|
Post by bigbombr on Oct 30, 2017 5:49:58 GMT
An interesting thread, though 13 pages is too much for me to parse at present. I have not played the game enough to get into the fray in terms of "what weapon systems" seem particularly effective. A quick glance at the thread suggests to me that that is the main theme of the discussion, and the possibly unusual argument I'd like to make is that: The question posted in the OP is different. "What will become the main dominant of future space battle?" Even assuming that the simulation is accurate (which is a fair foundational assumption) tech, and seat of the pants tactics based on tech can only ever answer part of such a question. Tech, and the tactical opportunities and constraints it affords inform such questions, but history suggests that the answers to such questions emerge from how social entities--if not specific leaders--appraise and act on those opportunities and constraints. Social entities and specific leaders are always primarily explicable (though not completely explicable) in terms of their developmental context. To select one recent period characterized by tremendous innovation and change, and also a great variety of warfare: the flintlock and the myriad types of cannon were crucial to how wars in mid 18th through mid 19th centuries were fought (a period that includes the American Revolutionary War, the Seven Years War, the Napoleonic Wars, the War of 1812. But the nature of these technologies, and the common doctrines that pervaded is insufficient to understand the variety of wars of the period. To gain an understanding one must delve into the meat of history in all its subtleties, paradoxes and (in hindsight) apparent lapses of rationality by nearly everyone in positions of authority. Take for example, the "Ferguson Rifle". This was a breach-loading design, possibly the very first practically useful one and certainly one of the very first to be used in military service. At the time, almost all firearms (including small arms and cannon) were muzzle loaded: charge, packing and shot were rammed down the barrel of the weapon from the muzzle. This placed a hard cap on the fastest possible reload time of such weapons, thus a hard cap on how fast even the most crack veteran regiments could unleash salvos. New recruits were slower, but not dramatically so, and with sufficient drill and one battle under their belt, most soldiers could rapidly achieve "maximal" rate of fire. Muzzle loaders had many effects that rippled through how combat unfolded and how wars were fought, but among the other notable factors: the necessity of ramming the projectile and charge down the barrel made rifling impractical. Rifled muskets were uncommon, thought not exactly rare, and were in fact the preferred weapon among most frontier dwellers where killing an adversary or critter with a single shot and at considerable range were appealing goals. But for a regiment of soldiers, the much slower rate of reloading did not _seem_ to most military thinkers at the time to be a reasonable tradeoff for the increased accuracy afforded by rifling. The other factor of note was that a muzzle-loaded weapon was best reloaded from a standing or at most a kneeling posture. Loading one while prone throughout the entire loading cycle was more or less impossible and indeed, even performing the ramming and priming latter stages of the cycle while prone was problematic. The guns were designed to be loaded with the muzzle upright and doing it any other way posed a risk of a misfire or worse. The Ferguson Rifle (and breach loaders in general) did not suffer several of these deficiencies. Because of the charge was added and the fact there was no need to ram the load down the barrel, the weapon could be reloaded almost as easily from a prone or semi-prone position as from a standing posture. Also, rifled barrels would have been much more feasible for a weapon like the Ferguson, though I'm not certain if those were a part of the actual weapon in its limited prototype use in the American Revolutionary War (ARW). As the wiki explains As a point of comparison, the Brown Bess muzzle loader (which was the most common weapon used in the ARW) could only manage 3 to 4 rounds per minute. Now we are all gamers who have the benefit of hindsight and even if you are not a student of 19th and 20th century warfare, we are all probably aware at least in vague terms that (a) high accuracy at long range, i.e., rifled barrels; and (b) higher rates of fire, are almost universally desirable in warfare. Nonetheless, the Ferguson Rifle saw only very limited action in the ARW. As far as I'm aware, breach loaders of various designs crop up at various points throughout the 19th century and their impact was repeatedly the same: treated as an expensive novelty and regarded with incredulity. It was not until the American Civil War and the Sharps Repeating rifle that the clear battlefield dominance of the breach loader became clear and from that point on the muzzle loader was obsolete, and avoided by all war planners and war fighters ever since. Had British leadership been sensible, rational and at least marginally receptive to innovation in the 1770s, they might have recognized the tremendous potential of small units of Ferguson rifle equipped sniper/skirmishers and equipped enough of them to deploy them as supplements to standard musket and grenadier units and moreover, adopt some of the "less honorable" tactical doctrines of ambush, hit-and-run and sniping which the rebels used to great effect. One would presume that the British Empire, quite possible the greatest empire the world had ever seen up to that point (and arguably still to this day given their language and much of their core culture have become the language and culture of the Internet! ) would have the good sense to adapt its doctrines or rather its dogmas, as well as its logistics, tactics and strategy in a rational way. Fighting the Colonial rebellion in the same way they had fought in the Seven Years War, or any other conventional war in Europe seems pretty foolish from our perspective, but that is what they did and that, quite simply is why they lost. They showed up expecting a largely deforested agrarian landscape, with ample roads and abundant small communities dotting the landscape at short intervals and where massive cavalry charges and "set-piece" battles like those which prevailed in the battlefields of Prussia in the preceding years would determine the outcome of the war. The war they found was not what they came prepared to fight and they got bogged down and eventually lost. All of this to say: I believe that what COADE has done is to provide us with an invaluable model of how one critical aspect of near-future space warfare--or at least ship-to-ship combat off Earth--might be opportuned and constrained by technology. This is a laudable contribution both to gamer culture, to gaming and to history and military science. I'm disappointed to see the game has not drawn more attention than it seems to have drawn. But for all the edification and entertainment it offers, I don't think the game is (in its present form) sufficient to judge "the main dominant of future space battle?" So much will depend on the financial factors that finally click and compel the very first business enterprises of dramatic scale, meaning profits so impressive that they are a watershed in history and will subsequently be identified as the beginning of a new, rapid and frenetic Space Rush in which myriad players on Earth scramble to get their piece of the loot from outer space. In order to stay true to its objective: to produce a simulation of space combat that was not misled by any specific "vision" the game has achieved its goal, but also failed to address likely or tenable broader contexts. I became aware of this game based on a response in a thread I started in a forum full of old crusty Grognards of questionable ilk, and here is what the person who brought COADE into the discussion had to say at one point: Having played the game a good bit now, I think that is a very fair and accurate synthesis, and I hope no one regards it, or the position I'm taking as criticism, much less undue criticism of COADE. The game is delightful, well-made, remarkable! Moreover, it has dutifully fulfilled its objective: to model space-based combat with as conservative and hard-science fiction as possible. But the nitty-gritty details of space combat, or rather one model of them which makes as few assumptions as possible about broader context, are only part of the scope for answering what will be the future dominant in space warfare. I largely agree. Every module, from railguns (long term barrel ablation?) to radiators (heat gradient? coolant pressure? coolant mass?) is oversimplified. And coolant piping, electrical wiring, communication, sensors, structural integrity and much more isn't taken into account at all. But it's much better than rampant speculation.
|
|
|
Post by Kerr on Oct 30, 2017 7:09:00 GMT
matterbeamThis assumes that the missiles themself have to catch the target, this changes if you are already at low relative velocity to the target. Or if the missiles don't catch the target but instead they ambuscade the target. And missiles can still be disposable at higher tech levels, Metallic hydrogen and Metastable helium allow for advanced nuclear thermal core performance, and Antimatter Catalyzed fusion allows torch missiles to consist out of only an pellet injector, and bladeshield with a magnetic coil in it, a power source/generator, and a micro trap array filled with a few micrograms of antimatter. An simple 200kT Solar station in Sun orbit can put of 50 kilotons worth of AIM Fuel daily. Your Whipple-PDW missiles are expendibles, instead of carrying a heavy whipple shield you could carry hours worth of sand for your sandblaster. It also gets problematic as soon as the missiles are carrying warheads. Me neither, but the Laser weapon calculator is still there? Have you tried using the link on "Online Calculators" at Atomic Rockets? Or tried different platforms? Add vapor pressur and mechanical stress and you have the way how Luke Campbells Calculator calculates laser damage. And seriously, if my 1GW fires for one second and covers 2.43m², 411MJ/m² it won't be just vaporizing 0.5mm worth of aluminium, that's 1.35kg aluminium heated up to 300MJ/kg. And last time I checked aluminium doesn't vaporizes at 300,000K. That may be true, but even the unfocused Futuristic Casaba produces 0.28km² at 300Mm, that's 3GJ/m² applied in roughly a microsecond. That's your entire ship covered with 38cm TNT. And if you try to aim for longer distances the travel times get absurd and the spears of nuclear fire get easily avoidable.
|
|
|
Post by matterbeam on Oct 30, 2017 13:41:00 GMT
matterbeam This assumes that the missiles themself have to catch the target, this changes if you are already at low relative velocity to the target. Or if the missiles don't catch the target but instead they ambuscade the target. And missiles can still be disposable at higher tech levels, Metallic hydrogen and Metastable helium allow for advanced nuclear thermal core performance, and Antimatter Catalyzed fusion allows torch missiles to consist out of only an pellet injector, and bladeshield with a magnetic coil in it, a power source/generator, and a micro trap array filled with a few micrograms of antimatter. An simple 200kT Solar station in Sun orbit can put of 50 kilotons worth of AIM Fuel daily. Your Whipple-PDW missiles are expendibles, instead of carrying a heavy whipple shield you could carry hours worth of sand for your sandblaster. It also gets problematic as soon as the missiles are carrying warheads. Me neither, but the Laser weapon calculator is still there? Have you tried using the link on "Online Calculators" at Atomic Rockets? Or tried different platforms? Add vapor pressur and mechanical stress and you have the way how Luke Campbells Calculator calculates laser damage. And seriously, if my 1GW fires for one second and covers 2.43m², 411MJ/m² it won't be just vaporizing 0.5mm worth of aluminium, that's 1.35kg aluminium heated up to 300MJ/kg. And last time I checked aluminium doesn't vaporizes at 300,000K. That may be true, but even the unfocused Futuristic Casaba produces 0.28km² at 300Mm, that's 3GJ/m² applied in roughly a microsecond. That's your entire ship covered with 38cm TNT. And if you try to aim for longer distances the travel times get absurd and the spears of nuclear fire get easily avoidable. If the missiles are deployed without enough deltaV to catch targets, then they are limited to a narrow range of tactical options. For example, your opponent can avoid ever building up a high relative velocity to you, make their insertion burns at the edge of the planets, creep into combat instead of swooping in... it basically gives your opponent the ability to negate that weapon system entirely! Even if battle tactics revolve around forcing a high speed pass to make missiles worthwhile, the missiles will still need enough deltaV to match the displacement of a target spaceship that turns 90 degrees and burns as hard as possible laterally. This means a performance of higher power to weight ratio than the target spaceship. This becomes difficult to achieve when your targets have, for example, the same antimatter catalyzed fusion reactors and metallic hydrogen emergency boosters. The laser weapon calc is back online - I think the Wayback machine website was down for maintenance. I've had a look at the Armor rating and Armor hardness to find this experimentally: Armor hardness determines the penetration rate, while the armor rating is a yes/no check on whether the intensity of the laser is high enough to create impulse shock. Impulse shock here is taken as enough energy deposited on a small enough surface to create supersonic shockwaves in the target material. The quadrupole-focused Casaba Howitzers allows for smaller nuclear yields to be effective at the same ranges as the larger ones - this is especially important when the Casaba Howitzers are being mounted on missiles. You want the warhead to be as lightweight as possible while increasing the stand-off firing range as much as possible. For example, a futuristic 'nuclear lance' might get a directivity of 0.1 milliradians or 0.00057 degrees. At a fusion-driven 3000km/s particle velocity, we can calculate the spread as much as 30 meters over 3000km. The spread velocity is 30m/s. If the quadrupole lens can reduce this spread velocity to 3m/s, then the directivity is increased to 0.000057 degrees. It will have 100 times the penetration capability of another warhead of the same yield - in other words, you can substitute a a 10kt yield warhead for a 1Mt yield one. Also, this method of focusing a Casaba Howitzers allows you to use the high efficiency propulsion-configuration pulse charges (85%) and focus them as if they were warheads and gain a (0.85/0.05): 17x penetration rate for the same yield. With multiple quadrupole focusing stages and a wide-angle Casaba Howitzer, you can easily get 85% efficiency and microradian directivity. A 1kt warhead becomes as powerful as a 1Mt warhead.
|
|
|
Post by Kerr on Oct 30, 2017 15:55:06 GMT
matterbeam This assumes that the missiles themself have to catch the target, this changes if you are already at low relative velocity to the target. Or if the missiles don't catch the target but instead they ambuscade the target. And missiles can still be disposable at higher tech levels, Metallic hydrogen and Metastable helium allow for advanced nuclear thermal core performance, and Antimatter Catalyzed fusion allows torch missiles to consist out of only an pellet injector, and bladeshield with a magnetic coil in it, a power source/generator, and a micro trap array filled with a few micrograms of antimatter. An simple 200kT Solar station in Sun orbit can put of 50 kilotons worth of AIM Fuel daily. Your Whipple-PDW missiles are expendibles, instead of carrying a heavy whipple shield you could carry hours worth of sand for your sandblaster. It also gets problematic as soon as the missiles are carrying warheads. Me neither, but the Laser weapon calculator is still there? Have you tried using the link on "Online Calculators" at Atomic Rockets? Or tried different platforms? Add vapor pressur and mechanical stress and you have the way how Luke Campbells Calculator calculates laser damage. And seriously, if my 1GW fires for one second and covers 2.43m², 411MJ/m² it won't be just vaporizing 0.5mm worth of aluminium, that's 1.35kg aluminium heated up to 300MJ/kg. And last time I checked aluminium doesn't vaporizes at 300,000K. That may be true, but even the unfocused Futuristic Casaba produces 0.28km² at 300Mm, that's 3GJ/m² applied in roughly a microsecond. That's your entire ship covered with 38cm TNT. And if you try to aim for longer distances the travel times get absurd and the spears of nuclear fire get easily avoidable. If the missiles are deployed without enough deltaV to catch targets, then they are limited to a narrow range of tactical options. For example, your opponent can avoid ever building up a high relative velocity to you, make their insertion burns at the edge of the planets, creep into combat instead of swooping in... it basically gives your opponent the ability to negate that weapon system entirely! Even if battle tactics revolve around forcing a high speed pass to make missiles worthwhile, the missiles will still need enough deltaV to match the displacement of a target spaceship that turns 90 degrees and burns as hard as possible laterally. This means a performance of higher power to weight ratio than the target spaceship. This becomes difficult to achieve when your targets have, for example, the same antimatter catalyzed fusion reactors and metallic hydrogen emergency boosters. The laser weapon calc is back online - I think the Wayback machine website was down for maintenance. I've had a look at the Armor rating and Armor hardness to find this experimentally: Armor hardness determines the penetration rate, while the armor rating is a yes/no check on whether the intensity of the laser is high enough to create impulse shock. Impulse shock here is taken as enough energy deposited on a small enough surface to create supersonic shockwaves in the target material. The quadrupole-focused Casaba Howitzers allows for smaller nuclear yields to be effective at the same ranges as the larger ones - this is especially important when the Casaba Howitzers are being mounted on missiles. You want the warhead to be as lightweight as possible while increasing the stand-off firing range as much as possible. For example, a futuristic 'nuclear lance' might get a directivity of 0.1 milliradians or 0.00057 degrees. At a fusion-driven 3000km/s particle velocity, we can calculate the spread as much as 30 meters over 3000km. The spread velocity is 30m/s. If the quadrupole lens can reduce this spread velocity to 3m/s, then the directivity is increased to 0.000057 degrees. It will have 100 times the penetration capability of another warhead of the same yield - in other words, you can substitute a a 10kt yield warhead for a 1Mt yield one. Also, this method of focusing a Casaba Howitzers allows you to use the high efficiency propulsion-configuration pulse charges (85%) and focus them as if they were warheads and gain a (0.85/0.05): 17x penetration rate for the same yield. With multiple quadrupole focusing stages and a wide-angle Casaba Howitzer, you can easily get 85% efficiency and microradian directivity. A 1kt warhead becomes as powerful as a 1Mt warhead. The example was rather meant for an enemy spacecraft that was already moving at high speed. No it doesn't mean a higher power to mass ratio, first off, your missiles can have a fraction of the Delta-v as the target does. Your target doesn't want to burn all it's fuel for a single swarm of missiles. And it needs to use half of its fuel to slow down again. And they would most likely have an better propulsion system as my missile otherwise there arrise problems. Outrunning is, if fusion is availible for both missiles and ships, not econimical. Let's say the target has comparable acceleration capabilities as the missiles and also have twice the exhaust velocity. If the enemy ship has 600km/s it can outrun the 300km/s missiles, but at the cost of having to use the remaining 300km/s to slow down. Both missile and ship have the same mass ratios. Isp's, ship 1.2e5, missile 6e4. Using pure fusion allows over an magnitude better Delta-v for the ships, but then they need very high power to weight ratios to have enough acceleration. And in my opinion, a ship that had to use most of it's delta-v is as bad as a ship that has a destroyed armor or broken weapon systems. Both need time and money to restore. The increased range sounds doesn't sound that useful, because of the relatively long travel times the beams have dodging becomes a possiblity. But the use of quadrople-focusing sounds interesting with high efficiency casaba units. Which could give the same Casaba Howitzer 4-8x bigger blast areas at the same areal energy density. 1kT huh? 1 microgram antimatter and 100g LiD and you have an 1kT explosion. Laser-ranged Casaba Howitzers the size of an football and weighing only 5-10kg? Neat. I also made a little analysis on your pellet guns, compared to an comparable FEL. The results showed that an FEL laser requires 7x more mass. That it needed 3x as much energy, and that it requires 4x as much radiator area. While also only putting out 40% less energy per second compared to the same 1GW Pellet Gun. 950MW Kinetic Energy vs. 650MW Laser energy, note that kinetic damage is more efficient than laser damage to make matters worse. The only "problem" that remains is that your 90m 3100km/s Pellet Gun produces whooping 5e10m/s² of acceleration!
|
|
|
Post by matterbeam on Oct 30, 2017 22:04:23 GMT
The example was rather meant for an enemy spacecraft that was already moving at high speed. No it doesn't mean a higher power to mass ratio, first off, your missiles can have a fraction of the Delta-v as the target does. Your target doesn't want to burn all it's fuel for a single swarm of missiles. And it needs to use half of its fuel to slow down again. And they would most likely have an better propulsion system as my missile otherwise there arrise problems. Outrunning is, if fusion is availible for both missiles and ships, not econimical. Let's say the target has comparable acceleration capabilities as the missiles and also have twice the exhaust velocity. If the enemy ship has 600km/s it can outrun the 300km/s missiles, but at the cost of having to use the remaining 300km/s to slow down. Both missile and ship have the same mass ratios. Isp's, ship 1.2e5, missile 6e4. Using pure fusion allows over an magnitude better Delta-v for the ships, but then they need very high power to weight ratios to have enough acceleration. And in my opinion, a ship that had to use most of it's delta-v is as bad as a ship that has a destroyed armor or broken weapon systems. Both need time and money to restore. The increased range sounds doesn't sound that useful, because of the relatively long travel times the beams have dodging becomes a possiblity. But the use of quadrople-focusing sounds interesting with high efficiency casaba units. Which could give the same Casaba Howitzer 4-8x bigger blast areas at the same areal energy density. 1kT huh? 1 microgram antimatter and 100g LiD and you have an 1kT explosion. Laser-ranged Casaba Howitzers the size of an football and weighing only 5-10kg? Neat. I also made a little analysis on your pellet guns, compared to an comparable FEL. The results showed that an FEL laser requires 7x more mass. That it needed 3x as much energy, and that it requires 4x as much radiator area. While also only putting out 40% less energy per second compared to the same 1GW Pellet Gun. 950MW Kinetic Energy vs. 650MW Laser energy, note that kinetic damage is more efficient than laser damage to make matters worse. The only "problem" that remains is that your 90m 3100km/s Pellet Gun produces whooping 5e10m/s² of acceleration! The power to weight ratio, the deltaV capacity, the performance... all I'm referring to is the following equivalence: Say the distance between missile launcher and target is D. The target has an acceleration capability of AT. The missile has an acceleration capability of AM and a total deltaV of DV. DV is divided into DVC for adding to the closing velocity, and DVM for combat maneuvers. We need AM>AT. This is where the 'missiles are more powerful per kg than spaceships' requirement comes from. Continuing The target will accelerate to a velocity VT after thrusting continuously at AT for a time T. So, VT=AT*T. T is equal to the distance D divided by the closing velocity DVC. So, VT=AT*D/DVC The missile's deltaV reserve DV must be divided between adding to DVC or countering the target's VT. Increasing DVC will give the target less time to maneuver, so VT decreases. However, DVM must exceed VT or else the target will escape the missile, but increasing DVM cuts into the DVC reserve. Putting all these equations together, we get DVM>AT*D/DVC So DVM*DVC>AT*D However, we know that DVM+DVC=DV, so DVM and DVC can only be fractions of DV. We wish to maximize the AT*D envelope that the missile can match or exceed, so the best solution is DVM=0.5 and DVC=0.5, or half of the missile's deltaV capacity each. For example, a 10km/s deltaV missile can cover an AT*D envelope of 25000000m^2/s^2 if it divided its DVM and DVC half-half. This corresponds to a 1.02G target at 2500km. If the deltaV was split 20% for DVM and 80% for DVM, the envelope would be reduced to 16000000m^2/s^2. It would only be able to handle a 1.02G target at 1600km... However, there are complications. You want to minimize the time the missile spends floating in empty space. So, skewing the DVM/DVC balance towards DVM is recommended. Also, the spaceship might start accelerating in any number of directions away from the missile. This brings up the difference between AT and AM. Every m/s the target imparts in the same direction as the missile is removed from the DVM, so again we prefer having excess DVM. If your targets' AT is 50% of your missile's AM, then up to 50% of the DVM you carry onboard will be negated by the target. These consideration interestingly pop up in jet fighter combat. It is why for example a jet fighter at Mach 1.5 and turning at 9G might have a chance against a missile that boosts to Mach 4 and turns at 20G, by simply producing an AT*D combination that exceeds the missile's envelope. There's also the fact that missile is travelling so fast that turning at 40G at Mach 4 produces larger turning radiuses than a jet fighter turning at 10G at Mach 1. You mention the target not being able to dodge because it has to spend double deltaV to cancel its lateral movement. In practice, it will use high-thrust engines for the initial impulse and then spend longer with high Isp engines after the missiles have passed. Your FEL vs Pellet gun analysis is clouded by the fact that we don't have a concrete determination of the masses of either weapon, and that while the FEL produces more waste heat due to its lower overall efficiency... a lot of that waste heat is ejected at relatively warm temperatures. The Pellet gun needs to be cryogenically cooled to maintain superconductivity, and I have already demonstrated the massive energy penalty needed to run heat pumps powerful enough to suck up megawatts of waste heat against a temperature gradient that starts at <100K. A pellet gun firing a 1 gram projectile at 3100km/s produces 3100kgm/s of momentum. On a 1000 ton spaceship, it is enough impulse to add... 3.1mm/s of velocity.
|
|
|
Post by Kerr on Oct 31, 2017 21:13:00 GMT
The example was rather meant for an enemy spacecraft that was already moving at high speed. No it doesn't mean a higher power to mass ratio, first off, your missiles can have a fraction of the Delta-v as the target does. Your target doesn't want to burn all it's fuel for a single swarm of missiles. And it needs to use half of its fuel to slow down again. And they would most likely have an better propulsion system as my missile otherwise there arrise problems. Outrunning is, if fusion is availible for both missiles and ships, not econimical. Let's say the target has comparable acceleration capabilities as the missiles and also have twice the exhaust velocity. If the enemy ship has 600km/s it can outrun the 300km/s missiles, but at the cost of having to use the remaining 300km/s to slow down. Both missile and ship have the same mass ratios. Isp's, ship 1.2e5, missile 6e4. Using pure fusion allows over an magnitude better Delta-v for the ships, but then they need very high power to weight ratios to have enough acceleration. And in my opinion, a ship that had to use most of it's delta-v is as bad as a ship that has a destroyed armor or broken weapon systems. Both need time and money to restore. The increased range sounds doesn't sound that useful, because of the relatively long travel times the beams have dodging becomes a possiblity. But the use of quadrople-focusing sounds interesting with high efficiency casaba units. Which could give the same Casaba Howitzer 4-8x bigger blast areas at the same areal energy density. 1kT huh? 1 microgram antimatter and 100g LiD and you have an 1kT explosion. Laser-ranged Casaba Howitzers the size of an football and weighing only 5-10kg? Neat. I also made a little analysis on your pellet guns, compared to an comparable FEL. The results showed that an FEL laser requires 7x more mass. That it needed 3x as much energy, and that it requires 4x as much radiator area. While also only putting out 40% less energy per second compared to the same 1GW Pellet Gun. 950MW Kinetic Energy vs. 650MW Laser energy, note that kinetic damage is more efficient than laser damage to make matters worse. The only "problem" that remains is that your 90m 3100km/s Pellet Gun produces whooping 5e10m/s² of acceleration! The power to weight ratio, the deltaV capacity, the performance... all I'm referring to is the following equivalence: Say the distance between missile launcher and target is D. The target has an acceleration capability of AT. The missile has an acceleration capability of AM and a total deltaV of DV. DV is divided into DVC for adding to the closing velocity, and DVM for combat maneuvers. We need AM>AT. This is where the 'missiles are more powerful per kg than spaceships' requirement comes from. Continuing The target will accelerate to a velocity VT after thrusting continuously at AT for a time T. So, VT=AT*T. T is equal to the distance D divided by the closing velocity DVC. So, VT=AT*D/DVC The missile's deltaV reserve DV must be divided between adding to DVC or countering the target's VT. Increasing DVC will give the target less time to maneuver, so VT decreases. However, DVM must exceed VT or else the target will escape the missile, but increasing DVM cuts into the DVC reserve. Putting all these equations together, we get DVM>AT*D/DVC So DVM*DVC>AT*D However, we know that DVM+DVC=DV, so DVM and DVC can only be fractions of DV. We wish to maximize the AT*D envelope that the missile can match or exceed, so the best solution is DVM=0.5 and DVC=0.5, or half of the missile's deltaV capacity each. For example, a 10km/s deltaV missile can cover an AT*D envelope of 25000000m^2/s^2 if it divided its DVM and DVC half-half. This corresponds to a 1.02G target at 2500km. If the deltaV was split 20% for DVM and 80% for DVM, the envelope would be reduced to 16000000m^2/s^2. It would only be able to handle a 1.02G target at 1600km... However, there are complications. You want to minimize the time the missile spends floating in empty space. So, skewing the DVM/DVC balance towards DVM is recommended. Also, the spaceship might start accelerating in any number of directions away from the missile. This brings up the difference between AT and AM. Every m/s the target imparts in the same direction as the missile is removed from the DVM, so again we prefer having excess DVM. If your targets' AT is 50% of your missile's AM, then up to 50% of the DVM you carry onboard will be negated by the target. These consideration interestingly pop up in jet fighter combat. It is why for example a jet fighter at Mach 1.5 and turning at 9G might have a chance against a missile that boosts to Mach 4 and turns at 20G, by simply producing an AT*D combination that exceeds the missile's envelope. There's also the fact that missile is travelling so fast that turning at 40G at Mach 4 produces larger turning radiuses than a jet fighter turning at 10G at Mach 1. You mention the target not being able to dodge because it has to spend double deltaV to cancel its lateral movement. In practice, it will use high-thrust engines for the initial impulse and then spend longer with high Isp engines after the missiles have passed. Your FEL vs Pellet gun analysis is clouded by the fact that we don't have a concrete determination of the masses of either weapon, and that while the FEL produces more waste heat due to its lower overall efficiency... a lot of that waste heat is ejected at relatively warm temperatures. The Pellet gun needs to be cryogenically cooled to maintain superconductivity, and I have already demonstrated the massive energy penalty needed to run heat pumps powerful enough to suck up megawatts of waste heat against a temperature gradient that starts at <100K. A pellet gun firing a 1 gram projectile at 3100km/s produces 3100kgm/s of momentum. On a 1000 ton spaceship, it is enough impulse to add... 3.1mm/s of velocity. Thank your for the time you have taken to explain this to me, it isn't exactly what I meant but close enough to end this little discussion about my idea of performance dynamics between torch missiles and torch ships. My point was just that missiles would in most likelihood be acceleration orientated, but this adds an effective range to missile, as a function of the targets acceleration. To minimize the problem of downscaling inefficiencies missiles buses or missile drones would be used. I mentioned that it would be not economical to outrun a missile with Dv and acceleration on roughly the same magnitude. And what I mean by that is that outrunning missiles should only be considered if the missiles pose a significant thread to the target ship. And what parts to produce "high/medium" heat? I can only think of the optical cavity mirrors. The actual problem is that I treated the efficiency of FEL as Electricity > Kinetic (Electron Beam) > Optical/Electromagnetic. Which apparently can't be as I recently stumbled upon a chart of an 1MW FEL Airborne laser with 3MW Input and 2 MW Waste Heat, which correlates to a Wall-plug efficiency of 33%, although the specific power, even after removing space-weapon non important parts I got pathetic 14W/kg, neat for an lightly armored and highly explosive ICBM but not so much for an actual space-grade weapon. I assume that specific beam powers of 1kW/kg could become possible as soon as space warfare becomes possible as depicted in CDE, even if one a much lower scale. But Including Casaba Howitzers in the game shifts the focus back to missiles, as they have enormous damage potential compared to an 100ton/100MW FEL. Maybe if you have an way to pump up the frequency an Gyrotron would be nice thing to have, they seem a bit more matured at this point, but they can only produce microwaves-soft infrared. I referred to the acceleration of the projectile not the ship. How could anyone get to 5e10m/s acceleration for a multi-hundred ton object accelerated by an 2µg projectile moving at 3100km/s? with an impulse of 6.2kg-m/s?
|
|
|
Post by 𝕭𝖔𝖔𝖒𝖈𝖍𝖆𝖈𝖑𝖊 on Oct 31, 2017 22:29:16 GMT
Missiles have an distinct advantage over lasers and EM Guns in actual combat, you don't have to engage your enemy directly. Would you risk your live to get a few lucky shots with your laser if missiles can do the job without endangering you and your crew? Missile Warheads can come in several flavours. KKV: Keep it simple stupid. Flak: Hit me if you can. Nuclear: Everyone loves the smell of molten hulls in the morning. Casaba: Crude particle accelerator powered by nuclear destruction Mirror: It would be a pity if your 500GW FEL would just gather just. Missile delta-v becomes less relevant as ship delta-v increases, if you want to destroy that quick missile boat moving at 435km/s relative to you, you wouldn't use an missile with a delta-v of +435km/s, but use missiles as kirklin mines. For those who don't know what a kirklin mine is, they are some objects which just happen to be in the way of the ship, Preferbly cold and coated to be "stealthy", to use the ships velocity against them, which is a reason why hydrogen steamer could remain viable even with nuclear pulse/fusion propulsion. The more important factor is often how small you can make your missile. At sufficiently high tech levels your PDW weapons will be capable of nearly instantly elimating any thread. Against kinetic PDW's cross-section is important, if you make your missile twice as long but half as wide your survibility just doubled. This also applies somewhat to Laser PDW's. But usually more important is how light you can make your missile. If your armored missiles weights 50% more than their light/non armored missile then they have to survive 50% to pay of the increase in mass. The thing that limits the minimum size of a missile is it sensory and computing equipment. The later can be partially fixed by using a network with the other missiles to maximize computional power. The former depends on how good can a sensor become and what kind of target you have. But something as low as 5kg can work, even if it a bit hard. Casaba Howitzer Warhead could remove the need of micromissiles by instead supplying long-ranged spears of nuclear fire. Example: matterbeam futuristic Casaba Howitzer: Efficiency: 20% Directivity: 0.1mrad Energy: 830TJ Yield: 1MT Matterbeam used the "Laser Weapon Calculator" with the following results against aluminium: 10Mm: 20m diameter, 291mm (Penetration) 50Mm: 100m diameter, 2.33mm After using the calculator I saw something... odd, 30419MW/cm² Armor rating for aluminium, I am no Luke Campbell, but I think Aluminium can't survive 300TW/m² or whatever armor rating means. So I have gone to Luke Campbells Laser Calculator. With the following results. 100Mm: 200m diameter, 6.1m Alumnium, 50cm CNT. 300Mm: 600m diameter, 0.74m Alumnium, 6.56cm CNT. The results show that the Casaba Howitzer is actually more long-ranged than expected. (Matterbeam, history repeats itself.) What does that means? In the endless discussions with matterbeam back in the day he suggested that the futuristic Casaba Howitzer could mass as low as 250kg. Let's assume a world where Fusion propulsion is widespread, lasers hit the light-lag limit and can produce hundreds of gigawatt of power for Dreadnaughts (~100kt). Torch Missiles massing at about 500kg carrying 200kg fuel and 300km/s of Dv will be able to carry an 1MT Casaba Warhead, using maximum focus the warhead will cover an area of 0.28km², the target is an laser star with 5cm CNT armor. The beam will travel 30-20s to the target. The ship has enough time to dodge the beam with its powerful engines, problem is, the missile isn't alone and dozens of other casabas covered every direction with nuclear fire. The momment the beam hits the entire armor, every turret, every radiator not in the ships shadow is vaporized. The inner compartments survived due to the armor, but the plasma created from the armor damaged many crucial system. The Laser star is unable to fight on, nor to move, nor to sustain life support for the surviving crew members much longer. the problem with this agrument is that , with some of the guns we do use, we could engage targets at longer distances than a lot of the missiles.
|
|
|
Post by matterbeam on Nov 1, 2017 0:49:19 GMT
Thank your for the time you have taken to explain this to me, it isn't exactly what I meant but close enough to end this little discussion about my idea of performance dynamics between torch missiles and torch ships. My point was just that missiles would in most likelihood be acceleration orientated, but this adds an effective range to missile, as a function of the targets acceleration. To minimize the problem of downscaling inefficiencies missiles buses or missile drones would be used. I mentioned that it would be not economical to outrun a missile with Dv and acceleration on roughly the same magnitude. And what I mean by that is that outrunning missiles should only be considered if the missiles pose a significant thread to the target ship. And what parts to produce "high/medium" heat? I can only think of the optical cavity mirrors. The actual problem is that I treated the efficiency of FEL as Electricity > Kinetic (Electron Beam) > Optical/Electromagnetic. Which apparently can't be as I recently stumbled upon a chart of an 1MW FEL Airborne laser with 3MW Input and 2 MW Waste Heat, which correlates to a Wall-plug efficiency of 33%, although the specific power, even after removing space-weapon non important parts I got pathetic 14W/kg, neat for an lightly armored and highly explosive ICBM but not so much for an actual space-grade weapon. I assume that specific beam powers of 1kW/kg could become possible as soon as space warfare becomes possible as depicted in CDE, even if one a much lower scale. But Including Casaba Howitzers in the game shifts the focus back to missiles, as they have enormous damage potential compared to an 100ton/100MW FEL. Maybe if you have an way to pump up the frequency an Gyrotron would be nice thing to have, they seem a bit more matured at this point, but they can only produce microwaves-soft infrared. I referred to the acceleration of the projectile not the ship. How could anyone get to 5e10m/s acceleration for a multi-hundred ton object accelerated by an 2µg projectile moving at 3100km/s? with an impulse of 6.2kg-m/s? Missile dynamics, with complicating factors such as missile busses and armoring, should be discussed in a proper thread. FEL is a special case because it relies on cryogenically cooled magnets both for the electron accelerators and the wiggler. The energy input part is directly comparable to a particle accelerator or less complex pellet gun. All other lasers operate a high temperature. For most, it is a bad thing, as the M^2 value increases drastically with temperature. For fibre lasers, M^2 value is independent from temperature, so you can run 'hot': 500, 600K? A Gyrotron is a good example of existing 1kW/kg laser technology. Frequency doubling can make it useful in space - two 88% efficient frequency doublers in a row can convert a 1000nm beam into a 250nm ultraviolet weapon at the cost of wasting 22.6% of the beam. If you mean how you would accelerate a projectile to 3100km/s within a short distance of 90 meters, then you'd need a g-force of 5.44 billion. Applied to a 1 microgram projectile, it is a force of 53.4kN. To a 1gram projectile, it is 53.4MN. Using the equations by Luke Campbell here, I get there 90m coilguns: Microgram projectile. Stretched into a disk 1cm wide (this favours very lightweight yet strong materials) Field energy 4.8MJ 41 Tesla field across 90 meters Gram projectile Stretched into a disk 10cm wide Field energy 4.8GJ 1302 Tesla field across 90 meters. To make reasonable coilguns, you need to make them long and with large bores.
|
|
|
Post by SevenOfCarina on Nov 1, 2017 1:36:53 GMT
matterbeam , what are the implications of different fusion rocket fuels as far as missile-warship engagements are concerned? Most warships with terawatt-grade drives will be extremely concerned with minimizing neutron radiation and the like, so there are understandably only two reasonable options - D-He3 or p-B11, both of which offer fairly unremarkable specific impulses. As far as I understand, in order to minimize radiation from side D-D reactions in D-He3 fusion, the use of spin-polarized(?) He3 is necessitated, which apparently kills exhaust velocity. p-B11 fusion's high ignition temperature necessitates stupid huge particle accelerators and picosecond laser drivers, which eat heavily into the mass budget. Warship fusion rockets, thus, will probably have a lowish specific power, with a significant amount of mass dedicated to radiation shielding. On the other hand, D-T fusion is easily ignited and requires lower drive mass, is highly energetic with a fairly good exhaust velocity, but throws out a metric crapload of neutron radiation and bremsstrahlung. D-D fusion catalyzed(?) to result in the full burn-up of the synthesized He3 and T with more D also looks like a good bet. Both of the latter reactions appear to be decent candidates for missile drives, particularly if shell fusion is utilized to increase thrust, or if cold propellant is heated from the generated neutron and bremsstrahlung radiation and thrown out the back. Considering missile buses are unlikely to operate for days, issues arising from neutron activation and embrittlement can hopefully be ignored. Missile drives can also be optimized for performance at the cost of long-term operational reliability. All of these combine to imply that missile fusion rockets will likely have much higher specific power(?) than warship fusion rockets, although I can't tell how much, or if efficiency losses will offset any gain. Potentially, torch missiles and drones could outrun and outmanoeuvre warships. Note that I haven't done the math, so I'm probably horrendously wrong.
|
|
|
Post by matterbeam on Nov 1, 2017 9:48:06 GMT
matterbeam , what are the implications of different fusion rocket fuels as far as missile-warship engagements are concerned? Most warships with terawatt-grade drives will be extremely concerned with minimizing neutron radiation and the like, so there are understandably only two reasonable options - D-He3 or p-B11, both of which offer fairly unremarkable specific impulses. As far as I understand, in order to minimize radiation from side D-D reactions in D-He3 fusion, the use of spin-polarized(?) He3 is necessitated, which apparently kills exhaust velocity. p-B11 fusion's high ignition temperature necessitates stupid huge particle accelerators and picosecond laser drivers, which eat heavily into the mass budget. Warship fusion rockets, thus, will probably have a lowish specific power, with a significant amount of mass dedicated to radiation shielding. On the other hand, D-T fusion is easily ignited and requires lower drive mass, is highly energetic with a fairly good exhaust velocity, but throws out a metric crapload of neutron radiation and bremsstrahlung. D-D fusion catalyzed(?) to result in the full burn-up of the synthesized He3 and T with more D also looks like a good bet. Both of the latter reactions appear to be decent candidates for missile drives, particularly if shell fusion is utilized to increase thrust, or if cold propellant is heated from the generated neutron and bremsstrahlung radiation and thrown out the back. Considering missile buses are unlikely to operate for days, issues arising from neutron activation and embrittlement can hopefully be ignored. Missile drives can also be optimized for performance at the cost of long-term operational reliability. All of these combine to imply that missile fusion rockets will likely have much higher specific power(?) than warship fusion rockets, although I can't tell how much, or if efficiency losses will offset any gain. Potentially, torch missiles and drones could outrun and outmanoeuvre warships. Note that I haven't done the math, so I'm probably horrendously wrong. Terawatt grade is a pretty high level of power. We are talking about reactors that if coupled with a laser, could easily snipe spaceships at millions of kilometers of distance! The missiles will have to be very effective to stay in the game. Neutron radiation is something you want to avoid if you want high specific power fusion propulsion. At low power, you can just use shielding and passive cooling. At terawatts of power, you could have hundreds of gigawatts escaping a D-T reactor. They do not contribute to the propulsion and require huge amounts of shielding on top of a thermal management system that can handle hundreds of gigawatts of waste heat. With aneutronic fusion, especially p-B11, your shielding and cooling requirements are much lower and simpler. You mention igniting fusion as being difficult, but having TW output means you can easily skim off gigawatts of electricity from the reactor to power the ignition system. This can drive a very high power particle accelerator - it doesn't have to be huge either, as plasma wakefield accelerators allow for short accelerator lengths. The efficiency is poor, yes, but that's your ignition system. It doesn't matter much if your accelerator efficiency is poor if you're only diverting 0.1% of the reactor's output for powering it. Do car manufacturers today worry too much about how efficient the engine-starter dynamo motor? Not really. Cold propellant has a very poor neutron cross-section and so makes for a bad neutron shielding option. One trick to obtaining better missile performance without changing increasing power requirements is sacrificing your Isp and increasing your thrust. This shortens the time it takes for a missile to catch up with its target, so it has to spend less deltaV overall. 1
|
|
|
Post by Hicks on Nov 1, 2017 11:51:48 GMT
CatastrophicReEntry: That dosen't seem to pass the smell test. If both the ship and missile have the same type of thruster, then reletive dV is always dependent on the ratio of reaction mass to payload regardless of the size of the platform.
|
|
|
Post by SevenOfCarina on Nov 1, 2017 13:46:35 GMT
Terawatt grade is a pretty high level of power. We are talking about reactors that if coupled with a laser, could easily snipe spaceships at millions of kilometers of distance! The missiles will have to be very effective to stay in the game. Neutron radiation is something you want to avoid if you want high specific power fusion propulsion. At low power, you can just use shielding and passive cooling. At terawatts of power, you could have hundreds of gigawatts escaping a D-T reactor. They do not contribute to the propulsion and require huge amounts of shielding on top of a thermal management system that can handle hundreds of gigawatts of waste heat. With aneutronic fusion, especially p-B11, your shielding and cooling requirements are much lower and simpler. Going by my extremely feeble understanding of high temperature particle physics, shouldn't p-B11 fusion still produce bremsstrahlung? If I'm interpreting this study correctly, at the 300keV plasma energies necessary for p-B11 fusion, 600 gigawatt of bremsstrahlung X-rays can be expected for every terawatt of fusion power. This compares to 200 gigawatt per terawatt for D-He3, which still produces neutron radiation equal to 5% of the fusion power. Is there something about bremsstrahlung that intrinsically makes 400GW of it easier to shield from than 50GW of neutron radiation? Or have I misunderstood something? One trick to obtaining better missile performance without changing increasing power requirements is sacrificing your Isp and increasing your thrust. This shortens the time it takes for a missile to catch up with its target, so it has to spend less deltaV overall. In my opinion, merely catching up to a warship with terawatts of thrust power is of no consequence when a missile swarm is going too slow to clear the killzone before being wiped out by point defence lasers. Even standoff warheads like casaba-howitzers become useless when lasers can shred non-maneuvering targets at ranges of millions of kilometres, unless a missile has a high relative velocity (>1000km/s) and high acceleration (>1m/s2).
|
|
|
Post by Kerr on Nov 1, 2017 14:47:29 GMT
Terawatt grade is a pretty high level of power. We are talking about reactors that if coupled with a laser, could easily snipe spaceships at millions of kilometers of distance! The missiles will have to be very effective to stay in the game. Neutron radiation is something you want to avoid if you want high specific power fusion propulsion. At low power, you can just use shielding and passive cooling. At terawatts of power, you could have hundreds of gigawatts escaping a D-T reactor. They do not contribute to the propulsion and require huge amounts of shielding on top of a thermal management system that can handle hundreds of gigawatts of waste heat. With aneutronic fusion, especially p-B11, your shielding and cooling requirements are much lower and simpler. Going by my extremely feeble understanding of high temperature particle physics, shouldn't p-B11 fusion still produce bremsstrahlung? If I'm interpreting this study correctly, at the 300keV plasma energies necessary for p-B11 fusion, 600 gigawatt of bremsstrahlung X-rays can be expected for every terawatt of fusion power. This compares to 200 gigawatt per terawatt for D-He3, which still produces neutron radiation equal to 5% of the fusion power. Is there something about bremsstrahlung that intrinsically makes 400GW of it easier to shield from than 50GW of neutron radiation? Or have I misunderstood something? One trick to obtaining better missile performance without changing increasing power requirements is sacrificing your Isp and increasing your thrust. This shortens the time it takes for a missile to catch up with its target, so it has to spend less deltaV overall. In my opinion, merely catching up to a warship with terawatts of thrust power is of no consequence when a missile swarm is going too slow to clear the killzone before being wiped out by point defence lasers. Even standoff warheads like casaba-howitzers become useless when lasers can shred non-maneuvering targets at ranges of millions of kilometres, unless a missile has a high relative velocity (>1000km/s) and high acceleration (>1m/s2). At p-B11 Fusion temperatures bremsstrahlung power exceeds thermal power by 178%. 36% Thermal, 64% X-rays. If you are able to build magnetic nozzles able to withstand terawatts of power, and especially on missiles. Shouldn't you be able to place a magnetic coil on top of a casaba howitzer? It would create very tight beams because: 1. The is already directed 2. The coil can operate at magnitudes higher current then your normal drive coil, why? Because the coil is gonna be ionized anyway in the next 3.4 microseconds. As soon as casaba howitzers get ranges of light seconds (Which an normal +10MT Casaba have already do) your dynamic of laser superiority shifts. As the casabas present something similar to dozens of minutes - hours worth of your lasers output with ranges where light lag becomes a concern. The problem with the what I call the "Engine problem" and it's effect on massive available power is that your aren't limited by power, but by specific power. Getting more than 10kW/kg of specific power for your laser would be very hard and might come with high efficiency losses. Your fusion torch drives put out so much power that if it isn't properly dealt with, will melt your entire ship within seconds.
|
|
|
Post by EshaNas on Nov 1, 2017 14:53:48 GMT
In my case, I have antimatter beam core (drive) vessels with fission reactors in the MW range; formed out of a culture that wanted to zip around fast and not much else - transports for the most part; with automated ion drive probes and lesser fission engine (though up to gas cores) for 'cargo', whatever that may be. So we have zip cans running around that for some reason are now armed and shooting at each other, but their reactor tech throws out anything but gunpowder weapons and missiles for the most part, right?
|
|
|
Post by Kerr on Nov 1, 2017 14:59:55 GMT
matterbeam What do you think would be highest practically achievable specific power of an Laser while maintaining "good" efficiencies of over 50% ? All this opens a question, if you can have multi-terawatt engines, why not mount them on a big body and let the exhaust through MHD/Direct Conversion generators? A big asteroid/moon/planet could support laser with it massive waste heat rather easily, beam the power to your ship which is pretty just an relay mirror and destroy anything you want. The dominant weapon of future space battles would be the combat mirror/ your Laser Weapon Web. Power and more importantly mass won't be an problem anymore. Although this system had to use static combat mirror because of light lag. Still an replacement mirror is magnitudes cheaper than an laser star. SevenOfCarinachildrenofadeadearth.boards.net/thread/1455/future-tech-thread?page=36Neutrons and x-ray shouldn't be as big of a problem as you think they'll be if you just want interplanetary multi-g propulsion.
|
|