What was that? I couldn't hear you over the echo from my 1000sq ft cockpit
Caliber of a Huge Multigun/cannon
- Thread starter smegunit
- Start date
What was that? I couldn't hear you over the echo from my 1000sq ft cockpit
Sure, but for a given propellant charge we should be seeing much higher muzzle velocities if we're using lighter rounds. The weight should remain consistent across the board so we need to use existing firearms as a starting point.
In Elite the weapon emplacements are self-contained units. The gun and any ammunition must fit within the design weight for the hardpoint.
That's only because the game isn't an accurate sim where they've taken into account projectile weights. We know the projectiles must have weight, it's a firearm with a specific muzzle velocity and we have a reasonable maximum size for the projectiles given the calibre, ammunition capacity and reasonable material density limits. If you're starting from the premise that the projectiles have zero weight because the game designers have simplified a game mechanic then we're not discussing a reasonable engineering issue any more, we're just pointing out the obvious flaws in the gameplay.
The weight of a battleship shell is dramatically higher for the same muzzle velocity, on an order of at least 10X and more likely closer to 50X if we're using 20 kg projectiles for a class 4 cannon. Friction or gravity has nothing to do with it, we're talking muzzle velocities here. The consequences of firing the weapon in space means your muzzle velocity doesn't drop off once it leaves the barrel but you still have to generate the muzzle velocity in the first place with a suitably powerful propellant charge.
The apparent barrel size could be dramatically thicker than necessary for other design reasons but we still have to go by the weight limitations we see in the design, not just the visuals which clearly don't scale up properly in-game. It's worth remembering that a large barrel doesn't necessarily imply a large projectile depending on barrel thickness and there's no real reason why the projectiles couldn't be substantially smaller than the barrel diameter. If weapon weight, damage and projectile velocity all point in one direction for the weapon effectiveness they are more important than the apparent visual size when it is clearly out of the proper scale for a doubling of weapon weight. The game has set up a clear progression with a doubling of weapon weight going up with each hardpoint size and we have to take all the information into account knowing that some of it, such as the visual appearance, clearly doesn't match up properly for the larger guns.
Last edited:
Sure, Elite is fundamentally a fictional setting, but it's interesting to consider how the technology could work if was a real-life firearm design.
For example, let's build a Class 3 multicannon using an existing weapon as a starting point, walking through the design process as if it were a real firearm.
Comparing the Class 3 Multicannon to the 40 mm Bofors
We're gong to start with this weapon:
And try to create this:
Design Comparison
The best comparison we have as a starting point using existing autocannon designs would probably be the Bofors L/70 40 mm autocannon in terms of overall size and projectile weight. The main advantage of this comparison is that there are two versions of the Bofors, the L/60 and the L/70 version, which gives us some idea of how to scale up the design in terms of expected performance. Additionally the Bofors has seen widespread use as an anti-aircraft gun, a naval mount and is even carried by the AC-130 spectre gunship in an air-to-ground role so it's a weapon that has been used effectively in a variety of different roles and mountings.
Dimensions and Weight
The first issue to address is the barrel length of the Class 3 multicannon. Due to the extending barrels of the Class 3 multicannon it's not possible to get an exact barrel length but we can get a reasonable visual estimate based on the size of the hardpoint. The Class 3 large hardpoint dimensions are approximately 7.5 m long when stowed and approximately 10 m long when desployed with barrels extended. The barrel length for the Class 3 multicannon when extended is approximately 1/2 of the total length of the weapon which works out to approximately 5 m. The L/70 Bofors version uses has a barrel length of 70 calibres, i.e., 40 mm x 70 = 2.8 m. A 5 m barrel on the Class 3 mutlicannon would therefore be the approximately equivalent of a L/120 barrel in comparison. This is a relatively long barrel for an autocannon but the comparison does allow us to scale the weapon up reasonably well from the existing Bofors L/70 design.
Regarding total gun weight, the L/60 Bofors weighs 1981 kg or approximately 2 tons while the L/70 Bofors weighs 5150 kg or approximately 5 tons. Giving our assumption of 25% ammunition storage for a 8 ton weapon mount, that leaves 6 tons for the Class 3 multicannon. The additional barrels would increase the weight of the design compared to the single-barrel Bofors designs but a 6 ton weapon with 5 barrels of L/120 length would be reasonable with modest weight-reducing strategies. We can currently achieve significant weight savings in existing firearm designs by replacing steel components with lighter materials such as titanium, for example, the M134D-T minigun design which uses this approach. It would be reasonable to keep the Class 3 multicannon design within a 6 ton weight limit assuming similar weight-reducing strategies were employed.
Projectile Weight and Muzzle Velocity
The projectile weight for the L/60 Bofors is 900 g for the high explosive 40x311 round at a muzzle velocity of 880 m/s. The L/70 fires a longer 40x364 round which could propel a similar projectile at a higher muzzle velocity of 1030 m/s. The muzzle velocity of the L/70 is similar to that of the M61 Vulcan's 20 mm rounds or the GAU-8 Avenger's 30 mm rounds so again this scales well with previous comparisons, again assuming that we're keeping the muzzle velocity constant and simply increasing the projectile weight.
If we wanted to estimate the advantages of a longer barrel length in the Class 3 multicannon, we can compare the muzzle velocity for the L/60 and L/70 versions of the Bofors design. In this case the muzzle velocity increases from 881 m/s to 1021 m/s from the L/60 to the L/70, giving a muzzle velocity that is roughly proportional to barrel length. With an L/120 barrel on the Class 3 multicannon we could reasonably expect that the considerably longer barrel would generate a muzzle velocity of around 1600 m/s, i..e, approximately double the length and muzzle velocity of the L/60 barrel, which would match the in-game projectile velocity.
Rate of Fire
In terms of rate of fire, the L/60 Bofors has a rate of fire of 120 rpm while the L/70 version has a substantially higher rate of fire of 330 rpm. The class 3 multicannon has a rate of fire of 6.7 rounds per second or approximately 400 rpm. It wouldn't be difficult to achieve a fire rate of 400 rpm with a 5-barrel gatling design so that is not a difficult issue to scale up as we're only increasing the ROF by approximately 20% over the Bofors L/70. The 5-barrel design, especially if it is externally powered, could also provide considerable improvements in sustained fire and reliability over the single Bofors L/70 gun.
Ammunition Weight
The cartridges for the Bofors weigh approximately 4.8 pounds, or 2.18 kg, which means the 900 g projectile weight is approximately 41% of the total cartridge weight, close to the 50% assumption I had been using in my prior post. This means an ammunition load of 2100 rounds would weigh over 4.5 tons, which is over 50% of the weapon weight, and that would leave less than 4 tons for the gun itself. This is an issue in terms of fitting both the gun and the ammunition load within the 8 ton limit, but it's not insurmountable even with modern technology if we use caseless rounds, which can reduce of the total cartridge weight substantially compared to conventional rounds. If we assume a very efficient caseless design combined with modest advances in propellant it could be possible to design a 1 kg round where only 10% of the total cartridge weight consists of a highly efficient propellant that propels a 900 g round. This would be necessary to get the weight down to 1 kg per round or approximately 2 tons for 2100 rounds of ammunition. It would also keep the weapon's ammunition storage and feed systems more compact as well, which would be another advantage.
Performance Comparison
Essentially in comparison to the 40 mm Bofors L/70, the gatling design of the Class 3 multicannon fires rounds with approximately 2.5X more muzzle energy than the single L/70 gun, and also achieves 1.2X the fire rate due to the gatling design. That means that the combination of the increased fire rate (due to the gatling design) and the higher muzzle velocity (due to the longer barrel length of 120 calibres) would create a weapon that is 3X more powerful and effective than the single L/70 Bofors, while being very similar in overall weight and dimensions.
We do know, however, that the stock Class 3 multicannon design in Elite is not at its design potential. If we push it further to the current Engineering limits with a Grade 5 overcharged modification, i.e., using rounds that are approximately 45% more powerful while maintaining a similar ROF, we can produce a weapon that is nearly 50% more effective. That now puts an overcharged Class 3 muticannon at approximately 5X the overall effectiveness of a single L/70 Bofors given the combined increases in damage, rate of fire and muzzle velocity.
Additionally, in terms of overall weapon effectiveness there's the argument that the explosive contained in the Elite autocannon rounds could be substantially more powerful and could use armor-piercing materials which are more advanced than current rounds. There's also the issue of using experimental rounds such as incendiary or corrosive rounds as well. Since we have no way of measuring or quantifying this, however, it's purely speculative and we don't really have any in-game comparisons to use to assess this properly. This could, however, explain in-game effectiveness that was substantially higher in comparison to a modern round of similar calibre and muzzle velocity. It is worth noting that when combined with the design advantages of a Class 3 multicannon that already provides approximately 5X the effectiveness over a single Bofors L/70 gun, these factors could produce firepower that is even more effective than the above comparison would suggest, and this could result in a gun design that is 10X (or more) effective than the single Bofors L/70.
Caveats and Limitations
An argument could be made that a Class 3 multicannon could use stronger and lighter materials or manufacturing technologies to achieve substantially higher performance in certain areas. Conversely, there's the issue that the weapon needs to operate in a vacuum, at extreme temperatures and under high g-forces during ship maneuvers. Additionally we're assuming that the weight of the gun includes the servos and tracking system that is built into the weapon mount for a gimballed weapon. If we take the gun comparison at face value it would seem reasonable given current technology to make the basic design work within the weight and perfomance limits. Assuming that improvements in materials and design would be balanced out by the dramatically harsher and more demanding operating environment that the gun would be subject to in space would make this an issue that we wouldn't necessarily need to address as part of our comparison. In other words, whatever advantages the design gets in terms of more advanced technology would be used to allow it to operate at a much higher level of reliability in a much more demanding operating environment and that is really a different discussion. It could also explain why Elite guns would be bulkier than modern weapons of similar weight, i.e., they may require more rugged or bulkier designs with thicker barrels or other special design requirements compared to modern firearms while achieving much higher overall performance at a similar weight. In particular, the apparent size of the thicker barrels in Elite compared to the calibre of the ammunition would actually make sense given that the barrel would need to withstand much higher operating pressures to achieve the higher muzzle velocities involved and would likely be heavily overbuilt and engineered to operate effectively and reliably in space.
The overall conclusion here is that using known parameters for weapon weight, calibre, barrel length, muzzle velocity, ROF and ammunition storage could result in a practical and effective firearm design. There would be additional factors to consider in terms of the weapon's performance given the operating environment and other design issues but the core design features would be reasonable and effective based on current principles of firearm design.
Last edited:
Maybe they're airsoft multicannons, which would also explain the negligible weight of the ammunition...
if the ammo mass is your only issue.
i have always wondered how the ammo is fed into the weapon to begin with.
or how you would make a railgun with three rails.
or power a laser without connecting it to a power source.
It's actually not the air flow of the rotating barrels that cools a multi-barrelled weapon and allows it to achieve a high ROF, it's that the effective ROF is spread out among multiple barrels. A 5-barrelled gatling weapon for example would only be subjecting each barrel to an effective ROF of 1/5 of that of an equivalent single-barreled weapon, which results in much lower barrel wear and heating. There are liquid-cooled autocannon designs that exist, the most notable example here is probably the 23 mm cannons mounted on the ZSU-23-4, but the additional complexity of maintaining an effective and reliable coolant loop in a vacuum environment at a wide range of operating temperatures would probably not be as effective as simply using a gatling design instead. Additionally the gatling weapons in Elite are externally-powered (we see them spin-up prior to firing any rounds) and the reliability of an externally-driven gatling design has additional reliability advantages over a single-barrel design. For example, misfires are easily cleared with an externally-powered gatling weapon since it can simply cycle to the next barrel and eject the misfired round which would provide another important design advantage over a single-barrel design.
Last edited:
None of it makes sense, but then I don't think it was ever supposed to. We may as well be debating the necessity of wands in the Harry Potter universe.
I'm aware of this, but cooling a rotating multiple barrel assembly without airflow seems like it would be vastly less practical/efficient than cooling a single barrel. Doesn't matter how many barrels you have if they all rapidly become too hot to use.
The same advantages in loading.ejecting could be achieved with a single barrel revolver cannon design.
For any given set of operating conditions however the barrel heating and wear will still be reduced in direct proportion to the number of barrels. This is true even if there is no airflow or external sources of cooling because the heat is being generated directly by the firing of the rounds and the effect they have on the barrel when fired. With a gatling design you can either achieve the same ROF and subject each barrel to a proportionally lower heat/wear load or drive the barrel assembly at a proportionally higher ROF compared to a single-barrel weapon. Many gatling weapons actually have selectable rates of fire so you can choose an appropriate ROF (usually full speed or half speed) depending on the situation. The weight penalty and spin-up time are inherent disadvantages of a gatling design but it does result in much better sustained ROF, improved reliability and reduced barrel heating/wear.
Yes, a revolver cannon would have some of the reliability advantages of a gatling weapon, and the relative advantage of lower spin-up time as well compared to a multi-barrel gatling weapon, but you would only get the advantages of reduced barrel heating/wear with a multi-barrel gatling design.
Last edited:
I've always thought that the large ship designs in Elite are a breath of fresh air, since most space games have you piloting tiny little snub fighters, and not the hulking bricks we have here. Besides, this is space, everything can be scaled up, you just need the technology to drive it... and in the 34th century, they have the technology!
You can save a ton of ammunition weight by going with nuclear propellant and a lighter projectile while having the exact same impact energy.
i have measured the outer diameter of the Class 4 Multicannon's barrel. its ~34 cm.
to bad its not modelled hollow, so you have to guess the diameter of the actual bullet
the visible length of the barrel is 9.4m (including the "muzzle break")
to bad its not modelled hollow, so you have to guess the diameter of the actual bullet
the visible length of the barrel is 9.4m (including the "muzzle break")
Not with a muzzle velocity of 1,600m/s you can't.
That's interesting, it definitely seems that the class 4 multicannon and cannon visuals are where the dimensions get really out of scale. From what I can tell the largest multicannon ammunition that would be reasonable for the class 4 multicannon given the weight and projectile limits would be 50 mm rounds, which are much smaller than the 340 mm barrel diameter you measured. The easiest explanation here is to basically ignore the massive barrel diameter and assume that the barrels are unusually thick due to Elite structural materials having unusually low density for their volume or simply because the guns need unusually thick barrels for some other reason.
Would it be possible for you to post similar measurements for barrel diameter and length for the class 3 multicannon? I've estimated the maximum reasonable ammunition for that weapon to correspond to 40 mm rounds based on maximum weight and projectile limits and I'm wondering how oversized the barrels would be for 40 mm rounds.
What exactly is "nuclear propellant"?
Setting off a nuclear bomb inside the breech of a firearm wouldn't achieve anything beyond destroying the firearm in question. Even if you could design a firearm with a material capable of withstanding an internal nuclear explosion then you would just build ship armor using that same material and the ship would literally shrug off nuclear warheads.
I'd say they're a little bit bigger than the tomatoes gun I'd say 500mm
I think the ships were scaled up for a very simple reason: visibility at typical combat ranges (say 0 - 5 km). Otherwise we would be looking at specks just a few pixels wide far off in the distance. I don't know why they didn't scale up the human figures too because that's what causes the "single chair in a ballroom" effect of cockpits.
ok, the class 3 multicannons inner barrel diameter seems to be something around 9cm, the outer diameter goes up to 14cm (cone shaped)
the class 4 cannon barrel is 42cm inside, 75cm outside, the visible part ~5.5m long (making the whole cannon ~15m long)
so, for the cannon - comparing it to the yamato's about one inch off
if you go with the trend, the class 4 multicannon has a caliber around 22-25 cm
Last edited:
ok, the class 3 multicannons inner barrel diameter seems to be something around 9cm, the outer diameter goes up to 14cm (cone shaped)
the class 4 cannon barrel is 42cm inside, 75cm outside, the visible part ~5.5m long (making the whole cannon ~15m long)
so, for the cannon - comparing it to the yamato's about one inch off
if you go with the trend, the class 4 multicannon has a caliber around 22-25 cm
Interesting, the scaling certainly goes well of the charts for the class 4 multicannon and cannon but it looks like the visuals do support a very thick barrel relative to the apparent projectile size which does help quite a bit in explaining some of the discrepancies.
I think I'll try approaching the problem from the opposite direction, i.e., assuming the visuals are accurate and trying to ignore the need to keep the total weight of the hardpoint and ammunition within the outfitting limits. I'll have to assume that ammunition storage is completely separate from the weapon mounts themselves to even make this vaguely possible but I'll try to see if I can potentially make the projectile sizes work using lower material density limits for the ammunition.
Looking at the apparent caliber of the internal barrel diameters, we've got the following estimates from your measurements (assuming a ratio of 0.6 for the class 4 multicannon's ammunition diameter compared to the barrel diameter, i.e., an average of the measured ammunition/barrel ratios for the weapons with visible barrel interiors):
Class 3 Multicannon: 90 mm (approx. 3.5 inch) ammunition, 140 mm (approx. 5.5 inch) barrel
Class 4 Multicannon: 200 mm (approx. 8 inch) ammunition, 340 mm (approx. 13.5 inch) barrel, 5.5 m barrel length
Class 4 Cannon: 420 mm (approx. 16.5 inch) ammunition, 750 mm (approx. 30 inch) barrel, 9.4 m barrel length
If you have a measurement for the visible barrel length for the Class 3 multicannon I'll start doing the calculations using the visible projectile calibres as a starting point and see how we could fit that type of a weapon into the existing designs using much lower-density materials for the firearm and ammunition.
Last edited: