Date: Sun, 16 Jul 95 01:02:01 -0400 From: Derek Wildstar Subject: Re: How Nasty Nukes Are (Td#346) > Les wrote: > I took a 1 MT weapon, which according to the sci.astro FAQ is 4.2*10^9 MJ, > and assumed that all of that energy would be available in an attack. > I calculated that flux in MJ/cm^2 at various ranges, and took that as the > intensity in the formula for laser DV. > > Range (m) DV > 1 457 > 10 45 > 50 9 > 100 4 While I agree with your general approach (spread 4.2*10^9MJ over spheres of various sizes), I'm not sure it's reasonable to model it as a single laser beam. IF you assume that the laser model is appropriate for a nuke (and it may well be - the bulk of the energy emitted is as soft X-rays, approximately equivalent to a TL-15 tunable laser), the penetration factor should also be figured as well. In addition, the nuclear explosion attackes the entire exposed surface area of the ship - some provision for this should be made, because all exposed weapons and equipment will be affected. Here's some suggested rules to play with (enjoy!): Nuclear Weapon Damage Range 100MT Weapon ------- 1MT Weapon --------- 10KT Weapon -------- Pen Area Pen Area Pen Area 0 1/259229-810092 33753H 1/25923-81009 3375H 1/2592-8101 338H 1 1/1462-4570 190H 1/146-457 19H 1/14-46 2H 2 1/731-2285 95H 1/73-229 10H 1/7-23 1H 5 1/293-914 38H 1/29-91 4H 1/3-9 1h 10 1/146-457 19H 1/14-46 2H 1-5 1h 25 1/59-183 8H 1/6-18 2h 1-2 -- 50 1/29-91 4H 1/3-9 1h --- 100 1/14-46 2H 1-5 1h 250 1/6-18 2h 1-2 -- 500 1/3-9 1h --- 1000 1-5 1h more --- -- Rad Hit 10km 1km 100m Damage Effects: A nuclear explosion within the "Rad Hit" range of a spacecraft will produce a radiation hit, resetting computers (just as if the ship were hit with a particle beam weapon). Explosions beyond this range have no effect on a spacecraft. Ground Zero: Determine the hull surface location nearest the detonation (use the hull surface locations diagram from T:TNE or BL), and the distance from the hull of the ship to the nuclear device. This location is attacked with the penetration and damage value listed in the table above, exactly as if it were hit with a TL-15 laser. In addition, all systems which appear in the Surface Hits damage tables for that location are damaged with the number of hits indicated in the "Area" column. In some cases, there will be excess damage (any "Area" hits above 5H are automatically excess damage); this is resolved normally. Primary Damage: All hull surface locations which share an edge with the one nearest the detonation are also attacked. The penetration, damage, and area damage effects depend on the relative length of the ship and the distance to the nuclear explosion. If the overall length of the ship is smaller than the range to the explosion, then the primary damage range is the same as thr ground zero range; due to the angle of the hull to the radiation of the explosion, use one half (but never less that 1-1 or 1h) of the penetration, damage, and area damage values that were used at Ground Zero. If the overall length of the ship is larger than the range to the explosion, move down one row from the ground zero range on the chart; this is the primary damage range. Use the penetration, damage, and area damage values from the chart for this new range. Apply primary damage exactly like Ground Zero damage (except that the range is larger, and therefore the damage is less); note that this may affect systems which already recieved damage atground zero (this is allowed). Secondary Damage: All hull surface locations which share an edge with one of the primary damage locations are also attacked. The secondary damage range depends on the primary damage range and the length of the ship. If the overall length of the ship is smaller than the priary damage range (determined above), then the secondary damage range is the same as the primary damage range; due to the angle of the hull to the radiation of the explosion, use one half (but never less than 1-1 or 1h) of the penetration, damage, and area damage values that were used in the primary damage. If the overall length of the ship is larger than the primary damage range, move down one row from the primary damage range on the chart; this is the secondary damage range. Use the penetration, damage, and area damage values for this new range. Apply secondary damage exactly like Primary Damage (except that the range is larger, and therefore the damage is less); note that this may affect systems which already recieved damage at ground zero or in the primary damage area (this is allowed). Examples: 1) A 1MT weapon explodes about a shiplength (25 meters) astern of a Broadsword-class mercenary cruiser. Ground Zero is location 20, and it is attacked with 1/6-18, of which 13 points (2 minor hits) penetrates the ship's hull armor. There are no systems exposed to a surface explosion in this area, so no additional damage is done. The Broadsword is longer (at 28 meters) than the distance to the explosion, so the primary damage area (locations 16, 17, 18, and 19) is treated as if it were 50 meters away. These locations are attacked at 1/3-9 (which does not penetrate). However, the airlocks, cargo hatches, antennas, and docking ports in these areas all recieve minor hits anyway. The primary damage range, 50m, is larger than the length of the ship (28m), so the secondary damage area (locations 10, 11, 12, 13, 14, and 15) recieves half the damage that the primary area does. Unfortinately, 1/3-4 damage doesn't penetrate anything. However the 1h (half of 1h, but never less than 1h) surface damage now affects more systems: airlocks and antennas in these areas, for a total of 6 more 1h results on each (and pretty effectively destroying the antennas and airlocks on the aft hemisphere of thie ship. 2) A 10KT contact nuclear mine detonates 1 meter (the length of it's contact sensing elements) from the hull of Midu Agashaam-class Destroyer, in hull location 7. 41 points of damage penetrate the hull, for 2 major hits. In addition, the antenna in that location recieves an additional 2H. The ship is much longer than a meter, so the adjacent primary damage area locations (3, 9, 10, and 13) are attacked at 1/7-23, of whih 14 points of damage penetrates, for 2 minor hits in each location, plus two major hits on both the antenna in location 10, and the airlock in 13). The ship is also longer than two meters, so the secondary damage area (locations 1, 2, 5, 6, 11, 12, 15, 16, and 16) are attacked with 1/3-9 (which doesn't penetrate), however, antennas, airlocks, and EMM radiators in these areas recieve 1h each time they appear in the damage table. "Bruce Johnson" writes: > Of course, the radiation effects will be greater in a vaccum (all > that energy's gotta go ) so there will be a LOT of very > high energy radiation in all directions, spread all across the > spectrum. Actually, no. Without an atmosphere around the blast, nearly all the energy should come out as either high-speed neutron radiation or "soft" X-rays. The bulk of the energy will be in the form of the latter. In an atmosphere, these "soft" X-rays are absorbed by the surrounding air, heating it to very high temperaturs (and thereby creating the fireball and blast effects). The fireball re-radiates a considerable amount of energy, spreading it over a broader range of lower frequencies. These effects don't happen in space. > So a shiny or white surface > will be able reflect a lot of the energy back, and the armor should > easily handle the rest, it had better...your average solar flare is > going to put out energy on the order of a nuke going off nearby, and > do it for days to a week at a time. I don't think that nukes put out > the high energy particles like solar flares, it's mostly photons > (very high energy photons, to be sure, but photons nonetheless). Actually, no. At detonation, the majority of a nuclear weapon's energy output is "soft" X-rays (yes, these are photons, folks). Just about any type of matter absorbs this radiation efficently, and since FF&S assumes that TL-15 tunable lasers would operate in these ranges, it's a safe assumption that starship hull will be just as easily damaged by nuclear-explosion-generated soft X-rays as it is by a laser weapon. wildstar@quark.qrc.com ------------------------------------------------------------------------------ "A shining New Era is tiptoeing nearer ..." "... and where do we feature?" Date: Tue, 18 Jul 95 13:37:40 -0400 From: Derek Wildstar Subject: Re: How Nasty Nukes Are (Td#350) lhowie@dilbert.lrmi.com (Les Howie) asks: > > (( useful tables omittedd )) One more Nifty Thing. The values in the tables I gave previously can be adjusted for different sized nukes. The general formula is: Multiplier = sqrt(Desired Yield / Table Yield) In other words, if you want values for a 20KT warhead, multiply the 10KT penetration, damage value, and area hits by sqrt(20/10), or 1.4142. Here's a table to help you out; instead of saying "* .333333", I've given it as "/ 3", indicating division by three. Yeild Table and Mult 2.5KT 10KT / 2 40KT 10KT * 2 90KT 10KT * 3 111KT 1MT / 3 250KT 1MT / 2 4MT 1MT * 2 9MT 1MT * 3 11MT 100MT / 3 25MT 100MT / 2 Round all fractions to the nearest (in other words .5 and above rounds up, less than .5 rounds down). The only exceptions are that penetrations less than 2 round down to one, and penetrations or damage values less than one indicate no effect. Area hits work the same way as long as you are working with major hits; less than 1 major hit (but at least a half of a major hit) becoems two minor hits; less than half a major hit (or half of two minor hits) becomes one minor hit. > These are excellent rules, and I will use them. The only thing needed for > space combat use now is a set of rules for getting a missile inside this > sort of range. I think I've posted rules for that before. :-) Check the back issues of TML, or use the following quick summary: To qualify for a "short range" attack, a missile must: 1) end it's flight in the same hex as it's target 2) have remaining maneuver G's to match the target's evasion G's 3) survive any point-defense fire Roll a normal missile "to-hit" roll, with the following diff mods: "Impact" = 3 levels harder "Near" = 2 levels harder "Far" = 1 level harder MFDs can be used to offset those difficulty mods. Once a hit is acheived, roll 1d6 on one of the following tables to determine the exact distance from the explosion to the target vessel. Apply a -1 DM to this roll if the target ship did not evade at all. Impact Near Far Die Distance Distance Distance 0 0 10 100 1 0 10 250 2 1 25 500 3 1 25 500 4 2 50 500 5 2 50 1000 6 5 100 2000 > question: how should armour protect against the "rad" hit? Not at all; invest in radiation-hardened electronics and computers if you want to survive radiation hits (ie: "fib" fiber-optic computers). wildstar@quark.qrc.com ------------------------------------------------------------------------------ "A shining New Era is tiptoeing nearer ..." "... and where do we feature?"