Where could we launch Orion? Hypothetical launch sites for Nuclear Pulse Propulsion Spacecraft.

Orionblamblam said:
Depends on the role of the nuke. Davy Crockett was designed in part to leave a place filthy, and it did so by incomplete fission.
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Point conceded there.


Orionblamblam said:
And Davy Crockett formed the basis of the 10-M Orion pulse unit.
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Then that's a particularly poor choice of design, as it is sacrificing significant amounts of thrust potential by not completely burning fuel.
 
Scott Kenny said:
Then that's a particularly poor choice of design, as it is sacrificing significant amounts of thrust potential by not completely burning fuel.
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The Orion pulse unit would have been on the order of a kiloton, which is the upper end of the W54's potential. The lower "Davy Crockett" end of the potential was about 25 *tons.* It achieved that shitacularly low yeild by being intentionally ineffective... the blast was almost incidental, with "here's some fallout for your infantry, Commies" being the point of the device. But when set for the upper yield, it was much more efficient, though still kinda crappy. But getting *any* sort of decent efficiency at a mere 1 kiloton remains a challenge. And for a 10-meter Orion, 1 kiloton is roughly where you want to be. Going more powerful doesn't increase thrust... it breaks your ship.

The first gen of 10-meter Orion pulse units would almost certainly have been W54 derived. Ted Taylor claimed to have figured out how to make vastly more efficient low-yield devices, which would have fed into later-gen pulse units. The explanation as to why the US never developed more efficient bitty-bombs is several-fold:
1:The nuclear arsenal never had that many bombs, so there wasn't a lot of incentive to spend the billions needed to make substantially more efficient ones. A single Orion mission would require more identical pulse units than there were of any other kind of nuke in the US arsenal, so making them more efficient would have been vital.
2: If the US *did* develop a nearly fission-free nuke in the kiloton range, then that would be proof that it was possible. The Soviets would eventually figure it out as well, quite possibly aided by espionage. That would allow them to build a bajillion nukes. That's bad.
3: If the Soviets figured out how to build a bajillion cheap low-fissionables nukes, then eventually China, India, Pakistan, North Korea, Syria, Iran, SPECTRE, the IRA, the PLO, the WEF, Soros, the SAG and all the other well-funded scumbags and villains in the world would *eventually* either figure it out and start making their own, or just buy them from drunk Wagnerites with a couple kegs of bathtub vodka.
 
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Orionblamblam said:
The Orion pulse unit would have been on the order of a kiloton, which is the upper end of the W54's potential. The lower "Davy Crockett" end of the potential was abotu 25 *tons.* It achieved that shitacularly low yeild by being intentionally ineffective... the blast was almost incidental, with "here's some fallout for your infantry, Commies" being the point of the device. But when set for the upper yield, it was much more efficient. though still kinda crappy. But getting *any* sort of decent efficiency at a mere 1 kiloton remains a challenge. And for a 10-meter Orion, 1 kiloton is roughly where you want to be. Going more powerful doesn't increase thrust... it breaks your ship.
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The point is that incomplete nuclear burn reduces your thrust, and fuel burn that spits out more neutrons than necessary really cramps your potential thrust. In a pure fusion charge (using pure fusion because I don't have data for a pure fission one), 40% or more of the energy in the reaction comes out as neutrons, which then don't contribute to thrust.

Got any recommendations for a non-Graduate-level breakdown of how much energy goes out in what form of energy for fission?


Orionblamblam said:
The first gen of 10-meter Orion pulse units would almost certainly have been W54 derived. Ted Taylor claimed to have figured out how to make vastly more efficient low-yield devices, which would have fed into later-gen pulse units. The explanation as to why the US never developed more efficient bitty-bombs is several-fold:
1:The nuclear arsenal never had that many bombs, so there wasn't a lot of incentive to spend the billions needed to make substantially more efficient ones. A single Orion mission would require more identical pulse units than there were of any other kind of nuke in the US arsenal, so making them more efficient would have been vital.
2: If the US *did* develop a nearly fission-free nuke in the kiloton range, then that would be proof that it was possible. The Soviets would eventually figure it out as well, quite possibly aided by espionage. That would allow them to build a bajillion nukes. That's bad.
3: If the Soviets figured out how to build a bajillion cheap low-fissionables nukes, then eventually China, India, Pakistan, North Korea, Syria, Iran, SPECTRE, the IRA, the PLO, the WEF, Soros, the SAG and all the other well-funded scumbags and villains in the world would *eventually* either figure it out and start making their own, or just buy them from drunk Wagnerites with a couple kegs of bathtub vodka.
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I think we're having a bit of a cross-talk about the word "efficient".

What I am talking about is simply making sure that all available fissionables fission. This doesn't really let you use significantly less fissionables per boom, there's a flat minimum size involved there. All it does is get the most boom out of what you have.

Yes, compared to Fat Man and Little Boy they're using far less fissionables for a 20kt boom. Those two bombs were 16% and 1.7% efficient, respectively. (Gun types are particularly poor)

But the Fat Man pit, all 6.19kg of it, is pretty close to the minimum possible fissionable mass, you're not making 6x 20kt booms out of it with a more efficient implosion lens.
 
Scott Kenny said:
But the Fat Man pit, all 6.19kg of it, is pretty close to the minimum possible fissionable mass, you're not making 6x 20kt booms out of it with a more efficient implosion lens.
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"It has been alleged that the British "Wee Gwen" warhead was a copy of the W54.[7] Though never put into production, Wee Gwen was to contain 1.6 kilograms (3.5 lb) of plutonium and 2.42 kilograms (5.3 lb) uranium.[8]"
 
The logical launch site to me has always been land-based from one of the tiny islands that were already used for extensive nuclear testing. French Polynesia or the Marshall Islands, maybe Johnson Atoll. Hell, see if the Norwegians will sell Bouvet Island, it's literally over a thousand miles from anywhere inhabited.

And regarding the warheads (specifically the questions about thrust efficiency), don't forget about the research done into shaping blasts directionally.
 
Ravinoff said:
The logical launch site to me has always been land-based from one of the tiny islands that were already used for extensive nuclear testing. French Polynesia or the Marshall Islands, maybe Johnson Atoll. Hell, see if the Norwegians will sell Bouvet Island, it's literally over a thousand miles from anywhere inhabited.
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Yes, those are the usual suspects for direct Orion liftoffs.


Ravinoff said:
And regarding the warheads (specifically the questions about thrust efficiency), don't forget about the research done into shaping blasts directionally.
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Already part of the Orion thrust bombs, they're shoving about 80% of the bomb's energy against the pusher plate.
 
Ravinoff said:
see if the Norwegians will sell Bouvet Island, it's literally over a thousand miles from anywhere inhabited.
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It might be a Not Practical place to build a launch facility,
It's not just the island's location that counts against it. Much of the island is permanently covered in ice with no opportunity for agriculture. Also, there are very few easy landing points around the coastline of the 49 square kilometre island.
The island “enjoys” a marine Antarctic climates which is dominated by heavy clouds and fog. The warmest month of the year (February) has a daily mean average temperature of just 2°C.
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Today, there is virtually no sign of human activity at Bouvet, with the exception of a single weather station located at Nyrøysa. This is the most common landing point on the island created by a rockslide in the 1950s.
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www.lifeinnorway.net

Bouvet Island: The World's Most Remote Island

A dependent territory of Norway, Bouvet Island in the South Atlantic Ocean is the world's most remote island. Here is its fascinating story. Where is the most remote part of Norway? Many might instantly think
www.lifeinnorway.net www.lifeinnorway.net

Weather station text link goes to, https://www.yr.no/en/forecast/daily-table/2-3371122/Norway/Bouvet Island/Bouvet Island

Bouvetøya has a maritime Antarctic climate. Westerly winds dominate the area, but the wind strength is not particularly great. The average temperature at sea level is around -1 °C, and the monthly average is about 1 °C in January and -3 °C in September. The island is usually shrouded by cloud or dense fog. By a fluke, a Norwegian expedition in 1985 experienced completely clear skies long enough to photograph the entire island with a view to making a map.
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www.npolar.no

Bouvetøya (Bouvet Island)

Bouvetøya is a Norwegian volcanic island in the Southern Ocean. Bouvetøya is one of the most isolated islands in the world and 89 percent of the island is covered by glaciers. Bouvetøya is the Norwegian claim area in the seethe of the polar regions we have the most knowledge about. The island...
www.npolar.no www.npolar.no
 
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Scott Kenny said:
That disagrees with the data on the Atomic Rockets site, which appears to be taken directly from the NASA reports on Orion.
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Can't exceed 50% for an external Orion drive. Consider: the theoretically best pulse unit would be one that converts its impulse into a tightly collimated "beam." This is what was *attempted* with the channel filler, propellant, etc. But to obey the laws of physics, there'd be a precisely equivalent beam going *the* *other* *way.* Equal and opposite. Obviously you might have a tight beam on one side and a diffuse hemispherical blast on the other, but every bit of energy going to the side is energy not going along the beam axis. So at best you'd get 50% of your energy converted into the beam that hits the ship. The rest goes elsewhere.

And with the real-world pulse unit designs, the atom bombs went off more or less spherically. The radiation case around the bomb redirected some of the prompt X-rays into the channel filler... but only some, and the bulk of the blast continued more or less unopposed. There's no such thing as a material that weighs only a few dozen pounds you can wrap around a kiloton nuke that's going to do doodly-squat to impede the blast.

If you have an internal "Helios" type system, you can contain all the energy of the bomb and utilize it for thrust, But here you're heating up a large mass of water or some such and redirecting it out a nozzle. Far heavier, lower Isp, lots of structural issues.
 
Perhaps lunar caves could help with containment?

Fill one with air and a nuke and that could get a heavy craft going at least.
 
Might I suggest Johnston Atoll? That island is so f'd up environmentally, you can't do anything to it that hasn't been done. It has an airfield, wharfs and piers, and is in a great location far enough from anything else if something went wrong nobody would care particularly.

johnston-atoll-aerial.jpg
 
The whale warriors would blockade it.

Starship might allow a piece-by-piece assembly.

A lunar thunderwell with just a single nuke or three might be the best we can hope for....blast a heavy craft off the Moon them retrofit...
use other engines.

Here a nuke is just serving in place as SRBs.
 

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