[rdmckenzie]

Context: At this point in history, the USA and USSR had aircraft fleets on constant patrol with tanker resupply. The concept was to simultaneously shorten the response time of strategic nuclear forces by having them "idle" nearer the target zones than their home bases and more importantly to reduce the potential losses of such strategic strike forces to a "bolt from the blue" preemptive & disarming attack. In a world where the President and SAC command would have to wait hours for B-36 & predicessor aircraft to make their way to their targets in Russia.

There were three real issues with this project: shielding weight, landing weight and politics. 1. Shot down or crashing, one of these aircraft would be a "dirty bomb" and could generate a nuclear contamination disaster. This alone made the project risky. Remeber, during the heyday of strategic nuclear bombing shootdowns were expected & ariplane to target assignments were made on the basis of the expected (and dismal) survival rate of inbound bombers. Also a single crash on US soil would have been... politically unpopular. 2. The lead, graphite and cement used to shield static nuclear facilities doesn't exactly work when trying to build an airplane, which made crew shielding dubious and reduced the loiter time of such a vehicle to the radiation tolerance of the crew. 3. A mich more minor issue was that of building landing gear that could hold the weight of the reactor on landing let alone a crash.

All that asside, a flying nuke plant is a great idea and I for one would not be surprised to see this idea resurrected for extreme loiter duration robotic aircraft :/

[riobard]

Could they use a drone instead of manned aircrafts to address point 2? So there's no need to shield and thus saving the weight.

[Scramblejams]

IIRC some work was done to evaluate shielding only the relatively small area around the crew and avionics, saving considerable weight. However, it was soon discovered that radiation exposure can dramatically reduce the fatigue life of metallic materials. So, some (large) amount of shielding is still necessary.

[marcosdumay]

Our computers are even more sensitive to radioactivity than our bodies.

Maybe yes with a drone based on TTL or some other "old" standard. Probably no with CMOS... Well, with a nuclear plant on board, I guess one can generate enough energy for a TTL computer.

[Houshalter]

But computers don't take up nearly as much space. You would only need to shield that one specific spot where the computer was rather than the whole cockpit.

[lostlogin]

Wouldn't you need to shield the wiring too? That stuff goes everywhere. Im not certain on the need for this though.

[eksith]

Yes, every particle crossing the copper can create an anomalous signal that can switch a 0 to 1 or visa versa. If you have enough of those, the program(s) will eventually crash. On the processors themselves the L1/L2 caches are vulnerable, but beyond that, the ROM could also get corrupted making hard resets impossible even after a crash.

Fiber optic cables aren't immune to this either : http://misspiggy.gsfc.nasa.gov/tva/meldoc/cabass/rad.htm

[emiliobumachar]

I think you are talking about SEUs.

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

[rdmckenzie]

Arguably, but the D-21 drone [1] was... a mess & a failure. Line Of Sight radio control was the only real option.

[1] http://en.wikipedia.org/wiki/Lockheed_D-21

[ceejayoz]

I'm confused. The D-21 wasn't nuclear, and we've clearly fixed the problems with drones they had during that program. What's your point?

[wtracy]

Unmanned aircraft were impractical during the Cold War, which is the only point in history when nuclear-powered aircraft were seriously considered. Drones are workable now, but political considerations alone make nuclear aircraft a non-starter today.