 The Stars are not Far, Mars Mission 2071. |
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 Nov 10 2006, 12:06 AM
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#126
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Prime Runner  Group: Banned Posts: 3,732 Joined: 1-September 05 From: Prague, Czech Republic Member No.: 7,665  |
To be fair, Demerzel assumed a temperature which his own sources gave as an example of a temperature that was orders of magnitude too cool to get meaningful power out of a fusion reaction. Even then he was getting results of approximately 2 kilograms a second getting hurled out the back. That's astronomically (pun intended) more than would actually be required at the "real" temperatures such a device would operate at, but even so it came out to 345 tonnes - which isn't orders of magnitude outside the realm of possibility. So once you account for the fact that Demerzel was deliberately picking an impractical temperature that sounded impressive, we're totally on track. -Frank |
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Nov 10 2006, 12:09 AM
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#127
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Shadow Cartographer Group: Members Posts: 3,737 Joined: 2-June 06 From: Secret Tunnels under the UK (South West) Member No.: 8,636 |
Sorry, but the objections do not fall into 1. Current Mars missions don't use these timescales or 2. It will destroy the Shadowrun universe. For the first, no one has bothered using current plans as a arguement against you as we (a) say that SR2070 has different technology and (b) accept that you've dispensed with any kind of economic sense that constrains RL missions. For the second, cannon Mars exploration is not in dispute and nor has anyone questioned that being able to send players to another planet in two days opens up new adventure possibilities. The actual objections in this thread, and I fail to see how you omitted this, are that it contradicts known physics and pushes the game from realism into Star Wars technology. And please note, before you bring it up again, that I said known physics no technology. No-one cares if you want to whizz your players to Mars and back for the sake of an adventure. You'll note that I've twice tried to offer you some helpful suggestions on making it more believable. But several of us do care if you keep insisting that it's actually realistic. If you sincerely believe this, then we're trying to help you. |
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Nov 10 2006, 12:20 AM
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#128
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Running Target Group: Members Posts: 1,206 Joined: 9-July 06 From: Fresno, CA Member No.: 8,856 |
Frank, you fail to understand the difference between Fuel used as mass inside a fusion reactor and Reaction Mass.
You still believe that my objection to the Mass required to accelerate your ship has to do with fuel consumed in the Fusion reaction. My objections don’t come close to the objections you think I have, and that alone indicates that you’re failing to grasp the basic problems you’re facing. Let me clarify my objection by exclaiming, “What’s the rush?!?” Okay having shouted that out let me try putting it another way, maybe you’ll consider an economic argument. Someone above said Nature Abhors a Vacuum. How about this, Corporations Abhor a Waste of Money. Case 1: 100,000 kg ship Burning two days at 1g. Your jet shoots at 0.01c, a tremendously fast speed, ridiculously fast in fact. You need 216,451 kg of Reaction Mass to throw behind you. This is important so I’ll repeat it: REACTION MASS NOT FUEL! REACTION MASS NOT FUEL! REACTION MASS NOT FUEL! Case 2: 100,000 kg ship (same ship) Burning 20 days at 0.01g. Same jet propulsion just throttled down for less dm/dt but still 0.01c output speed. You need 12,910 kg of Reaction Mass. You get the same distance in either case. What is more expensive, 36 days of astronaut pay, or 200,000 kg of boosting to orbit. And that’s assuming you’re taking a tiny little space shuttle sized craft. Keep in mind that when you decide on a cost per kg to boost into space 100 :nuyen: still means 20 million nuyen in extra reaction mass compared to 36 days pay. That’s more than half a million nuyen a day . . . What’s that you say? Time is money? Well any corp to stupid to be able to plan out two months doesn’t deserve the AAA status necessary to make this all feasible in the first place. NOTE: For the record the output speed for the above jet would require a plasma rocket over 100 times (two orders of magnitude hotter than the sun). |
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Nov 10 2006, 12:30 AM
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#129
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Great Dragon Group: Members Posts: 5,537 Joined: 27-August 06 From: Albuquerque NM Member No.: 9,234 |
Because getting to Mars isn't the problem with Orion (it can do that), it's getting it there TOMORROW! |
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Nov 10 2006, 12:31 AM
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#130
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Shadow Cartographer Group: Members Posts: 3,737 Joined: 2-June 06 From: Secret Tunnels under the UK (South West) Member No.: 8,636 |
*Sigh* Now we get three pages of debating economics and statements about how fusion provides inifinte cheap energy so boosting Xkg into orbit isn't a factor, guiding comets in to extract reaction mass in space without raising it from Earth and spirits using movement power to raise it all effortlessly at the cost of five mages afternoon salary. :( And all needlessly because the heat and propulsion problems were never overcome. Demerzel - Physics was enough and now it will be forgotten. :( :( :( |
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Nov 10 2006, 12:38 AM
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#131
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Running Target Group: Members Posts: 1,150 Joined: 19-December 05 From: Rhein-Ruhr Megaplex Member No.: 8,081 |
Sorry, but that must be one of the worst plans, ever. How are you even going to hit the next railgun without a margin of error (among other things)? (and of course they would drift off after the first shot) If you believe wikipedias numbers, you could boost several million tons into space with nuclear pulse propulsion for about 70 us-cent per kilogram, and some radiactive fallout, with todays technology (the fallout being one of the reasons why this isn't done). |
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Nov 10 2006, 12:41 AM
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#132
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Running Target Group: Members Posts: 1,206 Joined: 9-July 06 From: Fresno, CA Member No.: 8,856 |
Sorry, your right the physics is enough.
The thing though that there are so many problems, I just can't stop coming up with new problems to point out. The answer is simple. Take a couple months, and give up on a couple days and it's problem solved. |
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Nov 10 2006, 12:41 AM
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#133
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Shadow Cartographer Group: Members Posts: 3,737 Joined: 2-June 06 From: Secret Tunnels under the UK (South West) Member No.: 8,636 |
Hmmm. I'm worried if you didn't think I was joking. I even put a ;) at the end of it. |
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Nov 10 2006, 12:43 AM
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#134
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Running Target Group: Members Posts: 1,206 Joined: 9-July 06 From: Fresno, CA Member No.: 8,856 |
And on a side note I could teach you more about interplanetary trajectories than I could about fusion.
Interplanetary tranfer orbits is undergrad physics. If you take constant accelleration it makes it grad level. |
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Nov 10 2006, 01:20 AM
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#135
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Prime Runner Group: Banned Posts: 3,732 Joined: 1-September 05 From: Prague, Czech Republic Member No.: 7,665 |
So ridiculously fast that... a particle of Helium-3 at the base reaction temperature (100 KeV) is most probably going 2535722. m/s - 85% of that, and after the reaction it's temperature shoots up to 18.4 MeV and our He-4 going off into space at 29787994 m/s that's about 1 order of magnitude faster than you were willing to grant. That makes a much more favorable reaction mass, don't you think? BTW, we can all follow along with these equations, because there's an online calculator: http://hyperphysics.phy-astr.gsu.edu/hbase.../kintem.html#c4 So don't just let Demerzel roll you over with the fact that he can do them at all. Now that I've actually taken the time to step-by-step it, the problem with his stuff isn't that he's doing any of the math wrong. The problem is that the arbitrary inputs he's selecting are orders of magnitude slower, colder, and less impressive than an actual fusion reaction. The solar temperature, for example, is an average of fusion reactions and billions upon billions of earth sized lumps of matter which are not presently fusing - to bring the example home, this is essentially talking about your exhaust stream as if it had a temperature that was the average temperature of the actual exhaust stream, the unexploded fuel, and the shielding on your reactor. Needless to say, that's a generalization which is automatically going to short everything by a lot. With an order of magnitude more speed than Demerzel was "graciously" allowing, the equations look a lot better. So much better in fact, that this isn't even a new idea. -Frank |
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Nov 10 2006, 02:18 AM
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#136
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Target Group: Members Posts: 47 Joined: 26-February 02 From: London, England Member No.: 1,680 |
@ Knasser:
"The presence of elves doesn't mean you can dispense with realism. It means clinging to it is even more important than it was before! " So stealing this for my sig (and to hand out on little cards to stupid players). |
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Nov 10 2006, 02:46 AM
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#137
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Midnight Toker Group: Members Posts: 7,686 Joined: 4-July 04 From: Zombie Drop Bear Santa's Workshop Member No.: 6,456 |
Screw the rail guns, just use a laser sail. All you need is a giant laser canon with LOS to the craft. The advantage is that you can also use it to beam power to the surface of the earth and/or kill people that you don't like.
All kidding aside, it only takes a force 24 spirit with 32 successes on an Force 48 Astral Armor spell to withstand the void reliably. It is extremely unlikely to summon such a spirit but it is not beyond possibility. |
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Nov 10 2006, 03:11 AM
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#138
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Moving Target Group: Members Posts: 524 Joined: 12-April 06 Member No.: 8,455 |
Have a corp cut a long-term deal with a free spirit, load it up with karma "donated" by workers (or SINless).
But then, it still can't do anything in space. It could survive, but there's no mana there for it to draw in to use its powers... unless you're going to invent a rule to allow extra karma to be burned to sustain powers in a mana void (I don't think it's reasonable to allow normal quickening to do that, it just sustains the process of drawing in and using ambient mana). Now, if you think big, and take a small station with enough mana for your spirit to work with, then maybe you don't need engines at all... Frank, I understand what you're saying, but the catch is, a fusion plasma drive is very low-thrust unless you add lots of (cold) reaction mass as an afterburner--which weighs a friggin' lot--or unless you scale up the reactor so massively that it burns fuel fast enough that it has enough plasma being output that it effectively replaces the reaction mass... and that ain't in the 10GW power plant range, that's many orders of magnitude larger. To push a ship--and all the fusion fuel (which doubles as reaction mass in this case) at that speed would generate so much heat that if it *was* properly converted into electricity, it would be more juice than the planetary power grid (guessing here, I'm *not* a physics major). |
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Nov 10 2006, 03:34 AM
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#139
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Midnight Toker Group: Members Posts: 7,686 Joined: 4-July 04 From: Zombie Drop Bear Santa's Workshop Member No.: 6,456 |
Of course it can. In space, it simply gets a -12 penalty to its force. If its force is greater than 12 then it can still use its powers. |
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Nov 10 2006, 04:01 AM
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#140
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Prime Runner Group: Banned Posts: 3,732 Joined: 1-September 05 From: Prague, Czech Republic Member No.: 7,665 |
Absolutely. So even if Blood Spirits worked the way Lars intended them to work, an Blood Mage should be able to make a Force 12 Spirit of Man, Blood Invoke it, feed it two people, have the spirit cast Astral Armor on itself until it gets 36 hits, and then just fly through space handing out Force 12 Movement to things. Then you could get to Mars in one day with a base Acceleration of only 1.75 m/s^2. But that rule is still broken even if we use the "intended" version, so I'd prefer to not rely on it. And I honestly don't think I have to. With the actual speed of particles in the reaction, we could get the kind of moentum we're looking for by launching 33 grams out the back in the initial second. That's less than six tonnes even before we count in the fact that your mass is shrinking en route. In fact, that's such a small mass reduction that we almost don't even have to calculate he fact that our mass is falling over time - but we really should (for one thing it drops the reaction mass requirements even more). It drops required reaction mass down to a little over 5 tonnes each way for our 100 tonne craft. We could be moving the Nimmitz if we wanted to - we'd only be throwing out 33 kilograms a second for 172,800 seconds. More than we're willing to do, but not more than we are able to do. A 100 ktonne craft could get to Mars in 2 days on about 5 kilotonnes of reaction mass. That's totally doable if for some reason you wanted to bring a pre-fab skyscraper to Mars in a hurry. -Frank |
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Nov 10 2006, 04:07 AM
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#141
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Target Group: Members Posts: 79 Joined: 23-August 06 Member No.: 9,205 |
I think that was a typo. In previous posts, he's been talking about 0.1c as a high-speed thing, and 0.01c as a reasonable-speed one. In the same post, further down, he mentions .01c as a reasonable-speed acceleration, making me think that putting .01c as too high is a typo that was meant to be 0.1c. |
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Nov 10 2006, 04:38 AM
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#142
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Moving Target Group: Members Posts: 236 Joined: 6-September 04 Member No.: 6,634 |
OK, I'm breaking my promise, but Dem, Knass, why are you falling for this. Frank consistantly ignores your imploring statements that he pay attention to the reaction mass and not the mass needed to run a fusion reaction. He either isn't listening or is baiting you. Drop it; people either understand or they never will (these boards aren't the best physics classroom).
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Nov 10 2006, 05:27 AM
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#143
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Prime Runner Group: Banned Posts: 3,732 Joined: 1-September 05 From: Prague, Czech Republic Member No.: 7,665 |
That's a consistent claim, and it's not even true. I did the calculations on the reaction mass using the actual temperature created by the actual fusion reaction in question. It requires 33 grams of reaction mass per 100 tonnes of vehicular mass per second at those speeds. Demerzel did some perfectly fine calculations for speeds that he pulled out of his ass that were very much lower than the actual speeds of particles coming out of a fusion reaction, and came to the conclusion that particles at those reduced speeds would require an intractable amount of reaction mass. But with the actual temperature of a post reaction particle (18.4 MeV), the reaction mass is 33 grams per 100 tonnes per second. It's not an intractable amount. In fact, it's a hand wavable amount, since we don't know how much the fusion drive masses. -Frank |
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Nov 10 2006, 08:17 AM
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#144
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Shadow Cartographer Group: Members Posts: 3,737 Joined: 2-June 06 From: Secret Tunnels under the UK (South West) Member No.: 8,636 |
Well firstly a concern that Frank actually believes this. It's kind of a duty to help him understand where he's going wrong. Secondly, the concern that by accompanying his hand-waving with a lot of numbers, he's going to misinform people with less of a grasp of physics. And thirdly, and this hadn't occured to me until Demerzel pointed it out, Frank is one of the freelancers and if this sort of stuff made it into cannon it would do damage to Shadowrun's hitherto good(ish) track record on realism. Also, some sense of solidarity with Dem who can't be the lone voice of sanity here. ;) |
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Nov 10 2006, 08:32 AM
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#145
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Moving Target Group: Members Posts: 394 Joined: 19-May 03 From: In your base eating your food. Member No.: 4,607 |
Physics aside I really hate the idea of a two day trip. 'nuff said.
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Nov 10 2006, 09:39 AM
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#146
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Midnight Toker Group: Members Posts: 7,686 Joined: 4-July 04 From: Zombie Drop Bear Santa's Workshop Member No.: 6,456 |
Actually, I was thinking of Ally Spirits as it is, on a whole, a more reliable process than Force 12 Blood Invoking. 197 karma gets you a Force 24 Ally with the Sorcery skill. That's a drek-pot load of karma, but it is certain possible given the number of corporate-produced foci on the market. It will require a grade 6 initiate and most of the time the binding will fail or the drain will push the magician into physical overflow. However, if done in a hospital with medical care on standby and with sacrificing to make some of the drain magically healable, it is realitivly safe (compared to being shot in the face in an ally behind a seedy bar), and it will work eventually if the magician tries enough times. Since the Ally spirit rules places karma payment after the bnding ritual multiple attempts are possible. Such attempts don't even create Free Spirits. The spirit just dies if the binding fails (so I doubt that it would use Edge to resist and ensure its own destruction).
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Nov 10 2006, 01:32 PM
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#147
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Moving Target Group: Members Posts: 236 Joined: 6-September 04 Member No.: 6,634 |
Frank, you just keep on putting together facts that might be true but simply don't mesh in regards to making a ship for actual realistic travel. So sure, I guess you are right about everything you are saying; if a fusion reaction makes particles go fast (even if that speed is random movement amongst the particles, essentially HEAT) you must be then able to use that as reaction mass and shoot it out the back. Anyone who wants to believe you without any further evidence should do so as well, but honestly do yourself a favor and talk to an expert (physics professor) offline and let them show you what we are trying to say. Either that or quit your job and become a theoretical physicist immediately because if you are correct you have turned the universe on our head as anyone with a solid physics background knows.
You don't understand why the "very fast" particles of the fusion reaction cannot simply be applied as a reaction mass. You are plugging and playing equations that you don't fully grasp the consequences and meanings of. You are being willfully ignorant, and it is unfair to anyone who might believe you, so please at least put a disclaimer that you have no science background, you only play a scientist on the Dumpshock Forums. |
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Nov 10 2006, 02:41 PM
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#148
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Midnight Toker Group: Members Posts: 7,686 Joined: 4-July 04 From: Zombie Drop Bear Santa's Workshop Member No.: 6,456 |
Lets screw the physics discussion here and talk about the real issue. Money.
You can, today, at this very moment, as I type, build and fuel a rocket-ship capable of accelerating at 1g for 2 days straight if you have access to unlimited funds. And there lies the issue and the out. If you throw enough money at the problem then it will solve itself* If you throw enough money at the problem it will solve itself and we're talking about megacorps here. They spend more money on toilet-paper, annually, than a fully-fueled giant rocket-ship of this sort would cost. "You see this?", says Damian Knight, "This is a billion nuyen note. It is the only billion-nuyen note ever made. It is actually worth 6 billion nuyen in the currency collector's market because it is so rare. Do you know what I'm going with this billion nuyen note? I'm going to wipe my ass with it. Why? Because I'm rich, that's why. Because I'm so rich that I can wipe my ass with a billion nuyen every time I go to the bathroom and I wouldn't even notice. See that old ragged dish towel there? That's the original Mona Lisa. Yes, the original. The one in the Louver is a fake. I know, its hard to tell with all of the barbecue stains." Can it be done? Sure. It most certainly can be done. It might be expensive as hell. But, to paraphrase one of the great leaders of the 20th century: We choose to go to Mars. We choose to go to Mars in two days and do the other things, not because they are cheap, but because they are cool, because that goal will serve to demean and demoralize the best of our competitors and rivals, because that challenge is one that the public is willing to accept, one that is easier if we don't postpone, and one which we intend to win, and the others, too. *Actually, the team of highly skilled slave-engineers chained in your dungeon will solve it to the motivational whipping of the Oompa-Loompa slave-drivers. |
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Nov 10 2006, 04:02 PM
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#149
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Immoral Elf Group: Members Posts: 15,247 Joined: 29-March 02 From: Grimy Pete's Bar & Laundromat Member No.: 2,486 |
Instead of endlessly repeating "You're wrong Frank", maybe one of you should actually take his numbers (as he keeps asking you to) and prove him wrong. Don't make up other numbers and equations to muddy the waters (unless his figures are in fact actually incorrect). He has given you the numbers and equations he used to come up with his theory, but as yet nobody has fully addressed the issue as he portrays it.
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Nov 10 2006, 04:11 PM
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#150
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Moving Target Group: Members Posts: 340 Joined: 18-September 06 From: Chicago (CZ) Member No.: 9,422 |
2nd SR is a FICTIONAL setting used for fun! I want to see Frank go to Mars in two days. That way I can figgure out what happened to those dragon bones.
Shake things up for a chance? I'm sure we all like change otherwise SR would have died as a product a long long long LLLLLLOOOOOONNNNNNGGGGGG time ago. |
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