Lighter-than-air craft rise again
bbc.com
bbc.com
"We're sorry but this site is not accessible from the UK as it is part of our international service and is not funded by the licence fee. It is run commercially by BBC Worldwide, a wholly-owned subsidiary of the BBC, the profits made from it go back to BBC programme-makers to help fund great new BBC programmes."
O.o
Could somebody who can see the video give us a 2 line description so we can see if it's available locally at a different URL?
Make sure you get a dedicated IP address though.
Edit: Link for the lazy - https://www.astrill.com/
Can anyone recommend BBC Worldwide a good copywriter?
In some future, more rational society, blimps would be tested for their resistance to a microburst, and if they failed, they would not be allowed to carry passengers. It's not true now, and every famous lighter-than-air disaster except Hindenburg involved the craft being pushed down to the surface entirely out of control.
http://en.wikipedia.org/wiki/Microburst
Picture of a microburst: http://en.wikipedia.org/wiki/File:Microburstnasa.JPG
Perfect word. It's not an exaggeration to say that most of our conversations about (a given topic) "A" aren't about "A" at all, but its symbolic or metaphysical version.
You'll see that, at least according to Wikipedia, the main threat to aircraft is the combination of a microburst and an inexperienced pilot, in contrast to your parent's claim that non-rigid aircraft simply lose all control.
But that's exactly right. A large, slow craft like the Macon cannot be controlled in conditions of vertical air motion. Pilot skill is no longer an issue. It's equally true, by the way, for rigid lighter-than-air craft -- once they go outside their controllable envelope, they're in the hands of nature.
Ha, it's an inverted submarine!
http://en.wikipedia.org/wiki/Submarine#Submersion_and_trimmi...
How would they descend otherwise, release helium and reload before taking off?
> “The biggest advancement is our buoyancy management system that allows the vehicle to operate autonomously - without the hundreds of people that you saw grabbing the Zeppelin type airships”
or this:
> The system gets around a major drawback of traditional airships [...where] ropes and docking stations are needed on the ground to stop a vessel floating off.
Too wasteful, and uneconomic. The way they control their buoyancy is by compressing the helium to reduce buoyancy, then later releasing it from a special storage tank to increase buoyancy. BTW this is how submarines control their buoyancy -- they displace water with air in set-aside volumes made available for this purpose, which increases the craft's overall buoyancy. Then, when they want to descend, they recompress the air and allow water back into the set-aside areas.
They mention that on the descent, they mix outside air with the remaining helium in the ballasts.
Aren't you going to lose a lot of the helium in this process?
Wouldn't it be easier to have a sealed bladder that inflates/deflates with pressure changes?
Anyway you're right: a scientifically literate journalist would probably have explained the rationales behind this non-obvious choice.
> They mention that on the descent, they mix outside air with the remaining helium in the ballasts.
If that's true, I gave them too much credit for intelligence. :)
> Helium is expensive, and is only going to get more so in the coming decade or so.
Yes, true, and it's yet another example of something we could be paying attention to before it's too late. But we probably won't.
> Wouldn't it be easier to have a sealed bladder that inflates/deflates with pressure changes?
I have to confess that to me this seemed obvious, because it's more or less how a submarine works (the submarine doesn't have a flexible bladder, it just pushes water around with air, but it's the same basic idea).
The plan for the Hindenberg (a rigid frame airship, of course, not a blimp) was to have concentric gas cells -- spherical gas-bags inside the truss framework. Each outer sphere full of helium would contain a large inner sphere of hydrogen. The He would effectively insulate the H2 gas from atmosphere, reducing the fire hazard, while taking advantage of the superior lift provided by H2; to descend, they could simply vent hydrogen (via a valve out the top of the lift cell). Unfortunately the US helium export ban put paid to that plan, forcing them to use only hydrogen. The rest is history.
(Another key breakthrough in the early noughties (of the 20th century) was the invention of Blaugas -- a gaseous combustible fuel that was of neutral buoyancy in air. You could store fuel in gas cells and pump it straight to the engines without having to make any trim adjustments.)
Blimps -- non-rigid airships -- use concentric gas bags as well: there's an inner cell hidden within the outer lift cell that can be inflated or deflated with air to maintain internal pressure (keeping the outer bag taut but not over-pressurized) and regulate lift. But the ability to compress or liquify helium is indeed a valuable new technique that will reduce operating costs enormously for future airships.
I also like the transportation focus presented by this article. Perhaps having a useful application (IE retrieving large things that are difficult for helicopters to retrieve) will help to encourage the market for all types of lighter-than-air craft.
Would cruise ships have happened without cargo ships first being designed? My guess is no, because cruise ships largely piggyback off of a technology that is industrially very useful. I do not think that a recreational company would dump so much money into finding ways to make ships more economically feasible. That takes industry, where the need is more obvious, and the potential demand is much easier to predict.
For comparison, the S-64 Skycrane (a heavy lift helicopter), weighs 19,000lbs, can lift 20,000lbs, and is 70ft long.
The Zeppelin NT, a modern semi-rigid airship, has an unloaded weight of 24,000lbs, is almost 250ft long, but only had a payload capacity of 4,200lbs.
http://www.bbc.co.uk/news/uk-19676639
We could always use hydrogen, which is even lighter and therefore more efficient than helium. There's just the problem with it being highly flammable.
Not to mention that Hindenburg wasn't that much of a disaster - of 97 people, 61 survived, which is not bad at all for an airship the size of three 747's (or six if you don't include the wingspan) chockfull of hydrogen.
To put it simply, you can set off magnesium with a blowtorch. You can set off hydrogen with a match.
Gasoline vapor is a completely different story, and the reason you think of gasoline as explosive. But, this doesn't generally prove to be a problem, in part because motorcycles (and just about every type of vehicle) have pressure vents so that the tank doesn't become dangerously pressurized.
Though maybe it will work out this time, who know. It’s not like this is some sort of earth shattering innovation, so whether it works or not seems pretty unimportant to me.
Even with compressing the helium to land again, I guess it could be more energy efficient, but it would take forever to reach it's destination. People typically fly in jets because they are fast, not because they are fuel efficient.
Unfortunately it's quite expensive starting at $375 for a 45-minute flight.
Couldn't get the video unfortunately. I'm in the UK, the VPN I used was Hotspot Shield, it's free.
Does anyone know if this has been done, or if it's at all feasible?
Oh great, now we can give the final blow to that annoying Nature!