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Post by nerd1000 on Nov 8, 2016 10:18:40 GMT
It's stated in the books that missiles/torpedoes are essentially small Epstein drives with a tracking system and warhead, and that they can hit a target on the other side of the Solar System. But don't the book also say that a ship the size of the Roci is about the lower limit in terms of what you can mount an Epstein on? Maybe the Roci is the lower limit for a reusable Epstein drive, as opposed to the 'burns itself out after 30 seconds of firing' missile version? Alternatively, maybe the missiles are similar in size to the Roci herself. It would explain them carrying a nuke big enough to literally reduce the Canterbury to radioactive dust.
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Post by nerd1000 on Nov 7, 2016 7:32:09 GMT
You dig up flourite and make flourine from it. Reserves on Earth alone are estimated at 230 million tonnes, and we have an entire solar system to mine for the stuff. 230 MT is not very much at all. There are ship designs that use kilotons of the stuff. Would only take a few years of s couple fleets like that running around to deplete the supply, especially when you consider how much of it must be used to lift it into orbit. Good point, I wasn't thinking of people using kilotons of fluorine in a single ship. If we take into account the industrial consumption of the stuff there's probably not much left for using it as propellant. Of course from a logistics standpoint there's not much sense in using flourine as a propellant at all- it's simply too toxic, corrosive and cryogenic. Outside of edge cases (like really tiny missiles) the extra performance simply isn't enough to justify using fluorine rather than oxygen (which is very easy to come by). What might be slightly more sensible is chlorine trifluoride. While it's just as toxic and corrosive as fluorine it does have the very nice property of being a liquid at a little below room temperature, which makes storage far easier.
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Post by nerd1000 on Nov 6, 2016 14:09:38 GMT
I've got nothing better to do, so I went one step further and wrote up a little over 400 words to 'test the waters'. Premise is that in the aftermath of the campaign there's a bunch of ships running around tidying up orbiting debris and salvaging valuables from the ships Admiral PC wrecked. Our protagonist (Alexy) is a USTA citizen who took a job on a RFP salvager (RSF Bose, named for the famous physicist), desperate for some cash and a safe place to sleep (as you can imagine, the situation in the former USTA is not great).
The inside of a EVA pod is quiet.
Not silent, mind. There's still the hum of air-con, the hiss of escaping gas as you fire your thrusters, your own breathing... but it's still a kind of quiet you rarely experience on a station packed with people. Sometimes I find it soothing, being away from the noise and bustle of a horde of people flying through space in a titanium can. Other times it reminds me how alone we really are out here, so far from the cradle we so foolishly destroyed.
“EVA Seven. Correct course zero point three radial.”
Not that I ever get any real peace and quiet for long. I pull the microphone boom towards my mouth, simultaneously tapping the control panel to program in the desired burn. The pod's attitude thrusters are already nudging me onto my new course as I press the transmit button on my control stick.
“Copy... burn complete.”
Almost as soon as I let go of the button another voice needles its way into my headphones.
“Nice job pressing the button on the console, spaceman.”
There's always one. I check the transmit log, confirming my suspicions, and press the transmit button.
“Shut up Mohammed.”
“Don't get mad, uster. An angry spacer's a dead spacer. You should know, seeing how the Admiral taught your girl Overkill that lesson the hard way.”
The mission controller's voice crackles over the comms again.
“EVA four and seven, keep this channel clear for mission critical traffic.”
“Just keeping the newbie safe, boss.”
Mission control briefly drops her professional veneer.
“Shut up Mohammed. And as for you Alexy, stop responding to his bullshit. It just encourages him.”
I smile in spite of the scolding. Today's mission controller is Chandra, a diminutive thirty five year old from Mars and the only person on board the Bose who really makes me feel welcome. Somehow it's impossible to dislike her, in spite of everything her people have done to mine.
“EVA seven, your target should be three hundred metres away. Bearing 030, elevation fifteen degrees.”
I haven't been in this business for long, but there are some things you have to learn quickly. My eyes jump to the spot, searching for the derelict I'm supposed to be salvaging. The high resolution displays that substitute for windows in the pod helpfully provide an enlarged image, shifting from visual to infra-red for easier identification. I recognize the long, pointed shape right away. It's a Devastator missile. The same kind that rained devastation on my world.
It might be fun to arrange one of those round-robin writing exercises where each person gets control of the story for so many words before passing it on to the next.
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Post by nerd1000 on Nov 6, 2016 12:16:58 GMT
I suspect that many, though not all, hull materials are such that the interior space after they are pierced would be rather inhospitable - spalling and related shock damage, radiated heat from molten hot segments, and so on. The odds of such a compartment being able to keep fighting meaningfully, both in terms of the crew being able to fight and (critcally) the control linkages to the various ship systems being in working order, seem remote whether or not there's actual killing of the crew involved. That being said, agree with you that low profile mechanical counter-pressure suits and SCBA gear seem mandatory even for comparatively minor damage - beyond the risk of depressurization, IIRC the figure on airliner cabin fires is that if you're not out within 60-90 seconds, the fume exposure is either fatal or sufficiently incapacitating as to make escape impossible. So even if you kept atmosphere through the damage, there's plenty odds you might be wishing you hadn't. True to some degree. On the other hand, the rounds we fire at enemy ships are usually tiny little hypervelocity pellets, so the amount of spalled material is likely to be pretty small. The best point of reference is probably the effects of HEAT warheads (which achieve similar impact velocities to our railguns) on armoured fighting vehicles- a tank is a very confined space, yet when a tank is knocked out the crew usually survives unless the ammo explodes or they were directly in the path of the incoming projectile. Our crew modules contain no explodey bits and generally have much thinner plating than a tank while also having much larger volume for the crew to be spread out in, so I think most command modules could be penetrated many times without all the crew being killed. No debating the fact that pumping 500 bullets into a crew module will take it out, but sometimes our modules are disabled by a single round that's lucky enough to get through the armour when all other hits were successfully deflected. Control links to the rest of the ship are actually pretty easy to protect- they're going to be electrical wiring or fibre optics, which are small (thus unlikely to be hit) and easy to armour or provide extra redundancy. Any computers that rely on the command module atmosphere for cooling will overheat, though running a liquid cooling loop probably makes a lot of sense for them anyway (Ensign Bob's PlayStation on the other hand is toast). The module can also have internal subdivisions that block fragments and heat effects while also allowing you to seal off breached sections, so even assuming the module gets hit by one of the stock 286mm coilgun's 10 kilo dinner plates at 5 km/s it might be able to retain partial functionality (Bob and the rest of his section, however... well they won't be needing their PlayStation any more).
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Orion
Nov 6, 2016 11:38:35 GMT
Post by nerd1000 on Nov 6, 2016 11:38:35 GMT
Well, that's kinda trying to build a Orion drive out of depleted uranium and duct tape and hope that it magically works. It really need to be a real module to actually work. No, from a physics standpoint there's no reason it shouldnt work. Sure, it doesn't have the shock absorbing pistons but thrust should still have been applied. Especially after 100+ detonation less than 10 meters beyond the pusherplate. What I mean is within the physics model of the engine there should be no reason that multiple nuclear explosions detonating against a reasonable thick slab of tungston wouldn't produce *some* force. Especially after if such explosions are propelling a burst of plasma from vaporized material (s-gel, polyethylene, tin, osmium, and other materials I tried). It's an odd peculiariarity that I wasn't expecting. I would guess that the nukes are modeled as a a "360 degree laser" as mentioned in one of the laser threads. QSwitched, if you're reading this please don't take it as an complaint. But I am curious. Any reason why a psuedo-NPP wouldnt work? I believe Q said that it does work, but efficiency is dismal because there are no nuclear shaped charges.
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Post by nerd1000 on Nov 6, 2016 10:42:47 GMT
So, it seems that Fluorine-Hydrogen combustion rockets are competitive with, or even possibly superior too, methane and decane NTRs even for capship usage. This of course poses a possible logistical problem: How do you get that much Fluorine? Hydrogen, methane and decane are little problem, since hydrogen and carbon are quite abundant in the solar system, but Fluorine isn't - Carbon is ~4800 times more abundant in the Solar System than Fluorine is. You dig up flourite and make flourine from it. Reserves on Earth alone are estimated at 230 million tonnes, and we have an entire solar system to mine for the stuff.
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Post by nerd1000 on Nov 6, 2016 10:36:43 GMT
If you do enough damage to a crew module to pierce the armor, it pops. It's dead. It's gone. Modeling the insides of the modules to calculate the exact effects of every impact would not really be feasible, and a sufficient number of sufficiently big holes means that anyone in that pressure vessel isn't going to be contributing much of anything useful to the engagement anyway. So from a gameplay standpoint, it probably makes sense, but how realistic is it? One atmosphere of pressure shouldn't be enough to make it pop like a balloon just because you poke a hole in it, right? Realistically, shouldn't a lot of the high velocity kinetics - assuming they've not caused spalling, or shrapnel bouncing around inside the armor layer, and no explosives or anything - be going just about fast enough to punch clean through without shedding too much velocity or dumping too much energy into the crew module (well, depending on what's in their trajectory)? Small hole in, slightly messier hole in any intervening object or crew and messiest hole out. Worse if there's spalling from the armor layer. Worst if it starts bouncing around the insides of the module. And I figure the way to simulate multiple pressurized compartments is by using multiple crew modules (and eat the extra WW and AC technicians - not literally, even as emergency rations), so if there's too many or too big holes to patch in a module, and probably not enough spacesuits to go around, a penetrated crew compartment is at the very least mission killed. But I'm not really a hard physics numbers guy - thoughts? /This thread brought to you by: Insomnia, all those snips from Atomic Rockets with small holes being punched in crew compartments, that one scene in the Expanse, and a bunch of others. Here's another thing: Why wouldn't the crew (knowing that they're going into combat) put on space suits so that they can survive any depressurization event and (potentially) even keep fighting?
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Post by nerd1000 on Nov 3, 2016 12:27:25 GMT
You want crazy, stupid, silly ship designs? I give you the Heart of Gold, a ship where I made every part I could out of gold. It has gold armour, gold propellant tanks, gold radiators, gold crew compartments, gold railguns (firing gold bullets) and a reactor using gold as the moderator, control rods, coolant pumps and half of the thermocouple. Propulsion is provided by seven gold decane NTRs. To my annoyance, there are some parts you cannot practically make from gold: the radiation shields (sadly gold is quite bad at blocking neutrons), reactor neutron reflectors (see above), nuclear fuel, NTR control rods, thermocouple N-type material (I used platinum) and various parts for which you can't choose the material like the inside of the command modules. Naturally its combat effectiveness is somewhat... lacking, though it is capable of beating the stock beamcraft in a 1v1 if you use ignore range on the railguns.
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Post by nerd1000 on Nov 3, 2016 11:12:54 GMT
I don't think you realize how mind-bogglingly big the strategic map is. To paraphrase the Hitchhiker's Guide, you may think 4,000km is a long way, but it's just peanuts compared to space. To give an idea though, that'll only get you 1/10 of the way around Earth's equator. It's also just under 2/3 of the Earth's radius, so if you're in orbit around Earth you can take a look at it and get an idea of how short your range on the strategic map would be. A laser big enough to do noticeable damage on the strategic map would be so big and so power-hungry, it would have to be mounted on a large battle-station or an asteroid/planet. As for longer engagement ranges, I think those might have to wait until missiles get better code for controlled-homing (which is technically supposed to be how you get through long-range engagements, but right now it doesn't work). It wouldn't hit the whole map, just a small bubble around itself, since a strategic map attack should still account for the loss for power with distance, also the laser might have be interrupted if the attacking ship is doing a burn due to vibrations throwing off the aim at long ranges. 10m radius laser is not all that big compared to some hydrogen deuterium ships in the game, I think mine is 45m across, so the laser could easily fit on the front of it. But here's the thing, in game terms, it is really boring to sit through a 4000km real time intercept, so some way of auto-resolving long range laser damage on the strategic map could be a reasonable approach to alleviate the boredom while keeping large lasers in play, if their long range hitting power is as the game's current mechanics suggest. Time acceleration in tactical view might be a solution to this.
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Post by nerd1000 on Nov 3, 2016 5:03:56 GMT
Hmm, what about putting timed flak cannons on a drone flying at high speed toward an enemy, firing a few shots and then trying to impact as a KKV? That would be quite a large cloud of hypervelocity debris, and such a cloud couldn't be stopped once it's been launched. It won't work especially well in-game because flak clouds only last a fraction of a second (much to my dismay- if they lasted longer I could manually detonate my flaks at a distance and get a good spread that way). IRL however I don't see any reason it couldn't work other than the fact that it's essentially the same as using a flak missile (which could probably produce the same number of hits for less weight and cost).
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Post by nerd1000 on Nov 3, 2016 0:02:37 GMT
Don't write missiles off just yet. A NEFP warhead that can land penetrators on target from over ~2 km away circumvents this defense, though those would still be vulnerable to AMM interception. Whether or not such a warhead can be made reasonably remains to be seen. I would love for NEFP'S to be able to that do that, but until we get a better targeting algorithm I think flak has a shot**. BUT what's to stop more effective flak from stopping the more effective missiles? A 2km standoff NEFP might still be hit by a 2.1km range flak shell after all. **Note, I haven't tested these shells myself yet. If the proxy fuses worked better the flak storm approach could work at any range. Ultimately it will be limited by gun muzzle velocity- if the time of flight is too long enemy missiles can jink out of the way. NEFP is probably limited by either accuracy or the fate of the projectile. It is possible that the pusher plate of existing designs is vapour by the time it reaches full speed, but 10kg of gaseous osmium at 4000 kps will still drill through almost anything unless range is long enough to spread out before impact.
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Post by nerd1000 on Oct 31, 2016 11:37:24 GMT
Certainly an interesting idea. One problem with a slush-storage-tank is that it is, itself, going to require cooling, and a 195.4 K radiator is going to be colossal. Still, if it's designed to only be used when your radiators have been shot off.... Heat pumps would help here.
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Post by nerd1000 on Oct 30, 2016 14:21:32 GMT
Yea, your problem is that you have maxed out the ingame sliders for power from a nuclear thermal rocket. You are now in the shitty trade space between throwing more mass out the engine on the same power, or not. It sounds like the request for the dev is: "Can we please have more than 500kg of fissiles in the nuclear thermal rockets?" Yeah that is exactly what I asked for in the first post and the point of the thread. I want bigger NTRs then are currently possible. I should note that, in my experience, the bigger you make your thruster the harder it is to keep the thing from melting or cracking from thermal expansion. I guess this is caused by the square cube law- the thruster dissipates heat through its surface area, while it generates heat through its volume, so bigger thrusters are harder to cool. I guess you could circumvent the problem by making the chamber from one of the ultra-refractory ceramics that melts at a higher temperature than the reactor, but those materials are weak and very dense so the engine would be extremely heavy. There may be an upper bound on the size of an effective NTR, at least for our purposes. Related topic- has anyone else noticed that regenerative cooling has no effect on engine weight or cost?
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Post by nerd1000 on Oct 29, 2016 11:46:50 GMT
Are lithium and boron broken somehow? It seems crazy that it's a perfect engine bell, turbopump, and aftershave, but nobody uses it IRL. Boron is used in the form of boron fiber reinforced plastic, but the stuff is very expensive so it only sees use in high-end applications like fighter jets. Based on some quick reading the mechanical properties of the fiber composite are even better than the amorphous element in many respects.
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Post by nerd1000 on Oct 28, 2016 0:10:27 GMT
Hmm I just realized I really like that counter missile of yours. Can you post all the bits that goes into it so I can mess around with the design myself? I'm interested also! I'd like to try them out against my main workhorse missiles. Sure thing! I'm pretty proud of the engine in particular. I realized that running an oxidizer-rich mixture would bring my engine temperatures down and increase my average fuel density -- fluorine has a density of 1.5 tons per cubic meter -- so I'm running a 40% surplus on fluorine in a H2F2 rocket. Exhaust velocity is still over 4km/s, and TWR is over 600. I'm using magnesium for the injector purely for flavor reasons: a lithium injector would burn hot enough that the hydrogen would be completely redundant. If we ever get hybrid rocket motors, lithium/fluorine is gonna be a great fuel mix. Edit: I use graphite aerogel as the gimbal "armor" because it's extremely light, extremely cheap, and if anything hits the engine the missile's out of commission anyway. The warhead is a pretty standard pocket nuke. I'm certain there's room for improvement, but the main advantages are that A) it weighs half a kilo, and B) it can still do nuke-related activities. For a counter missile, keeping mass down is pretty important. The fuel tanks are pretty standard UHMWPE tanks. The oxidizer tank is split into two pieces so I could get the precise amount of oxidizer I wanted. Other than that, just make sure the radius is under 5 cm. I don't think they're worth a screenshot. The launcher takes minimal power, requires very little radiator area, and fires once every three seconds. This seems to work out just fine against salvos of between 10 and 30 missiles. I'm using a 200 round attached magazine for a total mass of under three tons and a total cost of 13.0 kilocredits. Considering as Strikers cost 9.83 kc each, I'm pretty happy with the system. Edit: The thing isn't armored, because the missiles are non-explosive and once you're in gun range, counter-missiles are redundant. I believe I selected boron nitride as the casing material due to its high specific heat capacity and high melting point; those properties appear to help harden the module against any stray nukes. If you're going for flavour on that engine, you should be aware that (to paraphrase Derek Lowe) at 700 degrees C fluorine starts to dissociate into monatomic radicals, thereby losing its gentle and forgiving nature. I doubt there's a nozzle material in the universe that would stand up to contact with a mixture of monatomic fluorine and hydrogen fluoride at 6000K... So for roleplay I suggest switching to fluorine/methane and running fuel rich like the stock stinger drone thruster. You'll lose a bit of performance of course...
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