I always iamgined it as a catch all terms to describe the largest of conventional (solid ammunition) guns. I've typically only seen it used to describe starship weapons and fortress emplacements.

This suggests they have a huge recoil or power/cooling requiremnts and need to be embedded for the neccesary stablisation. I imagine they operate just like any other artilelry piece or alrge gun just in a different scale.

I don't think autoweapons are caseless, autocanons and auto guns certainly are. perhaps your thinking of boltguns?

 

I think a Macrocannon, as alluded above, just means a sodding-great gun of some kind, probably throwing out commensurately large shells.
I would imagine that most of these types of guns would be carried on huge, mono-task vehicles, with the entire carriage being designed to cope with any recoil and muzzle-flash. Others would, by necessity, be built into turrets and fortifications where the complex damping systems could keep it on-target and allow it to fire quicker.
Shells might be anything from high-ex, to kinetic slugs, to chemical dispersants. They might even be able to reach into low-orbit, the kinetic penetrators being very good against large, high altitude targets.

GFP

 

Just about all I know about Macro Cannons comes from this...

 

Just about all I know about Macro Cannons comes from this...

Dude! That's an awesome pic. Where's it from, a BFG book or something?

 

Well thats **** stupid.

When you consider that with current day technology 20Km/s speeds have been achieved with modern day railguns (on a very small scale admittedly) something that is traveling at 20Km/s will travel 36,000Km in 30 minutes - thats about a 10/th of the way to the moon!

If you are firing at a moving target not only are they ridiculously far away, they will have also moved before the projectile gets there and if you are firing at a stationary target on a planet then after half an hour its no longer bloody stationary - it will have moved 1/48th of the way around the planet (Assuming its earth sized and speed).

So they are either close up weapons, or they are utterly useless.

 

Maidel: They rely on both closeness and sheer volume of fire. Also, you don't need a direct hit if you can just create a big enough explosion(or equivalent) - note the lines going down and the gun crew down there... now compare their size to that of the shell being fired.

Big enough explosion should be achieved with some ease.

 

Maidel: They rely on both closeness and sheer volume of fire. Also, you don't need a direct hit if you can just create a big enough explosion(or equivalent) - note the lines going down and the gun crew down there... now compare their size to that of the shell being fired.

Big enough explosion should be achieved with some ease.

You do comprehend quite how far 36,000KM is?

Remembering that space is three dimensional 36K KM by 36K KM by 36K KM is 46,656,000,000,000 KM3.

The effective blast range of a 100MT nuclear warhead is perhaps 150miles. Thats roughly 250Km in each direction. So each blast would be 15,625,000 KM3. You would need 2,985,984 warheads in order to fill that area with blasts.

Judging by the size of those missles by the size of the tiny little people at the bottom they are about 3 times the height of a man and about 8 times the length. So each missle fills up about 220m3.

Therefore one salvo fired at that range needs 656,916,480m3 of space.

These huge battleships are (please correct me if im wrong) 11Km long and judging by the model I have they are about 1km wide and 2Km tall. Thats 22,000,000,000m3.

Therefore ONE salvo of macrocannons that are roughly comparable with the largest blast humans can create today would need 1/33 of the entire ships volume in missiles.

Thats one volley.

Thats not practical as weapon.

 

Fleet doctrine is always changing, though. BFG mentions it used to be all about closing with the enemy, slugging it out at close range and trying to board what's left. Then, the Carriers came into the ascendancy, changing the way of fighting to stand-off engagements. The Macrocannon could be a hold-over from the days of close range fighting, retained in newer ships as a contingency, should the enemy get close. There's always the chance, as well, the fleet doctrine might veer back to close range, and then who'll be ready?!

GFP

 

Boltguns are not caseless, Auto-weapons (Autocannon, Autogun, Autopistol) are not (usually) caseless.
You're thinking of Assault Cannons, which does fire caseless ammunition, which is why the had the potential to explode in 2nd edition.

Macrocannons are apparently railguns that fire explosive shells, making them technically caseless, but also odd.
That said, I would imagine that given how the Imperium names things, "Macrocannon" is probably applied to any very large gun that fires shells, and possibly even ones that fire plasma or las or decommissioned tanks. The Imperium of the 41st millennium is not known for standardization.

 

Yes but do we know what the standard engagement range is? I always believed it to be somewhere between 10 and 20,000 thousand k's with under 5000 being considered 'knife fighting' close.

If that's the case then they have more practicality as a weapon.

Boltguns are not caseless, Auto-weapons (Autocannon, Autogun, Autopistol) are not (usually) caseless.
You're thinking of Assault Cannons, which does fire caseless ammunition, which is why the had the potential to explode in 2nd edition.

Actually bolts are caseless. Their self propelled rockets, they don't have nor need cases. I point you towards every space marine codex description of the bolter in the wargear section and the 3rd edition weapon's page in the fluff section (the one with the schematics and descriptions of the lasguns, assault cannon, meltagun etc).

 

Macrobatteries appears to be applied to most starship weapons, yes (with some exceptions like Nova Cannons and Torpedoes). At least, if GW was paying any attention when FFG wrote the Rogue Trader RPG rules.

 

The macro cannon used to be a titan weapon in the age of the old epic space marine. Large solid shell weapon. Caseless goes without saying. Probably solid or liquid propellant. As far as accuracy, the spped of the shell can be mitigated somewhat by advanced targeting systems.

 

I would imagine that a target's moving would be taken into account, should a Macrocannon be fired over long-ranges. Just like Fighter Pilots using cannon in dogfights would 'lead' the target and fire where it was going to be, not where it was, an enemy's course would be taken into account so that shell and ship would intersect at some future point.
However, I think this weapon is rightly being thought of a short-ranged; it would depend on how quickly large Warships could change course during a battle is the void- too quickly and no shot will ever hit home at long-range. Of course, if a shot is going to take 30 mins to hit the target then it does have the advantage of being 'stealthy' in some respects. The initial firing would be easily detectable, but after that the shell is, basically, an inert slug. It might be large when compared to a Human, but in the vastness of space, a Macrocannon shell would be an insignificant speck. In this way it might be more of an area denial weapon, multiple ships fire a volley in a certain direction, hoping that the enemy will be forced to change course out of concern that they might be hit because they can't detect the shells in transit; this also could carry a psychological edge, the fear of being hit causing enemy Commanders to react, rather than dictating the course of the battle.
Just some thoughts a-rattlin' around my noggin.

GFP

 

The actual base of a ship model represents very close range around the ship, no more than a few thousand kilometres...

Few thousand kilometres: let's make it an nice easy 2000km.
Radius of a clear base is approximately 2cm. (little bit less I think)

So BFG has a scale of about: 1cm = 1000km

Average Imperial weapon battery in BFG has a max range of 30cm.

So, Imperial weapons batteries have a range of roughly 30000km.

Max Time of flight:
30000/20 -> 3000/2 -> 1500secs -> 25mins (at max range)



So imperial weapons batteries take, at most, roughly 25 minutes to reach their target. It doesn't seem that farfetched that the Imperial ships have some kind of targeting computers that do target prediction. It's not like ships in BFG are small and maneuverable and capable of changing their heading very quickly. Capital ships need to move 15cm (15000km) to be able to turn 45 degrees. Also, no timescale is given in BFG. A game turn could be well over an hour for all we know.

 

Course calculations are certainly taken into account in 'naval' warfare. I recall numerous scenes where 'firing solutions are plotted'. This would suggest that the ship's and its targets movement speed, likely course etc are all calculated and used.

Here directly from the rulebook "...Each battery consists of rank upon rank of weapons, plasma projectors, laser cannons, missile launchers, rail guns, fusion beamers and graviton pulsars. Batteries fire by salvoes, using a coordinated pattern of shots...

Additionally given that their in game effects are represented by the placement of blast markers we can possible extrapolate that indeed as Giant Fossil Penguin suggests that they work via area denial and saturation. They are probably designed to explode in huge radius rather than say penetrate the hull of the ship directly, instead they buffet it, knocking down shields wrecking turrets, causing surface damage and spreading electromagnetic radiation/interference. Then lances, super accurate and fast travelling deliver the killing blow, carving into the hull of the ship.

 

You have to take in account the momentum and inertial of the target. It's make the cube into a cone and taking also the problems to quickly change course and speed in bigger battleships the cone reduces more.

Surely main targetings systems don't rely on visual range but in electronic emissions (or heat that is well in the cold vacuum) to make the finging. The later is better because if the temperature is decreasing (moving to red) it tells you it getting away and if it's go purple (violet range) you're closing.

In WWII commanders needed to take account of the the enemy ship (weight, speed, course, lastest maneuvers). Mixing that you could make an aproach to launch the torpedoes and ammo.

So you got a cone region of the space, more little as bigger the ship is. You don't need to saturate the entire solar system to get the enemy hit. You just has to use maths and apply engineering!