Why Dirigibles?

[Fred Brackin]

Originally Posted by RyanW

One thing that is interesting is that, in Venus' dense CO2 atmosphere, oxygen and nitrogen are lifting gases. A floating city above the clouds at 1 atm is awesomely steampunk but plausible, with outside work done in shirtsleeves and a face mask.

At altitudes where you would not have to wear an extreme environment suit outside for either pressure or heat that buoyancy would be much reduced. Also, I think there might be sulfuric acid clouds up there.

I have in the past been relatively sympathetic for schemes that involved blowing up Venus. Or at least blowing off its' atmosphere. It probably is the least useful piece of real estate in the Solar System that you can theoretically stand on the surface of.

[AlexanderHowl]

Actually, the science is sound, the upper atmosphere is carbon dioxide, which is denser than oxygen and nitrogen at that elevation. Sulfur dioxide is much denser, so it stays in the lower atmosphere. It is actually possible with current technology to safely build floating cities in the upper atmosphere of Venus, there is just no economic reason to spend the hundreds of billions of dollars needed to build it.

Venus's atmosphere possesses one important resource: nitrogen. While the atmosphere of Venus is only 3.5% nitrogen, it is 93 times as massive as the Earth's atmosphere, so it possesses four times as much nitrogen as the atmosphere of the Earth. If you blew off the atmosphere of Venus, you would lose four-fifths of the available nitrogen in the Inner Sol System.

[tanksoldier]

Originally Posted by Fred Brackin

Is this instead of airships getting a 3 year head start?

This is intstead of serious develpment being terminated.

Had airship develpment continued they would be as advanced today over the Hindenberg as the A380 is over the Ju 52.

Even in the 1930s an airship wasn't cheaper then a train; it required a large crew in both the ship and on the ground for operation.

Cheaper than laying tracks all over the US, and can go where tracks haven't been laid.

[Pomphis]

I don´t see that. The main problem is lifting gas, and we already have hydrogen. Hull materials have advanced, but the results are small. Same for engines. It´s a bit like with swords: they simply can only be advanced so far. At some point guns become better.

[Pomphis]

Originally Posted by tanksoldier

Cheaper than laying tracks all over the US, and can go where tracks haven't been laid.

If there is enough traffic, railroads are cheaper. There is a reason we have more railways than airships: money.

And to go to places which are hard to access they have to compete against helicopters. which need much less crew, no crew at all at the place they go to, are faster, better maneuverable, have a lot less drag and are far more capable to deal with wind and bad weather.

[Anthony]

Originally Posted by tanksoldier

This is intstead of serious develpment being terminated.

There's a reason serious development got terminated. In the end, LTA craft need to be something upwards of a hundred times the volume of heavier than air, and that means they have inferior transport efficiency unless much much slower (including the need to operate at lower altitudes, the equivalent of a transport aircraft at 600 mph is a zeppelin at around 80 mph).

[Fred Brackin]

Originally Posted by tanksoldier

This is intstead of serious develpment being terminated.

Had airship develpment continued they would be as advanced today over the Hindenberg as the A380 is over the Ju 52.

At least a few years ago there was a Ju-52 still flying. Not so for any rigid airship.

Several years ago I tried building advanced and speculative dirigibles with GVB. I tried advanced materials and engines at TLs up to 11 (3e still TL10 in 4e). I tried mega-sizing them I even tried a combined lifting body dirgible with vectored thrust.

That last one was instructive as it functioned better when I deleted the lifting gas.

Anything you could do in the way of tech upgrades for a dirigible works better for a straight airplane or a helicopter or especially for a vectored thrust lifting body.

[AlexanderHowl]

Yes, dirigibles only make sense in a couple of special circumstances. The first is the provision of aerial transportation for newly colonized planets with substantial atmospheres before the development of substantial fueling infrastructure. The second is the provision of affordable transportation within that upper atmospheres of greenhouse planets or gas giants. Outside of those two special circumstances, they really do not make that much sense.

[Fred Brackin]

Originally Posted by AlexanderHowl

Yes, dirigibles only make sense in a couple of special circumstances. The first is the provision of aerial transportation for newly colonized planets with substantial atmospheres before the development of substantial fueling infrastructure. The second is the provision of affordable transportation within that upper atmospheres of greenhouse planets or gas giants. Outside of those two special circumstances, they really do not make that much sense.

Your first exception is probably not accurate. Every time I've tried to build them dirigibles burned more fuel on a per mile basis that conventional aircraft.

[Anthony]

Originally Posted by Fred Brackin

Your first exception is probably not accurate. Every time I've tried to build them dirigibles burned more fuel on a per mile basis that conventional aircraft.

That might be limits of VE; with properly designed engines, your fuel requirement will be Drag * Distance / Efficiency, and if you go slowly enough the dirigible is lower. The problem is that 'slowly enough' is really really slow.