What is the best energy source for an unmanned airship?

[farmerben]

Suppose you wanted a heavy lift sky crane with about 50 tons lifting capacity.  Being unmanned, hydrogen gas is acceptable, as is methane.  A methane balloon though twice as large is less prone to leaks than hydrogen and helium.  Recalling that buoyancy is the equal to the mass displaced , rather than the mass of gas in the balloon. 

It would be desirable to have large multi-axis propellers to give powerful and accurate crane controls.

So what is the best power source?  A fuel cell?  A combustion engine?  It's hard for me to see how solar or wind could be used, but maybe I'm wrong about that.

 

 

[StrandedonEarth]

Is solar power at 23W/g good enough?

https://www.nature.com/articles/nmat4388#:~:text=d%2C Power-per-weight,g−1 with PU).

[DDE]

Wind is a bit problematic on an untethered platform that is heavily affected by wind. Solar is the obvious example for "standby power" with batteries, fuel cells or flywheels for storage.  And I don't think you'll get away without an ICE of some sort for the active segment of your positioning work.

[farmerben]

how would you deploy solar panels?  a kite tail solution does not seem elegant especially in conjunction with a crane

 

[StrandedonEarth]

3 minutes ago, farmerben said:

how would you deploy solar panels?  a kite tail solution does not seem elegant especially in conjunction with a crane

 

Cover the top half of the gasbag with flexible PV panels...

[RuBisCO]

at ~50 km above the surface of Venus its like being in full sunlight on earth from all directions so you could put the solar panels on any surface, all around the balloon, even pointing straight down.  

[Nuke]

how thin are your solar panels? if you can replace the upper skin with thin film solar cells then electric seems the way to go. 

[kerbiloid]

Airship accuracy sounds like oxymoron.

It will spend more energy to stay at the point than a helicopter to fly.

[magnemoe]

9 hours ago, kerbiloid said:

Airship accuracy sounds like oxymoron.

It will spend more energy to stay at the point than a helicopter to fly.

Yes. so I guess how you would use this is to drop down cables you connect to heavy trucks or hard points you then use this to position it correctly

[Shpaget]

Are we talking about lifting gas or actual fuel? Why would the answer be any different than for any other aircraft?

Jet A-1.

[DDE]

1 hour ago, Shpaget said:

Are we talking about lifting gas or actual fuel? Why would the answer be any different than for any other aircraft?

Because if you expend fuel, you also need to decrease lifting force. This usually means venting the gas. Which, in case of methane, is bad, and in case of helium, prohibitively expensive. Helium blimps used to have exhaust condensers to recover at least some of the mass of the fuel burnt in their ICEs.

I'm not sure that was on anyone's mind but my own, though.

[Piscator]

Luckily we don't need to worry about the environmental impact of methane as a lifting gas since it's completely unfeasible in this role anyway. Half the lifting capacity doesn't sound too bad at first, but simply building your airship twice as large is only a solution if you somehow manage to keep the structural weight the same. Which is of course impossible. Even if the square-cube-law works in your favour - and I'm not convinced it does in this case - you would likely end up with a monstrosity of a vessel just to get of the ground.

[kerbiloid]

If the airship is firmly attached to the ground by ropes, why not just use an electric cable?

[StrandedonEarth]

10 hours ago, kerbiloid said:

If the airship is firmly attached to the ground by ropes, why not just use an electric cable?

Not a bad idea; however, I'm assuming these would be used in remote locations where there is no power grid connection. Granted, the first cargo hauled in could be generators...

[kerbiloid]

31 minutes ago, StrandedonEarth said:

Not a bad idea; however, I'm assuming these would be used in remote locations where there is no power grid connection.

 

23 hours ago, magnemoe said:

drop down cables you connect to heavy trucks

 

I even dk.

[farmerben]

Actually I was thinking the airship could handle tricky cargoes.  For example, wind turbines are difficult to haul and install.  An airship could preassemble them and drop them anywhere in Texas...  There are also offshore applications.

Edited September 14, 2022 by farmerben

[SunlitZelkova]

1 hour ago, farmerben said:

Actually I was thinking the airship could handle tricky cargoes.  For example, wind turbines are difficult to haul and install.  An airship could preassemble them and drop them anywhere in Texas...  There are also offshore applications.

I wonder to what extent airships are restricted by wind in comparison with helicopters.

Those sound like jobs for something like the S-64 Skycrane rather than a dirigible.

[darthgently]

8 hours ago, SunlitZelkova said:

I wonder to what extent airships are restricted by wind in comparison with helicopters.

Those sound like jobs for something like the S-64 Skycrane rather than a dirigible.

One thing for certain is the vast cross sectional area of airships make most of the power demand simply fighting wind.  Keeping one stationary for precise lifts would almost certainly require ground anchor points.

But KSP doesn't have wind so in game not a problem

Edited September 15, 2022 by darthgently