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I never got the fascination for Orion. Why on earth should a spaceship carry a gigantic pusher plate? Carry hydrogen instead and put through a conventional fiss

I never got the fascination for Orion. Why on earth should a spaceship carry a gigantic pusher plate? Carry hydrogen instead and put through a conventional fission engine. That gives you a much more controllable engine and should save you a lot of dry mass.

MichaelCollins 4y ago
> I never got the fascination for Orion. Explosions are cool. Orion is space-orc technology, extremely cool.
ClumsyPilot 4y ago
Because despite having insane amount of energy in Uranium, you can't tap into it. Uranium melts at 1000 degrees centigrate, so thats your rough upper limit for how much your reactor can heat hydrogen. If your Uranium melts, it will be leaving the rocket with the hydrogen and spreading radiation everywhere. Basically like Orion but worse. A normal chemical rocket reaches higher temperatures. A nuclear bomb will heat anything to millions of degrees. Much more efficient, and any exhaust is moving so fast it will escape the solar system without bothering anyone, provided its pointed the right way.
- mr_toad 4y ago
  Nuclear thermal rockets have been tested to around 3000K. The limiting factor is the material containing the nuclear fuel. Chemical rockets need oxygen, which is heavy and limits Isp. Nuclear rockets can use pure hydrogen and achieve higher Isp.
api 4y ago
As far as I know the iSP (specific impulse) of Orion is a lot higher, which may result in better overall performance. There are some high temperature nuclear rocket engine designs though, like nuclear gas core rockets. They're crazy reactor designs you would never try running down here inside a biosphere but have energy densities far higher than anything else save a bomb.
pinewurst 4y ago
(a) Much much higher ISP even including pusher plate mass (b) We can build bombs and pusher plates now ;)
zabzonk 4y ago
no "conventional fission engine" has ever flown - there may be reasons for this
- voldacar 4y ago
  Yeah the reason is that Richard Nixon cancelled Project Rover, which had long since demonstrated that a safe and reliable nuclear engine was totally feasible
- mr_toad 4y ago
  An experimental nuclear powered plane has flown. And while no nuclear thermal rocket engine has yet flown, there have been ground tests.
  - nradov 4y ago
    Well not really. A couple of aircraft have flown with nuclear reactors onboard, but the reactors weren't used to generate power.

MichaelCollins 4y ago

> I never got the fascination for Orion. Explosions are cool. Orion is space-orc technology, extremely cool.

ClumsyPilot 4y ago

Because despite having insane amount of energy in Uranium, you can't tap into it. Uranium melts at 1000 degrees centigrate, so thats your rough upper limit for how much your reactor can heat hydrogen. If your Uranium melts, it will be leaving the rocket with the hydrogen and spreading radiation everywhere. Basically like Orion but worse. A normal chemical rocket reaches higher temperatures. A nuclear bomb will heat anything to millions of degrees. Much more efficient, and any exhaust is moving so fast it will escape the solar system without bothering anyone, provided its pointed the right way.

mr_toad 4y ago
Nuclear thermal rockets have been tested to around 3000K. The limiting factor is the material containing the nuclear fuel. Chemical rockets need oxygen, which is heavy and limits Isp. Nuclear rockets can use pure hydrogen and achieve higher Isp.

api 4y ago

As far as I know the iSP (specific impulse) of Orion is a lot higher, which may result in better overall performance. There are some high temperature nuclear rocket engine designs though, like nuclear gas core rockets. They're crazy reactor designs you would never try running down here inside a biosphere but have energy densities far higher than anything else save a bomb.

pinewurst 4y ago

(a) Much much higher ISP even including pusher plate mass (b) We can build bombs and pusher plates now ;)

zabzonk 4y ago

no "conventional fission engine" has ever flown - there may be reasons for this

voldacar 4y ago
Yeah the reason is that Richard Nixon cancelled Project Rover, which had long since demonstrated that a safe and reliable nuclear engine was totally feasible
mr_toad 4y ago
An experimental nuclear powered plane has flown. And while no nuclear thermal rocket engine has yet flown, there have been ground tests.
- nradov 4y ago
  Well not really. A couple of aircraft have flown with nuclear reactors onboard, but the reactors weren't used to generate power.