Project Orion / Project Daedalus

The Daedalus probe did not use pusher plates, it used magnetic confinement (which was a valid way of controlling the relatively small quantities of plasma it produced per pellet). And in regards to the "nuclear explosions", one was individual nuclear shaped charges, and one was small fuel pellets ignited by a complex array of electron beams. They used the same fuel, but that's more or less where the similarities end.
 
Prophet141 said:
The Daedalus probe did not use pusher plates, it used magnetic confinement (which was a valid way of controlling the relatively small quantities of plasma it produced per pellet). And in regards to the "nuclear explosions", one was individual nuclear shaped charges, and one was small fuel pellets ignited by a complex array of electron beams. They used the same fuel, but that's more or less where the similarities end.
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It's still a pulsed nuclear detonation.
 
If we were in the plane section and wanted to talk about turboprop cargo aircraft, nobody would barge in with a C-17 and go "Oh, well, it burns the same fuel and has some of the same engine architecture, it's basically the same technology." Yes, both have compressors, combustors, and turbines, but that's where the similarities end.

So we have basically two options. The first is to keep this page for nuclear pulse propulsion projects, in which case we might as well include Project Medusa or Project Longshot too.

Or we could separate them into their own topics because it would be easier to distinguish between the two.

And another thing; where does this page say it's about nuclear pulsed propulsion? It's just about two extraordinarily tangentially related projects.
 
Scott Kenny said:
Prophet141 said:
And another thing; where does this page say it's about nuclear pulsed propulsion? It's just about two extraordinarily tangentially related projects.
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Where it said "Orion" and "Daedalus"?
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Then we might as well call it "Big nuclear spaceships".

I direct you to this article here ( https://en.wikipedia.org/wiki/Project_Daedalus ) and to this article ( https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) ). I can understand the confusion, since they both technically employ inertial confinement, but one uses nuclear fission to so whilst the other uses electron beams. Needless to say, that's a big difference. Then of course there's the way the plasma interacts with the spacecraft; one uses a mechanical pusher plate, the other magnetic fields which some literature will say acts as a pusher plate. One is capable of redirecting almost all of the fuel used, one is dependent on how tight a cone a nuclear shaped charge can produce.

And I see that you didn't address my options, just my question.
 
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Prophet141 said:
Scott Kenny said:
Prophet141 said:
And another thing; where does this page say it's about nuclear pulsed propulsion? It's just about two extraordinarily tangentially related projects.
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Where it said "Orion" and "Daedalus"?
Click to expand...
Then we might as well call it "Big nuclear spaceships".
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NERVA-type nuclear thermal would also fit under that description, as would a nuclear powered ion drive.

Yet neither one is a nuclear pulse drive.
 
In the same way that a turboprop and a fighter jet's turbofan both count as turbine engines but are distinctly different. I'll add another option; we rename this thread to Nuclear Pulse Propulsion Projects and include some other designs.
 
Prophet141 said:
In the same way that a turboprop and a fighter jet's turbofan both count as turbine engines but are distinctly different. I'll add another option; we rename this thread to Nuclear Pulse Propulsion Projects and include some other designs.
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Seconded!
 
Glad that we can agree on that! Here's project Medusa, which employs the same concept as Project Orion (detonating nuclear charges (or similar) to generate thrust, but does so with something more akin to an over-engineered and robust solar-sail instead of a pusher plate, and the associated weight savings. Instead of the massive shock absorber systems the acceleration can be damped by paying out the cable connecting the capsule and the solar sail. (https://www.centauri-dreams.org/2012/07/20/medusa-nuclear-pulse-propulsion-and-the-sail/). The major issue I have with the functionality of the design is how resistant to wear and tear such a canopy would be. And of course it would still be hysterically expensive since it still requires an enormous number of nuclear bombs to be practical. 1688306727843.png

I'm more of a fan of the Daedalus concept and similar ones to it. External ICF (to distinguish from Internal ICF, which is basically what a thermonuclear weapon is) allows for a more controlled and efficient use of fuel.
 
Prophet141 said:
Glad that we can agree on that! Here's project Medusa, which employs the same concept as Project Orion (detonating nuclear charges (or similar) to generate thrust, but does so with something more akin to an over-engineered and robust solar-sail instead of a pusher plate, and the associated weight savings. Instead of the massive shock absorber systems the acceleration can be damped by paying out the cable connecting the capsule and the solar sail. (https://www.centauri-dreams.org/2012/07/20/medusa-nuclear-pulse-propulsion-and-the-sail/). The major issue I have with the functionality of the design is how resistant to wear and tear such a canopy would be. And of course it would still be hysterically expensive since it still requires an enormous number of nuclear bombs to be practical.
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If your bombs are properly spaced from the "sail", there should be very little wear caused by the bombs themselves.


Prophet141 said:
I'm more of a fan of the Daedalus concept and similar ones to it. External ICF (to distinguish from Internal ICF, which is basically what a thermonuclear weapon is) allows for a more controlled and efficient use of fuel.
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I've read one analysis of the Rocinante's drive from The Expanse that used external ICF. 2.2kg of D+3He per second, and I'm assuming one pulse every 1/100 of a second or so for a nice smooth acceleration. Fusion fuel is biased to minimize neutron production, as neutrons do bad things to crew and produce no thrust. Drive power of 98 terawatts or so(!!!), pushes a fully loaded Roci around at 1.8 gees. Detonation point is about 300m aft of the Roci, so your fuel pellet launcher needs to put a 22gram pellet downrange at 30kps. A repurposed fuel pellet launcher would make one heck of a good slugthrower, since an undetonated fuel pellet would impact at IIRC 2200grams of TNT equivalent.

It's from Matterbeam's Tough Guide to SF blog.
 
Scott Kenny said:
Prophet141 said:
Glad that we can agree on that! Here's project Medusa, which employs the same concept as Project Orion (detonating nuclear charges (or similar) to generate thrust, but does so with something more akin to an over-engineered and robust solar-sail instead of a pusher plate, and the associated weight savings. Instead of the massive shock absorber systems the acceleration can be damped by paying out the cable connecting the capsule and the solar sail. (https://www.centauri-dreams.org/2012/07/20/medusa-nuclear-pulse-propulsion-and-the-sail/). The major issue I have with the functionality of the design is how resistant to wear and tear such a canopy would be. And of course it would still be hysterically expensive since it still requires an enormous number of nuclear bombs to be practical.
Click to expand...
If your bombs are properly spaced from the "sail", there should be very little wear caused by the bombs themselves.


Prophet141 said:
I'm more of a fan of the Daedalus concept and similar ones to it. External ICF (to distinguish from Internal ICF, which is basically what a thermonuclear weapon is) allows for a more controlled and efficient use of fuel.
Click to expand...
I've read one analysis of the Rocinante's drive from The Expanse that used external ICF. 2.2kg of D+3He per second, and I'm assuming one pulse every 1/100 of a second or so for a nice smooth acceleration. Fusion fuel is biased to minimize neutron production, as neutrons do bad things to crew and produce no thrust. Drive power of 98 terawatts or so(!!!), pushes a fully loaded Roci around at 1.8 gees. Detonation point is about 300m aft of the Roci, so your fuel pellet launcher needs to put a 22gram pellet downrange at 30kps. A repurposed fuel pellet launcher would make one heck of a good slugthrower, since an undetonated fuel pellet would impact at IIRC 2200grams of TNT equivalent.

It's from Matterbeam's Tough Guide to SF blog.
Click to expand...
One issue that I've seen brought up regarding D+He3 fusion is that you can't easily dictate which atoms fused with one another. If you could reliably make it a D+He3 reaction you'd be fine, but as it is you'd likely see some neutron emitting Deuterium on Deuterium reactions too. Perhaps by having an He3 rich mixture you could reduce the number of D+D reactions (which would of course be a waste of He3)?
 
Prophet141 said:
And of course it would still be hysterically expensive since it still requires an enormous number of nuclear bombs to be practical.
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That's the beauty of it. If you wanted a *single* 12 gauge shotgun shell to be manufactured from scratch, it'd cost as much as a laptop. But when you start making them in the millions, they become dirt cheap. Medusa would be dependant upon a vast number of essentially pure fusion nukes in the low kiloton range (or even sub kiloton). We have currently no good idea how to make them. However... pretty much by definition they would be composed almost entirely out of fusion fuel... lithium deuteride, D+He3, whatever. And in industrial quantities, the actual materials would be dirt cheap. So once you've spent the doubtless large fortune figuring out how to make the things, actual manufacturing should be cheap.

Aiding this is the fact that pure fusion nukes are *vastly* useful devices. Somebody storming your borders? Not a problem. Need to carve a big-ass canal? Not a problem. And most importantly... need a ready source of terawatts of electrical power? Very definitely not a problem. Forget tokamaks... small fusion bombs gives you fusion power on a vast scale using technology that otherwise would have been available in the 1960's. So once you've figured out how to make your Medusa-nukes... however much you spent developing them will be quickly paid for by replacing the environmentally destructive coal, natural gas, solar and wind turbines with clean, efficient and badass nuclear pulse fusion powerplants.
 
Orionblamblam said:
Prophet141 said:
And of course it would still be hysterically expensive since it still requires an enormous number of nuclear bombs to be practical.
Click to expand...
That's the beauty of it. If you wanted a *single* 12 gauge shotgun shell to be manufactured from scratch, it'd cost as much as a laptop. But when you start making them in the millions, they become dirt cheap. Medusa would be dependant upon a vast number of essentially pure fusion nukes in the low kiloton range (or even sub kiloton). We have currently no good idea how to make them. However... pretty much by definition they would be composed almost entirely out of fusion fuel... lithium deuteride, D+He3, whatever. And in industrial quantities, the actual materials would be dirt cheap. So once you've spent the doubtless large fortune figuring out how to make the things, actual manufacturing should be cheap.

Aiding this is the fact that pure fusion nukes are *vastly* useful devices. Somebody storming your borders? Not a problem. Need to carve a big-ass canal? Not a problem. And most importantly... need a ready source of terawatts of electrical power? Very definitely not a problem. Forget tokamaks... small fusion bombs gives you fusion power on a vast scale using technology that otherwise would have been available in the 1960's. So once you've figured out how to make your Medusa-nukes... however much you spent developing them will be quickly paid for by replacing the environmentally destructive coal, natural gas, solar and wind turbines with clean, efficient and badass nuclear pulse fusion powerplants.
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And there's the catch. Until we have a reliable method of detonating fusion bombs we're stuck with fission ignited weapons. Technically speaking everything else about Medusa (and Orion) is just a matter of cost and determination, with a little development to create components sturdy enough or otherwise suited for the challenge. Pure fusion weapons are a step further. Then again, if there was a concerted effort I'm sure that we'd see advances on that front.
 
We have laser ignition already.

A Medusa paraboloid that has a beam hit it could focus it to a point.

A simple BB gun shoots NIF pellets backwards and towards the focus point.

A two-fer.

It could be that fusion for propulsion might be easier than for power generation this way.

As the pellets are depleted in system where most acceleration takes place…it further unfolds to just be a beam rider.
 
Prophet141 said:
Scott Kenny said:
Prophet141 said:
I'm more of a fan of the Daedalus concept and similar ones to it. External ICF (to distinguish from Internal ICF, which is basically what a thermonuclear weapon is) allows for a more controlled and efficient use of fuel.
Click to expand...
I've read one analysis of the Rocinante's drive from The Expanse that used external ICF. 2.2kg of D+3He per second, and I'm assuming one pulse every 1/100 of a second or so for a nice smooth acceleration. Fusion fuel is biased to minimize neutron production, as neutrons do bad things to crew and produce no thrust. Drive power of 98 terawatts or so(!!!), pushes a fully loaded Roci around at 1.8 gees. Detonation point is about 300m aft of the Roci, so your fuel pellet launcher needs to put a 22gram pellet downrange at 30kps. A repurposed fuel pellet launcher would make one heck of a good slugthrower, since an undetonated fuel pellet would impact at IIRC 2200grams of TNT equivalent.

It's from Matterbeam's Tough Guide to SF blog.
Click to expand...
One issue that I've seen brought up regarding D+He3 fusion is that you can't easily dictate which atoms fused with one another. If you could reliably make it a D+He3 reaction you'd be fine, but as it is you'd likely see some neutron emitting Deuterium on Deuterium reactions too. Perhaps by having an He3 rich mixture you could reduce the number of D+D reactions (which would of course be a waste of He3)?
Click to expand...
Yes, the fuel mix is very He3 rich to minimize neutron production. As mentioned, neutron production in this case is bad, because in addition to cooking your crew it costs you lots of thrust. IIRC something like 40% of the fusion energy in a D+D reaction goes out in a neutron, that's a huge loss of thrust.

For electrical power production, when you don't care about extracting every newton of thrust, the fuel mix can be closer to stoichiometric (or whatever the word is in nuclear engineering for not leaving any unburned fuel) or even D rich if the D+3He ignition will also ignite D+D. There, you can use a lot of water and heat it to boiling to extract energy, all by stopping the neutrons.
 
Helion, a company aiming to produce an He3+D fusion reactor has caught some flak for what appears to be insufficient neutron shielding around their prototype reactor. Perhaps they'll operate their reactor on an He3 rich fuel mixture to preserve component life (and reduce shielding requirements).
 
publiusr said:
We have laser ignition already.

A Medusa paraboloid that has a beam hit it could focus it to a point.

A simple BB gun shoots NIF pellets backwards and towards the focus point.

A two-fer.

It could be that fusion for propulsion might be easier than for power generation this way.

As the pellets are depleted in system where most acceleration takes place…it further unfolds to just be a beam rider.
Click to expand...
As Scott Kenny mentioned above, if you want a decent acceleration you'll need something more capable than just a BB gun (or even a gun) to eject those pellets. Additionally, the energy output of a fusing pellet is going to be considerably smaller than a nuclear weapon with a yield of hundreds or thousands of tons of TNT. It will also not be directed (at least as far as I know) so most of its energy will not be captured by the sail. As such you'd need a more efficient way of capturing its energy. Since the amount of energy is not catastrophically gigantic, it will likely be possible to contain it with a magnetic nozzle.

So, we now have a beam-ignited pellet-fuelled rocket that directs its thrust through a magnetic nozzle. This sounds suspiciously like the Daedalus method of propulsion instead of the Medusa or Orion methods.

But you do raise a good point about the Medusa proposal in that once it's fuel is depleted it may be reconfigurable into a beam propelled craft.
 
Prophet141 said:
As Scott Kenny mentioned above, if you want a decent acceleration you'll need something more capable than just a BB gun (or even a gun) to eject those pellets.
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That particular speed is caused by wanting a high frequency of detonations for smoother acceleration, and the 300m standoff between the ship and the detonation point.

Given a detonation frequency of 1/second and a standoff of 30m, an ordinary BB gun is perfectly acceptable.
 
True, I suppose that a lower standoff distance is required given that the sail has no crew within it and isn't as vulnerable to the radiation.
 
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Michel Van said:
Orion in this forum

Orion external links
here look in eAPR on Orion, only $23 (18,3€) Buy them !

Project Daedalus

its the first "real" design for Interstellar flyby probe to Barnard's Star (5 lightyears from here)
made by the British Interplanetary Society,
Conducted between 1973 and 1978 by a group of a dozen scientists and engineers, led by Alan Bond
the Space Ship is a two stage with Laser Fusion engine fueled by deuterium and helium-3 pellets
after ignition the Probe accelerated next two years to 7.1 % of the speed of light
After the stage separation. the second stage accelerated for 1.8 years, to 12% of the speed of light
the probe reach Barnard's Star in 50 years after launch
25 years before arrival, Probe begin examining the area around Barnard's Star for Target planets
and drop probes at flyby true Barnard's Star system
receive the data and transmit them to Solarsystem

external links
en.wikipedia.org

Project Daedalus - Wikipedia

en.wikipedia.org en.wikipedia.org
www.daviddarling.info

Project Daedalus

Project Daedalus was one of the first detailed design studies of an interstellar spacecraft.
www.daviddarling.info
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About the termination of this project Capture d’écran 2021-05-16 à 10.57.40.png
 
Seconded. Most fascinating part is near the end, 1963-65. When Dyson and Ted Taylor try to gets Orion rescued by NASA only to be rebuked by Milton Klein and Harold Finger pushing their own nuclear space engine: NERVA.

At this moment they "shrink" Orion to 10 m diameter so that it fits the Saturn V.

And thus the S-IC, for a brief moment, carries three very different spaceships on its shoulders
a) the Saturn V Apollo stack
b) RIFT: Reactor In Flight Test, that is a NERVA as a third stage in place of S-IVB
c) The shrunk Orion: 880 tons and 10 m diameter.

Apollo, NERVA and Orion meet around the S-IC. Which allows a direct comparison of their respective performance, starting from the same Saturn booster stage.

End result ? even shrunk to sub-optimal size, Orion still outperform the other two by order of magnitude.

"All in the family"

Project_Orion_Saturn-V_compatibility.png
 
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And the details of a nuclear pulse unit bomb
Archibald said:
Seconded. Most fascinating part is near the end, 1963-65. When Dyson and Ted Taylor try to gets Orion rescued by NASA only to be rebuked by Milton Klein and Harold Finger pushing their own nuclear space engine: NERVA.

At this moment they "shrink" Orion to 10 m diameter so that it fit the Saturn V.

And thus the S-IC, for a brief moment, carries three very different spaceships on its shoulders
a) the Saturn V Apollo stack
b) RIFT: Reactor In Flight Test, that is a NERVA as a third stage in place of S-IVB
c) The shrunk Orion: 880 tons and 10 m diameter.

Apollo, NERVA and Orion meet around the S-IC. Which allows a direct comparison of their respective performance, starting from the same Saturn booster stage.

End result ? even shrunk to sub-optimal size, Orion still outperform the other two by order of magnitude.
Click to expand...
Could you imagine an Orion spaceship functioning in the high terrestrial atmosphere (above 50-60 km?) ; at the time of the prevention of atmospheric nuclear explosions (1962)!
 
Nope indeed. What a lot fails to appreciate is that Orion nukes not only would screw the biosphere with radiations: they would also play havoc with the van Allen belts.
So the only safe place to start an Orion drive would be the Earth-Moon Libration points, either EML-1 or EML-2. But go transporting Orion very heavy pieces to EML-2 in the first place !
 
Archibald said:
Seconded. Most fascinating part is near the end, 1963-65. When Dyson and Ted Taylor try to gets Orion rescued by NASA only to be rebuked by Milton Klein and Harold Finger pushing their own nuclear space engine: NERVA.

At this moment they "shrink" Orion to 10 m diameter so that it fits the Saturn V.

And thus the S-IC, for a brief moment, carries three very different spaceships on its shoulders
a) the Saturn V Apollo stack
b) RIFT: Reactor In Flight Test, that is a NERVA as a third stage in place of S-IVB
c) The shrunk Orion: 880 tons and 10 m diameter.

Apollo, NERVA and Orion meet around the S-IC. Which allows a direct comparison of their respective performance, starting from the same Saturn booster stage.

End result ? even shrunk to sub-optimal size, Orion still outperform the other two by order of magnitude.

"All in the family"

View attachment 721804
Click to expand...
About a possible NASA rescue(1964) Capture d’écran 2024-03-06 à 19.22.12.png
 

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