tahrikmili Posted December 9, 2009 Share Posted December 9, 2009 I'm fine tuning by Blood Angels army and I'm trying to decide how to equip my droppodding Veteran Assault Squad. They currently have 2 Meltaguns, and I have an option to give them up to 3 Combi-Bolters (or Power Weapons or Power Fists). I'm not sure how to fine tune this option. I'm torn between the following choices: 1. Going for 2 Meltaguns and 3 Combi-Plasmas (hoping that 2 Meltaguns will be able to pop all armor the turn they arrive, and the Combi Plasmas will be useful later on, against MEQ/TEQ squads) 2. Going for 2 Meltaguns and 3 Combi-Meltas (this should PROBABLY take out even a Land Raider and make their points back instantly but they become rather useless afterwards) 3. Going for 2 Meltaguns, 2 Combi-Plasmas and 1 Power Fist or Thunder Hammer 4. Going for 2 Meltaguns, 2 Combi-Meltas and 1 Power Fist or Thunder Hammer What say you B&C? How many Meltas does it take to somewhat reliably (75% chance or above) take out a Land Raider in one turn? I don't have the rulebook with me so I can't calculate :D EDIT: Or alternatively, can someone clarify how the mechanism works? 8 + 2d6 = 14 means glance, > 14 means penetration, correct? 1d6+1 on the damage chart, so that means 5+ is destroyed? Can someone correct these numbers so I can work it out myself? Link to comment Share on other sites More sharing options...
tahrikmili Posted December 9, 2009 Author Share Posted December 9, 2009 Worked it out for myself: Probability of a Meltagun to miss completely: 2/6 = 33,33% Probability of a Meltagun to hit but fail to penetrate: 4/6 * 15/36 = 60 / 216 = 27,78% Probability of a Meltagun to hit, penetrate but not destroy: 4 / 6 * 21 / 36 * 4/6 = 25,93% Probability of one Meltagun failing to kill a Land Raider (or other AV14): 33,33% + 27,78% + 25,93% = 87,04% Hence, chance of successfully destroying a Land Raider with one Meltagun is 12,96% Chance of completely failing with two Meltaguns is (87,04%)^2 = 75,76% Chance of destroying a Land Raider with two Meltaguns is 24,24% By the same logic: Chance of destroying a Land Raider with three Meltaguns is 34,06% Chance of destroying a Land Raider with four Meltaguns is 42,60% Chance of destroying a Land Raider with five Meltaguns is 50,04% Destroying a Land Raider with any kind of certainty requires about 10 Meltaguns. (75,04% - talk about diminishing returns) so the question is: Should I take 5 and make my chances 50,04% or take 4 and a Power Fist and leave my chances at 42,60% Tough choice! EDIT: Updated below to include chance of Wrecking the vehicle as well! Link to comment Share on other sites More sharing options...
pingo Posted December 9, 2009 Share Posted December 9, 2009 What's wrong with just wrecking it? I forget: is it possible to wreck or destroy with a melta? I don't have the rules on me :S Link to comment Share on other sites More sharing options...
tahrikmili Posted December 9, 2009 Author Share Posted December 9, 2009 Nothing except that i forgot about it. 5 wrecks and 6 destroys on the damage chart right? I will update my calculations. EDIT: Probability of a Meltagun to miss completely: 2/6 = 33,33% Probability of a Meltagun to hit but fail to penetrate: 4/6 * 15/36 = 60 / 216 = 27,78% Probability of a Meltagun to hit, penetrate but not destroy or wreck: 4 / 6 * 21 / 36 * 3/6 = 19,44% Probability of one Meltagun failing to wreck or destroy a Land Raider (or other AV14): 33,33% + 27,78% + 19,44% = 80,55% Hence, chance of wrecking or destroying a Land Raider with one Meltagun is 19,45% Chance of completely failing with two Meltaguns is (80,55%)^2 = 64,88% Chance of wrecking or destroying a Land Raider with two Meltaguns is 35,12% By the same logic: Chance of wrecking or destroying a Land Raider with three Meltaguns is 47,74% Chance of wrecking or destroying a Land Raider with four Meltaguns is 57,90% Chance of wrecking or destroying a Land Raider with five Meltaguns is 66,09% Wrecking or destroying a Land Raider with any kind of certainty requires about 7 Meltaguns. (78,00%). So the questions is: Should I trade 8,19% more likelihood of wrecking or destroying a Land Raider (66,09% vs 57,90%) with a Power Fist that will help me out when I get assaulted? Opinions please ;) EDIT: Further edited to include chance of wrecking on a Glance a couple posts below. Link to comment Share on other sites More sharing options...
Toshiro Posted December 9, 2009 Share Posted December 9, 2009 I think you forgot the second melta advantage, that it has +1 on damage table. So chance not to destroy or wreck is only 3/6 for normal vehicle (2/4 for open topped). Link to comment Share on other sites More sharing options...
tahrikmili Posted December 9, 2009 Author Share Posted December 9, 2009 I actually did remember the +1 but forgot the wreck result, the final calculations above your post reflect both. Link to comment Share on other sites More sharing options...
Brother_Kluft Posted December 9, 2009 Share Posted December 9, 2009 To penetrate : 2/3 to hit x 21/36 to pen x 1/2 to wreck or destroy = 19.4 % To destroy on glance : 2/3 to hit x 5/36 to glance x 1/6 to wreck = 1.54% Total : 20.94% chance Explanation To pen a raider you need a 15. You have str 8 with the melta so you need a 7 on 2d6. So you must not roll 2,3,4,5,6. There are 15 ways to roll 2,3,4,5,6. Hence there are 36-15 ways to roll 7+. So you pen on 21/36. After the pen you need a 4+ do destroy which is 1/2 You can destroy a raider on a glance with ap1 also. You have str 8 from melta, so you need a 6 to glance [no more, no less]. There are 5/36 ways to make a 6 on 2d6. So your chance to glance is 5/36. Then to destroy you need to roll a 6 (which results on a 5 on the chart, wrecking the vehicle) Therefore you need 75/20.94 = 3.58 melta guns to kill with a 75% chance. You only forgot the chance to kill on a glance. Link to comment Share on other sites More sharing options...
pingo Posted December 9, 2009 Share Posted December 9, 2009 Therefore you need 75/20.94 = 3.58 melta guns to kill with a 75% chance. Forgive me, it's a lot of years since I studies maths. But doesn't that mean for a 100% chance of killing the raider it is: 100/20.94 = 4.78 melta guns? But you can never be 100% certain of killing it as you could roll ones for everything. I may have misunderstood though: apologies if so. Link to comment Share on other sites More sharing options...
tahrikmili Posted December 9, 2009 Author Share Posted December 9, 2009 Therefore you need 75/20.94 = 3.58 melta guns to kill with a 75% chance. Forgive me, it's a lot of years since I studies maths. But doesn't that mean for a 100% chance of killing the raider it is: 100/20.94 = 4.78 melta guns? But you can never be 100% certain of killing it as you could roll ones for everything. I may have misunderstood though: apologies if so. You are correct, his math is wrong. Obviously 5 Meltaguns do not guarantee a destroyed Land Raider. The problem is that you can't add probabilities to obtain the chance of at least one of them happening. You have to find the chance of one of them happening, then the chance of none of them happening, and substract that from 100% as I did above. This takes into account the chance of one Meltagun succeeding, two succeeding, ....., all five succeeding. He is correct in saying that my calculation ignores the chance to destroy on a glance, but his math is also incorrect. Going with his figures (which I assume and which look to me right) T The chance of one Meltagun wrecking or destroying a LR in one hit is 20.94% The chance of one Meltagun failing to wreck or destroy a LR in one hit is 79.06% Therefore the chance of two Meltaguns failing to wreck or destroy a LR is (79.06%)^2 = 62.50% Hence the chance of two Meltaguns wrecking of destroying a LR is 100% - 62.50% = 37.50% I do not have access to a calculator at the moment I will post the chances for 3, 4, 5, etc. Meltaguns soon. BUT! I do not have the damage chart in front of me and I didn't know you could destroy a LR with a glance. Can someone confirm? EDIT: The chance of three Meltaguns wrecking or destroying a LR is 1.00 - (.7906)^3 = 50.58% The chance of four Meltaguns wrecking or destroying a LR is 1.00 - (.7906)^4 = 60.93% The chance of five Meltaguns wrecking or destroying a LR is 1.00 - (.7906)^5 = 69.11% The chance of six Meltaguns wrecking or destroying a LR is 1.00 - (.7906)^6 = 75.58% So a 6th meltagun ensures a 75% chance to kill a LR (which I'd call relatively reliable) and the 5th meltagun only adds 8.18% chance to wreck or destroy a LR. Quite marginal compared to how much defensive benefit a Power Fist will give. Link to comment Share on other sites More sharing options...
Gornall Posted December 9, 2009 Share Posted December 9, 2009 Yeah, it's possible to kill on a glance. Glance is -2 AP1 is +1 For a total of -1 off the result. Rolling a 6 (explodes) turns into a 5 (wrecked). Link to comment Share on other sites More sharing options...
tahrikmili Posted December 9, 2009 Author Share Posted December 9, 2009 Yeah, it's possible to kill on a glance. Glance is -2 AP1 is +1 For a total of -1 off the result. Rolling a 6 (explodes) turns into a 5 (wrecked). Then the math I posted above is correct. I will add to it very soon. EDIT: I edited it to include probabilities for 3-4-5-6 meltaguns. Link to comment Share on other sites More sharing options...
Frosty the Pyro Posted December 9, 2009 Share Posted December 9, 2009 To penetrate : 2/3 to hit x 21/36 to pen x 1/2 to wreck or destroy = 19.4 %To destroy on glance : 2/3 to hit x 5/36 to glance x 1/6 to wreck = 1.54% Total : 20.94% chance Explanation To pen a raider you need a 15. You have str 8 with the melta so you need a 7 on 2d6. So you must not roll 2,3,4,5,6. There are 15 ways to roll 2,3,4,5,6. Hence there are 36-15 ways to roll 7+. So you pen on 21/36. After the pen you need a 4+ do destroy which is 1/2 You can destroy a raider on a glance with ap1 also. You have str 8 from melta, so you need a 6 to glance [no more, no less]. There are 5/36 ways to make a 6 on 2d6. So your chance to glance is 5/36. Then to destroy you need to roll a 6 (which results on a 5 on the chart, wrecking the vehicle) Therefore you need 75/20.94 = 3.58 melta guns to kill with a 75% chance. You only forgot the chance to kill on a glance. Almost had it but you blew it at the end. You are correct about the 21% chance to kill with a shot, but you messed up the math for multiple shots. What you did is a wieghted average, which is fine for dealing wounds to a unit, as if you get 5 sucesses you deal 5 wounds, but it falls apart vs vehicles, were 5 successes still only kills one land raider. Foruma you a looking for is 1-(F)^M were F is chance of failure, 79% for a 21% chance of success and M is melta shots fired This means chance to wrek/splode a landraider is 21% for one shot 37.6% for two 50.6% for 3 61% for 4 69.2% for 5 75.6% for 6 80.1% for 7 84.8% for 8 88% for 9 90.5% for 10 using goal seek it requires 5.884 shots to get exactly 75% Edit: adding chance in other situations If you can reroll to hit (alla vulkan he'stan, masterwork, or twinlinked guns) then shots chance 1= 0.279835391 2= 0.481362936 3= 0.626495941 4= 0.731015596 5= 0.806286952 6= 0.860494718 7= 0.899533233 8= 0.92764739 9= 0.947894211 10= 0.962475255 If you are BS 5 with no reroll then shots chance 1= 0.262345679 2= 0.455866103 3= 0.598617279 4= 0.703918302 5= 0.781594056 6= 0.838891912 7= 0.881157922 8= 0.912335628 9= 0.935333997 10= 0.952298844 And if you are BS 5 and can reroll shots chance 1= 0.306069959 2= 0.518461098 3= 0.66584569 4= 0.768120286 5= 0.8390917 6= 0.888340897 7= 0.922516394 8= 0.946231798 9= 0.962688629 10= 0.974108519 If they get a cover save (unlikely at melta ranges) then shots chance 1= 0.104938272 2= 0.198864502 3= 0.282934277 4= 0.358181914 5= 0.425533195 6= 0.485816749 7= 0.53977425 8= 0.588069545 9= 0.631296815 10= 0.66998789 12.5= 0.75 Link to comment Share on other sites More sharing options...
Deus de Mortalis Posted December 9, 2009 Share Posted December 9, 2009 I love to use HAMulator. It works and is legit. While not the end-all, be-all, it helps out a lot and saves tons of time. http://hamulator.genostech.com/ Link to comment Share on other sites More sharing options...
minigun762 Posted December 10, 2009 Share Posted December 10, 2009 Just to be an ass, wouldn't you have to look at the probability of getting multiple immobilized/weapon destroyed results and killing it that way? Link to comment Share on other sites More sharing options...
Gornall Posted December 10, 2009 Share Posted December 10, 2009 Just to be an ass, wouldn't you have to look at the probability of getting multiple immobilized/weapon destroyed results and killing it that way? You first... Link to comment Share on other sites More sharing options...
Frosty the Pyro Posted December 10, 2009 Share Posted December 10, 2009 Just to be an ass, wouldn't you have to look at the probability of getting multiple immobilized/weapon destroyed results and killing it that way? its going to be slim as you need 5 or 6 hits to kill it that way (1 for imobilization, 3 or 4 for the weapons, and 1 more to boost to wrecked). I can crunch the numbers if you realy care. Edit Chance for a success is .1605 or 16% to get 5 succeses (3 weapon destroyed, 1 imomobilized, 1 boost to wreck) the chance is shots chance 5= 0.000106486 6= 0.000464068 7= 0.001679184 8= 0.0038843 9= 0.007586716 10= 0.013181479 So at the 10 shots of melta your are going to be boosting your chances by ~1.3% for counting a weaponstrip kill, and thats if they dont take the storm bolter or multimelta (or heaven forbid both) So if you want it destroyed, and have TEN meltas going in the chance is only increased by Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.