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Project Orion: A discussion of Science and Science Fiction


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4 hours ago, kerbiloid said:

So, to follow the Sagan's suggestion, the humanity should first significally increase the nuclear weapon production rate.

"This has made a lot of people very angry and been widely regarded as a bad move." - Douglas Adams

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2 hours ago, Gargamel said:

"This has made a lot of people very angry and been widely regarded as a bad move." - Douglas Adams

I was always having a feeling that there is something wrong with the space enthusiasts' suggestions.

Edited by kerbiloid
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  • 5 weeks later...

I don't think orion is great, I think you can get the same power with less, y'know, NUKES! I think it's an outdated idea to use, y'know, NUKES! for propulsion. 

As for nuclear power, I think it's great! I think alot of people's fears about it are overblown based on the few incidents that have happened. The only thing I don't support in terms of nuclear powered things is, y'know, NUKES!

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currently the only means of interstellar travel within the limits of current engineering and technology.  you just need the bucks and the desire to build one. 

nuclear power could have saved us from the current climate crisis, if not for the stupidity of some operators/designs and fear mongering involved from those opposed. 

nukes are ok. if it wasn't for those we would be in ww3 by now.

Edited by Nuke
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It's not a rocket.

Or it is but very (in/per)verted, if treat the nuke as a single-pulse rocket engine shooting at the jet reflector direction.

Though, the same does any turbojet in reverse mode.

Edited by kerbiloid
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If you don't like the Orion, you don't have to use it. Personally I think it'd be useful being earlier on in the tech-tree (if there is one) given how we invented nukes at the same time as jet engines... Will be fun, albeit slightly unethical to use it on Kerbin. I doubt it'd have good efficiency though.

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13 minutes ago, RocketSimplicity said:

If you don't like the Orion, you don't have to use it. Personally I think it'd be useful being earlier on in the tech-tree (if there is one) given how we invented nukes at the same time as jet engines... Will be fun, albeit slightly unethical to use it on Kerbin. I doubt it'd have good efficiency though.

We may have invented nukes at the same time as jet engines, but we weren't anywhere near utilising it for pusher plates. If Kerbal technological advancement is the same as Earth's, then Orion comes sometime after Ion propulsion. Maybe after Nuclear propulsion or nuclear reactors. We're still not sure how the tech tree is going to work in KSP 2, so it could be entirely unexpected.

Edited by intelliCom
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It is an interplanetary (allegedly interstellar) craft of massive size that can be constructed with 1960s tech (might even be a bit harder now that everybody who has ever built a battleship is easily 90+ if not dead).  What more do you  want?

Catches are that it requires a large number of nuclear explosive devices (the smaller the craft, the smaller and more numerous the nukes), and that thanks to a mistake in ignoring the magnetosphere, the original calculations for safety only work if you launch/build the thing in Antarctica (otherwise all the "fallout" comes back to Earth and lots of people die).

Great book on the subject: https://www.goodreads.com/book/show/21243.Project_Orion

 

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With the reached yield-to-mass ratio ~5.5 Mt/t  the planned Doomsday Orion with 10 Gt SUNDIAL warhead would be weighting about 2 000 t.

(With the planned 11 Mt/t - twice lighter).

Anyway, its launch mass was iirc ~4 800 t, say 5 000 t.
The pusher plate diameter ~23 m.

Space Shuttle launch mass was ~2 000 t, including ~800 kg of orbiter and orange tank.

So, to lift the Doomsday Orion to the thin air you need ~12 SRB of Space Shuttle. Not that much.

After separation, the Orion should use its own nuka-engine to reach LEO.

It average T/W should be ~1, like any upper stage provides.
Coincidentally, it's also the human normal gravity, but this doesn't play a role.

The required delta-V is the same, ~6 km/s.

Thus, the burn will take same 600 s of time, like any rocket needs.

The pulse rate is about 2 nukes per second, 2 Hz.

Thus, you need 1 200 nukes to reach LEO.

And the same amount (but of lower yield) you need for a smaller Orion. Say, the 100 t & 10m "Saturn V Military Orion", using Saturn V first stage instead of SRB.

You need ~5 000 t * (6 000 m/s)2 / 2 ~= 9*1013 J ~= 2 kt of kinetic energy.

They were able to focus ~6% of the yield energy in desired direction. That's the last open info.
Obviously, they couldn't focus 50% from the rear hemisphere.

So, let's take that they can focus ~10% of energy.

So, you need 200 kt of total gross yield.

Adding gravity, drag, plate heating,  and other losses, let's take it by an order of magnitude greater. ~2 000 kt.

So, you need ~1 200 nukes of 1..2 kt yield to put the Doomsday Orion to LEO.

According to the open Western data, such yield is provided by a  DT-boosted charge with ~3..4 kg of fissile materials (235U pusher and 239Pu sparkplug).

The 100 t / 10 m Military Orion is by ~50 times lighter. It requires ~1 200 charges of several tens tons yield.

The known US uranium deuteride tests of mid-1950s (Ruth and Ray) have reached ~200 t of yield with no plutonium.
It's said that it can be used as a sparkplug instead of Pu.

So, both Orions need the same DT-boosted fission charge of two-point initiation scheme with 3..4 kg of uranium (no plutonium).
The single-point detonation provides ~0.1 kt yield for 10 m Orion, the full detonation provides 1..2 kt for the 23 m Orion.

So, in total you need just 5 t of oralloy for any reasonable Orion.

5 t (i.e. 6 km/s) more to send it to Mars or deliver to the Moon L2.

Same to return back.

So, you need just 15..20 t of oralloy per flight.

It's normal for relatively rare usage.

***

If case of crash, 20 t of U won't add any significant radioactivity to nature.

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5 hours ago, wumpus said:

 

It is an interplanetary (allegedly interstellar) craft of massive size that can be constructed with 1960s tech (might even be a bit harder now that everybody who has ever built a battleship is easily 90+ if not dead).  What more do you  want?

 

The most detailed proposals were for Mars or Saturn but some were made for other stars.

I don’t think the lack of battleship experienced shipbuilders is a problem. We have been building cargo ships the size of battleships (some bigger than battleships) for decades.

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3 hours ago, kerbiloid said:

With the reached yield-to-mass ratio ~5.5 Mt/t  the planned Doomsday Orion with 10 Gt SUNDIAL warhead would be weighting about 2 000 t.

(With the planned 11 Mt/t - twice lighter).

To fully understand Sundial, a "bit" of context regarding nuclear testing and Edward Teller in specific is needed, if you want the brief skip to the last paragraph, but for the full context we need to start at the beginning. A well known piece of history is the fact that scientists feared that the trinity test would lead to the atmosphere undergoing a chain reaction of fusion. This was fortunately not the case, however it would be far from the last time we ignited significant portions of the atmosphere. Ivy Mike  was the first in a series of thermonuclear weapon detonated, oftentimes called a nuke, the soviets had the best description for it as a "thermonuclear complex". This design utilized the teller ulam design, which basically allowed you to chain together nuclear weapons with increasing efficiency. Thanks to the stationary nature, liquid deterium was used as the fuel due to the need for cooling not being a concern. Due to the nature of this new design, no one was certain how much force it would bring before detonation. After the detonation, Edward Teller in California detected it on a nearby seismometer, and proceeded to telegram a head of a los alamos project "Its a boy". The project by all means went far above expectations, being the fourth largest bomb detonated by the us to this date. While this design was far from the most efficient design, its raw size more then enabled its success. With the data given by Ivy Mike, the United States decided to do the first series of thermonuclear weapons testing, Operation Castle. 

If Ivy Mike is to be described as a thermonuclear complex, Castle Bravo would best be described as a thermonuclear building. While still taking place on the marshall islands, the forcibly relocated natives of this island were significantly closer to the tests. Due to either apathy to the people living there, incompetence, or some combination, no one bothered to calculate the effect of wind on fallout. While significantly smaller and far more optimized then Ivy Mike, it was still a far fetch from the mobile and spherical weapon we tend to associate with nukes. This test was expected to be only 5 megatons of force. As nuclear weapons experience hotter temperatures and pressures, not only does more of there mass undergo fusion, more fusion reactions that require higher energies occur, meaning that the yield to mass ratio can increase essentially exponentially. The test was triple of what was expected, the largest bomb detonated by the US to this day. US sailors and servicemen nearby experienced radiation. Children of the nearby tribes seeing the fallout, with no one in the tribes aware of the testing, mistook the fallout for snow and began playing with it. Due to the US not warning basically anyone of these tests, Japan got a grim reminder of there fate just 7 years earlier when a Japanese fishing boat was also subject to significant radiation. It took 3 days for the tribes of the area to be relocated once again away from this radiation, after this test they were subjected to a series of tests to better understand the effect of this radiation, unaware of the nature of these tests. The radiation this test and many others still effect its inhabitants today.

While Castle Bravo was far greater then its expected yield, the same could not be said for Castle Koon. Castle Koon was designed by the same place Edward Teller was working at, the Livermore branch of the University of California (now better known as Lawrence Livermore National Laboratory). Utilizing an exotic secondary stage, the design was a dud due to a design defect. Due to this, the planned follow up test of this design was cancelled. Seemingly due to this cancellation, we get brought back to Edward Teller. Likely in spite, Edward Teller proposed Project Sundial, while the specifics aren't known, this device would have likely used the chaining of the teller ulam design to an extreme. Sundial was composed of two projects, Gnomon, which was a one gigaton primary bomb, and Sundial, which would cover the rest of the ten gigatons. Alex Wellerstien, the nuclear historian behind NUKEMAP with its ten gigatons of force, calculates that sundial would be powerful enough to set all of the UK and Ireland on fire. This device would likely rely on nearly pure fusion energy, and due to the intense temperatures involved there would likely be an extremely high rate of fusion. We don't know the specifics of how this device would work, and this is leaving the history territory and going into personal speculation territory, but I think I have an idea on some of the specifics. Before the Teller Ulam design, Edward Teller had the idea now known as the Classical super. In short, it would be a conventional fission weapon, and the temperature from that alone would be enough to trigger a runaway chain reaction of nearby pure deuterium. This didnt quite work with our nukes, however it could possibly work if you had extremely high temperatures.

The interesting thing about sundial is the fact that it needs a separate extremely powerful nuke for it to work, while teller ulam design can chain stages together, why would you design a 9 gigaton secondary stage and a one gigaton primary stage separately? In fact, why was Gnomon described as a primary stage in the first place? Teller Ulam design is also known as the Sausage design because you can link a bunch of similar stages to get your desired effect. In order to get up to that gigaton metric, you'd likely need many stages of nukes to get up to this point, and at that point why break that staging chain up, having it described as two separate stages is a really interesting detail. While we may never know, I have a feeling (emphasis on feeling, the specifics on how it would work is classified) that Sundial utilized a form of the classic super design, using Gnomon as the primer, and having Sundial be basically pure deuterium (and likely tritium) undergoing a runaway reaction. If this were to be the case, and this design were to work then this means that this design would likely have far greater efficiencies then current designs due to not needing nearly as many structural components. If my math is correct, a complete fusion of a ton of mixture of deterium and tritium would yield 92 megatons of tnt, while it's unreasonable to expect all reactants to fuse, this also doesn't account for the additional yield of additional non deuterium-tritium fusion. All things considered, ballparking here but it isn't reasonable to expect a yield to mass ratio of 50 Mt/t if not higher., bringing the weight down to only 200 tons.

Edited by Strawberry
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4 hours ago, Strawberry said:

If my math is correct, a complete fusion of a ton of mixture of deterium and tritium would yield 92 megatons of tnt, while it's unreasonable to expect all reactants to fuse, this also doesn't account for the additional yield of additional non deuterium-tritium fusion. All things considered, ballparking here but it isn't reasonable to expect a yield to mass ratio of 50 Mt/t if not higher., bringing the weight down to only 200 tons.

1. It were  Teller's words in 1962, after the Dominic tests, that it would be posible to improve from 5+ to 11 Mt/t, and make a 50 Mt bomb of standard 4.5 t mass.

But it would require a spherical geometry and ablative compression instead of the T-U scheme, as more effective.
Thus, the bomb would not fit the standard bomb bay geometry (8 ft wide) and would be impractical.

The T-U scheme was then anyway scrapped in favor of quasi-spherical secondaries of sub-megaton range (like the W88's Cursa and its W76 ancestor), preferred by the Soviets from the very beginning for the technical economy reasons.

2.  The deuterium is cryogenic, while the gigaton charges like Sundial, Gnomon, and two others, were to be on duty, either behind the Moon, or ready to start.
So, it needs a massive cryostat.

And the liquid deuterium density is just 200 kg/m3, while LiD is 820 and doesn't need a cryostat.

Thus, while the pure-D was studied for the gigaton, it would be as of no use, as other liquid deuterium designs.

3. Any fusion fuel is not just heated by the primary nuke, it's compressed by its massive metal hull which is heat by the heavy-atomic (thus, U or Pb) outer casing.

So, any fusion bomb efficiency would be far from the ideal 80 Mt / t of pure D-T.

***

As even 11 Mt/t was never achieved irl, this makes to think that the ideal 200 t would be irl several times heavier, i.e. ~1000 t.

Edited by kerbiloid
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On 8/31/2022 at 2:15 AM, intelliCom said:

Is Orion really a good rocket engine?

Just as long as you don't try to use the thing for a takeoff. And since it apparently needs to be repeated at least once a week, it does not make a good SSTO.

Edited by Codraroll
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2 hours ago, Codraroll said:

Just as long as you don't try to use the thing for a takeoff. And since it apparently needs to be repeated at least once a week, it does not make a good SSTO.

It was more of a rhetorical question for discussion's sake. I love Orion myself, just wanted to see what others thought about it, get some criticism of it going too.

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On 8/31/2022 at 12:33 AM, intelliCom said:

Orion comes sometime after Ion propulsion

It's not so complicated as you might think.  It was discussed in a feature video, and as that video says there were scale tests with conventional explosives.  The main obstacle to Orion drives were nuclear test ban treaties.  So Orion drives, at least for humans, could very well have been invented before ion engines, or around the same time.

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17 hours ago, SunlitZelkova said:

The most detailed proposals were for Mars or Saturn but some were made for other stars.

I don’t think the lack of battleship experienced shipbuilders is a problem. We have been building cargo ships the size of battleships (some bigger than battleships) for decades.

The point of "battleships" was the construction of thick armor plating.  Building that pusher plate would take relearning some lost skills.  The size of the thing wouldn't matter,  except that you'd presumably make it in Antarctica (or possibly build it on a barge and tow it to a soon-to-be ice free arctic summer).

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15 hours ago, kerbiloid said:

1. It were  Teller's words in 1962, after the Dominic tests, that it would be posible to improve from 5+ to 11 Mt/t, and make a 50 Mt bomb of standard 4.5 t mass.

But it would require a spherical geometry and ablative compression instead of the T-U scheme, as more effective.
Thus, the bomb would not fit the standard bomb bay geometry (8 ft wide) and would be impractical.

The T-U scheme was then anyway scrapped in favor of quasi-spherical secondaries of sub-megaton range (like the W88's Cursa and its W76 ancestor), preferred by the Soviets from the very beginning for the technical economy reasons.

If you're going to have a bomb such as sundial, fitting in a bomb bay wont be possible at all. Unless you go with the initial suggested delivery message of putting it in your backyard and destroying the world, for terrestrial matters only real practical method of transportation of something such large would be a cargo ship. If you plan to have a multi gigaton bomb in space you are going to need to assemble in space, and complex construction at that. With design constraints like this the main thing that matters here for sending such a nuke to space is mass, shape doesnt really matter anymore as whatever shape it is its going to be a pain to construct. 

15 hours ago, kerbiloid said:

2.  The deuterium is cryogenic, while the gigaton charges like Sundial, Gnomon, and two others, were to be on duty, either behind the Moon, or ready to start.
So, it needs a massive cryostat.

And the liquid deuterium density is just 200 kg/m3, while LiD is 820 and doesn't need a cryostat.

Thus, while the pure-D was studied for the gigaton, it would be as of no use, as other liquid deuterium designs.

It's important to note that unless I missed a primary source, none of the primary sources I could find had the details of sundial (understandably) classified. Also Sundial both began and ended before project orion begun, there was no plans to have sundial in specific in space. We simply dont know how sundial would've worked, however due to the aforementioned delivery constraints, having to cool down gas would not be a concern. It is far easier to fit a cryostat in a stationary complex or a large spaceship then a tight airplane with not much space.  Deuterium comes with better energy efficiency per mass and considering the fact this thing would've likely had significant mass it would've likely gone for deuterium to cut down on it. 

15 hours ago, kerbiloid said:

3. Any fusion fuel is not just heated by the primary nuke, it's compressed by its massive metal hull which is heat by the heavy-atomic (thus, U or Pb) outer casing.

So, any fusion bomb efficiency would be far from the ideal 80 Mt / t of pure D-T.

This is the case for standard thermonuclear weapons, considering the fact this project was Teller's baby, I doubt it would use standard design. While the specifics were classified, in the same report that mentioned Sundial it was also mentioned that Tellers team was also looking into air breathing thermonuclear nukes to cut down on weight at the same time, it's honestly more likely that whatever the design was it was using something exotic instead of something normal. To me the design that seems most likely would be a return to the classical super concept, as if it could be possible to get it to work it would drastically save on weight and costs. 

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26 minutes ago, Strawberry said:

If you're going to have a bomb such as sundial, fitting in a bomb bay wont be possible at all

Teller said this not about SUNDIAL, but about the post-B41 bomb.

27 minutes ago, Strawberry said:

If you plan to have a multi gigaton bomb in space you are going to need to assemble in space

Assemble a thousand-ton heavy charge in space? When its charge would weight several hundred ton alone? Even not funny.

Especially since such assembly would be likely stopped by an opponent nuke in process.

Sundial is to be launched in one piece secretly, unless it would be intercepted, and very probably right on the launchpad.

31 minutes ago, Strawberry said:

Also Sundial both began and ended before project orion begun, there was no plans to have sundial in specific in space. We simply dont know how sundial would've worked, however due to the aforementioned delivery constraints

We know definitely that no planned chemical rocket could lift thousand(s) tonnes.

Even the Nexus versuion with gaseous nuclear engine on the upper stage.

Orion is the only option, and it's mentioned. So, it's useful as an example of the Orion ship.
Also it matches the known Orion mass range, and its 23 m diameter matches the Nexus and Dragon, so is useful as an estimation example.

33 minutes ago, Strawberry said:

Deuterium comes with better energy efficiency per mass and considering the fact this thing would've likely had significant mass it would've likely gone for deuterium to cut down on it. 

Deuterium efficiency was 15/82 Mt/t last time when it was tested, and it was replaced with LiD as soon as possible (in two years) exactly due to its extremely poor energy-to-mass ratio.

35 minutes ago, Strawberry said:

This is the case for standard thermonuclear weapons, considering the fact this project was Teller's baby, I doubt it would use standard design.

The Teller-Ulam scheme is doing this as well, just it's based on cylindric implosion.

And exactly to improve the ratio, Teller himself mentioned the spherical implosion.

36 minutes ago, Strawberry said:

While the specifics were classified

The specifics of the deuterium test is well-known.

And the last T-U scheme charges have been dismissed decades ago.

And in any case, you need a heavy casing to absorb X-ray and heat the heavy shell to compress the fusion core, so the fusion fuel will take much less than 100% of the charge mass.

 

 

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52 minutes ago, kerbiloid said:

Orion is the only option, and it's mentioned. So, it's useful as an example of the Orion ship.
Also it matches the known Orion mass range, and its 23 m diameter matches the Nexus and Dragon, so is useful as an estimation example.

You cant use Orion in atmosphere, even ignoring the environmental effects the structural effects of an atmosphere wouldnt allow the nuke to support itself. You cannot transport a nuke of this size to space no matter what way you do it, while construction wouldnt be easy, in the hypothetical you were to transport a multi gigaton nuke to space for some reason, you will need to construct it, while this is far far from easy, its basically your only option for such a nuke.

58 minutes ago, kerbiloid said:

Deuterium efficiency was 15/82 Mt/t last time when it was tested, and it was replaced with LiD as soon as possible (in two years) exactly due to its extremely poor energy-to-mass ratio.

The specifics of the deuterium test is well-known.

And in any case, you need a heavy casing to absorb X-ray and heat the heavy shell to compress the fusion core, so the fusion fuel will take much less than 100% of the charge mass.

I should've mentioned that I was referring to theoretical efficiency instead of deuterium instead of efficiency in practice, using the fuel in a more efficient manner would give it a greater energy to mass ratio, while this is pure speculation I'm pretty sure Sundial intended to do this through something similar to the classical super design to where you generate extremely immense heat and pressure through pure brute forcing it and generating from just a separate nuclear explosion (to an extreme), if this were to work if you brute force this enough (through say.. a one gigaton explosion), you could get it to far higher efficiencies then normal. This design wouldnt need many of the complexities of normal nukes and thus save a lot on weight

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7 hours ago, Ember12 said:

It's not so complicated as you might think.  It was discussed in a feature video, and as that video says there were scale tests with conventional explosives.  The main obstacle to Orion drives were nuclear test ban treaties.  So Orion drives, at least for humans, could very well have been invented before ion engines, or around the same time.

Still, in a gameplay perspective, making Orion engines come first would make Ion feel really out of place. Considering how the NERVA equivalent was put at the end of the tech tree anyway, Orion should be after that.

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54 minutes ago, intelliCom said:

Still, in a gameplay perspective, making Orion engines come first would make Ion feel really out of place. Considering how the NERVA equivalent was put at the end of the tech tree anyway, Orion should be after that.

It could still be balanced if Orion was (a) prone to blowing itself up if launch in-atmo, (b) very heavy, (c) very expensive, (d) unthrottleable other than altering pulse frequency, and (e) produced actual thrust pulses so great that they would overwhelm the gee-limits of most in-game parts.

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