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Airships, Not Just For Steampunk
Jun. 7th, 2011 11:13 amBlimps and their cousins zeppelins feature heavily in steampunk fiction. They also periodically enjoy "revivals" where people advocate for more / new uses of blimps. I think the magazine Popular Science has them on the cover about once every two years.
Well, via![[livejournal.com profile]](https://www.dreamwidth.org/img/external/lj-userinfo.gif)
jaylake, I found this blog entry about helium hokum. Basically, the Joseph Dick, the author, takes work done by Theodore Von Karman in the 1950s (a book called "What Price Speed") which allows one to plot energy efficiency vs speed. This allows a simple comparison between various transportation mechanisms.
To nobody's surprise, trains and container ships are by far the most efficient, but of course somewhat slow. On Dick's graph, airships and modern cargo jets have about the same energy cost (measured by dividing horsepower by payload times speed) but the airships are way slower, running only marginally faster than freight trains. Airships are faster than water-ships, but at a vastly higher energy cost.
In short, airships just don't cut it for long-distance cargo. But what about short-distance cargo? One of the perennial proposals for airships is to replace helicopters for local heavy lift, like in logging operations. Since Dick didn't run the numbers, I did.
I used as my helicopter the Karman K-Max, which is a newer helicopter optimized for external heavy lift. Maybe that's not entirely fair, but the new blimp would have to compete with the new helicopter. So I did the math. I have to admit, the math was tricky (consistent units matter) and I ended up doing it in metric. The key calculation is efficiency for which I got the helicopter at 0.67 (1044kw power / 3.1 metric ton payload x 51 meters/second speed x 9.81).
Plotting that 0.67 on a scale, you see that the helicopter costs twice as much as the blimps for roughly the same speed! So, yes, for some short-distance cargo and hauling, a blimp is optimal.
Well, via
jaylake, I found this blog entry about helium hokum. Basically, the Joseph Dick, the author, takes work done by Theodore Von Karman in the 1950s (a book called "What Price Speed") which allows one to plot energy efficiency vs speed. This allows a simple comparison between various transportation mechanisms. To nobody's surprise, trains and container ships are by far the most efficient, but of course somewhat slow. On Dick's graph, airships and modern cargo jets have about the same energy cost (measured by dividing horsepower by payload times speed) but the airships are way slower, running only marginally faster than freight trains. Airships are faster than water-ships, but at a vastly higher energy cost.
In short, airships just don't cut it for long-distance cargo. But what about short-distance cargo? One of the perennial proposals for airships is to replace helicopters for local heavy lift, like in logging operations. Since Dick didn't run the numbers, I did.
I used as my helicopter the Karman K-Max, which is a newer helicopter optimized for external heavy lift. Maybe that's not entirely fair, but the new blimp would have to compete with the new helicopter. So I did the math. I have to admit, the math was tricky (consistent units matter) and I ended up doing it in metric. The key calculation is efficiency for which I got the helicopter at 0.67 (1044kw power / 3.1 metric ton payload x 51 meters/second speed x 9.81).
Plotting that 0.67 on a scale, you see that the helicopter costs twice as much as the blimps for roughly the same speed! So, yes, for some short-distance cargo and hauling, a blimp is optimal.
