Could They Ever Return?

[PaulGazis]

To get the ball rolling on this particular forum, how many of you think that large rigid airships, similar to or larger than the Flying Cloud (169 meters long, with 70,000 cubic meter volume, approximately 10 times the size of the Zeppelin NT) could make a comeback? It’s impossible to watch movie footage from the Age of the Great Airships without feeling a twinge of wonder, but what would such vessels be good for in our world today?

Large airships have several unique capabilities
1) They have limitless endurance.
2) They don’t need an airport.
3) They can stop and hover forever.
4) Fog, clouds, and low visibility are not much of a problem.
5) They can lift heavy things.

They also have unique limitations
1) They will never be much faster than 150 km/hr (100 MPH).
2) They can’t go much higher than 2km (6000') without significant sacrifices in performance.
3) Ground handling is difficult.
4) They have a history of trouble with severe weather.
5) Ships much smaller than 10,000 cubic meters can’t carry much fuel or cargo.

Airports seem to be the key. Captain Everett’s world never needed them, so it never developed them, which would give airships a significant advantage over airplanes. But in our world, with its extensive network of air terminals and their associated infrastructure, airplanes will always be faster, cheaper, and be able to carry more people and cargo by making more flights. This suggests that in our world, large airships will be limited to missions that involve long duration, substantial cargoes, or operation from places without large airstrips. There are any number of possibilities, such as survey work, surveillance, offshore resupply, transport of large cargoes to or from rural areas or urban centers. Are these enough to justify a multi-billion dollar development effort to resurrect a lost technology to build and fly a fleet of large 100 million dollar aircraft? Who knows?

But if they did come back, wouldn’t it be cool?

[stratplans]

It's a long time since I read The Big Lifters by Dean Ing, but I seem to recall he offered some pretty logical scenarios for them doing so. I'll have to reread it in my MyCoFT (Mythical, Copious Free Time ).

[Nelson]

I'm confused by the idea that an airship doesn't need an airport. In Captain Everett's world, there are no runways... but Cairns, Darwin, Kupang, even Sarah's village, all have aerodromes. Sure, they range from a major facility with hangars to a simple mooring mast on the shore, but airports range from major international hubs to little municipal strips. An airship mast is probably cheaper and easier to set up than even the most modest 3,000 x 75 feet of straight and level asphalt, but it still has to be done, the airship needs a prepared site. A Twin Otter on floats, on the other hand, only needs a fishing dock and a rusty steel drum of avgas.

Are airships more fuel efficient per ton carried over distance than a cargo plane? Looks like it! Let's evaluate in terms of how many tons of cargo can be pushed one mile with one gallon of fuel (or how many miles a gallon of fuel pushes one ton of cargo, same thing)

Latécoère 26 (1926): 4.2 mT*NM/gal (557 kg avgas for 1700 km, 930 kg cargo)
Lockheed C-130H (1964): 4.3 mT*NM/gal (9530 gal for 2050 naut.miles, 20 tons cargo)
deHavilland DH.89A Dragon Rapide (1934): 4.9 mT/NM/gal (76 gal avgas, 456 NM, 1788 lbs cargo)
Canadair CL-44 (1959): 9.53 mT*NM/gal (7857 gal, 2500 NM, 30 tons cargo)
Antonov An-124 (1982): 16.4 mT*NM/gal (432 knots, 3160 gal/hr, 120 tons cargo)
R-505 Flying Cloud (fic-1926): 54.6 to 84.2 mT*NM/gal (5162 gal for 12672 naut.miles, 22.3 [85% inflated] to 34.3 [100%] tons cargo)

Captain Everett wins big time! And that's even before we remember that the airplanes are burning high-quality Jet-A (Airnav: $4.35/gal) -- except the Dragon Rapide, which burns LEADED high-octane aviation gasoline (Airnav: $4.59/gal) -- while the Flying Cloud is taking on nice cheap diesel (AAA: $2.85/gal). But the Antonov will move your cargo from Frankfurt to Lakehurst with a crew of four working eight flying hours; the airship will need at least as many crew, doubled or tripled to work in shifts, for three days! Even if you don't care about speed, even ignoring that the extra crew and their bunks and breakrooms displace even more paying cargo from your airship, you have to pay those people for their flying hours, and I expect that'll outweigh any fuel savings.

Plus, if you don't mind sub-100mph speeds anyhow, why are you flying, when you could be transporting by train or ship, FAR more efficiently in both fuel and manpower?

train: 310 mT*NM/gal (from American Assoc'n of Railroads claim of 400 short ton * statute miles / gallon)
container ship Emma Maersk (2006): between 900 and 1500 mT*NM/gal (6724 gal/hr, 25.5 to 31 kts, 11,000 to 15,000 20ft containers with max 21.6 mT cargo each)
generic mid-1970's bulk cargo ship: 1950 mT*NM/gal (50,000 tons, 13 kts, ~27 tons of Bunker-C per day, figures from dear old Nelson's Dad)

So no, I don't think airships are coming back for a transport role.

Now for the good news, remember that Antonov plane? Aviation Week suggests the Russians are going to start building them again, to feed a market of around 70 worldwide. Different sources online put the 'list price' of an An-124 anywhere from $80m to $200m. So if you CAN find a niche that nothing else will fill, it CAN make sense to start a production line for a small number of ~$100m aircraft.

Here's a small nice to fill: fighting forest fires. Oh, not as the bomber, the bombers should remain fixed-wing aircraft with quick turnaround times. But the airship could replace the "bird-dog" aircraft, the spotter, an airborne command post and control tower. Control cab for the airship, separate chart & radio room for the fire boss, breakroom/kitchen, lavatory, and bunks, remaining on station for days at a time. A role like this won't justify an airship building industry... it could make an existing airship industry more profitable, though.

[PaulGazis]

Thanks, Nelson, for providing those fuels consumption figures for modern transport aircraft! Rest assured that I will work them into the story. They may not appear directly, but they will almost certainly become part of the economic background I’ve been building to make everything hold together.

Your points about airports are well-taken. As I reflect upon your analysis, I realize that the situation is more complicated than I had represented in my original post. A complete Air Station, with all of its masts, sheds, tracks, handling trolleys, hydrogen plant and storage, cargo and passenger facilities, and the like, could be every bit as substantial as a modern air terminal. But unlike fixed-wing aircraft, which generally must land at an airstrip to offload cargo and passengers (unless the cargo and passengers are extremely tough, equipped with parachutes, or the ground is covered with a thick layer of foam rubber), an airship could, in principle, touch down in any clearing big enough to hold it or transfer things by hoist. In practice, I cannot find many records of hoist operations, but there were plenty of instances of full-sized ships operating from the most rudimentary of facilities. I've attached a scan from Dick and Robinson's Graf Zeppelin & Hindernberg of the 'Afrika-Ship', L-59 -- one of the first large cargo-carrying Zeppelins -- to illustrate what I mean by 'rudimentary

L59, the Afrika-Ship, in 1917 operating from what only be described as an 'unimproved field'

L59_HandlingParty_r75.jpg (46.22 KiB) Viewed 2727 times

Viewed in this light, a large airship could be viewed as a slow and unwieldy but extremely stable ultra-heavy-lift helicopter with 100% IFR capability, intercontinental range, and an endurance measured in days. Surely a vehicle like that must be good for something. But what? I like your idea of an airborne command and control center. I’ve added it to my list of Things The Royal Navy Airship Service Does, and it may appear in the story when Captain Everett finally has cause to reflect about his service in Palestine.

[RbSned]

One proposal that sometimes turns up is that of an airbourne hotel/cruise ship.
Never seems to happen though, lack of finance or just lack of vision amongst the money men?

[peterh]

I can't help but think that, in a military context, they'd be completely useless in our world, because it would be The Most Vulnerable thing up there. Too slow and unwieldly to quickly maneuver(sp?) out of harm's way, the 6000ft ceiling would be too low, and they're so ruddy big that anyone could hit them where it would hurt most.

Am I right in thinking that we're looking at civilian purposes only? For observational purposes, they'd be great.

Another thing that tickles my fancy: if you've got radio-controlled boats, cars, helicopters and planes, why not radio-controlled airships?

[RbSned]

You mean like this?
http://www.youtube.com/watch?v=NHiBDACYVc8&feature=related
Or possably,
http://www.youtube.com/watch?v=UKOUvK-xrgw

[Nelson]

Thanks, Nelson, for providing those fuels consumption figures for modern transport aircraft!

Hey, I can't write fiction worth a darn, thanks for YOUR work. All I did was math, and I'm having fun with it.

The numbers I gave for aircraft are very rough. The C-130 is meant to put things in difficult places while being shot at, it is NOT a shining example of efficiency, but I wanted something with a similar payload to the Flying Cloud. I'm sure there must be another 20-25 ton payload aircraft that'd do better. I'll pull some of the reference books at work tomorrow. And I'll see if I can find appropriate numbers for airplanes circa 1926. [EDIT: added DH.89A and CL-44, and the Laté 26 mailplane used by the Aéropostale. If there is one tragedy to your revised history, it is this: there is no room for Antoine de Saint-Exupéry to be flying mailplanes over the Sahara.]

A complete Air Station, with all of its masts, sheds, tracks, handling trolleys, hydrogen plant and storage, cargo and passenger facilities, and the like, could be every bit as substantial as a modern air terminal.

Hydrogen plant and storage, eh? If the airship's engines were hydrogen powered as well (no fancy space-age fuel cells, I'm talking about feeding hydrogen gas into a piston engine, same as you would with propane or natural gas, same as the Graf Zeppelin did with "blaugas" fuel), the air station's hydrogen plant would be good for both lift gas and fuel. No airport in the word can produce Avgas or Jet-A. Advantage: Airship! Would make ballasting more interesting though, as you'd lose LIFT as you consumed fuel (the Graf Zeppelin's "blaugas" advantage was that blaugas was similar density to air, so consuming fuel changed the ship's weight very little; Sarah must to vent around 100 cu.ft of hydrogen to offset the weight Flying Cloud loses burning a gallon of diesel). Hmm.

a large airship could be viewed as a slow and unwieldy but extremely stable ultra-heavy-lift helicopter with 100% IFR capability, intercontinental range, and an endurance measured in days.

Good point. The CN Tower in Toronto shows a video of the tower's assembly, which involved a lot of pieces being hosited up by helicopter (Sikorsky S-64 Skycrane, I think). An airship could probably do that, and with bigger pieces (the S-64 lifts around 9 tons). The airship could load up at an air station, fly to the cargo's destination in the middle of nowhere, drop the payload, vent a bunch of hydrogen to offset the dropped weight, and fly back to the air station.

Is there a good solution for picking up loads in the middle of nowhere, though? When you take the cargo onboard, you need more lift. Do you fly under-inflated carrying tanks of compressed gas to reinflate when you make the pickup? Or do you fly to the pickup site with a swimming pool's worth of water to dump? (After today's story update, if the City of Brisbane finds a gas station in the desert, it still can't reach Darwin. If it takes on diesel fuel, the ship will be too heavy, not many 1920's gas stations offer hydrogen and the only ballast left to drop is the passengers. For every 25 gallons of diesel they take on, one person gets left behind...)

[PaulGazis]

Thanks for looking up those numbers, Nelson! I'll be looking forward to them. The fixed wing aircraft of Captain Everett's world are closer to those of 1920 in our world, since this is one area where their technology has lagged behind ours, but any and all performance figures will be useful.

I agree about de Saint Exupery. There is certainly room for authors aboard airships -- Neville Schutte leaps to mind -- but the fine tradition of mid-century aviation writing that began with works like Wind, Sand, and Stars and continued through Rold Dahl's Going Solo (yes, the author of James and the Giant Peach was a combat pilot in WW-II!) would be missing from Captain Everett's world. I do have to decide what happened to some of the authors and public figures connected with early aviation in our world, so if there are any particular names you're interested in our you have any suggestions, please feel free to open a new topic on the 'The World' subforum and start a list!

Quite a few people tried to run airship engines using hydrogen in our world during the 10's and 20's, but these experiments do not seem to have been satisfactory. Indeed, one senses some very real fear in contemporary reports (e.g. "The run was discontinued after several backfires. The engineer is still hiding in a closet somewhere in Brighton'). The Graf Zeppelin's blaugas engines seem to have been a unique item, never to be repeated. The one thing that did seem to work -- as I'm sure you are aware -- was running exhaust from the engines through a condensor to recover water from the combustion process. If done properly, this would weigh even more than the burned fuel. This became standard practice on the large American ships, and the condensors are plainly visible in old photos such as the one I included in a blog post (http://paulgazis.com/blog/2009/10/12/co ... -happened/) sometime back. But this was a 1930's technology that Everett's world has only begun to develop, and the weight of the condensors could be prohibitive on a medium-sized ship with a high fixed weight such as the Flying Cloud -- this is one of the vessel's weaknesses.

You're quite right about hoist operations. Unless one builds some manner of hybrid airship/helicopter, the only way to lift the cargo would be to drop water ballast. This is all well and good -- unless, of course, the load happens to be sitting in the middle of a big sheet of sodium. And it would certainly be possible to vent hydrogen when the cargo is delivered. But this would limit the ship to one load per sortie, after which it would have to return to a station to regas and reballast. The alternative would be to devise some way to way to resupply the ship in the field. The airmen of Captain Everett's world have developed several ways to do this... but these could be improved, so I'm definitely in the market for more ideas here, and I'd welcome suggestions!

[RbSned]

Since airships have a huge surface area why not cover the outer surface with solar panels and use the power to drive the props?
Also, why are you assuming a modern airship would be restricted to a ceiling of 6000 ft?
Surely modern materials and technologies allow for solutions to the gas expansion problem and cabin pressurisation for fixed wing aircraft has been around for decades.