PaulGazis wrote: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.]
PaulGazis wrote: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.
PaulGazis wrote: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...)