Nuclear powered aircraft ?

[inca]

Was chewing the cud in the pub last night and got chatting about oil crisis etc.

Mooted point was why no-one had tried to create a nuclear reactor small enough to power a jet aircraft?

Is it impossible or just too expensive?

[thefunky1]

Total stab in the dark but i suspect it might come down to basic physics of lift vs weight. Any kind of nuclear powerplant would like be very heavy as would the ancillary materials needed eg cooling systems and insulation to shield the cabin so it's perhaps not economically viable in the short term to be considering it??

Although Iran may yet surprise us all (sorry, couldn't resist.)

This purely a half baked guess though so please don't tear me apart.

[LondonJ]

Theoretically possible I suppose, though you require a critcal mass of nuclear matter to begin the reaction. In a power plant this creates heat which is used to produce steam, which turns turbines etc. If the aircrafts power was produced in this way then a substansial amount of water would be required. Secondly, think about what would happen if things went wrong, say a plane exploded in the air, thereby spreading nuclear material for hundreds of miles (unlike in submarines where it would probably just contimate the nearby ocean).

['India-Mike]

Not the best link on the subject but gives you an appetite for more.......

http://americanhistory.about.com/library/prm/blwingedatom2.htm

[conor_mc]

I suppose the first point is, who'd fly in it?

All nuclear-powered ships are military, hence their "passengers" don't have too much of a choice of whether to sail in a nuclear-powered vessel, other than not signing up - unless they're conscripted of course. Besides which, everyday airline passengers aren't trained to deal with emergencies on board, military crews are.

Add to that the inherent dangers of flight (what goes up must come down) as opposed to sailing the high sea's (what floats will float, power or not) and you're gonna struggle to get willing passengers.

Now there may be a "market", for want of a better phrase, in freight ops, potentially even replacing sea-freight to a large extent if it was cost-effective.

I suppose the other problem is that if there was an accident, the footprint of the accident in a current airliner would be measured in about 1-10 square miles. A nuclear airliner, well you could have an accident footprint of 100's of square miles.

On a technical level, I'm not sure how you'd convert nuclear fission into thrust in an airplane. Nuclear ships rely on steam turbines to turn a screw at maybe 50 rpm (at a guess) - so you'd need to find another method of thrust that would be powered by nuclear fission/fusion, but capable of outputting an awful lot more rpm.

It's an interesting exercise all the same, thinking through the why's and why-not's of the argument.

[pax britanica]

The US airforce played with the idea of nuclear propulsion for aircraft in the fifties or early sixties with a plan to build a version of the massive Convair B36 witha reactor driven power plant. I suppose if you are starting out with ten engines there is an incentive to try and rationalise things even if it involves something like lead which is hardly an ideal component for any aviation application .

I am not sure if the link will work but type' B36' in Google and you will find sooner or later

http://www.cowtown.net/proweb/nb36h.htm

With fuel prices and todays technology who knows whether the idea might get brought back -can hardly use wind or wave power on an aircraft can you
PB

[Wizofoz]

Was tried in the 1950s' by both America and the USSR. I believe the russians actually flew an aircraft with an experimental nuclear engine as well as conventional ones. I don't think the American effort got past the drawing board.

The main problems are the obvious ones. Radioactive exhaust, radiation shielding for the crew and passengers and flying around with an atomic reactor on board (imagine the first time one crashed!!).

Theoretically possible but with some HUGE hurdles.

Interesting article
HERE (http://www.megazone.org/ANP/)

Edited to say- read this realising the previous four replys crossed with mine!!!

[allyn]

This might be of interest (http://en.wikipedia.org/wiki/Project_Pluto)

[Volume]

Accordind to an article in "Luftfahrttechnik 7 (1961) Nr.2" from February 10th 1961, page 44, General Elecrtic did test a modified J-47 with an externally installed nuclear powered heat exchanger.

The 60´s have been an interesting time for engineers, when everything seems possible and problems were there to be solved.
Some of the (today silly looking) statements from the article. (translated from german) :
The danger of a crash are neglectable, it does make no difference whether a nuclear powered plane crashes, or a conventional powered (which meant piston engines these days ;) ) crashes onto a nuclear power plant.
The danger of radiation is also neglectible, air shields gamma radiation very well, so the exposure to passengers is comparable to exposure during medical x-ray (which was believed to be safe these days ...). Only problem might be the flight crew, which is exposed for a longer duration, but next generation aircraft will fly high altitude anyway, so cosmic radiation will be about the same danger...

Google revealed the following links :

Nuclear Airplanes (http://www.nuclear.com/history/Nuclear_airplanes.html)
NASA (http://history.nasa.gov/SP-4306/app-b.htm)
(scroll down to "Nuclear Research Reactor Facility (1956-1961)" )
Aircraft Nuclear Propulsion (http://www.megazone.org/ANP/tech.shtml)
Technology (http://www.atomicengines.com/ANP_tech.html)
Atomic powered Aircraft (http://www.islandone.org/Propulsion/AtomPlane.html)

[swh]

Would make one quiet and fuel efficent SST, maybe the french and japs can incorporate that into their design.

[Rocket2]

It's beeen tried by NASA, see this weeks Flight International (23 - 29 August 2005) Page 39 (Straight & Level) "The land that time forgot"
R2