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Stinger
The Knights of Chaos
General
Joined: 30-Apr-2002 00:00
Posts: 1833
Location: United States
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 Posted: 15-Apr-2004 12:04 Post subject: RE: Tank Guns |
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| I have to say that this concept has always made my brain hurt. If ACs really do fire in bursts (which is the way I understand them), then why do they do damage to a single location? |
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That is why I have always considered them as single shot rifles with an autoloader. As the weapon fires its one shell another takes its place. It always irritated the hell out of me to read in the novels how the pilot "walked the rounds up the leg and hitting the torso".
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Stinger
If it's "creepy" to use the Internet, military satellites, and robot aircraft to find a house full of gorgeous young models so I can drop in on them unexpected, then FINE, I'm "creepy". Howard Wolowitz. BBT.
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Vagabond
Mercenary
Mr. Referee
Joined: 04-Feb-2002 00:00
Posts: 5617
Location: United States
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| Posted: 15-Apr-2004 14:35 Post subject: RE: Tank Guns |
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On 2004-04-15 12:01, Wanallo wrote:
I always thought it made sense with AC\'s firing single rounds, I mean, armour can only be so effective against shells, It doesn\'t matter if your MBT mounts classified Chobham armour, Reactive or whatever, they can still only take one or two shots max, as armour advances so will the weapons to penetrate them. Only stands to reason will be same in 3025+
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but your using real world logic here. you cannot do that in this case. after all, the games uses FASA pyshics not the real thing, so if FASA says that a normal single shot 120mm cannon round bounces off mech armor like i fly off your wind shield, then that is what happens. accordingly, if they, FASA, say an AC fires a burst then it fires a burst.
as to comment on the reasoning of burst spread and not rolling multiple locations, using my previous comments i point out that that is how FASA wanted it, yet i can use an example of modern day weapons to try and give some sort of logical reasoning by using the avenger cannon of the a-10.
http://www.fas.org/man/dod-101/sys/ac/equip/gau-8.htm
The maximum firing rate is lower (4,200rds/min versus 6,000), and the firing rate per barrel is lower again; each GAU-8/A barrel fires a maximum of 10rds/sec, while the M61 barrel fires nearly 17. ( http://www.military.cz/usa/air/in_service/weapons/cannons/gau8/gau8_en.htm paragraph 1)
Each GAU-8/A barrel is some 80 calibers in length. The muzzle velocity of the GAU-8/A is about the same as that of the M61, but the heavier, more advanced ammunition is not only more destructive but has better ballistic properties. It decelerates much less rapidly after leaving the barrel, so that its time of flight to 4,000ft (1,200m) is 30 percent less than that of an M61 round, and the projectile drops a negligible distance - barely 10ft (3m) - in the process. The accuracy of the GAU-8/A, installed in the A-10, is rated at \'5mil, 80 percent\', meaning that 80 percent of rounds fired at 4,000ft (1,800m) will hit within a circle of 20ft (6.1m) radius; the M61 is rated at 8mil. ( http://www.military.cz/usa/air/in_service/weapons/cannons/gau8/gau8_en.htm pragraph 4)
Using this information you can figure the ROF, rate of fire, of the avenger at 100 rounds per BT Turn. i will cute this in a quarter to adjust for assumed fire time per turn, so the ROF is 25 rounds per turn or 10 seconds. 80% of these rounds when fired at 1800m will hit within a 12.2m diameter circle or a 6.1m radius circle. accordingly, if we reduce this 1800m range to 450m, 15 hexes in BT, then it is safe to assume that 80% of these 25 rounds, 20 rounds, will hit within a 3.05m diameter circle or a 1.525m radius circle or within a ruffly 5ft radius circle.
now assuming that an AC/2 fires a 30mm round in a 5 round burst then an AC/2 fires 1/5th the number of rounds per turn that an avenger would. this allows me to assume that the recoil of the gun would be severaly less then that of the avenger thus decreasing further the bullet spread to 1 or 2 feet with a possible max of 3 feet. this means that 4 out of 5 rounds from an AC/2 would hit within a 2 to 6 foot wide spread at 15 hexes. which when compared to the height of a mech, between 9 and 12 meters or 30 to 40 feet, allows a fair amount of room for a single location hit.
well got to run so i gotta rap this up.
i hope my examples and evidence gives a convincing argument on the reasoning of rolling 1 hit loaction for an AC that fires in bursts, and just to insure my own peace of mind i am not presenting this info to convert people just to give a well reasoned argument supporting my position.
peace!
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one must work hard to cultivate the mind and body. and one must always cultivate the mind.
//^(^_^)^\\
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ralgith
Blighted Sun Battalion
1st Company
"Ralgith's Renegades"
Colonel
Joined: 18-Aug-2003 00:00
Posts: 2021
Location: United States
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| Posted: 15-Apr-2004 15:59 Post subject: RE: Tank Guns |
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Way to go Vagabond. Ya said basically the same as I did, but gave a much better detail and used a modern weapon of approx the same caliber as a b-tech weapon. Good research and what not man.
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Colonel Ralgith t'Mayasara
Blighted Sun Battalion
1st Company 'Ralgith's Renegades'
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Vampire
Free Worlds League
Lieutenant Colonel
Joined: 05-Feb-2002 00:00
Posts: 912
Location: Spain
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| Posted: 15-Apr-2004 18:11 Post subject: RE: Tank Guns |
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Well, if you check out my site, I have a couple essays on this subject, but for once, I have let you people figure out the answer 
And what Ruger said, he heard it from me, credit where credit is due 
Answering the original question.
A Battletech autocannon is far more powerful than a standard tank cannon of today.
The equivalent of your 105mm tank cannon is an AC/10, the difference being that the autocannon fires a burst of four rounds instead of just one projectile. Recoil and the need to keep a tight grouping of shots into the standard 2x1 target (representing the frontage of a tank, or a hit location in a 'Mech) means that Battletech autocannons have shorter ranges than their single shot 20th century predecessors.
Smaller autocannons have longer range because recoil is more controllable, making them keeping precision over most of their effective range.
On the other end of the scale, the AC/20 it's a massive monster of a 150-200mm tank gun, with shells double the size and power of the 105mm , one. It's massive weight and caliber means a shorter barrel that coupled with the high recoil makes a gun with tremendous penetration but that it's only precise enough with a tight grouping over a short range. It's optimized for killing power , but it's not very efficient.
Why the need of bursts? Well, forget all that crap about ablative armor, that only would apply to energy weapons. Basically, there's a limit on how big a gun you can mount on a 'Mech or tank, and there's a limit on how much armor can be mounted. The idea behind the autocannon is that since you can't keep increasing the penetration of the gun, you fire several rounds, and hope for the best, that one of the projectiles will hit a weak spot on the armor or a previous hole left by other weapon hits.
With so many rounds being fired, eventually one is going to strike a killing blow.
So what damage would do a single 105mm tank gun round to a 'Mech? Assuming the 'Mech mounts enough armor to stop a round, you would have to be lucky. Meanwhile, every time your tank fires a round, your tank is hit by a four round burst.. odds is that one will end striking the turret ring, a hatch, the side, the rook and kill your tank.
In game terms? 2 points for a 105mm, maybe 3 for a smoothbore 120mm.
That's why they said a 'Mech had the firepower of a company of tanks of the 20th century. Specially true if it were older tanks, like an M-60 or T-72, with steel armor.
An M1 Abrams or Merkava would fare slightly better, though not much, that's why the Merkavas got creamed by the Mackie though that test was jury rigged in the 'Mech favor for propaganda purposes.
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Memento audare semper
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Jade_Dragon
8th Sword of Light
Sho-sho
Joined: 05-Feb-2002 00:00
Posts: 1323
Location: United States
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| Posted: 21-Apr-2004 09:50 Post subject: RE: Tank Guns |
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I believe the TRO 3026 lists the Demolisher's AC 20s as 185mm.
I also seem to recall from the Gray Death series that the Marauder 3R's AC5 is a 120mm while the Shadow Hawk's AC5 is something like a 90mm.
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The JadeDragon
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Blasty McNasty
Free Worlds League
Corporal
Joined: 06-Jan-2004 00:00
Posts: 65
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| Posted: 21-Apr-2004 19:17 Post subject: RE: Tank Guns |
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I believe the Chemjet AC/20 is fluffed as a 230mm single shot per turn of fire weapon.
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"And Blasty said: A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed. And all rejoiced." - The Word of Blasty, verse 22:2
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Seraph
Blighted Sun Battalion
2nd Company
"Seraph's Slaughter"
Major
Joined: 11-Mar-2004 00:00
Posts: 1744
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| Posted: 21-Apr-2004 20:58 Post subject: RE: Tank Guns |
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on the mechbuster atmospheric fighter mounts a Zeus 75 which " fires a four round burst of hyper-velocity depleted uranium armor penetrators(HDUAP)."
The hetzer mounts a 150mm ac 20 that fires a ten round burst.
The saladin mounts a 200mm ac 20.
The warrior VTOL mounts a 30mm ac 2 which fires a ten round burst.
The monitor naval vessel mounts 2 185mm ac 20's.
The demolisher mounts 2 185mm ac 20's.
Those are from the 3026 TRO. briefly scanned a couple other TRO's but didn't notice bore diameter mentioned in the fluff.
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If ignorance is bliss, then why are you so miserable?
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Blasty McNasty
Free Worlds League
Corporal
Joined: 06-Jan-2004 00:00
Posts: 65
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| Posted: 22-Apr-2004 01:39 Post subject: RE: Tank Guns |
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I'm sorry, the Chemjet is 185mm. Whihc I think is what is on the Demolisher.
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"And Blasty said: A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed. And all rejoiced." - The Word of Blasty, verse 22:2
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Havoc~Ronin
Federated Suns
Major
Joined: 13-Nov-2003 00:00
Posts: 427
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| Posted: 22-Apr-2004 08:49 Post subject: RE: Tank Guns |
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So, if one was to draw a conclusion from all these entries and the data presented, it would have to be that although the weapon system classification appears to be standard, AC2, AC5, AC10, AC20, etc..., this is not the case. It seems that different manufacturers produced different caliber of weapons under the same category. Take the AC20 as mentioned in Seraph's last post. This would result in a huge logistical nightmare for a battalion or regiment deploying different mechs and vehicles of the same weapon classification. Battlefield salvage and weapon replacement opens a whole other can of worms. Hell. are all the different manufacturers of LRM and SRM launchers and missiles producing capable sizes or do they also differ?
(I think I am going to return to the land of innocent ignorance and play the game as if I did not read any of these threads.)
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"Ours is not to question why, ours is just to do...."
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Vampire
Free Worlds League
Lieutenant Colonel
Joined: 05-Feb-2002 00:00
Posts: 912
Location: Spain
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| Posted: 22-Apr-2004 11:54 Post subject: RE: Tank Guns |
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On 2004-04-22 08:49, Havoc~Ronin wrote:
So, if one was to draw a conclusion from all these entries and the data presented...,
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It would be that FASA fluff writers hadn't a clue, and barely could tell wich was the business end of a gun.
Those figures are just random numbers written at whim to look cool, no real thought about what's the exact caliber and RoF of an autocannon. That's why canon explanations where so vague and contradictory and they came up with ludicrous ideas such as "walking fire" and RACs.
Simply put, they had no clue. After all, FASA got the technical background info on 'Mechs from another company (Hero Games)
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| It seems that different manufacturers produced different caliber of weapons under the same category. This would result in a huge logistical nightmare
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You answer your own question. Clearly those figures mean nothing, though they give some idea of what would be the actual calibers, averaging from the entries.
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| are all the different manufacturers of LRM and SRM launchers and missiles producing capable sizes or do they also differ? |
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Well, to their credit, FASA realized that missiles of a certain size are very much alike, and standardized the missile calibers in one of the latest readouts (3060, I think). However, in typical fashion they screwed up and gave SRM a caliber of 60 (sixty) milimeters... even less than the universally accepted size for LRMs (75mm)
Answering your question. All that variety of calibers it's not only a logistical nightmare, but it also doesn't make sense from a ballistics viewpoint.
For example, some misguided souls say a Class 5 autocannon can be a small caliber, fast firing gun, ( say 50 mm, 10 round bursts) or a larger caliber , slower firing gun (like the often quoted Whirlwind autocannon in the Marauder 120mm, 3 round bursts)
Hogwash. The ballistics of antitank guns is that the higher the round speed, the greater the penetration (damage) and to achieve those velocities larger propelling charges are needed. That's why we have gone from 75mm tank guns in WWII to 105mm or larger today.
So considering the combined recquirements of penetration power of each individual projectile, and the need for burst fire to maximize chances of a penetrating hit somewhere, or in the worst case leaving the target armor riddled with holes weakening it and creating openings for follow up weapon attacks, plus the weight of the ammo expended in each burst, you can deduce that there's a very narrow range of possibilities.
Say, for an AC/5, you can have a 75mm round or a 80 mm one. Borth rounds have the shame weight , 10 kg, and the only differences are that the 80mm has a shorter shell casing, but it has the same amount of propellant as the narrower one.
What I'm trying to say it's that only one size of shell will fill the performance recquirements for each class of autocannon, variations are minimal.
To illustrate this point , I'm going to use rifles of WWII as an example:
The British had the Lee Enfield rifle firing the .303 in (7.6mm), the US had the Springfield 30-06 (7.62mm) and the Germans had the Mauser 7.92mm
All the rifles share the same mechanism, and the basic performance of their respective cartridges it's the same. Differences are minor, yet the ammunition is incompatible between them.
Given that? Why not standardize to a common caliber? After WWII this was done to the .308 Winchester (7.62mm NATO) in all those countries.
With autocannons happened the same. One can imagine that in the Age of War, each House had it's own ammunition standards, just as today NATO tanks fire 120mm rounds, and the Russian ones fire 125mm, and the Terran hegemony had its own.
Note that I said that each House military had its own standard. No military procurement office is going to take bullshit from weapon designers each making its gun different from the others. Amstrong and Kallon autocannons might be built slightly different, but both share a common set of specs set by the customer.
Now, when the Star League formed, this would cause a logistical chaos, specially given the added complications of interstellar transport , and remember that in that time the HPG hadn't been invented yet, further complicating the recordkeeping.
So one of the first measures of the Star League for the Reunification War would have been a mandatory standardization of all ammo guns to the SLDF standard. Plus, such a move would keep the armaments and munition industries busy.
The SDLF standard calibers were kept during the entire Star League era, and when the Succession Wars started, the Successor Lords and generals had more pressing matters to deal with than a change in ammunition, specially when no major improvement could be gained.
By the 2nd Succession War, even if a House wanted to change it's ammunition, it no longer could afford to do so, and by the time of the 3rd Succesion War, sharing the same ammo as your enemies was a blessing more than a drawback, so the SLDF standard has been kept since then.
Though I don't have anything to do with the Clans, I'd point out that given their traditionalism and their dislike of waste, they would have kept with the SDLF standard. They would have huge ammo stockpiles to begin with, no real reason to change, and maybe even considered than down the road they could retrieve ammunition from Star League era caches left behind.
All this applies to missiles as well, and they are much simpler than cannon ammunition.
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Memento audare semper
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Blasty McNasty
Free Worlds League
Corporal
Joined: 06-Jan-2004 00:00
Posts: 65
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| Posted: 22-Apr-2004 15:51 Post subject: RE: Tank Guns |
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Actually, I believe that in the Supernova's fluff it mentioned that the Clans were suffering from a shortage of ammunition.
Anyways, yes, standardization would have likely occured in the IS, and thus the Clans, long ago.
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"And Blasty said: A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed. And all rejoiced." - The Word of Blasty, verse 22:2
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Nightmare
Lyran Alliance
Kommandant-General
Joined: 03-May-2002 00:00
Posts: 2214
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| Posted: 22-Apr-2004 22:11 Post subject: RE: Tank Guns |
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Quote:
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On 2004-04-22 15:51, Blasty McNasty wrote:
Actually, I believe that in the Supernova's fluff it mentioned that the Clans were suffering from a shortage of ammunition.
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"The Supernova's design replaces the autocannon of the King Crab with clusters of large lasers, a choice that stemmed from a shortage of ammunition."
But then again, a shortage is no reason to go about creating new types of ammo. You would be desperate to put your factories back to work producing ammo for the units that need it.
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A tree fall in the forest, and no one is around, and it hits a mime. Does anyone care?
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Gangrene
Federated Suns
Leftenant General
Joined: 04-Feb-2002 00:00
Posts: 939
Location: United States
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| Posted: 22-Apr-2004 22:45 Post subject: RE: Tank Guns |
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The "shortage of ammunition" does not refer to the clans production, but the King Crab design. The King Crab in TRO2750 only has 1 ton of ammo (5 shots) per autocannon.
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Gangrene
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Alexander
Heavy Horse Merc Brigade
Commanding Officer
Joined: 04-Feb-2002 00:00
Posts: 828
Location: Canada
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| Posted: 22-Apr-2004 23:44 Post subject: RE: Tank Guns |
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I have a problem, in general with FASA weapons. I'm not going to go into mechanics, or calibers, or ranges, but, instead just the sheer numbers of differnet weapon systems.
I realize that scientists being scientist always want to come up with stuff that's new and better than the stuff that came before, but there has to come a time when the governments, or those controlling the financing say enough.
Supply is a huge issue with any unit in the field, and mine is no exception. My 'Mech forces possess nearly every type of IS and Clan weapon available in 3060 (except for Max Cheese tripe). My supply system is overburdened trying to accomadate all the weapons, so I've gone to carrying spares and ammo for only the most common systems. I carry some LRM ammo, SRM ammo, some Gauss slugs, and that's about it. I play ACs as each having a different type of ammo (therefore AC-2 and AC-20 aren't inter-changable), and there are too many types that I don't normally bother with anymore than a few tons available for the most common (AC5, and AC10).
Still, once the ammo trucks are loaded, there isn't much room for everything, leading to fractional loads of ammo, or none of particular types being carried. That's why I'm moving away from that with my convential forces. I'm moving to a single platform, with a single main weapon (AC10) with a single backup weapon (MG). This way I can guarantee the I can have that type of ammo loaded on a truck, ensuring that all my units get atleast a little of what they need.
Do I miss some of the different weapons? Sure. But, I find it easier to keep my units running in extended campaigns where resupply becomes a factor.
Alexander
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Commanding Officer, North West Armoured Cavalry
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Sir Henry
Team Bansai
Senior Tech Specialist
Joined: 04-Feb-2002 00:00
Posts: 4899
Location: United States
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| Posted: 23-Apr-2004 06:14 Post subject: RE: Tank Guns |
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Tanker, I'm sure I could get you almost anything you needed, but on a consistant basis... Probably not....
Q Div is very important... 
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Sir Henry
A Dragon in the disguise of a bunny, is still a Dragon.
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