Power transmission challenge (airborne nuclear reactors tethered to airships)

[Avimimus]

Hello,
I know we have some brilliant and experienced engineers here on the forum. I was wondering if you guys could advise me about solutions to a problem.
The goal is a nuclear powered airship. The reactor is on a separate balloon so that distance can act as shielding.
The problem is that the transmission distance probably makes gas or liquid cycle engines impractical. So a lightweight power collection and power transmission system is necessary (probably ending in an electric drive system).
So what do you think would work? How light could this system be made and how long should the connecting cable be?
How would you approach this?

 

[cubit]

Given the balloon is large it may make a good target for microwave based power transmission.

On a related note I recently watched a documentary 'Planes That Never Flew 4 of 4 The Atomic Bomber'. It appeared that based upon a 21st century risk management approach that an airborne nuclear reactor is a bad and extremely expensive idea that stemmed from the USAF wanting an equivalence to the nuclear submarine.

Solar + fuel cells would be less problematic IMHO.

 

[Avimimus]

Well the basic idea here is to produce a rigid airship without the ballast problems that plague these lighter-than-air designs (and enough surplus power to achieve 300 km/h cruise and active trim).
The added benefit of the airship, is that the self-contained nuclear reactor can be released in an emergency and the natural buoyancy ensures a soft-impact - massively lowering the chances of a breach.
Bascially - it is a match made in heaven...

 

[Bill Walker]

Rigid airships have a long history of disastrous crashes, with anything but soft landings. That may not be the best place for a reactor.

I agree that solar cells charging fuel cells would be much nicer. With a closed loop recovery of the water in the fuel cells your need for ballast is greatly reduced.

 

[Avimimus]

Could such a system produce enough power to displace the air around a large air-ship (at 300 km/h speeds - i.e. almost three times the speed of a conventional airship).

The concept also involves mounting the reactor separately so it can be jettisoned and using multiple redundant lifting bags, along with a couple of control thrusters and extensive impact padding - so the reactor would land more softly than the rest of the ship.

 

[Bill Walker]

Look back at the history of rigid airship crashes, and ask yourself why and when you would need to jettison the reactor.

Because of severe weather, that had lead to failures in multiple redundant lift bags in the main ship; or in combat, with damage to multiple redundant lift bags in the main ship. Your jettisoned reactor will be immediately exposed to the same situations. Reactors falling from the sky, even under partial control, are probably not desirable.

 

[Avimimus]

I agree. I'm a couple billion short of actually realising a prototype.

Still - it would have unlimited range and would be much safer than a fixed-wing nuclear powerplant - You'll grant me that. Mounting it in a separate compartment not only means less shielding, but much more ability to build in safety features using up-to-date technology (as the non-cargo envelope could dedicated all of its lifting weight to the reactor and its safety equipment).

http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Small-Nuclear-Power-Reactors/#.UdBGhhRZT4g

 

[Bill Walker]

Still - it would have unlimited range and would be much safer than a fixed-wing nuclear powerplant - You'll grant me that.

Far from much safer. Look for a book called Airshipwreck in your library. About half of ALL rigid airships ever built crashed, mostly due to weather or mechanical failure. For that to be safer than large fixed wing aircraft would mean 700+ Boeing 747s crashed so far, compared to the actual number of about 52 total losses so far.

 

[grcoffman104]

Remember, when the B-36 tooled around with the reactor in it, it was followed by a ship with paratroops to jump and secure any crash site. As now we ( USA) don' t have an extra two dimes to rub together, imagine the costs of this type of response from the private sector. And, ( worst case ), the howls from the soccer moms when the air-bagged reactor lands during Ashley's team photos. Oh Mother, pass the smelling salts and Band-aids!

Gerry
A Cynical High School Cop in Texas

 

[Avimimus]

Well I've reviewed those accident lists... I've even thought of joking about how there have only been two fatalities in the last fifty years (much less than fixed winged aircraft) ;D

But for the sake of argument:
- An excess of power could help prevent crashes through more powerful thrusters and plenty of heaters.
- Modern materials and design could reduce the likelihood of a structural failure.
- Helium could be used instead of hydrogen.

Because it is a large, rigid bodied airship with a considerably higher power to volume ratio than past airships it could be made more docile and almost as controllable as fixed winged aircraft.

So back to the original question - if you had to engineer it - how would you transmit power?

 

[_Del_]

If you're stuck on nuclear/electric the answer was already given to you: you should just use microwave transmission. Why would you want to make your reactor airborne is still a mystery to me.