Is it even possible to build a sci-fi-esque reusable space ship

If the EmDrive is true, maybe.

If the EmDrive is BS, definitely not.

I think it's certainly possible. The only real obstacle is Delta-V, and that could be improved drastically with more efficient engines (which are at least theoretically possible with current technology). Even an Orion drive might be able to do it, if you could somehow find a place that you'd be allowed to take off from.

>>7646770
>proven physics
yes

>near term technology
how far is fusion? you tell me


It's all about energy&power density f a m.

>>7646805
>How far is fusion? you tell me

Not sure what you mean, I think fusion as a power source is usually believed to be 30 years away (isn't everything) but even then a facility that produces power via fusion would be way too damn big/heavy to incorporate into any sort of spacecraft. Fission, like the kind used in subs might be a better option.

>>7646804
remember the VentureStar from the 90s? The main problem with that was the fuel tank, which can now be built using modern composites; but that is irrelevant since the program was cancelled.

>>7646770
>randomly adding a yank flag next to ours for no reason
Kek.

>>7646770
If the emdrive works
definitely

If Dark Matter can be condensed and used in 20 mg capacity you can make the journey from earth to mars in 30 days in and 30 days back...

>>7646821
>VentureStar

My nigga.

I will always hate Lockheed Marting for fucking up.

Why did they fixate on composite tanks?
Jesus fucking Christ. We could have an SSTO 15 years already.

>>7646826
>for no reason
assuming your people ever get this nonsense to work, you know good and well that your gov will never truly invest more than a handfull of shekels; may as well just remove the brit flag altogether

>>7646816
Fusion has been 20 years away since 1956.

>>7646831
even if emdrive works the delta-v is pathetic, it won't leave Earth just nudge it in space

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>>7646835
>Why did they fixate on composite tanks?
They didn't, I thought at the time they were trying to build the tank out of aluminum.

>>7646836
They're already working with Airbus. Sorry lad, it's ours. Cry louder, that should help your cause.

>>7646849
Good luck with that.

>>7646848
I read that one of the main reasons that the program failed was that management was pushing for composite tanks. Very aggressively.

It was certainly the composite tank failures that cancelled the program.

Aluminum would be good enough, especially for the prototype.
If a prototype ever flew, the program wouldn't be cancelled.
But it did, and now how can you convince someone to revive it in 2015?

Skylon isn't really going to be tested in hypersonic conditions anytime soon and all the new scramjets are developed for fancy cruise missiles, not space access.
RIP SSTOs, I wanted to see you fly in my lifetime but I guess that's not happenning.

>>7646816
Fission has a really shitty power to weight ratio.
It's barely good enough to fly a plane, but not a rocket or SSTO.

I mean, yeah, Project Orion would work, but that's kind of pushing it.

Fusion will be fat and stupid at first, but without gamma rays or fallout it'll be a good power source.

>>7646831
You don't need Emdrive for 60 day round trips to mars. Existing ion and plasma engine designs can do the job without having to rest all our hopes on something that may or may not even work.

>>7646835
Venture Star is only one of many SSTO projects to be fucked up. I'm still irked that the DC-X team never got the support they needed.

>>7646842
The delta-V is infinite (assuming you have unlimited power). What it lacks is thrust.

>>7646770
I can't get behind the whole one vehicle thing.

Your best bet: A shuttle with SABRE engines on the wings and a methane rocket at the aft and on the bottom to launch from Mars.

Dock the shuttles with a mothership in orbit that uses fission powered ion engines for a faster round trip.

>>7646816
Fission's a problem for taking off from Earth because you have to contain the exhaust. It also suffers from issues of minimum scale. A conventional solid-core nuclear thermal rocket isn't a lot better than a chemical rocket, particularly for taking off from the Earth's surface (due to impulse density and thrust-to-weight ratio).

Fusion can, in principle, scale down without limit and have non-radioactive products. He3-He3 or proton-boron fusion should be pretty much completely clean, while the tritium pollution from a D-T or D-D fusion rocket should be of somewhat less concern than fission fragments and transuranics (we should expect radioactive hydrogen to disperse itself fairly quickly in the environment and be diluted effectively into the tremendous mass of water, with no tendency to be concentrated in living things), although it wouldn't be clever to launch such a rocket from cities.

>>7646770
>Is it even possible to build a sci-fi-esque reusable space ship that can take off from Earth, fly to another planet, then take off again and return to Earth in one piece
The better question than "can we?" is "should we?". Reusable staged chemical rockets and propellant production from space resources are going to be a lot more straightforward to engineer, and probably cheaper to build and use, than sci-fi superships.

The same coal-fired steam that powered the industrial revolution remains the cheapest source of mechanical power for electrical generation, despite the invention of nuclear technology which needs a millionth as much fuel. Chemical rockets might remain our best option for lifting off from planets indefinitely after the invention of fusion rockets.

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I think the limiting factor is the energy density of the fuel. Modern rockets are constrained because they need to carry a lot of fuel. For efficiency, they shed external tanks as they climb. This means that the vehicle gets much smaller between each stage of the journey. Unless the ship was able to refuel mid journey, modern rockets would be insufficient for a journey to another planet and back.

The likely solution is antimatter fuel. Antimatter is about 10 orders of magnitude more energy dense as anything on this chart. Thats 10^10x more. A lot.

>>7646892
No no you misunderstood.

20mg of Dark Matter being used as fuel for a rocket can take us to mars and back.

Not the emdrive.

>using only proven physics, and near term technology?
>>7646924
>anti matter he says
>>7646928
> then dark matter

fuck exotic matter, this thread is for pleb-matter only.

>>7646928
The idea proposed at conferences now is quite simple.

Get hot fusion to efficiency.
Make dark matter containers smaller.
Use hot fusion to power the creation of dark matter.
Create way of exploiting dark matter and drawing power.

>>7646928
That's science fiction. No one is sure what dark matter is really made of. There are a few competing theories, but nothing concrete.

>>7646877
Actually the Thrust-to-weight ratio issues of Fission Rocket engines are overstated. While its true that the early NERVA models had ratios below 1, they improved the mass flow in later designs which allowed for better performance. It would still on the low side, but the superior specific impulse could make it a worthwhile choice.

Also I think its worth pointing out that Gas Core Reactor designs would have decent thrust to weight ratios if we could build the fucking things. Dealing with Gaseous Uranium at 25000 Degrees is always a fun engineering exercise.

>>7646868
Maybe they were trying to save weight? Anyway, the composites were impossible at the time, but can be done now.

Hell I don't know if a program can be brought back from the dead, but I doubt it. It's hard enough to convince the gov to pay attention what it does now since it is unrelated to war, abortion or drug legalization.

>>7646892
>existing engine designs
>60 day round trip to mars
lol no

>>7646935
Antimatter is near term technology. We've produced it (https://en.wikipedia.org/wiki/Antimatter#Artificial_production), there are cost estimates on manufacturing it ($250 mill for 10 miligrams), and NASA has written articles about using it for spacecraft fuel (http://science.nasa.gov/science-news/science-at-nasa/1999/prop12apr99_1/). Its hardly exotic matter at this point.

If there was a viable alternative, I would consider it. But nuclear, while energy dense, is too slow decaying to be used as rocket fuel and other conventional sources don't add up.

>>7646907
Why not just used fuel cells or RTG to power the ion engine?

>>7646946
I don't think any fission rockets in any form are a wise choice.

>>7646770
Wow, that's a really tall order. Even the idea of a single-stage reusable Earth-orbit-Earth craft is pushing the bounds of plausibility.

Orion nuclear pulse could get you from Earth to orbit to Mars, but no way you're *landing* on Earth with an Orion drive.

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>>7646957
>Antimatter is near term technology

We have produced it yes. We haven't produced enough to use for fuel, and it cost so damn much it wouldn't be worthwhile even if we could. Forget antimatter, that's Star Trek stuff.

nuclear pulse propulsion could do it easily
Chemical engines run into physical issues of fuel efficiency.

You are talking single stage to mars and back, that'll never happen on chemical engines.

>>7646877
>Fission has a really shitty power to weight ratio.
Still 1000 times better than any chemical fuel engine

>>7646957
The problem with antimatter is that you'd need like hundreds of gigawatts to make even a gram a day.

>>7646958
>Why not just used fuel cells or RTG to power the ion engine?
Low energy density.

>>7646958
>I don't think any fission rockets in any form are a wise choice.
Well, if you really need to do manned travel to another planet they're pretty much the only plausible choice, and will remain so for another 50+ years at least. At least for orbit-to-orbit no one's really going to be bothered by the radiation.

>>7646966
This/

>>7646939
my bad.
Antimatter.
Didn't realize they were different.

>>7646966
That's fine - we only need enough antimatter to bring us to the Mars and back, a few micrograms. Logically, that's the same amount of energy in the rocket fuel we were going to use. We're just condensing that energy into something lighter and easier to lift.

>>7646962
Say what you will about antimatter, but energy density IS the limiting factor in any rockets that wants to land on multiple planets. Any design will need to address the weight problem.

>>7646958
I disagree on them not being a wise choice. There is a reason many of NASA's design reference missions use them. Solid Core Nuclear rockets are a technology we've had since the 60s that provide a rocket with decent thrust and specific impulse.

>>7646961
>but no way you're *landing* on Earth with an Orion drive.
How no?
You just fire in reverse with the nukes, and there could be strap on rockets for the final deceleration.

But it would be rather pointless to land a project orion vessel, better to build it to be deconstructed & turned into useful habitats.

>>7646977
I address the weight problem by limiting the number of fuel rods in my fission core to the min. needed, and by using light-weight shielding for the radiation.

>>7646984
>You just fire in reverse with the nukes
>Why would this be a bad idea?

>>7646984
Why irradiate one planet, when you can irradiate two for the same price amirite?

>>7646985
Nuclear power is too slow decaying, man. You cant lift a rocket with a rock of uranium.

>>7646991
>>7646990
sometimes sacrifices must be made

>>7646985
Even with 100% enriched fuel, you'd still have 1/10 the energy/mass of fusion or 1/1000 the energy density of matter/antimatter.

>>7646990
fission power source > atomic rocket

>>7646992
>decaying
>what is fission

>>7646992
Use a different system for lifting into orbit, the nuclear power is used for transit BETWEEN planets, not take off from either.

>>7646998
There'd still be a radiation issue though. Not as bad as an Orion drive, but it's still not feasible to fully shield an atomic rocket core. You could put a shield in front of the reactor to protect the crew, but that wouldn't help the people on the ground.

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>>7646993
>sometimes sacrifices must be made
kek

>>7647003
Lifting into orbit is the bulk of the problem, though. We've launched rockets that have orbited nearly every planet in the solar system - cross system travel is cheap. Landing and liftoff is expensive.

>>7647004
You couldn't block all of the radiation, but then you don't really have to.

Plenty of people work and live around reactors that are larger and produce more radiation than the power source in such a craft would. Your bigger problem would be micrometeorite impacts and protection from the radiation that is already in space.

>>7647014
Those reactors you're talking about are shielded. Research and power plant reactors don't need to worry about weight so they can afford all the shielding you need. You can stand right next to one and get less radiation than you would from standing out in the sun.

>big mothership enters geostationary around mars and never de-orbits
>deploys small craft to land on mars
>once expedition is done, use balloon to lift small craft to near-orbit
>mothership lowers down cables with wenches and pulls small craft up into geostationary orbit
>exit back to earth

>>7647018
you need lighter shielding

>>7646978
>Solid Core Nuclear rockets are a technology we've had since the 60s that provide a rocket with decent thrust and specific impulse.
Solid core fission rockets offer a large expense and serious risk in return for a modest improvement in upper stage performance.

While they've got good specific impulse, they need very low-density all-liquid-hydrogen propellant (most of the propellant mass of hydrogen-fueled chemical rockets is dense liquid oxygen, so the overall density is several times better) to achieve it, and the thrust-to-weight ratio is much poorer than chemical rocket engines.

This mean a high empty weight, which makes the specific impulse less of an advantage than it seems. A planned nuclear upper stage for Saturn V would only have about doubled the performance, and developing a reusable nuclear stage would be a whole other can of worms.

Nuclear thermal rockets might be a very good option for ISRU (easier to find and purify some fluid you can put in a tank and boil than produce balanced amounts of fuel and oxidizer), but they're not much help for getting off Earth.

Can anyone describe to me what an anti-matter rocket even looks like? Do you combine it with regular matter and it just makes an explosion that you hope you can control and direct to produce thrust?

Or are you guys just going 'muh energy density'?

>>7647021
>>7646907
same thing?

>>7647025
Isn't the effectiveness of shielding largely based on mass?

>>7647028
Most likely you'd use some kind of magnetic fields to control and direct the reaction without it coming into contact with matter.

>>7647004
Isn't it only with those gas core nuclear rockets that have an issue of making all the propellant radioactive?

>>7647028
Assuming you had infinite money to build such a contraption:
It looks like a regular rocket with tanks for Hydrogen and um, anti-Hydrogen. The anti-Hydrogen is stored in a tank with a strong magnetic field to prevent the rocket from looking like a big tube that explodes and kills everyone.

>>7647030
Is it possible to Orion Drive AND use VASMIR at the same time?

Or Orion Drive once the rocket leaves earths half way to mars point and robots to mine so as to avoid radiation?

>>7647035
>Isn't the effectiveness of shielding largely based on mass?

Not entirely, but even if you focus just on the mass it's also still relative. H2O works well, and would actually be better than lead.

>>7647028
>it just makes an explosion that you hope you can control and direct to produce thrust
It reacts and annihilates. There's a spray of charged particles, gamma rays, and a fair amount of the energy escapes as neutrinos. I wouldn't be inclined to call it an "explosion" unless you were doing it in pulses. It could just be the intersection of two particle beams.

As long as it happened on one side of a barrier, there would be thrust.

>>7647038
Even without making the propellant radioactive, a reactor core still emits radiation.

>>7647028
Yep, very similar to the way conventional rockets combine rocket fuel and oxygen to make explosions they hope to control. The main difference is conventional rockets require the fuel to be dumped behind them (so they obey the Tsiolkovsky Rocket Equation) whereas antimatter rockets don't. (Well they do, but to a much less relevant degree)

>>7647051
That was the most concise explanation I have heard in a while.
Thank fuck we have you here.
Also. We need this baby up and running soon. So we can spend on energy like it was nothing.

http://www.dailymail.co.uk/sciencetech/article-3290389/Stellarator-reactor-turned-time-Strange-twisted-design-finally-make-fusion-power-reality-say-scientists.html

>>7647044
unfortunately I think the only way this ship could even take off is with the reverse-- orion to leave earth, vasmir en route and orion will cause fallout, vasmir is efficient but lacks thrust

>>7647059
Wait, are you saying that antimatter rockets wouldn't have to obey the rocket equation?

>>7646770
>Skylon
>American flag

>>7647072
The rocket equation dominates the motion of conventional rockets because of huge amount of fuel they dump. The amount of fuel used by an antimatter rocket would be small enough that the rocket equation is much less relevant.

>>7647072
I think he means to say they would, but it wouldn't matter. The specific impulse would be so high, the reaction so energetic, and the propellant so costly, that the limiting factor would always be something other than how much fuel you can carry.

>>7647069
Then what about a triple system? and parachute / glide back down?

>>7647072
There is a special version of the rocket equation used for Antimatter rockets.

>>7647068
So the only thing that makes this thing different from a tokamak is that the plasma is twisted?

>>7647074
Sabre engines are a shinning example of American engineering. God bless the best nation on Earth.

>>7647084
Conventional Rocket
VASIMIR
parachute

return mission?

>>7647085
Isn't that just a shortcut? They still obey the same basic rules regarding exhaust velocity and mass ratio, right? (apart from the fact that the delta-v would need to take relativity into account)

>>7646770
>Is it even possible to build a sci-fi-esque reusable space ship that can take off from Earth, fly to another planet, then take off again and return to Earth in one piece using only proven physics, and near term technology?
Do you get to refuel it on the other planet?

I'm sure it's possible using multiple reusable stages... you might even get a practical system out of it. Doing it with a single stage would sacrifice virtually all payload and utility, if it's even possible at all. It would definitely be a major feat of structural design and engineering to build an SSTO with a high-enough mass ratio for interplanetary missions, including the TPS for aerocapture/reentry.

>>7647086
Tokamaks depend on a current in the plasma to increase confinement, while stellarators confine the plasma entirely with the external magnetic field. This is less efficient, but also less tricky.

>>7647084
>Then what about a triple system?

Like SABRE, VASMIR, and Orion systems combined in one craft?
I think it could work but I would just get rid of Orion. As for parachutes/wings I guess what's best depends on where you want to land and how much you weigh. I've never seen Skylon depicted without wings but I don't know enough to comment on why this is.

>>7647098
Do you get to refuel it on the other planet?

Of course. Every sci-fi planet has a fuel station where you can resupply while awaiting your next mission.

>>7647107
Why get rid of Orion?
ok wait I have an Idea.
List the fuel types used by each system please.
And what engine system would dark matter use?

SABRE = ?
VASMIR= ?
ORION= ?
X = Dark Matter

>>7647086
Pretty much. It works out much more efficiently mathematically. It has to do with the way the magnetic fields interact to deter confinement.

>>7647021
>mothership lowers down cables with wenches
Well that's not very practical, but I'm not complaining.

>>7647092
Its not any more of a shortcut than the regular rocket equation is.It's just a more complex equation, because, as you mentioned, you need to account for relativity.

>>7647117
But keep in mind the mothership is still moving, as is the planet....

>>7647086
Yes...before you won't believe how they managed to fuck up the manual adjustments of the electromagnets keeping the plasma in line....

Hellishly inefficient... But with 3d printing...
things got a whole lot fucking easier...

>>7647124
geostationary orbit, my friend

>>7647138
I'll start climbing.

But seriously, space elevators are interesting, may start another thread for them.

>>7646948
>>7646821
>Reusable cryogenic composites are viable now
Ehhhhhhh.... there has definitely been a ton of progress in the area but I'm not convinced it's mature enough to be used in a reusable system yet. Making a fiber-reinforced plastic that remains tough and resilient at cryogenic temperatures is one thing; making one that can hold up to repeated thermal swings of such enormous magnitude is a different matter. Thus far, it sounds to me like their main approach to withstanding micro-cracking that occurs as a result of thermal cycling has been simply to use layup patterns that obstruct fracture propagation through the matrix, but that will only get you so far. For a reusable system I really feel they need to find a better matrix than what's currently available (something with low thermal expansion, no phase changes throughout the temperature range, and of course an acceptable toughness at cryogenic temperatures).

>>7647144
Are you saying that the mothership with cables idea is equivalent to a mobile space elevator? Interesting....

>>7647171
wow that is crazy

>>7647163
High-density-impulse room-temperature fuels (like H2O2/RP-1 or NTO/UDMH) might be better for a reusable SSTO than high-specific-impulse fuels (like O2/H2) anyway.

Higher density impulse gives you better thrust-to-weight-ratio engines and smaller fuel tanks, while room-temperature fuels give us more material options and keep the materials within circumstances we have reliable data on.

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>>7646770
How do you intend to land?

>>7646912
Oh hi Elon, I didn't know that you posted on 4chan, how's work?

>>7647237
will the second stage be reusable too?

>>7647193
I actually agree with you, but ours is a minority opinion. Nearly all SSTO research has focused on LH2-based fuels. Dense fuels demand a far higher mass ratio, but this is easier to achieve than with LH2 since the fuels aren't as cold and are so much more dense (thus allowing the tanks to be built much smaller and lighter, without insulation). On top of that, the thermal stresses on the fuel tanks are a non-issue with room-temperature fuels, so reusable composite tanks are easily viable already. SSTO has been possible with dense fuels ever since Atlas, but the only practical appeal of SSTO is reusability, which was never an option with Atlas.

But to be perfectly honest, I'm really not a big proponent of SSTO in the first place. I think a reusable 2-stage system or semi-reusable 3-4 stage system is far more practical and offers better performance.

Also
>H2O2/RP-1
Except as a comparatively safe monopropellant, I personally don't see much reason to ever use peroxide over either N2O or N2O4.

>>7647269
I've seen some rocket designs that use CH4 as a fuel.

>>7646816
Lockheed Martin Compact Fusion Reactor ready for off the shelf ca. 2019 - alegedly.

>>7647290
That reactor is a meme.

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>>7647290
Yep, seems plausible to me.

>>7646912
good post

>The better question than "can we?" is "should we?".
should be obvious but for some reason it is not to most people

>>7647277
Yeah, LNG yields a bit better specific impulse but a bit less density than RP-1, but I don't see a whole lot of net advantage or disadvantage either way against RP-1. If you want to see real, decisive performance gains from the fuel/reducer side, you're going to have to get a bit more exotic, like methylacetylene or something.

>>7647269
>>H2O2/RP-1
>Except as a comparatively safe monopropellant, I personally don't see much reason to ever use peroxide over either N2O or N2O4.
H2O2/RP-1 has better density impulse. H2O2 is an excellent engine coolant and its catalytic decomposition is ideally suited to driving a turbopump in a quasi-hypergolic staged-combustion cycle, while RP-1 offers good lubricity (which can be further improved on if needed), works well as a hydraulic fluid, and can also serve as a regenerative coolant or carbonizing curtain coolant.

They are also both cheap and relatively non-toxic (you could dip your hand in a barrel of pure H2O2 and breathe the air over it without protective equipment, and while this wouldn't be pleasant, you could wash off with water, go to the hospital, and would probably recover with no permanent harm).

You have to keep surfaces that come in contact with H2O2 scrupulously clean, but that's true for pretty much any oxidizer.

Most of the objections to H2O2 you might be familiar with (from "Ignition!" for instance) are based on trying to make it into a storable missile propellant, where its tendency to degrade over time, with evolution of gas, made it unsuitable.

>>7647325
When I read about LNG I think the proposed advantage was automated fuel production or recycling maybe?

>>7647354
>>7647325
Methane/oxygen is a nice combination for some unexciting practical reasons.

They're both liquid at the same temperature, and boil at near each others' temperatures, so they can be stored together with insulation between them. The optimal mixture ratio requires roughly equal volumes of fuel and oxidizer. This makes for a lot of potential symmetry in designs, which saves design effort and money.

They can each be boiled to pressurize their own tanks, they can each be partially combusted and boiled to power a turbopump.

A reusable vehicle that has experienced a failure and wants to come in for a landing can do an emergency dump of both propellants without worrying about any of it falling to the surface and causing fires.

This is also the cheapest propellant combination around, and offers the best specific impulse short of hydrogen. The density isn't terrible either.

Methane makes an excellent, non-coking regenerative coolant.

Where kerosene's safety comes from being hard to ignite, methane's comes from evaporating and dispersing rapidly in the wind. Methane is VERY easy to ignite with oxygen, so the ignition systems don't have to be anything elaborate or requiring special consumables. Spark ignition would be adequate, acoustic ignition is possible.

It's a very good combination for reusable launch vehicles.

>>7647423
>>7647354
Oh, and methane and oxygen are some of the simpler things to synthesize on Mars, the moon, or on volatile-rich asteroids.

>>7646805
We'd need more than fusion, matter anti-matter interactions would do the trick though

>>7647538
Controlled matter/antimatter collisions on a practical scale are probably more than a century away st best. You'll be a senior citizen by the time you even see fusion on a level that it can be used to power some cities, let alone as spacecraft propulsion. Nether is anywhere near 'near term'.

>>7646795
This better fucKung be bait

>>7646804
An orion drive could land and return to orbit a thousand times with no problem but maybe heat shielding, with fusion orion drives you can go past 10 percent the speed of light with a huge payload.

>>7649043
Orion has serious problems with lift-off and touchdown. The solutions were pretty much handwaved. It was always more of a physicist's vision than an engineer's design. The "Yeah, we can do that." they gave has the same quality as a similar sentiment toward fusion power: it was based on no experience and did not account for important details.

If you want to go for dirty fission propulsion, the nuclear saltwater rocket is probably a more realistic design.

>>7649089
?
Fusion has serious practical and material limitations, with handwaving about "muh magnetics" to pretend things are doable.
There are no such issues with project orion.

>>7649110
>There are no such issues with project orion.
How the flying fuck would you know if there were?

Saying that Project Orion would be easy to make work is based on the same sort of handwaving as saying that fusion would be easy to make work.

"Well, this obviously can't take off directly from the ground, but we'll work something out, maybe with a huge pile of high explosives."

"Well, in our model, the explosion comes out of our nuclear shaped charge as a neat, regular cone every time, so the plate gets a nice smooth push with no hot spots or hard debris, at every altitude and air pressure from the ground to space. Surely this is what would happen in reality, although we've never done any experiments with it."

"It would take more bombs to get to orbit than have been set off in the history of nuclear testing, which has involved many fizzles and surprises, but surely these ones would all work perfectly."

Project Orion is still half-baked as fuck. If they had fully funded it from the 60s to now, with carte blanche to spray unlimited plutonium and fission fragments into the air, they might still not have a working vehicle.

>>7649089
The problems with lift off are severely overrated. In addition, these problems weren't exactly hand waved away. A lot of research has been done on the effects of air bursts of nuclear weapons including numerous tests,The engineers on the project were well aware of the results of these tests. For an Orion drive almost all of the detonations will be at high altitude. Air bursting nuclear weapons produce very little fallout and don't have much of an impact to people on the ground. During the 50s when people gave less fucks, the USAF actually had people stand around while they live fired air to air nuclear missiles 60,000ft above them. As long as you don't look directly at the flash of the bombs you're fine. The only real launch concern is EMP, and even this is overstated. Its been awhile since I read up on Orion so I forget the specifics, but they figured that the EMP effects can be reduced via launching in remote areas and plotting your trajectory to go through certain latitudes where the earth's EM fields won't cause it to travel as far.

You are correct about the landing however. Once you've done your deorbit burn and are in the atmosphere you're going to be descending through a nuclear fireball.

As for NSWR, a NSWR is functionally, a continually detonating Orion drive. Almost all of the launch and landing concerns of Orion are shared by NSWRs with the added concern that any fuel that leaks from your tanks while cruising will clump together, reach critical mass and result in a nuclear explosion.

>>7647423
>A reusable vehicle that has experienced a failure and wants to come in for a landing can do an emergency dump of both propellants without worrying about any of it falling to the surface and causing fires.
Not necessarily. If it's liquid, it may fall a considerable ways before it completely boils away. Especially if it's subcooled; as LNG would be when in direct thermal contact with LOX as you're suggesting.
>and offers the best specific impulse short of hydrogen.
No, there are several reductants that outperform methane. None as cheap and safe as methane, though.
>non-coking
Yes, methane is very good in that regard.
>methane's comes from evaporating and dispersing rapidly in the wind.
Even without wind, methane only ignites in air at between 4 and 17% concentration, as opposed to 4 to 75% concentration with hydrogen.
>>7647427
Yes, but it's not that hard to synthesize heavier hydrocarbons in turn from methane.

>>7649169
>As for NSWR, a NSWR is functionally, a continually detonating Orion drive.
Oh, fuck off. There's no detonation involved. There's no crazy shock absorber needed. The scale can be much smaller. If you think they're the same, you're nuts.

>Almost all of the launch and landing concerns of Orion are shared by NSWRs
Uh... no. NSWRs are like other rockets. They produce a steady thrust out of their nozzle. You can land with them the same as you'd land with chemical rockets.

Orion uses nuclear bombs to provide fixed increments of thrust. If you use them close to the ground, they blast the ground and the shrapnel shreds your pusher plate. There's no way to touch down gently, you just reach minimum altitude and fall, and no way to take off with your pusher plate on the ground.

The plan for lift-off was to build them on a foundation of high explosive, and set it off so perfectly and smoothly that it would push it into the air without doing any damage, so the first nuke could be set off above minimum altitude. Seriously, this was the best idea they come up with for launching them.

>with the added concern that any fuel that leaks from your tanks while cruising will clump together, reach critical mass and result in a nuclear explosion.
...as opposed to the perfect safety of accelerating a load of thousands of nuclear bombs by pushing them with thousands of nuclear explosions.

>>7649195

Why wouldn't you just build it in orbit, and use a normal rocket to come and go from it?

>>7649173
>If it's liquid, it may fall a considerable ways before it completely boils away.
Nah, if you dump LNG into the air while you're flying it won't get far. You'd need to be very low to the ground for there to be potential for it to hit the ground, especially if it's burning. Even if it did, it wouldn't pool and burn there.

>there are several reductants that outperform methane.
With oxygen? In practice, not just in theory? Can you give an example?

>it's not that hard to synthesize heavier hydrocarbons in turn from methane.
"Not that hard", but still much harder.

If you can get water, you can separate it into hydrogen and oxygen by electrolysis or thermal chemical processes (such as the iron oxide cycle). If you have hydrocarbons or ammonia, you can cook off the hydrogen by simply heating them until they separate. If you have hydrogen and any kind of more complex hydrocarbon or carbon, you can burn them with an excess of hydrogen and what you get is methane.

Methane's the product least sensitive to reaction conditions. If you want to make some other hydrocarbon, you'll be fighting to prevent methane from being produced.

>>7649203
>Why wouldn't you just build it in orbit
Project Orion ships would be huge. Totally impractical to lift into orbit with chemical rockets. And if you don't need the thrust to take off from a planet, there are much simpler, saner ways to get high specific impulse with nuclear power.

>>7649169
Project Orion was just a fun idea. You don't need it for interplanetary travel, and there are better methods for interstellar travel.

Amazing that anyone would even dream of taking it seriously.

>>7649258
Yeah this is exactly why so many of the proposals called for In-orbit assembly using what would become the Saturn Vs

With nuclear pulse propulsion, absolutely yes.

With advanced nuclear thermal definitely maybe.

If superconducting memedrive works, maximum Jetsons.

>>7647423
>Acoustic ignition
care to elaborate? Never heard of that before

>>7649195
>The plan for lift-off was to build them on a foundation of high explosive, and set it off so perfectly and smoothly that it would push it into the air without doing any damage, so the first nuke could be set off above minimum altitude. Seriously, this was the best idea they come up with for launching them.

The plan was to boost the whole thing into the upper atmosphere with a bunch of conventional rockets, or simply to build the thing in orbit, but if you already have enough conventional rockets powerful enough and cheap enough to do that...

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With dense plasma focus fusion propulsion, we could just say "fuck you" to aerodynamics and weight constraints.

>>7649169
>Once you've done your deorbit burn and are in the atmosphere you're going to be descending through a nuclear fireball.

The folks who designed Orion knew this wouldn't work. The only way you could land was simply detach the module from the main drive and land it on the surface (or position your orbiter into geostationary orbit, etc).

This caused another problem for Orion designers, how does a ship slow its velocity down without subjecting the ship and its crew to harmful ionizing radiation?

Did they ever address this before the project was canceled?

>>7649195
>and no way to take off with your pusher plate on the ground

The pusher plate would have been extremely heavy. It needed to be heavy and robust, due to the explosions from the nuclear shaped charges.

>>7650929
>>Acoustic ignition
>care to elaborate?
Well, it's kind of like you combine the idea of a diesel engine (or fire piston, though you might not have heard of those) with a whistle.

In a diesel engine, you compress the fuel/air mixture until the pressure heats it enough to ignite. In a whistle, a gas flow generates a standing wave, a region with peaks of high pressure.

Basically, if you blow a fuel-air mixture through a whistle hard enough to make pressure comparable to that in a diesel engine, you'd get ignition. Some things are much easier to light off than a diesel-air mixture. It works with monopropellants, too.

>>7649148
Project orion is very mechanically simple
It's just
"detonate nukes behind you at a regular basis"
It would really only take a couple years to produce a trial craft. There is no magic materials or technologies needed in producing it.
Things like controlled fusion require new technologies, new materials, and completely new designs.

>>7651561
>Project orion is very mechanically simple
>It's just
>"detonate nukes behind you at a regular basis"

Fusion power is very mechanically simple
It's just
"trap hot plasma with magnets"

>>7651570
....at least Orion doesn't have to worry about having a magnetic internal confinement system, or any of that fancy refrigeration shit to keep operating temps at a minimum.

At least Orion is a robust vehicle.

Can't say the same for the NIF, or the LHC, etc

>>7649169
>Once you've done your deorbit burn and are in the atmosphere you're going to be descending through a nuclear fireball.
As far as I understand, the fireball disperses fast enough that this isn't a real problem.
The amount of air you will be pushing aside since you are a flat brick traveling mach 20 should protect the vehicle itself.

Sure for final deceleration you'll need rockets or something else.

>>7651589
I'm sure there would be no surprises if we actually tried to get to orbit by riding the blasts of thousands of nuclear bombs.

It would go exactly as planned out on cocktail napkins by drunk 1950s physicists.

>>7651607
It is mechanically, very simple
Rockets have a lot of small parts, and are fairly complicated, anything goes wrong and the thing blows up.

>>7651471
Just surrounding the crew in tons of water, is sufficient shielding, you can do that when you have weight to spare.

>>7646965
For fission you have to carry a whole shit ton of metal together with the fuel, unless you're talking about blowing up a bomb behind you every now and then to push you forward.

>>7651611
...as opposed to a nuclear pogo stick that has to prime and launch hundreds of nukes in a few minutes, and take all of those blasts on a pusher plate with giant shock-absorbers, recoating it with oil between blasts to protect it.

>mechanically, very simple

>>7651627
Springs or hydrolics are mechanically, very simple
Sprinklers are mechanically, very simple

>>7651633
Sure, and pumps and combustion chambers are also "mechanically very simple".

>>7651607

Fermi introduced a famous paradox on a paper napkin.

Of course he wasn't drunk... Unlike some of his other, we'll known buddies.

>tfw teh Trinity Device was built with brains, balls, booze and betting

>>7651636
Rockets have a lot of fine details, lotta things to go wrong, materials pushed close to their breaking points, etc

>>7651686
>Rockets have a lot of fine details
...but a nuclear pogo stick would be exactly as simple to implement as it appears in a conceptual sketch?

>>7651724
It is an inherently stable, simple system

>>7651738
>>7651686
This is great deadpan.

>>7651738
Are you just going to keep asserting that a scheme to launch into space by riding hundreds of external nuclear detonations is "simple"?

Nobody ever got close to trying it, so nobody knows what kind of difficulties the actual implementation would involve.

As far as they got was a sketch of the idea, like a drawing of a rocket as two tanks with hoses to a box and a hole in the box, that fire comes out of.

Before people started actually making liquid-fueled rockets, they didn't know what was going to make it hard. The same is true of fusion.

The pusher plate has to take a thousand nuclear bomb blasts just to get to orbit. You're ready to just assume that this is a non-issue compared to running a liquid-fueled rocket engine?

>>7649242
>With oxygen? In practice, not just in theory? Can you give an example?
How about Syntin?
And LNG/LOX is still "in theory," it's a bit of a double-standard to ignore other options simply because they haven't been used yet.

>>7651804
They did a model with chemical explosives to show the idea is sound
They placed metal objects next to nuclear explosions to survive it without much ablation

>>7651845
>Syntin
That gets higher specific impulse than RP-1, but not higher than methane.

>LNG/LOX is still "in theory,"
Maybe it hasn't been used on a launch vehicle, but it has certainly been used on rocket engines and vehicles, such as the Project Morpheus lander.

>it's a bit of a double-standard to ignore other options simply because they haven't been used yet.
That's not what I mean. I mean that exotic fuels have been predicted to have high specific impulse, but when they build a test-stand engine, the performance isn't actually there. Like, the chemical reactions they expect aren't the ones that happen in a real combustion chamber.

>>7651881
>They did a model with chemical explosives to show the idea is sound
A bit like claiming a fireworks rocket is a proof of concept for Saturn V.

>They placed metal objects next to nuclear explosions to survive it without much ablation.
That's a long way from showing that a large plate can take hundreds of blasts.

>>7651896
>the chemical reactions they expect aren't the ones that happen in a real combustion chamber.
Another thing is that the theoretical specific impulse might be high, but a more efficient rocket engine can't be achieved because the fuel is unstable and unsuitable for regenerative cooling or high-pressure turbopumping. Performance suffers from low combustion-chamber pressure or heavy ablative cooling.

>>7651804
They were low power bombs you doob.

>>7646770
Depends on the planet.

If you wanted to go to some planet with next to no gravity, it'd be possible, if difficult.

If you wanted to go to say, Mars, you have problems.

Even then, it might be *technically* possible, but the undertaking would be massive beyond imagining. It'd be a whole lot more efficient to use the traditional boosters and have the return vehicle delivered to the destination planet first.

There's around-the-corner technologies that might make it more feasible though. But using the cave man science we have now, does involve a lot of brute force.

>>7651976
Oh how silly of me. OF COURSE if they're low-powered nuclear bombs, that makes everything easy!

>>7646877
Fission has a really fantastic power:weight ratio, you know, if you didn't have to build a reactor around it.

Uranium has a few million times more energy than diesel fuel by weight.

>>7652061
>Uranium has a few million times more energy than diesel fuel by weight.

...Which has what to do with the power-to-weight ratio, exactly? I've never seen a reactor design that got even close to 1 kW/kg.

>>7652078
NERVA was about 100 kW/kg.

Yes.

How? Antimatter. Currently we are getting it as more or less a byproduct of CERN experiments, but if we started to invest into deliberately producing it by building a enormous 50GWh nuclear facility and assuming we reach 1% efficiency in energy to matter conversion, we can make around 150 grams of antimatter a year. It takes a few milligrams to get into LEO and 10 grams to send a large ship to Mars in a month.

Let's assume that you are building your facility in India or China or somewhere where you don't need to have as much red tape and bribes and self important locals. A 50GWh facility which would usually cost $1-1.5bn per GWh could be built for $25bn for power and $5bn for production and running costs for a total of $30bn. In ten years it would produce around 1.5 kg total of antimatter, which gives us a price of $20 million per gram. You could probably launch a rocket into LEO multiple times with a gram while completely pissing and shitting on rocket equation because your total fuel size is eight orders of magnitude lower than your payload.

If Elon Muskyballs makes his reusable rockets we can put a minimum price per kg on a Saturn V sized rocket which converted its fuel into payload (so around a thousand tons):
Fucking around with energy requirements we can say that we can probably launch two 1kt rockets with a single gram. With a mass produced reusable Saturn V clone we could get within comfortable 100m per launch cost which gets us at laughable 100$/kg.

Of course next step would be creating a 10TW production facility at lagrangian points which would produce ten grams of antimatter a day. Getting to Jupiter in three months? Not a problem m8. A real deal space hotel, only 25k per person. Future is fucking endless.

>>7652513
>antimatter
>not realizing it costs trillions upon trillions of dollars per gram
>not realizing we couldnt even make a gram of it if money were infinite, because the sun would go nova before we were even close
>thinking we can make antimatter in a nuclear reactor

Jesus man. Talk about stupid.

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>>7646770
yes, see orion drive.

>>7652519
God damnit I thought summer was over.

>not realizing it costs trillions upon trillions of dollars per gram
Yes, we aren't really in a antimatter making business, thus we only get it in very small quantities as a byproduct, thus when extrapolated to a gram it appears extremely expensive. If there was a significant need for it, we'd focus on making it and making it very efficiently. 0.1% to 1% energy to matter conversion efficiency isn't unreasonable if you ask the experts.
>not realizing we couldnt even make a gram of it if money were infinite, because the sun would go nova before we were even close
See above.
>thinking we can make antimatter in a nuclear reactor
ISBN: 978-1576854945

>Jesus man. Talk about stupid.
Totally dude, cmon it's 2015 :^)

>>7652521
How do you even get that to orbit?

>>7652521
>CocaCola
wut

>>7652538
by detonating nuclear bombs beneath the pusher plate.

>>7652545
And what happens to the fallout?

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>>7652544
It's for giving those dirty commies a taste of capitalism!

>>7652548
it falls out. There's a reason why we haven't built these things....

>>7652557
Tbh op didn't say it shouldn't kill people it leaves behind so fair game

>>7652544
The Coca Cola company was consulted for their vending machine technology.

Project Orion predates variable-yield tactical nukes (where the yield is controlled with the amount of tritium injected into the hollow core before detonation).

The nukes have to be tailored to the air pressure and air speed to avoid blasting the plate, and nukes don't always go off properly. If one was a dud and they missed a pulse on the way to space, instead of bringing out the next in sequence as if it had worked, they'd need to bring out one that was suitable for the recovery, so they couldn't simply feed them in order.

Hence, vending machines and Coca Cola.