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Post by AtomHeartDragon on Feb 27, 2019 17:58:45 GMT
Could you use a laser as your heat source instead of a nuclear core or a resistor so you aren't constrained by the cores melting point? Then you could use like, tantalum hafnium carbide nozzles or something. Edit: Answered my own question with a three second google search. Laser Thermal Rocket has it's own sub section under Laser Propulsion on Wikipedia. Given that any sort of electrically powered heating elements boils down to a race to the bottom (achieve zero efficiency by converting all the input into waste heat), I don't think laser is going to make any difference unless it is external to the craft (along with power source) or unless you can achieve stupidly high temperatures and manage to outMPDT MPDTs in exhaust velocity or achieve similar velocities but much better thrust (both likely including external laser as part of a bundle deal, since you don't want that performance wasted on moving huge powerplant around, and you may settle for worse performance if it gives you huge mass cuts).
I wonder if fuel could be heated simply by passing current through it resistivity rather than utilizing a resistor. Similar to an MPD but not taking advantage of the lorentz force and just heating propellant resistivity. Perhaps this already exists. A resistojet where the propellant is the resistor. That's called an arcjet. I wonder if the benefits of the extra exhaust velocity would adequately compensate the added weight from the laser system and the extra inefficiencies that such a system would possess. Might be a good alternative to MPDs if you care less about weight and efficiency and want more thrust, yet still want more specific impulse than a NTR. I wonder if fuel could be heated simply by passing current through it resistivity rather than utilizing a resistor. Similar to an MPD but not taking advantage of the lorentz force and just heating propellant resistivity. Perhaps this already exists. A resistojet where the propellant is the resistor. Possibly, but you'd still be constrained by the temperature tolerance of the conductor you'd use to arch the power through your fuel resistor, although it might be a lot more mass efficient to not have a solid resistor.
Laser thermals would probably be a lot less mass efficient because you'd still need radiator area to cool the lasing medium, and they might not be higher temperature if your focusing lens has to contain the chamber temperature and pressure. Magnetically contained laser thermals could potentially make stupidly high temperatures though, if you wanted you could do things like have a solid tungsten rod as your reaction mass and feed it into the beam path to make 5,930*C boiling tungsten exhaust. Or osmium if you wanted the densest possible fuel storage. Or iron if you wanted something more abundant.
Or soot slurried in LH2/hydrocarbon/emulsified in water. Because if you reach such sweet temperatures, why squander them on shoving heavy atoms around instead of maximizing exhaust velocity? Rocket propulsion is about maximizing some combination of exhaust velocity and mass flow, not vaporizing the most vaporization-unfriendly (and thus impressive) stuff you can find.
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Post by AtomHeartDragon on Feb 21, 2019 18:54:12 GMT
How much do you trust your results when going 6 orders of magnitude outside of "model should more or less work here" bounds? Ummm, cool? But I have so many questions. Why Osmium rails and not Zirconium Copper or Ferritic Stainless Steel for efficiency? Or Vanadium Chromium Steel for strength? Or Amorphous Carbon or Reinforced Carbon Carbon for mass? AC works poorly for rails, even in CW railguns. Osmium is a good mixture of stiffness and strength, sometimes worth the mass hit. Or amorphous carbon for relatively lightweight stiffness. Osmium seems positively awful for any applications where you can't avoid having substantial volumes of material. I would try Amorphous Carbon, it seems to work really well for very heavy (0.5-10kg range) as well as many CW railguns. Maybe it's gentler on the barrel/projectile? Attached exploits simulation deficiencies for payload physics, this here likely exploits simulation deficiencies outside of model's reasonable fidelity range (as declared by the author). Pick your poison.
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Post by AtomHeartDragon on Feb 21, 2019 18:36:32 GMT
Oh another reason not to nuke a planet. You are trying to conduct regime change. As opposed to regime phase cha nge.
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Post by AtomHeartDragon on Feb 19, 2019 6:38:04 GMT
I mean the thing's got a gigawatt powerplant sitting right there, might as well add few CIWS railguns and lasers while you're at it. Anti-anti-missile missiles may also be worth considering; if you plan to hit the target at interplanetary speeds they will probably work better than anything else for clearing a path to the target. Making it sort of remotely guided kamikaze ship does make sense.
Shame than the AI doesn't know how to handle that (we really need the logic of "has warhead" == "is missile" == "should home in on target without dodging", by default, rather than "has weapons" == "should broadside and dodge everything"). That's one of the factors that motivated me into making a lot of payload based stuff - you don't have to worry about derpy AI and guidance if the thing has no say about where it is going.
What if you made a multi warhead payload with radial blast launchers creating a cone of micro nukes, some of which set with hard detonation ranges to detonate early and some of which with a delay to go off late to try and completely envelope the target? Goal being to ablate the radiators on all sides of a target and thermally disable it. I've not had much luck with the timing in the past but AtomHeartDragon's Ironblast Artillery Pack seems like it'd be a good starting point. Nuclear grapeshot? Be my guest.
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Post by AtomHeartDragon on Feb 18, 2019 18:57:04 GMT
The main problem with such huge missiles, is that they can be effectively countered by smaller ones. Absolutely true. But I'm having trouble make smaller missiles A) actually disable spacecraft with effective armor and B) actually get into range of spacecraft with effective weapons.
I can go about developing anti missile missiles after I've made effective missiles that are actually a threat for them to engage.
I suck too much at missile guidance to make an effective anti-missile but I do have rather effective circa 30kg design with a holy hand grenade warhead, that tends to penetrate whatever it engages, with part of the salvo following the leader and detonating inside. I usually mix them with flak version and launch them out of high-velocity MLRS when in direct combat.
Against capship-sized missile it should be more than sufficient.
You could sacrifice 3-5km/s or so of ∆v for a nice hefty armor cell around the warhead which could turn away most smaller missiles and point defence. They can take out your propulsion but 1 gigaton probably doesn't need much terminal guidance anyway. Depends whether or not your amour could stave off several, around 30kg, narrow kinetic impactors coming at around 7km/s and hitting the same spot. The main joke about such a missile is that while you can use multiply redundant engines, RCs and a honeycomb of narrow, small volume tanks, warhead is the one component you can't really make redundant.
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Post by AtomHeartDragon on Feb 17, 2019 10:29:41 GMT
I have typically found that smaller drones in large groups work better than large drones in many situations. So I created this railgun for use on my drones:
It is similar in power requirements to your original post, outperforms just about any conventional cannon on velocity alone, and is very light. Have you tried a similar size rail without the capacitor? I think it might actually work out a bit better in terms of fire rate and cost of the thing itself. The only low power weapon systems you want without capacitors are conventional cannons and launchers.
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Post by AtomHeartDragon on Feb 17, 2019 10:12:56 GMT
Assumed the laser would be able to destroy any maneuvering systems on the KKV as soon as the KKV was both in range and detected manoeuvring systems don't need to be exposed from the laser's location, so it would need to burn all the way through the hard way. With a well designed mission and KKV this might be barely more favourable than ablating the whole impactor.
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Post by AtomHeartDragon on Feb 17, 2019 10:08:18 GMT
For me I just use giant lasers targetting at the radiators and pray it doesn't kill the crew It's how I won the match in less than a second For gunship it's usually a good idea to vape crew radiators first. Then you can burn/poke through the hull and wreck the NTRs and power reactors at your leisure.
You will probably want to hurry with your boarding though.
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Post by AtomHeartDragon on Feb 16, 2019 11:11:16 GMT
Several points: - Do post module editor screenshot(s) - this will allow people to take a look without importing the design into CDE and running the game.
- IMO there is little point making EM (rail- and coil-) guns below 3-4km/s. In this case you could get similar performance out of 0.5kg conventional turret taking several W (instead of 200kW) and fitting comfortably in your pocket. I think the only worthwhile potential reason for making low velocity CG is CGs tending towards long, needle-like projectiles which may improve penetration, especially at low velocities.
- Lead makes poor momentum wheel material because, while dense, it is very weak. Osmium is usually the go-to material for momentum wheels because it's both the densest non-exotic material in existence and very strong. Reaction wheel mass can be minimized by minimizing excess diameter of the turret over the barrel - of course some tradeoff might be necessary here, but try to make the lightest wheels and make them spin as fast as possible within your power envelope first as a rule.
- For low power applications actuators perform much better than momentum wheels. Alnico offers good performance, but neodymium-iron-boron allows for the most compact ones and is usually the best (if expensive) magnet material for that. Anything below 1MW is usually a low power application. You could
- Hafnia is expensive but allows for the most compact, and thus lightest capacitors AFAIK.
- Your autoloader is overkill. With this weapon you could drop to as low as 1W without impacting performance. The practical rate of fire is capped at 33.3ms for engine reasons (there is rarely need to consider anything more except for quirky stuff like capacitorless gun staggering and purposeful thermal throttling) and if you have extra power to run loader and capacitor in parallel then reload time doesn't need to be shorter than charge time.
- Your barrel armour is overkill. With exit velocity this low this kind of accuracy is probably wasted - you won't be shooting ants, and at ranges where it would be useful to hit anything larger the target will have moved significantly before impact. Also, amorphous carbon or diamond would work better here.
- Your turret armour is weak. It's unlikely to be hit directly by kinetics, but it needs better flash and laser protection.
- Except for highly specific use cases you should probably always use magnetic metal glass for CG armature. It's painfully expensive but performs so much better.
- Considering hints above, even when sticking with coilgun, you could make the turret alone fit in the palm of your hand, track even faster, and reach 2km/s (without substantial tweaks to the coil apart from replacing it with VCS to withstand stresses of firing), with most mass, apart from the magazine, taken up by large-ish hafnia capacitor (putting the whole gun without ammo at slightly above 2kg). At this point you should probably detach the magazine even if it's not explosive and especially if it's filled with long, needle-like projectiles, because of how bulky it is.
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Post by AtomHeartDragon on Feb 15, 2019 18:09:11 GMT
The main problem with such huge missiles, is that they can be effectively countered by smaller ones.
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Post by AtomHeartDragon on Feb 14, 2019 6:38:08 GMT
Can you make one that isn't bigger than the battleship I wanted to mount it on? I have chosen to follow your request to the letter, and not to the intent. Meaning I've constructed the densest possible weapon system of 10GW power draw and 8km/s muzzle velocity and 1ton payload.
Ooh, that's nice, now it's only a one biggish fleet.
Can you do two more orders of magnitude?
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Post by AtomHeartDragon on Feb 13, 2019 21:48:44 GMT
Can you make one that isn't bigger than the battleship I wanted to mount it on? Or entire fleet. Or several hundreds of such fleets. My artillery pack launcher actually only fires once per 5s to conserve ammo and framerate (and I have recently reduced power draw to 1.5kW), but that's because it's an AoE weapon with high lethality and each shot is actually a burst.
So, yeah, I definitely agree.
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Post by AtomHeartDragon on Feb 9, 2019 18:19:07 GMT
Now,
- It's not an accurate weapon. There is some inaccuracy inherent to the contrived launch process (it uses notoriously inaccurate spinal guns as its aiming mechanism!), it fires unguided munitions and there is also a delay making it unsuitable against targets moving with large angular velocity.
- It's not an efficient weapon (with single-shot 1.72t "cartridge" being spent to launch a mere 210kg of kinetics).
- It's not a cheap weapon with all the aramid and UHMWPE fibers used for mass-efficient telescoping blast tubes.
- It's not the most useful application of the whole concept (assisted missile launch, for example, would be better, and the whole idea started as a way to fine-tune the assisted missile launch).
- It's not going to be effective against highly manoeuvrable (high-acceleration, low turnabout) targets or ones with more effective PD
- It's, despite my best efforts, still laggy
- It's not entirely safe weapon - in some (very rare) cases it can kill the launching ship
But, it does allow a fun-sized ship (750t) with fun-sized powerplant (804kW, with launchers themselves only taking 150kW while being terribly unoptimized - in fact I deliberately underclocked them to conserve ammo and framerate alike and to minimize launch velocity) sling 630kg salvoes of kinetic impactors per pop at 4.5km/s, with a bit of luck hitting stock-like targets from around 60km and usually shredding them:
Plus, the frangible countermass technique I use produces kickass-looking backblast:
The launcher pack itself is named "Ironblast" in tribute to certain very fun weapon from certain very fun z-doom mod.
I have also nicknamed it "scattergun". Not for its accuracy, mind you - it's because it tends to scatter a gunship if it hits it.
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Post by AtomHeartDragon on Feb 9, 2019 17:16:25 GMT
Doesn't matter, I suppose, since even if it worked the >1min reload time would render it completely useless in combat. Not necessarily, just don't miss. Effect on target should be plenty nasty. Even if you can expect hole the size of an airliner + a whole lot of spallation damage in the surrounding area (which I expect to be the result), you are still not guaranteed a 1hk against a large, well designed ship. Even if you were, it's easily defeated by simply sending in more than one ship - might even be of a tincan+popgun variety. You won't be firing this baby twice.
Anyway,
and now for something completely different: This is the whole ship because the kinetic weapon it uses requires quite specific setup.
It's a small (if a bit expensive) ship, just below 750t (qualifying it for 750t wonders thread) It is a low-powered design, not even bothering with a power reactor, instead relying on 8 >101kW RTGs (just shy of 9kg each) for power, due to personnel considerations. It is armed with battery of small, low-powered, low-velocity railguns on the nose, and an assortment of similarly performing, very small coilgun and conventional gun turrets, neither of which is its main weapon. It's main weapon is this: and it is a pre-aimed, free-floating recoilless artillery pack. Those packs are launched from three side-mounted electrical launchers, pre-oriented to aim at whatever the launching ship has locked its nose-mounted railguns on. At launch, the artillery pack activates its short burning UDMH DNTO motors that push it clear of the launching ship even as it manoeuvres, then rapidly fires off 6 launch containers and corresponding 6 frangible countermasses to balance the recoil, then self-destructs. Each launch container then serves as the kick-stage for an unguided ballistic trajectory shell: and, together with the rest of the launch system, endows it with relative velocity of around 4.5km/s.
A single salvo from all three launchers consists of 18 such shells, each massing 35kg the majority of which is comprised of variety of kinetic submunitions: - blast launched 2km/s penetrators hopefully killing some vital subsystems
- a ring of 6 unfolding 10m transverse continuous osmium rods inflicting severe structural damage to the hull and internals beneath, possibly breaking the target up
- cloud of micro-flak bomblets and a single large-ish follow up flak bomb damaging whipple shielding and stripping off radiators
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Post by AtomHeartDragon on Feb 8, 2019 14:55:45 GMT
Dunno if this is still open. Take my fuck-off coilgun. I find your gun's mass and heat jump conspicuously absent from your screenshot (but the acceleration curve alone indicates pretty well that it is a b0rkgun).
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