes to fly over a lot of weather, whereas a low flying blimp would have to fly around it (or through it in some cases). A deviation to stay clear of a thunderstorm is no big deal for a jet airplane, but it would add hours to a blimp's flight, assuming you've observed the storm and its direction well enough in time to avoid it (you probably can't outrun a thunderstorm in a blimp). Something like this is what tends to happen when you mix a blimp and a thunderstorm.
posted by zachlipton at 5:02 PM on May 23, 2011

GuyZero : pla, your analysis is backwards. more people-miles per gallon is better.

Right - Blimp=185, 747=75. 185 comes out 2.5x "better".
My apologies if I phrased that poorly, we agree completely. :)
posted by pla at 5:07 PM on May 23, 2011

Here is a decent read for you from my friend Dan who is working on a company to make practical airships. It doesn't go much into overall efficiency of the airship (but I bet if you contacted him, he'd give you more thought and accuracy than you would find here), but he does go into a decent amount of detail of the challenges and current options in airship design.
posted by plinth at 5:07 PM on May 23, 2011

There's a navla history museum at Moffet Field in Mountain View, CA that has a very extensive exhibit on the history of blimps and zeppelins in the US Navy. Bay Area residents will probably have seen the iconic Hangar One from the 101 which used to house zeppelins.

After the US navy lost 5 airships to bad weather they pretty much gave up on the idea. Admiral Moffet himself was lost on the 4th airship, the USS Akron.

So regardless of fuel efficiency (sorry for reading that backward pla, I'm gettin' old) the safety record of airships is terrible. I can't think of a less safe form of transportation. Empirically nuclear-powered vessels are safer than airships and nuclear power is no walk in the park.
posted by GuyZero at 5:19 PM on May 23, 2011

to be more specific, here's a bit from the wikipedia page for US Navy airships:
  • ZMC-2, a metalclad-airship built by the Aircraft Development Corp - 1929-41 (scrapped)
  • (ZR-1) Shenandoah - 1923-25 (crash in a storm)
  • (ZR-2) R38 (see below) - 1921 (crashed)
  • (ZR-3) Los Angeles - 1924-39 (decommissioned and dismantled)
  • (ZRS-4) Akron - aircraft carrier 1931-33 (lost in a storm 1933)
  • (ZRS-5) Macon - aircraft carrier 1933-35 (lost in bad weather)
And my bad, the Los Angeles didn't crash. So 4 airships lost, Moffet himself on the 3rd.
posted by GuyZero at 5:22 PM on May 23, 2011

US civil aviation consumption:
Total global aviation consumption:

The issue of blimps vs other forms of aviation are discussed in George Montbiot's "Heat".
See pg. 186: " airships, surprisingly, might be the best kind of transport" in examining air travel.
posted by PickeringPete at 6:47 PM on May 23, 2011

Strictly speaking a 'blimp' is a non rigid airship e.g. one without a supporting structural frame. An airship has a supporting frame. They are not the same thing. There's a reason why planes dominate aviation and that is because airships are a terrible way of transporting anything. They're extremely expensive, slow and dangerous. They can carry hardly any passengers or cargo and are incredibly difficult to handle on the ground. They have a massive drag coefficient as well. The rebirth of the airship has been confidently predicted every year since at least the first oil crisis in 1973 and it has never happened and it never will. The financial and practical costs of using airships instead of aircraft would be so crippling that you might as well ask how much energy would be saved if farmers just carried bags of carrots from the fields to the shops by hand instead of using lorries.
posted by joannemullen at 7:46 PM on May 23, 2011 [2 favorites]

The Aviation episode of Design E^2 spends a segment dealing with the costs of using airships. (You can watch from the site, it was part of the Transportation series, sorry about the flash.)
posted by thebestsophist at 8:38 PM on May 23, 2011

GuyZero writes "So regardless of fuel efficiency (sorry for reading that backward pla, I'm gettin' old) the safety record of airships is terrible."

The safety record of airplanes 80 years ago is terrible too, especially military aircraft. We haven't built enough airships and blimps to get over an experimental failure hump yet.
posted by Mitheral at 8:51 PM on May 23, 2011 [2 favorites]

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