Is the world really better off without hydrogen airships?

[Buzz Bloom]

Things are much different now then when the Hindenburg was a thing. People of the modern world have much better abilities engineer things to be safe, and effective.

Hi Evanish:

I agree that engineering has improved a lot, but I have to disagree that the improvement of engineering is sufficient to ensure safety. After an engineering design is completed, a model is built and tested. How much testing is needed to ensure safety? I think it is reasonable to say that frequently the profit economics of an enterprise requires reducing testing below an adequate level. This reduction results in odd and unexpected accidents, sometimes fatal. There seems to be examples in the news quite often.

Also:

https://en.wikipedia.org/wiki/Murphy's_law .​

Regards,
Buzz

 

[Eric Bretschneider]

So according to this page you can buy a 8246 2,000 gram Weather Balloon for $249. According to them this has a burst diameter of 30 feet. I assume that means that is the maximum it can be filled to. Since we aren't planning to doing a lot of changes in altitude we can probably fill it pretty close to it's burst diameter. Let say we are filling it to 28 feet, or 8.5 meters. Since it's basically round that gives us a volume of 325.47 meters square

From earlier we know that the most massive of the three discussed types of wind turbine weighs 334 tons assembled (I'm assuming they are metric tons here). From information I have in a previous post we know that 334 tons would take 277,616 meter square of hydrogen to lift, or 299,686 square meters of helium. That would come out to needing 853 of these balloons filled with hydrogen to lift the whole turbine with hydrogen gas, which would cost $212,397 in balloons, and $17,470 in hydrogen. For helium it would come out to needing 921 helium filled balloons to lift the whole turbine with helium, which would cost $229,329 in balloons and $909,397 in helium. These costs are remarkably low, especially for hydrogen. Someone please tell me if I'm making some kind of mistake here.

Not a bad start for an engineering estimate. I think you meant cubic meters rather than square meters.

Another thing to consider is that helium is a mono atomic gas while hydrogen is diatomic. Helium is the smallest molecule and it is notoriously difficult to make materials helium leak tight. The semiconductor industry uses helium for leak checking. If helium doesn't make it through a fitting, nothing else will.

For a reference, bulk liquid hydrogen was about $1 per 100 cf (gas volume equivalent at atmospheric pressure) in 2005. That gives you impurity levels in the ppb range, so you can discount the price somewhat for the application.

 

[Evanish]

Not a bad start for an engineering estimate. I think you meant cubic meters rather than square meters.

Another thing to consider is that helium is a mono atomic gas while hydrogen is diatomic. Helium is the smallest molecule and it is notoriously difficult to make materials helium leak tight. The semiconductor industry uses helium for leak checking. If helium doesn't make it through a fitting, nothing else will.

For a reference, bulk liquid hydrogen was about $1 per 100 cf (gas volume equivalent at atmospheric pressure) in 2005. That gives you impurity levels in the ppb range, so you can discount the price somewhat for the application.

You're right. I did mean cubic meters. Thanks for the correction. Good point about the impurity levels. I hadn't considered that.

Anyways I was on YouTube, and a channel I sometimes watch just came out with a video where he made a remote control hydrogen airship that I thought was a lot of fun so I'm sharing it here.

I'm thinking if the craft is only slightly heavier then air it makes landing a lot either. Maybe it would be a good plant to attach balloons to the cargo until it was just slightly heavier then air then us a helicopter to tow it around, or alternatively until it was slightly lighter then air then use a ground vehicle to tow it around. Not exactly an airship, but it seem like it could be financially feasible for some things.

 

[Mr lee]

its a now idea.
hydrogen, multi-rotor,and composites
the company http://aeroscraft.com/technology-copy/4580412172
has lift control by compressing in a tank and expanding gas in a bag to go up--a simple pump to go up and down
igor pastornik i think, designed

 

[skystare]

The biggest problem for rigid airships was delicacy - even in the helium filled ones. Three of the four US Navy helium airships were destroyed by weather, broken up or driven down. No rigid was fully stressed at the time of design; without modern computers the task was too vast. This might be achievable today, especially with lighter, stronger modern alloys and fabrics. One particular material of interest is aluminized mylar, which is orders of magnitude cheaper, lighter, and more gas proof (we had a helium party balloon floating around the basement for over a year!) than the rubberized cotton or Goldbeater's membrane gas bags of the 1930's. Especially as it is conductive and therefore doesn't build up static charges, it could reasonably safely contain hydrogen.

 

[Sherwood Botsford]

For the effect of weather, look up the USN ship Shanandoah. It was disassembled by wind sheer. The crash was gentle enough that many survived.

If they can be made reasonably reliable, they would fill a niche for short range transport. Right now it takes 3 hours to fly across the street: You need to be at the terminal 2 hours before the flight. You have 20 to 30 minutes fafing about getting off the plane, another half an hour for luggage.

In Alberta we used to have a municipal airport right downtown. Before 9/11 you could take a cab or bus to the airport, walk on (they had a raft of turboprop L1011's I think.) Get a flight to Calgary. Do your business in calgary, and return the same day. After 9/11 that vanished. The Muni closed.

The conflagration of the Hindenburg was mostly the burning aluminum/rubber paint on the skin. Hydrogen itself has so much lift that the flames are well above the craft. If an H2 tight non-flammable skin were available the Hindenburg would have burned much more slowly.

One poster mentioned using them as sky cranes. There are two issues here:

1. It needs to be absolutely calm or very steady to work. Given the siting selection criteria for wind turbines, this is unlikely. I suspect this is why heavy helicopters aren't used for this, although they are for assembling power line pylons. Mind you it may be possible to use a guyed airship. Airship comes in with a turbine nacelle: drops 4 light weight lines. Those are used to bring up 4 heavier lines, while dropping ballast to compensate for the weight. heavy weight lines are shackled in place. Radio link from the airship controls winch action. At this point, more ballast is dropped creating strong lift. Airship moves through winch action supplemented with engines. The problem is that the surplus lift has to be large compared to the wind forces on the airship, otherwise the airship will will be forced groundward by the upwind cable.

A different way for nacelles would be put a light weight spider on top of the tower. Lines are attached to the spider which then can be used almost as an x/y plotter to do the final positioning while the airship holds it up. This would be much like the system ships at sea use to bring a helicopter on deck. They winch it down while the chopper generates net positive lift. Still gets hairy.

If not used to construct, the problem becomes far easier. Package on skids that will take x m/s of impact. Now you need a flat spot and remote release. You only need a couple seconds of matching conditions. Be expensive, but if it save big roads, might be worth it.

2. For random delivery there are issues matching lift to load. I take 1 ton to Edmonton. I let it go. Now I have 1 ton of lift. I either need to compress a thousand cubic meters or so of H into a storage tank, spill it, or pick up a ton of ballast. To make this workable every delivery station would have a water tank. Arrive, anchor, drop load suck up water to match, move on. Pick up a new load: Anchor. drop off water ballast, pick up load. I don't see this happening for drone delivery.

3. Airships have such a high area to power ratio they are hard to control in breezes. And in serious weather, they need to run and hide. Given their airspeed, they may have a tough time outrunning a storm.

 

[Evanish]

2. For random delivery there are issues matching lift to load. I take 1 ton to Edmonton. I let it go. Now I have 1 ton of lift. I either need to compress a thousand cubic meters or so of H into a storage tank, spill it, or pick up a ton of ballast. To make this workable every delivery station would have a water tank. Arrive, anchor, drop load suck up water to match, move on. Pick up a new load: Anchor. drop off water ballast, pick up load. I don't see this happening for drone delivery.

For random drone deliveries, rather then tons I was thinking in terms of things like washing machines, driers and a weeks worth of groceries. Something like a drone flying from a central hub to the delivery location, lowering the load down with a winch, flaring off the excess hydrogen, releasing the load and then flying back to he central hub to resupply, and pick up the next order.

 

[Sherwood Botsford]

1 kg of H2 is worth about $2.
Density of air at STP is about 1.2 kg/m3
Density of H2 at STP is about 1/15 of this.
Lifting capacity of 1 kg H2 is about 14 * 1.2 = 17 kg.

So, yes, it may make sense.

Might make even more sense to power it with a hydrogen fuel cell.

Having a small compressor on board that can move hydrogen to/from a small tank however makes altitude control far easier.

May be merit in using a rigid airship formed as a lifting body. for better control. See: https://en.wikipedia.org/wiki/AEREON_26

The inability to function in even moderately bad weather is a set back.

***

Big advantage for LTA delivery aircraft: Much quieter than helicopter.

Downsides: Very tempting target for boys with paint guns, pellet guns and slingshots.

 

[Integral]

I find it sort of interesting that when talking about Hydrogen explosions this tread keeps referring to the Hindenburg. In this thread it has been pointed out that this was more of a varnish fire then Hydrogen, though I am sure the Hydrogen did nothing to slow it down. Wouldn't it be more correct to be discussing a more modern H explosion .

OK, NASA cannot make a foolproof H container. Can you?

 

[Eric Bretschneider]

The reference to the Navy Shenandoah is amusing. It was built in the early 1920s. The arguments against hydrogen dirigibles and airships in general are based on issues/incidents that are at last 70 years old!

Wind gusts are less of a problem. A modern airship with GPS could use station keeping thrusters similar to what has been used on ships for decades. The problem of keeping a 10s of kiltons ship in position in the open ocean isn't significantly different. It makes sense to try a modern version of an airship, but every time someone even hints at the idea the immediate response is "Hinderburg!"

Get over it.

 

[Baluncore]

The arguments against hydrogen dirigibles and airships in general are based on issues/incidents that are at last 70 years old!

Those who do not learn from history are condemned to repeat it.
The economic advantage of both He and H₂ lifted airships collapsed together 70 years ago.
There is no easier target for an anarchist/arsonist/terrorist, than a big bag of H₂.
The cost of airship insurance makes H₂ a commercial liability when compared with He.
Emotion and sentiment are insufficient justification to launch a high cost, high risk, commercial venture.

 

[Eric Bretschneider]

And those who are stuck in the past have trouble seeing the present or the future.

You remember the Hindenburg and equate it to a terrorist attack - how would a terrorist attack a dirigible? The obvious time would be just before landing/after takeoff. That would require someone to be inside the perimeter of some type of airport facility. Getting a bomb on board would require the same effort as getting a bomb on board a commercial airliner.

Try to shoot it down with a gun and you are making a 1,000+ yard shot. There aren't a lot of marksman who can make that shot. And put a bullet hole in a dirigible and you get a slow leak (soft landing with time to spare). Even if you manage to ignite the hydrogen, it has to mix with air before it can explode. You would have a hydrogen fire, not a hydrogen explosion. Ignite the fuel in a commercial airliner and you have burning fluid or flames trailing from the aircraft.

Below their stall speed, airplanes fall out of the sky.

If a terrorist or anarchist wants a target there are far easier targets than aircraft of any kind. Rush hour traffic for one. Many high school sporting events draw thousands of spectators and they are scheduled months in advance and on almost a weekly basis. How about the spectators watching events like the Boston Marathon (or pick your race). Miles of spectators in open environments that are impossible to secure.

By your arguments, the Titanic, Lusitania and Empress of Ireland mean that commercial cruise ships shouldn't be viable any more. Yet cruise ships carry far more passengers these days and your anarchist/terrorist concerns mean that 5,000+ people are at risk in a single unprotected vessel.

Arguments about high cost, high risk need a lot more justification than a single incident that occurred 80 years ago.

 

[russ_watters]

The reference to the Navy Shenandoah is amusing. It was built in the early 1920s. The arguments against hydrogen dirigibles and airships in general are based on issues/incidents that are at last 70 years old!

This is because such airships haven't been used much in the past 70 years.

This thread is getting silly, so it is locked.