WI: Project Orion succeeds

I've found unreliable sources that have put the cost of the plutonium in mini-nukes at $1 mil. - so 1/10th the DoE price. No idea how accurate those sources are - I would bet "not at all" is the answer.

You'd probably win that bet... If we assume 10 kg per pulse unit if we load them with uranium - and I would bet the actual number will be more like 5 kg, but let's go for a conservative case - then that's about $120,000 in fissiles per bomb. At 200 bombs to orbit, that's $24 million in HEU per launch. While that would buy a lot of rocket fuel, the main cost for rockets is the rocket itself, not the fuel, so I think this looks like a pretty reasonable number.
 
You'd probably win that bet... If we assume 10 kg per pulse unit if we load them with uranium - and I would bet the actual number will be more like 5 kg, but let's go for a conservative case - then that's about $120,000 in fissiles per bomb. At 200 bombs to orbit, that's $24 million in HEU per launch. While that would buy a lot of rocket fuel, the main cost for rockets is the rocket itself, not the fuel, so I think this looks like a pretty reasonable number.

Even the rocket itself isn't that expensive - the real cost of launching (say) 500 tonnes into orbit is the costs of production lines, ground crew, equipment maintenance etc.

Personally, I wouldn't settle for an orion that couldn't launch less than 4000 tonnes on a single vehicle - at that point, it is comparable to 10 Sea Dragon class chemical rockets.

Whether the 1 4000t orion or the 10 sea dragons are cheaper... Well, I'd bet on the Sea Dragons, but depending on the exact economic conditions, the orion has a fighting chance.

If the orion is 20,000t, then the orion is probably cheaper than the equivalent 50 Sea Dragons - at least in terms of marginal costs/launch. The Sea Dragon is probably cheaper if you factor in the costs of the development program.

At the point where a civilization is launching multiple 20,000t orion vehicles every year, then it is probably better than the Sea Dragon.

But if someone is launching enough to LEO to make it worth having 20,000t orion ships, I would have to ask them why they weren't using laser launchers instead.

fasquardon
 
I'm not too confident in your math here. But for the sake of argument, if it takes 72 tonnes of 1kt nuclear bombs to launch an orion, that is not "clearly better". Plutonium is expensive stuff!

Though details on the W54, the warhead on Davy Crockett and SADMs are still classified, points to it being U-235 device with 36 point implosion, per
_Swords of Armageddon_ by Hanson

HEU was far cheaper.
I think it would have been HEU or Oralloy, IMO

Edit: Pu-239 releases about 19 kilotons per kilogram that fully fissions, HEU 17. So the tradeoff in price to yield is worth it.
 
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I'm probably going to be replying to this over the rest of the week as I'm time limited at the moment but;

I classify Mini-Mag Orion and its relatives as a separate concept from original Orion. They won't work for surface launch, and it's surface launch that makes Orion interesting. Once you're out in space, there are lots of options for getting around efficiently, many of which - such as ion engines - are much better developed than EPPP.

Mini-Mag actually WILL work for surface launch if you can get around the little fact that it still uses nuclear explosions as propulsion :) At least one study I've seen pointed out that legally the current bans only apply to weapons testing, (since they are in fact written specifically to ban open air testing of such weapons) and that propulsion isn't a weapon and specifically the z-pinch sub-critical implosion system used in the Mini-Mag does not lend itself to weaponization and therefore does not in fact fall under the restrictions. Of course the actual concept is still NOT to launch from the surface since that's got other issues but to allow that testing is possible should anyone be interested in using the mini-mag system for planetary defense purposes.

Getting around in space "efficiently" is defined differently under different circumstances though. Sure an ion drive is probably one of the most overall efficient drives for interplanetary flight... As long as you don't mind taking quite a bit of time to get from point A to point B. If you've got an Orion drive in space you in fact don't have to take that kind of efficiency into account. And EP3 is apparently more developed than people tend to think. Flight testing appears to be the only place where EP3 lags behind but in fact that's actually the "simple" part which is why it has been continued to be pursued actively since it was first suggested.

I'm not sure I understand your comment here. It sounds like you think that, by "focus", I mean something different from "ensuring as much as possible of the plasma goes in the desired direction." The "focus" is directing as much plasma towards the plate as possible, because if you don't direct the plasma, the ship absorbs much less energy per propulsion unit, which cuts your exhaust velocity by a lot - at least 50%, and probably more for a small Orion. The difference between the Orion propulsion bomb and the CASABA-HOWITZER is a difference of degree, not of kind - both use a radiation case to channel the bomb's gamma-ray output to a pancake of tungsten, which turns into a fast-expanding cylinder of plasma; the Orion bomb tries to make a comparatively wide cylinder, while CASABA-HOWITZER makes a narrow one.

We know that there was at least one CASABA-HOWITZER test. The project bears strong similarities to the later PROMETHEUS project at Los Alamos, which was part of SDI in the '80s. We know that PROMETHEUS was based on an unnamed earlier project, most likely CASABA-HOWITZER, and that that earlier project achieved only "a fraction" of the plasma velocity they expected. I therefore conclude that the balance of evidence is that CASABA-HOWITZER failed to achieve the degree of focusing they projected it should. Therefore, I conclude that it is an open question whether the Orion propulsion units could be built with the degree of focusing assumed by the Project Orion study team.

My sources here are George Dyson's book, Project Orion, and Dan Fenstermacher's "The Effects of Nuclear Test-Ban Regimes on Third-Generation-Weapon Innovation", Science & Global Security, Vol. 1 (1990), pp. 187-223.

But you're assuming that CH levels of focused plasma were required and they weren't. Orion's plasma effect was demonstrated and it wasn't required that the plasma be as focused as CH where as to work CH had to have a much higher focus than Orion's pulse charges did. If CH only achieved a "fraction" of its plasma velocity and focus that has little to do with the Orion pulse units which were based on already proven plasma velocities and focus with relatively straight forward and simple methods. Again CH was planned as a LONG RANGE plasma weapon, something the Orion pulse units were specifically NOT designed to do.

And they tested precisely none of those methods because, by the time they got to that point, the PTBT was in force. Whether or not any of them would work is an open question. I've seen the pictures of stuff that has survived close proximity to a nuclear explosion - some of them have even been posted in this thread. But we're talking about taking a big steel plate and exposing it not to one, but to thousands of nuclear explosions, and it needs to maintain mechanical strength while it does so. This is a tall order, and the fact that there are solutions that work in theory does not mean they will work in practice.

Actually they DID test several of the proposed methods for wetting the surface with oil and did detailed studies of materials both before and after being exposed to a nuclear blast. Orion was proposed on evidence they found during atomic testing in the late 40s and early 50s there was active testing until the PTBT went into effect in 1963 and materials and effects testing continued using underground explosions as far as I can find evidence is still being gathered today. Mechanically it's well known that well built and designed structures can in fact withstand a very near miss by nuclear weapons, it happens to be the primary design criteria for nuclear hardened structures such as come buildings and facilities like nuclear weapons silos. This isn't "theory" it is in fact "practice" and most if not all this work is applicable to Orion.

Given the amount of fission products this thing produces, the fallout created by a failed launch is going to be much less than that produced by a successful one.

Actually no since a failed launch means there was NO burn-up of fissile materials where as a successful explosion significantly reduces the overall fissile material when generating the fission products.

I'm aware. But there's a wide separation between "suggested" and "turned into working hardware", and I don't think they could make the system actually work with the technology of the 1960s.

Actually they tested the concept in several fashions and the main outcome was it could be done with existing hardware IF they just built the system big enough. Avco's concept was a pretty massive CO2 laser which they admitted wasn't very efficient but had the advantage that no new technology would be required. The main issue which remains to this day is working out the pulse mechanism (the Avco design literally had a spinning plate with holes in the rim doing the "pulsing", crude as heck but it worked at least on a small scale :) ) since almost every concept required that the beam be pulsed. It's only been recently that continuous laser propulsion has been examined as pulsed was always seen as more efficient. Recent work has suggested that continuous might in fact be "better" overall but it requires more laser stations down-range than the pulse type did and looks to have some hard materials and payload limits as well.

Randy
 
And I'm going to point out, (again :) ) that you don't have chemical and Orion's competing in any scenario. You HAVE to have both since you can't land an Orion efficiently, (note that last word because while you CAN in theory land an Orion in the ocean the fine control needed wasn't available at the time AND it is only usable on Earth, every other destination is going to have a very large spot of high radiation and slag where the Orion touches down, not conducive to surface operations, and worse is that the mechanical pressures of landing on the pusher plate is VASTLY different than the shock mechanics of the drive itself and would definitely damage the pusher plate severely :) ) and you need chemical rocket propelled supplies and personnel to service the Orion's on-orbit. The designers, (especially but most proponents as well) tended to gloss over the whole issue of landing and surface operations but the fact is the Orion IS a brute force system that gets a lot of payload, (and structural mass) into space and from place to place but it's really, really bad at fine maneuvers or getting stuff from space to the surface.

And speaking of; Sea Dragon, was a TSTO "big-dumb-booster" which used RP-1 and LOX in the first stage and LH2/LOX in the second stage which means far less LH2 than suggested but more RP1 and it should be noted that the economics given for the SD are a bit dicey as pointed out by NASA to TRW and Truax; To get to the given price point, ($600 to $59 per kg) you needed a pretty hefty flight rate of around 4 launches a month at least. Each delivering around 550 tonnes to orbit which then had to be 'serviced' by an on-orbit infrastructure capable of handling and processing 2,200 tonnes per month of payload. And you can't launch people on the Sea Dragon which was another thing NASA pointed out. Truax disliked and disparaged the NASA suggested guidelines that led to the "Excalibur" design concept, (most often calling it "Subcaliber") but in fact it was a more realistic payload capacity that MIGHT have been applicable to an expanded space program.

Sea Dragon and Laser Launch are in fact some pretty good examples of the two extremes of seeking economics by forgetting the reason(s) you're going into space to begin with. (And really a LOT of the proposed "mass" launch systems run into this issue) Sea Dragon had far to much payload for any near-term space program, even supporting Orion's. Similarly most laser launch systems put mass' of payload into orbit in "chunks" of a tonne at the most. (Usually less) Sure that translates out to a lot of "chunks" over a 24 hour period but those chunks are spread out all over the place and have to gathered and transported to where they actually need to go so a lot of each "chunk" ends up being supportive of the on-orbit infrastructure rather than actual payload. Most 'mass' launchers have this problem and only avoid this when they are massive enough to place significant payload into orbit in a single launch rather than over time. And of course to reach that point their upfront cost and resources required get very high, very fast.

So you end up looking at chemical reusable rockets which while having a lower economic case than say Sea Dragon, normally have a lower up-front cost than most mass-launcher systems and also have the advantage of putting you payload where you want it on every flight without resorting to large on-orbit infrastructure. And at some point, someone will point out that you can have the best of BOTH worlds by having a large chemically propelled reusable rocket with a large payload and you can even avoid the need for ANY on-orbit infrastructure! (Hello SLS! :) ) But keep in mind that flight-rate is a key metric, things are cheaper the more often they are used. Sea Dragon, Laser Launch, even Orion is going to end up being more effective the more often its used but more importantly you have to take everything into account and that includes propellant costs, refurbishment costs, and payload capacity per flight as well as over time.

There is in fact no 'golden bullet' single system that will open space to the everyone. Mostly because there is no single overall "plan" by anyone for manned space travel. It's always been a hodge-podge of concepts that gain and lose ground over time because unlike anywhere on Earth there's no real 'drive' to move people or civilization into space. And that right there is where any POD has to come from to build a timeline on. As long as mankind is just going to dabble in space exploration then there's no real need for the extensive space faring infrastructure and travel that actually being "space faring" requires.

Randy
 
And speaking of; Sea Dragon, was a TSTO "big-dumb-booster" which used RP-1 and LOX in the first stage and LH2/LOX in the second stage which means far less LH2 than suggested but more RP1

I did say I was talking about a Sea Dragon-like all LOX/LH2 rocket, rather than the Sea Dragon itself.

it should be noted that the economics given for the SD are a bit dicey as pointed out by NASA to TRW and Truax

True enough. But in a world where there is enough demand for orions, there is enough demand for giant chemical rockets and IMO the giant chemical rockets have the advantage until you are launching absolutely monstrous payloads.

you can't launch people on the Sea Dragon which was another thing NASA pointed out

Too much acceleration on the second stage?

Similarly most laser launch systems put mass' of payload into orbit in "chunks" of a tonne at the most

There's nothing that stops you sending up larger and less evenly distributed loads - though the power supply gets more complex the lumpier demand gets.

fasquardon
 
I did say I was talking about a Sea Dragon-like all LOX/LH2 rocket, rather than the Sea Dragon itself.
Don't think that's possible.

The whole point of Sea Dragon, iirc, was you could build the sucker in ship yards to maritime specs and tolerances. I really doubt you can do that with an LH2 tank.

Besides, fuelling the thing at sea? You'd have to develop LH2 supertankers to do it. I don't even want to think about it.

I suspect they'd have had quite enough problems with LOX, if they actually tried putting it into practice. But at least LNG tankers demonstrate that that level of cryogenics is possible in sea-going vessels.
 
I did say I was talking about a Sea Dragon-like all LOX/LH2 rocket, rather than the Sea Dragon itself.

The one thing all the BDB access studies pointed out was you do NOT want to deal with LH2 as a propellant if you can avoid it in any way. SD had to use it to get enough performance but really they could have used either sub-cooled (LOX temps) propane or liquid methane (LNG) which would have significantly reduced the size of the second stage. The main reason they did not even suggest it was the lack of engine data on those propellant combinations and the fact that LH2/LOX data was readily available. The one company that actually suggested and did the work on an LH2/LOX "cheap" LV (https://en.wikipedia.org/wiki/Aquarius_(rocket)) was found to be less competitive even with some really low expectations of successful launches than other designs using less energetic propellants.

This was an issue with most LH2/LOX SSTO ideas, and it took a long time to come to terms with the idea that in some cases less IS actually more :)


True enough. But in a world where there is enough demand for orions, there is enough demand for giant chemical rockets and IMO the giant chemical rockets have the advantage until you are launching absolutely monstrous payloads.

Uhm, actually that's not true at all because "payload" isn't the metric under discussion and that's another 'fact' that tends to get stuck in people's heads about Orion. It's not about launching large amounts of "payload" at all but the fact you are getting a fully equipped and reusable interplanetary vehicle you just need to re-fuel and service in a single launch that would take a huge launcher, (like Sea Dragon) or multiple smaller launches to get any other way. You're not getting "payload" you're getting a space SHIP rather than a space craft.

It's not a competition because there is NO comparison. It has to be kept in mind even if you have Orion's you still need rockets to support them. The reverse isn't true.

Too much acceleration on the second stage?

As I recall since the engine wasn't that throttleable. (Though I'll point out the illustration DOES show a capsule and escape system)

There's nothing that stops you sending up larger and less evenly distributed loads - though the power supply gets more complex the lumpier demand gets.

As Jerry Pournell pointed out but your power demands get pretty ridiculous. The novel length work pretty much glossed over the power demands but his short stories pointed out you had to not only have a couple of nuclear reactors dedicated during the launch sequence you had to supplement it with what amounted to a set of F1 engines being used as MHD generators to get the peak power. Of course that assumed the one laser site, pulsed laser "bang-bang" launch system which while the most efficient is also the hardest to do.

Darth: the LH2 (and some of the LOX as well as keeping the LOX cold while traveling to the launch site) was generated on or near the site using nuclear power and electrolysis. In theory anyway. The suggestion was a "de-commissioned" nuclear carrier mainly so that the support and servicing crew could be switched out during the voyage to the equator for launch, but in general the whole support scheme wasn't every detailed more than generally.

The main issue though is the minimum necessary "through-put" in a system using SD equivalent LVs as support is to the point where you really DO want to find some way OTHER than rockets to loft payload.

Randy
 
The whole point of Sea Dragon, iirc, was you could build the sucker in ship yards to maritime specs and tolerances. I really doubt you can do that with an LH2 tank.

Maybe. Truax made his share of charitable assumptions.

Besides, fuelling the thing at sea? You'd have to develop LH2 supertankers to do it. I don't even want to think about it.

If I were going to do Sea Dragon I'd have an island or coastal launch complex with all the heavy industry and a pipeline out to the launch area.

The whole idea of fueling Sea Dragon using an aircraft carrier really was daft.

The one thing all the BDB access studies pointed out was you do NOT want to deal with LH2 as a propellant if you can avoid it in any way. SD had to use it to get enough performance but really they could have used either sub-cooled (LOX temps) propane or liquid methane (LNG) which would have significantly reduced the size of the second stage. The main reason they did not even suggest it was the lack of engine data on those propellant combinations and the fact that LH2/LOX data was readily available. The one company that actually suggested and did the work on an LH2/LOX "cheap" LV (https://en.wikipedia.org/wiki/Aquarius_(rocket)) was found to be less competitive even with some really low expectations of successful launches than other designs using less energetic propellants.

This was an issue with most LH2/LOX SSTO ideas, and it took a long time to come to terms with the idea that in some cases less IS actually more :)

All very true. I went with LH2 because it was the most expensive fuel and thus the most favorable comparison for an orion.

fasquardon
 
Maybe. Truax made his share of charitable assumptions.

Like any rocket designer ever :)


If I were going to do Sea Dragon I'd have an island or coastal launch complex with all the heavy industry and a pipeline out to the launch area.

Ehm, you launch these thing from DEEP water because they cause a huge wave when they launch. If your "launch area" is within range of a pipeline you end up replacing most of it after every launch.

The whole idea of fueling Sea Dragon using an aircraft carrier really was daft.

Well, yes and no. The Navy (or DoD, or AEC actually) wouldn't have allowed it but you weren't going to get enough electricity in the middle of nowhere without a nuke. On the other hand a self propelled "Nuclear Power Plant Island" might be both more feasible and pragmatic than trying to convert an aircraft carrier:
http://www.oecd-nea.org/ndd/workshops/innovtech/presentations/documents/ii-2-golay.pdf
http://www.osti.gov/scitech/biblio/5010637

All very true. I went with LH2 because it was the most expensive fuel and thus the most favorable comparison for an orion.

Well truly you'd be more comparative it you went with LH2 and FLOX for both expense AND hazards :)

Randy
 
Hah!

Would the pulse units really be that hazardous?

fasquardon

No, not really but I have actually seen ranting internet postings from people who believe that fluorine is far LESS toxic than any kind of radiation :)

Really it was more a suggestion to add to the cost of propellant. However I suspect that like anything else mass production of pulse units would lower costs.

Of course "selling" the idea of mass producing nuclear weapons... :)

Randy
 
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