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Comment by 3327 | Hacker News Reader

i wonder how efficient it is

50% more weight and 50% less fuel than cargo plane

So, dramatically less efficient than modern sea freight, while lacking the flexibility to deliver to inland airports that you get from air freight.

PS: Why did you answer your own question?

Because he found out the answer only after asking the original question, and answered it for anyone else who would have been curious.

exactly !

I would presume he went and looked up the answer, and then decided to share for anyone else asking the same thing.

I saw a documentary about this machine when I was younger, the plan was to use the "Caspian Sea Monster” only to military purposes, as probably anything designed in the URSS back then, mainly for movement of soldiers and tanks across the waters.

EDIT: The documentary provided above by manaskarekar says the same: http://youtu.be/xr8N0Z4Cl0U?t=23m11s

"From now one there's three ways to do things: the right way, the wrong way and the Max Power way!"

"Isn't that just the wrong way?"

"Yeah but faster"

I think the better comparison is a slower but more efficient aircraft.

No, it can also go to inland ports by flying short distances over ground at reduced efficiency. Most cities tend to be quite close to coasts.

As masklinn notes, the operating ceiling is 7500 meters (for which there is an efficiency hit). So long as the city is not too far inland, this outperforms air freight in all ways on paper.

Well, the thing has no landing gear, so the inland city better have a lake or something.

The 7500 meter figure, is that with cargo or without? Aircraft can typically do pretty amazing things with an empty cargo hold and a few sips of fuel in the tanks.

Honestly, I'm really having trouble seeing this thing as anything but a Soviet propaganda project with no real economic argument for it.

The thick, warm, rich air at sea level is not exactly the best operating environment for turbojets. And if there really was a benefit to harnessing the ground effect that outweighed the negative effects of low altitude, why not use a proper aircraft like an Antonov and just fly it low enough to take advantage?

And I assume the 50%/50% figure above is in relation to contemporary Soviet aircraft? Which where, themselves, thirsty compared to contemporary western aircraft let alone modern aircraft. The thing had 8 (Eight!) turbojets!

I think the implicit question is not "why aren't Soviet-era military jets competing with modern cargo planes?", it's "why isn't a modern version of this competing with modern cargo planes?". (The former is just comparing 1970s apples to 2010s oranges.) In this context, it's reasonable to assume a landing gear and modern engines.

Re: the Antonov, I think the idea is that it needs to be very low to utilize ground effect, and the only way to do this safely is over water with a hull capable of emergency water landings at the very least.

The economic problem is that flying near the ocean surface is quite dangerous. You can have swells as high as 50 feet and rogue waves even higher than that. This means that erkranoplan either to be built as sturdy enough boats to wait out storms and incur the economic penalty of waiting, or as capable enough aircraft to be able to fly over them. Either prospect makes them less desirable economically.

Please note that the Lun was not an obligate ground-effect plane: its ceiling was 7500m, though it obviously lost efficiency without ground effect and needed ground effect to take off and land.

I didn't know the Lun had that high a ceiling! There's still a potential problem if it can't land in a storm, however. It might climb above the swells, then run out of fuel at high altitude.

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