Spirit of Hope wrote:Manokan Republic wrote: The Dragon fire mortar literally does't mean any of the criteria he set out, and neither do most auto-loading mortars for that matter. It's not muzzle loaded, smooth-bore, always high angled, doesn't have to use various propellant charges and it has a recoil buffer. Do all these things mean it's not a mortar, even though the military calls it that?
You guys consistently prove my point that you are just about trying to hostilely nitpick irrelevant things to derail a conversation for no reason, focusing overly heavily on semantics instead of important base concepts. It's shallow and pedantic.
Uses the Dragon Fire mortar which weighs 1.5 tons as an example of what he is talking about.Manokan Republic wrote:It depends on the machine gun. A .50 caliber is 120 pounds, while 1200 rounds of ammunition would be 300 pounds, or 420 pounds. A 60mm mortar is only 40 pounds on a bipod, and 100 rounds of ammunition would be, 315 pounds. Assuming another 100 pounds or so for the autoloading mechanism, whatever it may be, that would be close to a .50 cal in terms of weight. Then there's 20mm and 15.5mm machine guns, 14.5mm machine guns, and so on and so forth which would be even heavier than a .50 cal. Dual-mounted .50 cals, quad-mounted 14.5mm etc. Of course there are arguments of weight, size, ammunition carriage, the mounting system, armor protection and so on and so forth that all effect size.
Depending on exactly what you used, it could be larger, smaller, around the same size, whatever. But if it's the equivalent of three machine guns, it's still quite tenable to add.
Says he can get a 60mm auto loading mortar for less than 500 pounds, including ammo.
Now I realize the Dragon Fire is a 120mm system, and you are talking about a 60mm system, but the weight for the dragon fire doesn't include ammo and you weight guess did. If we go by your "Assuming another 100 pounds or so for the auto loading mechanism" plus "40 pounds on a bipod" you get a weight of 140 pounds, a 20th the weight of the Dragon Fire.
The AMOS turret is 9,000 pounds, but it is 2 almost semi auto 120mm mortars and the armor needed to protect them. The NEMO is 3,000 pound turret with a 120mm mortar in it. You will notice a trend here, the systems are weighing more than you think they will and much larger than you think they will be. Will you get some saving from dropping from 120mm to 60mm? Yes. Will it drop your system from being a vehicles turret to being a RWS and the weight from thousands of pounds to less than 200? No.
This is not me "hostilely nitpick irrelevant things to derail a conversation for no reason," this is me showing how your concept as stated won't work. IF all you want is a MK-19 scaled up to 60mm, my back of the napkin math puts that in at around 600-700 lbs. But that won't be a mortar system.
The reason for the extra weight and complication is due to the need to adjust propellant charges and other fairly complex and erroneous things. One additional problem is that the mechanism is designed to work as a stand alone system, and so it has to be heavy enough to help absorb the recoil of the system, and it has additional recoil absorbing mechanisms due to the fact it's autoloading. These are nice to have, but not really necessary in all gun designs. There are two things I will mostly focus on, first that chainguns tend to be substantially lighter weight than most other types of firearms, and second the simpler the round fired the smaller the weapon can usually be. An example is the Japanese Ho-401 autocannon, which fired a 1.5 kilogram round at 495 m/s, double the velocity and slightly heavier than the average 60mm mortar (at around 250 m/s for a 1.25 kilogram round), held about 50 rounds, and was 150 kilograms, or 330 pounds, and was able to fire at around 80 RPM, more than sufficient for use as a mortar. While not very commonly used, it nonetheless demonstrates what is theoretically capable with such a weapon system. It is a pretty obscure example and I do think that the full cartridge weight of such a weapon was about, 5 pounds, so fully loaded it might have been pretty close to 500-600 pounds (although the gun itself is 330 pounds and not 140 pounds), so it's still quite small for something that was, more powerful than a 60mm mortar with a similarly sized round.
The 40mm Bofors CT cannon, a gun designed to mimic the ballistics of the 40mm bofors, is about 800 pounds, vs. the 10,000 pounds for the L/70 40mm Bofors autocannon. Bare in mind, this is firing a round much more powerful than a 60mm or 81mm mortar would be, and the base diameter is about as large as a 60mm round. So, not only can an autocannon be a mere 330 pounds to fire a round actually somewhat more powerful than a 60mm mortar, but a chaingun design, could in theory, be even smaller. The simpler firing mechanism doesn't rely on trying to use the recoil energy of the round fired to cycle, so it doesn't need a massive recoil absorbing assembly, or massive bolt and receiver to hold in the recoil force of the round rearwards. You could think of it as like a straight-pull bolt action, only using an electric mechanism to actuate the gun. Because all you need is the barrel and fairly small loading mechanism in to the breach, a chaingun typically afford to be much smaller. A good example is the 30mm x 113mm chaingun, a mere 120 pounds vs. the 80 pounds for a .50 caliber machine gun, which has 3.5 times less energy and who's round is about 5 times lighter weight.
Design has a heavy influence on how large a weapon can be. So for example, a browning .30-06 machine gun was 31 pounds, but the M1941 Johnson machine gun was only 13 pounds. As far as it goes, the M1 Garand was 8.5 pounds and BAR was 18 pounds. As time has gone on, non-blowback designs using rotating bolts became small enough to become viable even as rifles, and so what was once seen as impossible for an infantrymen to carry around, became the same weight as a standard bolt action in an M1 garand. There are 18 pounds 7.62mm guns, such as the Mk. 48 and PKM machine gun, while the M240 is still 27.5 pounds. Generally it's expected there is a trade off, in recoil or reliability, but there are various guns that can do the same thing for a much smaller size. What's enticing about chainguns is that not only do they tend to be very small, but extremely reliable as well, with a test by the military finding for example that: "29,721 rounds of endurance tests were fired with no parts breakage and without any gun stoppages ... It is significant that during firing of 101,343 rounds not one jam or stoppage occurred due to loss of round control in the gun or feeder mechanism ... [this] is in our experience very unusual in any weapon of any caliber or type." The 27mm autocannon is a mere 220 pounds and fires a round with 160,000 joules at 1700 RPM, vs. the M230 chaingun firing a 25mm round with 100,000 joules at 300 RPM or less, and being 260 pounds. Chainguns are not even the smallest design available, but they do tend to be more reliable.
So you are right in that, based on something insanely complicated and large like the Amos or Dragonfire, that maybe it would be really heavy and large. But something firing a round of equivalent power and payload doesn't necessarily have to be. By simplifying the design and not using things like, adjustable propellants or other whacky and annoying stuff, like keeping a muzzle loading option, and not using existing mortar rounds but instead something like a standard shell of equal power, in theory it can be a lot smaller. So a typical aluminum cased autocannon round, a caseless or cased telescopic round, or something like it, instead of it being muzzle-loaded or otherwise, bizarrely loaded. For a round this large belts don't make as much sense, and instead you would use some form of linkless belt, or design it to be reliable with a belt nonetheless. I realize there is a lot of talk about the semantics of what makes something a mortar, so let's for the sake of brevity go with, a mortar like-round. The advantage of a mortar is that they are usually very powerful for their size. An equivalent sized artillery piece would need to be much larger, as the lower velocity of the mortar system allows a much more powerful round to be fired. Velocity is exponential, so if we go from say, 75 m/s, to 150 m/s, the energy is not doubled, but quadrupled, meaning that for example a 40mm grenade launcher would have quadruple the recoil if we went from 75 m/s to 150 m/s. Similarly, going from 250 m/s to 750 m/s is 9 times greater energy, or roughly mortar velocity to artillery velocity, and so one can fire an absolutely enormous shell from a much smaller and lighter gun, that doesn't need to be as large to handle the recoil. Furthermore without a recoil assembly, the weapon can generally be a lot smaller than a comparative artillery piece (often times mortars being muzzle loaded), using something akin to a baseplate to absorb more of the energy than a much larger artillery system would need. Mortars tend to have smaller rounds than artillery on top of this, for example like with knee-mortars or the 60mm mortar, so they generally can be even smaller. Mortars also tended to be cheaper as most were unrifled, which further simplified the design and allowed it to be made to be very strong at low expense, using a simple high strength tube without having to cut rifling twists in to it (either weakening the barrel, or being expensive to cut such a hard piece of metal). A more complex firing system does reduce a lot of the advantage of cost and size, but increases it's potential firepower. The main goal here is power for size, or perhaps payload for size, to be kept as the advantage of a mortar-like system. Ideally you would fire mortar sized rounds at mortar velocity, rather than actual mortar rounds which would need to be muzzle loaded and the like. You could call it a really large low velocity autocannon, a really large grenade launcher, basically anything, but the effect of the size of the round is essentially the same.
