WI: Pluto ramjet for spaceflight

Karatchi wrote:
https://en.wikipedia.org/wiki/Project_Pluto
Is it possible use this for a nuclear aircraft which would launch (chemical) rockets from a high altitude? Possible PoD where NASA decides to use it?
What about Soviet nuclear ramjets?

Possible? Sure it could work I suppose but it's not practical or really feasible due to the way Pluto was designed and built. The main 'advantage' of a nuclear ramjet is it doesn't need fuel so can go very long distances. You don't need that for a launch-assist system so it wouldn't make much sense to use a nuclear ramjet for such a purpose.

As the engine for Pluto was basically an unshielded nuclear reactor, (by design) to act both as a damage additive to flying around at Mach-3 at low altitude and dispensing nuclear warheads it would spew lethal radiation over the area it flew but also to allow it to fly at all given the reactor was so heavy. Thrust-to-weight of the propulsion was actually pretty marginal compared to a more conventional ramjet engine and you want a high T/W for an accelerator stage in addition to high altitude. And this is before you get into the significant issues of radiation backscatter due to said unshielded reactor operating in the atmosphere which required heavy insulation/shielding of the command and guidance section of the Pluto which would have to be applied to any "payload" carried by the vehicle. (Among all the other reasons

I don't see any possible POD where NASA would consider, let alone choose a nuclear ramjet engine for propulsion outside a possible probe to one of the Gas Giant planets. (And note the reactor doesn't go on-line much before it enters the target atmosphere) NASA only considered NERVA for an upper stage propulsion system and then the reactor wasn't brought to criticality prior to stage separation AND it at least has a minimal shielding system which Pluto did not. There have been some recent suggestions of using nuclear augmented ram/Scramjet propulsion but unlike Pluto those reactors are based on the NERVA and do not directly induct or pass the air through the reactor but use reactor heated hydrogen bled into an air-augmented rocket system. (Simply the reactor is used to heat liquid hydrogen to high temperature which is then exhausted through a rocket system in which air is sucked in using the ejector effect initially and ram-air after lift-off. The hot hydrogen auto-ignites and burns with the oxygen in the air to increase thrust. Arguably it's not clear if it wouldn't be a better idea to simply inject Liquid Oxygen into the rocket nozzle as an augmenter than trying to cope with the complexity and weight of the ram/Scram-air inlets and exhaust system)

Randy
 

thorr97

Banned
No, the Pluto was a one purpose and single use only thing. That air breathing nuclear engine consumed itself in its operation. The thing literally spewed bits of itself out its exhaust as it ran. It was good for reaching its targets, popping off one of its several H-bombs at each of them, and then cruising around at 500' altitude while flying at Mach 3 - with its supersonic shockwave shattering almost everything it hit and the radioactive exhaust taking care of the rest - until its nuclear reactor engine disintegrated to the point it could no longer produce enough thrust to keep the thing airborne. At that point it'd crash into the ground and leave a truly nasty radioactive crater for the enemy to deal with.

Nope, that's not something useful for peaceful space launches...
 
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