Yet another Zeppelin idea

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Yet another Zeppelin idea

Postby Bluggo » Sat Oct 20, 2007 10:02 am UTC

It seems that many people in this forum share my opinion that airships are awesome.

What follows is an idea I had since I was a little child - it is not that original, so if no one built it I suppose that there is a good reason why it would not work: does someone here know it?

- Fact one: Dirigibles do not need energy to fly - they are lighter than air.
- Fact two: However, they are not aerodynamic - you'll need lots of energy if you want them to fly in a given direction with a reasonable speed.
- Fact three: In high altitudes, there are strong wind currents.

- Conclusion: If one attaches sails to an airship and exploits the winds, he can fly with a good speed using a minimal amount of energy.

I suppose there would be huge engineering problems in actually *building* a wind-powered dirigible; but is the general idea sound, or did I forget about something?

EDIT: corrected some grammar mistakes
Last edited by Bluggo on Sat Oct 20, 2007 10:17 am UTC, edited 2 times in total.
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Re: Yet another Zeppelin idea

Postby Gelsamel » Sat Oct 20, 2007 10:07 am UTC

I don't see too much of a problem if you only want to go where the wind blows.
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Re: Yet another Zeppelin idea

Postby Bluggo » Sat Oct 20, 2007 10:26 am UTC

Gelsamel wrote:I don't see too much of a problem if you only want to go where the wind blows.

Well, yes, but if I am not mistaken wind-propelled ships still had a good directionality - they could change direction by moving the orientation of their sails or of their rudder.

I am not so sure if a rudder would work for an airship, but the orientation of the sails could surely be varied - I was thinking along the lines of using an engine for getting into a current which goes in the general direction one wants to go, and then using the "sail" for saving fuel.

EDIT: thinking about it, I believe a rudder should work too, as long as there are no strong "sideways" currents - maybe one could "extract" the rudder from the hull when it is useful and "retract" it when it is not?
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Re: Yet another Zeppelin idea

Postby Gelsamel » Sat Oct 20, 2007 11:09 am UTC

If by "good" you mean that to go in any direction opposing the wind you have a zig-zag a ton. Then yes "good".

Also here is a fucking godly wind powered zeplin I pixeled in pain in about 10 seconds.

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It has shit tonnes of space for guns and missles..


Hmmm... flying gun fortress....
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Re: Yet another Zeppelin idea

Postby silent man » Sat Oct 20, 2007 3:37 pm UTC

I don't think that you actually need sails, depending on what you want to do with your airship. Since there is nothing providing resistance it would simply travel at the same speed as the air-current it is in. All sails would do is increase acceleration, because the larger surface area means more force. You would have to decide if that is worth the weight of the sails, but it certainly won't affect the maximum speed.


Also, I think that sailships mostly used the resistance of the water to create a resulting force that pushes them where they want to go. So unless you have a kite-like sail that you send up into a jet-stream while you stay in a different air-current, or you deform the whole airship to an airfoil-shape, I'm afraid your airship will go pretty much wherever the wind takes it.

But it'd still be pretty cool.

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Re: Yet another Zeppelin idea

Postby Bluggo » Sun Oct 21, 2007 5:35 am UTC

Ok, I understand your point.
Thanks!
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Re: Yet another Zeppelin idea

Postby Gelsamel » Sun Oct 21, 2007 5:45 am UTC

You're ruining my dream of a dragon zeppelin! D:
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Re: Yet another Zeppelin idea

Postby Solt » Sun Oct 21, 2007 8:21 am UTC

This is entirely possible and would work almost exactly the same way as in the water. Remember, air is also a fluid. It is indeed possible to sail/flysail into the wind. I believe the technique involves funneling the air through two sails, resulting in a higher speed flow and thus a low pressure zone (Bernoulli's law) in the front of your ship. Air pressure will do the rest, pushing you forward. Or you could zig-zag.

If dirigibles had continued into a golden age this might have happened, back before we realized that it was possible to move faster than 20 mph. However, it is now 2007 so fuck that. No force of nature tells mankind where he can and can't go.
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Re: Yet another Zeppelin idea

Postby Gelsamel » Sun Oct 21, 2007 8:39 am UTC

Ok now all we need is like a billion dollars to make a huge dragon airship with sails and heaps of guns on it.
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Re: Yet another Zeppelin idea

Postby Bluggo » Sun Oct 21, 2007 1:04 pm UTC

Or a flying hippie commune: "We gotta follow our wind, dude."

Airships: the best way of getting high!

"The answer is blowing in the wind..."

When I will decide to retire, after gaining economic supremacy over a continent or two and getting a handful of Nobel Prizes, I really think I will create something along these lines :wink:
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Re: Yet another Zeppelin idea

Postby miles01110 » Sun Oct 21, 2007 3:45 pm UTC

Gelsamel wrote:Also here is a fucking godly wind powered zeplin I pixeled in pain in about 10 seconds.


Har, you pixeled it in PAIN.

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Re: Yet another Zeppelin idea

Postby oxoiron » Mon Oct 22, 2007 10:34 pm UTC

Solt wrote:No force of nature tells mankind where he can and can't go.
Except for those pesky ones that prevent us from visiting the interior of a star... :wink:
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Re: Yet another Zeppelin idea

Postby silent man » Mon Oct 22, 2007 11:29 pm UTC

Solt wrote:This is entirely possible and would work almost exactly the same way as in the water. Remember, air is also a fluid.


Well, yes, but water has a significantly higher density than air. Also, when a boat sails into the wind, the water it moves through is generally moving at a different speed or even in a completely different dircetion than the wind. Add to that the variable angles of the sail and the boat itself and you have two vectors that you can add to go pretty much whereever you want. To exploit the same effect with an airship, it would have to be influenced by two different winds, going in different directions or at least at different speeds. To achive this, your airship would either have to be huge (on the scale of, say Manhattan) or you would have to be able to physically remove the sails from the rest of the ship as I already said.

Solt wrote: It is indeed possible to sail/flysail into the wind. I believe the technique involves funneling the air through two sails, resulting in a higher speed flow and thus a low pressure zone (Bernoulli's law) in the front of your ship. Air pressure will do the rest, pushing you forward.


Ok, I'm baffled. Since when does the Venturi effect affect the speed and density of the air IN FRONT OF the pipe/sails/whatever you are using to restrict it? With an airfoil shape, you can go at an angle, but you simply cannot make the wind move you opposite to the way it is blowing.

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True, but they CAN make us pay dearly for it.



I will post more thoughts and maybe some sketches after I've gotten some sleep.

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Re: Yet another Zeppelin idea

Postby photosinensis » Wed Oct 24, 2007 5:47 am UTC

Actually, it would be an amusing idea, putting sails on an airship. However, you'd probably need to take care to ensure that nothing gets caught in updrafts. A counter-weight system could be at least partially effective, but you'd probably want engines for that. At the very least, they can generate far more force than relying on gravity alone.

Of course, an even better idea would be putting Robert Plant, Jimmy Page, John Paul Jones, and the corpse of John Bonham on that airship. In fact, we can just leave out the airship, and that's still an awesome idea.
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Re: Yet another Zeppelin idea

Postby arbivark » Wed Oct 24, 2007 6:47 am UTC

I think the dragon design is the way to go. What it adds in, er, drag, it makes up for in visual appeal. Ever seen a goodyear blimp? They are cool. A goodyear dragon would be beyond cool.
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The dragon, in addition to its wings/sails, could have propellers, thin film solar panels, so as long as you are going in the general direction of the windstream, maneuvering is doable.
Designed well, the propellers could also function as windmills, to generate power when not being used for propulsion.

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Re: Yet another Zeppelin idea

Postby selfopening_door » Wed Oct 24, 2007 7:55 am UTC

Is it just me, or does the thought of a goodyear dragon zeppelin the size of Manhattan seem like a freaking awesome one? Beyond beyond cool! That's what I'm talking about! :mrgreen:
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Re: Yet another Zeppelin idea

Postby EricH » Wed Oct 24, 2007 5:45 pm UTC

arbivark wrote:The dragon, in addition to its wings/sails, could have propellers, thin film solar panels, so as long as you are going in the general direction of the windstream, maneuvering is doable.
Designed well, the propellers could also function as windmills, to generate power when not being used for propulsion.


By "when not being used for propulsion" you mean "when the airship is anchored"? That's the only time I can think of, that the ship could be moving at any appreciable speed relative to the surrounding air... But then, I didn't follow Solt's explanation, so I still don't know how to maneuver the airship at an angle to the wind, much less tack into the wind.
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Re: Yet another Zeppelin idea

Postby Indon » Wed Oct 24, 2007 7:42 pm UTC

silent man wrote:Well, yes, but water has a significantly higher density than air. Also, when a boat sails into the wind, the water it moves through is generally moving at a different speed or even in a completely different dircetion than the wind. Add to that the variable angles of the sail and the boat itself and you have two vectors that you can add to go pretty much whereever you want. To exploit the same effect with an airship, it would have to be influenced by two different winds, going in different directions or at least at different speeds. To achive this, your airship would either have to be huge (on the scale of, say Manhattan) or you would have to be able to physically remove the sails from the rest of the ship as I already said.


So it would be impossible to go against the wind if there were no current? I'm not so sure.

My knowledge of aerodynamics is, well, pretty bad, but it seems to me that if you were to make a low-pressure area that drew air from the direction you were going, or a high-pressure area that pushed air in the direction you wanted to move away from, then you could go against the wind. Right?

Now I just need to actually think of a configuration that would do that. Heh.
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Re: Yet another Zeppelin idea

Postby Berengal » Thu Oct 25, 2007 1:44 am UTC

The thing about sailships is that compared to the air, the water is solid, or at least solid enough to allow the ship to only go in two directions; forwards and backwards. It can then use airfoils to make the wind generate a force at an angle to it's direction and because of it's ability to negate one component of the force (only the component force parrallell to the ship's axis will provide any real thrust) it can go against the wind if it zig-zags. Of course, this is overstating it somewhat; a sailship will drift, but when compared to an airship, where a draft is completely useless...

How about adjustable wings instead, to generate lift? For the price of a little drag you gain free lift, not needing to worry about compressors/airbags or engines to provide it for you. Not really thought through, but it could work.

Also, is the main attraction of airships that they're much more energy efficient than airplanes for you people? I know that's much of it for me, along with them being airborne cruise ships.
The way I see it, crossing the atlantic ocean in airships vs airplanes is basically:
Airships:
- Travel time of 2-4 days
- Energy efficient
- You're in a flying hotel

Airplanes:
- Travel time of about 6 hours
- Energy consuming
- You're sitting in a single seat for the whole tripp

Now, total comfort can be calculated as comfort / travel time (A to B formula) OR comfort * travel time (luxury cruise formula). In the second case, the airship wins clearly, in the second, maybe not, depending on the emphasis on travel time.
Comparing pricing is rather moot, since there are no panatlantic zeppelin routes. I do however suspect it would be more expensive than travelling by airplane, unless the cost of energy increases dramatically. (The cost of unrenewable energy in the air travel industry is several factors below the cost in most other industries, so there is a chance of this happening in the near future, what with saving the green planet and all).
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Re: Yet another Zeppelin idea

Postby Gelsamel » Thu Oct 25, 2007 1:56 am UTC

[quote="Berengal"]How about adjustable wings instead, to generate lift? For the price of a little drag you gain free lift, not needing to worry about compressors/airbags or engines to provide it for you. Not really thought through, but it could work.[quote]

Maybe, but I never could hold a balloon under water properly.
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Re: Yet another Zeppelin idea

Postby Nimz » Thu Oct 25, 2007 2:16 am UTC

This thread makes me want to watch Last Exile. City-sized dragon-shaped flying boats fitted with turrets and guns: whether the boats are powered or not, the idea is definitely cool.
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Re: Yet another Zeppelin idea

Postby Gelsamel » Thu Oct 25, 2007 2:50 am UTC

Yeah Steampunk is sweet.

Also Steampunk GIANT HUGE flyingcities/fortresses with tonnes of guns = awesome.
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Re: Yet another Zeppelin idea

Postby Gyvulys624 » Thu Oct 25, 2007 3:17 am UTC

Make your Zeppelin out of Le(a)d.

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Re: Yet another Zeppelin idea

Postby __Kit » Thu Oct 25, 2007 4:48 am UTC

Gyvulys624 wrote:Make your Zeppelin out of Le(a)d.


Bahahaha.
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Re: Yet another Zeppelin idea

Postby Æshættr » Thu Oct 25, 2007 6:46 am UTC

You know, sometime last week as I was studying for my ham license, I got a neat idea for a radio-controlled zeppelin. I think it'd be cool to make a medium-sized autonomous zeppelin with light-weight solar panels on the sides and an onboard computer/GPS reciever. Then hook a few cameras to it and send it around the world. I'm still not entirely sure if that'd be legal even in the united states, but it'd be awesome.

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Re: Yet another Zeppelin idea

Postby silent man » Mon Oct 29, 2007 7:36 pm UTC

Æshættr wrote:You know, sometime last week as I was studying for my ham license, I got a neat idea for a radio-controlled zeppelin. I think it'd be cool to make a medium-sized autonomous zeppelin with light-weight solar panels on the sides and an onboard computer/GPS reciever. Then hook a few cameras to it and send it around the world. I'm still not entirely sure if that'd be legal even in the united states, but it'd be awesome.


Hmmmm, we could make the structure from carbon fibre composites or aluminium, depending on the size, possibly give it a catamaran-shape to get a nice and large surface for the solar cells...
Let's do it!!!
The only problem I could see would be replacing the lifting gas. Unless you want to build a hot air zeppelin, which would need a bunch of energy simply to stay aloft, that would be the chief limiting factor. Maybe someone has a good idea to solve this, but until then I'll just propose a stupid one: Use hydrogen as a lifting gas, and water as ballast. That way, if you need more hydrogen, because it diffuses throgh the walls or you loose it through the overpressure valve, you can use the juice from the solar cells/batteries to electrolyze it from the water ballast, making the zeppelin lighter at the same time! And the zeppelin could collect water either by catching rain, or maybe it could even be condensed straight from the air, depending on altitude. Another advantage to using hydrogen would be that it could be used as an emergency fuel-cell to keep the electronics running.

Now I know that this kind of setup is just asking for trouble, but it's all i can think of right now, and at the very least, we should get a nice ball of fire out of it. I hope some other people contribute ideas, and I would definitely help building it, if it can be arranged.




Indon wrote:My knowledge of aerodynamics is, well, pretty bad, but it seems to me that if you were to make a low-pressure area that drew air from the direction you were going, or a high-pressure area that pushed air in the direction you wanted to move away from, then you could go against the wind. Right?


Right. It is called an engine. Air/water/whatever always moves towards the area with lower pressure, to equalize pressures. When you reduce pressure somewhere and increase it somewhere else you are basically working against enthropy and therefor you must invest energy.

Having said that, I do believe that a wind driven Zeppelin is feasible for some purposes. Based on about five minutes of research on Google and some wild guesses, I think it could go pretty much anywhere, given enogh time. It would need some sails, or really vertical wings with an airfoil cross section and it might have to go around the world once or twice to get there, but if time is not an issue, it would be possible.
I for one would definitely join. Just imagine it: Our giant Zeppelin, with sharklike fins protuding from the top and the keel, casually drifting around the world like the flying party from the Hitchhiker's Guide, casting a mile wide shadow on the ground, holding cities ransom for supplies,...
Good times.

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Re: Yet another Zeppelin idea

Postby whatswithhumans » Tue Oct 30, 2007 9:34 am UTC

check this out... world war II japanese balloon bombs, pretty much just riding the currents with an interesting way to control altitude.

http://en.wikipedia.org/wiki/Fire_balloon

so, yes build that super dragon zeppelin and take over the world, or the radio one would be cool to just to you know hang out see the sites confuse a few small air forces...

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Re: Yet another Zeppelin idea

Postby zealo » Tue Oct 30, 2007 3:02 pm UTC

correct me if i'm wrong, but isn't the common name for un-powered (ie wind powered) airships BALLOON???

with no engine, it will go the same direction/speed as surrounding air with or without sails/wings. 'drag' from dragon wings would not be an issue.

seriously, someone build the manhatten sized dragon, much cooler than a banana.
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Re: Yet another Zeppelin idea

Postby EricH » Tue Oct 30, 2007 4:31 pm UTC

zealo wrote:correct me if i'm wrong, but isn't the common name for un-powered (ie wind powered) airships BALLOON???


Yes, but 'un-powered' is more accurate. Balloons are spherical because of the displacement/mass ratio, and have no need for streamlining. 'Wind-powered' is what we're talking about here, unless I've lost track of the conversation...

zealo wrote:with no engine, it will go the same direction/speed as surrounding air with or without sails/wings. 'drag' from dragon wings would not be an issue.


What's needed is an area of wind shear--so the airship can be in one air mass, and stick sails or wings into an adjacent air mass, that's moving with a different speed or in a different direction. At that point, the wind power can be used to sail (and streamlining helps, and 'airship' is a better term than balloon); but, since the airship has to stay on the boundary to maintain propulsion, its movement is still restricted to two dimensions.
If the airship and its associated wings/sails/kites are all within the same air mass, zealo is exactly right.
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Re: Yet another Zeppelin idea

Postby silent man » Tue Oct 30, 2007 4:45 pm UTC

zealo wrote:correct me if i'm wrong, but isn't the common name for un-powered (ie wind powered) airships BALLOON???


Touché!

Anyway, the thing needn't be ANY sprecific shape, it could be a giant likeness of a raptor, as long as it has the airfoils, it would be just as manouverable.
We could for example make it in the shape of a sword, flying tip-down and call it Damokles.



@whatswithhumans: Using discardable sand-bags as ballast isn't that novel. Also sooner or later you're going to run out and as I understood it, the idea was to have this zeppelin flying around for quite a while. Still pretty interesting link though.

And yes, it would need software and the necessary engine power to avoid restricted areas and airports.

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Re: Yet another Zeppelin idea

Postby whatswithhumans » Tue Oct 30, 2007 6:42 pm UTC

silent man wrote:@whatswithhumans: Using discardable sand-bags as ballast isn't that novel. Also sooner or later you're going to run out and as I understood it, the idea was to have this zeppelin flying around for quite a while. Still pretty interesting link though.


oh, sorry i meant that to be more focused on the automatic altitude control, if you coupled it with you water hydrogen idea it could be used to keep it within a nice range, just so you don't have to monitor the ships altitude all the time and adjust it yourself.(to low make hydrogen, to high dump hydrogen, collect water to keep it all going...)

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Re: Yet another Zeppelin idea

Postby Plague » Tue Oct 30, 2007 8:42 pm UTC

Æshættr wrote:I'm still not entirely sure if that'd be legal even in the united states, but it'd be awesome.


You don't really have to worry about legality unless you're in restricted air space. I'd worry a bit more about the backwoods hicks that'd shoot it down just for fun. (I live near East Texas, I can say that).

I kinda like to think that there are people out there who have been doing this sort of thing for a long time, creating little remote controlled air blimps in the shape of flying saucers and using them to terrorize rural communities.

The main problem with this thing, is that to provide enough lift to carry whatever fuel we use, AND make a significantly long journey, it's going to have to be BIG.

All the below info is taken from Wikipedia.

Spoiler:
UNUSED: a 12% efficiency solar cell having 1 m² of surface area in full sunlight at solar noon at the equator during either the March or September equinox will produce approximately 120 watts of peak power.
Spoiler:
Therefore the buoyant mass for one liter of hydrogen in air as: ... -1.202 grams.
Spoiler:
UNUSED: In the water at the negatively charged cathode, a reduction reaction takes place, with electrons (e−) from the cathode being given to hydrogen cations to form hydrogen gas:

Cathode (reduction): 2H2O(l) + 2e− → H2(g) + 2OH−(aq); E0=−0.83 V

At the positively charged anode, an oxidation reaction occurs, generating oxygen gas and giving electrons to the anode to complete the circuit:

Anode (oxidation): 2H2O(l) → O2(g) + 4H+(aq) + 4e−; E0=−1.23 V


I am assuming that your blimp is filled up with H2 gas to start with, and that we are only wishing to replace the amount of H2 gas that will eventually leak out. I am going to attempt to find out whether this idea is feasible given the combined weight of the solar cell and the fuel (H2O) required to keep a certain amount of H2 gas from leaking.

From the information in the spoilers above, we can see that it requires 2.06 V of energy to electrolyze 1 mol H2 gas from 2 mol H2O. We also see that it takes 1 Liter of H2 gas to displace -1.202 grams of weight. From this we should be able to find the weight of H2O required to make 1 Liter of H2 gas.

1 mol of H2 gas should fill .013427 m3, so 2.06V of energy should give us .01342 kL of H2 gas at an altitude of 1000m, and a temperature of 20 degrees Celsius, (I seriously doubt it will actually be 20 degrees Celsius at 1000m, but I was unable to find a temperature at that altitude)

However, 1 mol of fuel (H2O) weighs 18.0152 g. Taking the fuel and the amount of H2 gas required to lift that fuel alone (without all the equipment needed to store it, and the weight of the solar cells), you would need .014987 kL of H2 gas to lift 1 mol of fuel. Each mol of fuel you electrolyze will replace .01342 kL of H2 gas, which means you must start out with about .001567 kL H2 of extra gas in your blimp for each unit of fuel in order to lift the amount needed to replace the fuel as it leaks out of the blimp.

Someone should probably check my calculations to make sure everything's right. I think this means that the idea is feasible, but that it's impossible to create a blimp that could sustain itself without eventually refueling.

Now, if you could condense sufficient quantities of water vapor from the AIR, you could probably refuel in that way. But the condensor is simply more weight, which means we need more volume, which makes the balloon more massive. It's possible, but in order to be able to carry all of this equipment AND some people (because, of course, you'd want to take your friends), it'd have to be pretty darn big.

You could probably save some weight by using flexible silicone solar cells to collect the energy from the sun, just wrap them around the outside of your balloon to get maximum surface area. I'm not well versed in electrical physics, so I was unable to relate the 120 watts the solar cells produce to the 2.06 V of energy required to electrolyze the mol of H2 gas. If someone could do this, we could find out how much H2 gas we could produce in a given time, and then relate it to how much we would conceivably loose as it permeates through the blimp. Though with the solar cells on the outside, it'd probably keep a lot of the gas inside.
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Re: Yet another Zeppelin idea

Postby silent man » Tue Oct 30, 2007 10:10 pm UTC

@ Plague:
The whole hydrogen debate is is a sideline started by this post:

Æshættr wrote:You know, sometime last week as I was studying for my ham license, I got a neat idea for a radio-controlled zeppelin. I think it'd be cool to make a medium-sized autonomous zeppelin with light-weight solar panels on the sides and an onboard computer/GPS reciever. Then hook a few cameras to it and send it around the world. I'm still not entirely sure if that'd be legal even in the united states, but it'd be awesome.


As I understood it, the goal would be creating a small UNMANNED airship that could fly around independently for extended stretches of time to take pictures and generally be awesome. If there were people on it, they wouldn't have to carry the water with them, they could just go down to the nearest source of water to get their hydrogen. A computer controlled blimp/zeppelin couldn't do that. Even if it were advanced enough to correctly identify a suitable body of water, there might be some... complications. Picture this: You are relaxing in your (hypothetical) pool, when suddenly some monstrous thing comes down and starts guzzling your water.


Also: According to the standard atmosphere table, the temperature at 1000m is 281,5K, or 8,5°C. The densitiy of the air has also dropped to 1.112, but I don' have a tabe for the density of hydrogen at different pressures handy, so I can't tell right now how that will affect lift.

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Re: Yet another Zeppelin idea

Postby guntersmells » Sat Nov 03, 2007 1:27 pm UTC

I agree with Berengal earlier in this thread,

There wouldn't be enough control over the direction of the airship. Planes can only do this because they have lots of control surfaces and travel at high speeds.

Same goes with parachutes and hanggliders etc.

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Re: Yet another Zeppelin idea

Postby rflrob » Mon Nov 05, 2007 8:51 am UTC

Plague wrote:You could probably save some weight by using flexible silicone solar cells to collect the energy from the sun, just wrap them around the outside of your balloon to get maximum surface area. I'm not well versed in electrical physics, so I was unable to relate the 120 watts the solar cells produce to the 2.06 V of energy required to electrolyze the mol of H2 gas. If someone could do this, we could find out how much H2 gas we could produce in a given time, and then relate it to how much we would conceivably loose as it permeates through the blimp. Though with the solar cells on the outside, it'd probably keep a lot of the gas inside.


The trick is that Energy = qV. So, to make one mole of hydrogen gas, you'd need, if I'm doing my electrochem right, move a net two moles of electrons across those 2.06 V, for total energy of ~398kJ. This works out to running a 120W power source for about an hour.

Another way to look at it (and probably more accurate and less reliant on my sucky electrochem "skills") is to look up the different energies (enthalpies?) of hydrogen and water. Wikipedia says the enthalpy of combustion is -286kJ/mol, and since we're essentially performing the reverse reaction, that means we need to put in 286kJ/mol, bringing the time down to 40 minutes. So in an hour, we can burn about 27g of water.
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Re: Yet another Zeppelin idea

Postby Æshættr » Mon Nov 05, 2007 9:01 am UTC

silent man wrote:As I understood it, the goal would be creating a small UNMANNED airship that could fly around independently for extended stretches of time to take pictures and generally be awesome.


Exactly. The idea is to have a fully-autonomous (or at least semi-autonomous) zeppelin that can stay airborne for months at a time.

The main challenges I have with this Zeppeling UAV idea so far are:
-finding a light-weight material for the hydrogen (or helium, depending on how much lift is needed) container that is also very resistant to effusion.
-light-weight propulsion (enough to get around at a reasonable pace, and make corrections to avoid entering restricted airspace.
-a light-weight, low-power on board computer that can utilize GPS to automatically keep itself from entering restricted airspace (writing software to do this is trivial.) I've thought of using one of the laptops from the OLPC project, since they use about 5W at their peak power consumption, though I'm looking for something with more tolerance for high altitudes and low temperatures.
-light/flexible solar panels for power generation
-some kind of light-weight power storage so the whole thing doesn't have to drift helplessly at night. Either batteries or supercapacitors with switching voltage regulators are what I've come up with (the latter strikes me as a very bad idea due to the voltages involved.)
-speaking of high voltage, what about lightning? I don't live in an area with many lightning storms, but it's still something to keep in mind.
-altitude control, possibly by using the H2O ballast mentioned earlier and maybe some controlled venting or filling with the help of a small compressed tank of the gas used. Collecting H2O from the atmosphere at high altitudes might be a challenge, since the temperature is so low. Making H2 gas also requires extra equipment, I'm not sure how heavy such equipment would be. Getting the gas produced by the process to be compressed or put into the container portion of the zeppelin is another problem altogether.

There are, of course, more challenges aside from those, but those are the biggest ones. One thing that I left out of my first post was that the design should have a modular section so that other things can be attached depending on what the objective of the current flight is. For instance, having instruments attached to collect weather data, attaching a small repeater in the event of an emergency or for field day, or anything else that would be cool to attach to such a thing.

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Re: Yet another Zeppelin idea

Postby silent man » Mon Nov 05, 2007 12:40 pm UTC

These are my thoughts to the problems you mentioned. Please keep in mind that most of it is idle speculation and guesswork, and therefore subject to revisions once I actually get a clue.

- the materials of choice seem to be either metallized boPET (aka. Mylar) or PVF (aka Tedlar). Both are light, have a low permeability to gasses and are generally available/affordable. As for the hydrogen/helium part, the difference in lift is pretty much within the margin of error on my calculations (I am woking with the assumption that one cubic metre of gas will lift one kilogramm of zeppelin, based on Murphy's laws for zeppelins: Everything will turn out heavier than expected. And: Gas cells in plans have more volume than the ones in the actual zeppelin.) Thus, the deciding factors are a) replenishing and b) the fact that effusion losses will be higher for hydrogen.

- I am currently thinking of using engines and propellers from motorized rc-gliders made into ducted fans. Those are already designed to be light and efficient. A minimum of three engines would be needed for full manouverability, the number of engines that is required to at least hold its position against the wind to avoid restricted airspace would be dependent on aerodnamic properties.

- Can't really help you on the topic of computer hardware, although I am now wondering exactly what altitudes you intend to fly at.

- Almost the same for the solar cells, we'll have to check what is being sold, although I think I recently heard something about a new kind of solar cell/film that had a very high efficiency at low weight.

- For energy storage, using accumulator packs from rc planes might be the safest bet, since they are already designed for the highest possible energy density.

- Lightning: diverter rod on the highest and lowest point, connected by cables and a wire mesh around the hull, put the computer in a faraday-cage, and pray that you never have to find out if it works, because it probably won't. Oh, yea, we might also want to program it not to release hydrogen while in a thunderstorm.

- Sure, the equipment to produce hydrogen will be extra mass, but it should be fairly easy to connect to the regular filling system and it will almost certainly be lighter than any pressurized tank that I can imagine at the moment.


Concerning the interchangable "mission modules" you mentioned: The ability to carry a range of different payloads was pretty obviously part of the idea, at least from my point of view, and is already part of my plans.
If I ever feel artistic enough I may post some sketches of what I think this zeppelin could look like.

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Re: Yet another Zeppelin idea

Postby gmalivuk » Mon Nov 05, 2007 8:16 pm UTC

They've already got solar-powered planes that can stay up for quite some time. And there are plans to make ones that can stay aloft for weeks or months at a time. I've got to believe that a lighter than air craft, then, would be able to stay up far longer than this. The advantage of planes, of course, being their far greater speed.
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Re: Yet another Zeppelin idea

Postby zenten » Mon Nov 05, 2007 8:20 pm UTC

gmalivuk wrote:They've already got solar-powered planes that can stay up for quite some time. And there are plans to make ones that can stay aloft for weeks or months at a time. I've got to believe that a lighter than air craft, then, would be able to stay up far longer than this. The advantage of planes, of course, being their far greater speed.


I know there are solar powered balloons with small propellers that are used in the upper atmosphere for scientific research, but I'm having trouble finding online links.

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Re: Yet another Zeppelin idea

Postby rflrob » Tue Nov 06, 2007 6:37 am UTC

silent man wrote:- Sure, the equipment to produce hydrogen will be extra mass, but it should be fairly easy to connect to the regular filling system and it will almost certainly be lighter than any pressurized tank that I can imagine at the moment.


Offhand, I can't think why the hydrogen producing equipment need be much heavier than the water supply, a bit of salt, and two wires...
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