The long ranges the US plans to match to its artillery do not come from gun performance alnoe: the US will be relying on rocket-powered, gun-launched PGMs to reach those long ranges. We have posted up on other threads the pluses and minuses of these systems: mostly, because the rounds are getting more expensive, and are putting them into the region of surface-attack missile costs. The USN is opting for the 6"/155mm Advanced Gun System for its future DD(X). AGS is a massive mounting, and with these guided shells, is expected to engage targets out beyond 100miles. ANSR (Autonomous Naval Support Round) is currently a 5"/127mm munition to be fired from current naval guns. The manufacturer, ATK (Alliant Tech Systems) claims the round has reached 62 miles in tests. Numbers of 127mm weapons will remain in service alongside the 155mm gun of the DD(X), because many vessels will not be able to mount the massive gun turret and associated ammunition system. With GPS and IMUs (Inertial Measurement Units), CEP of these long range projectiles could actually improve considerably even compared to short-range artillery. Rocket assisted PGMs are definitely going to be the artillery projectile of choice for the future..

70km for conventional artillery in South Africa? It seems the West has got some learning to do!

I see - I was naive to believe that the 100+ mile ranges would be conventional projectiles. So assuming no augmentation on the actual projectile (no rockets, no base-bleed), what would you guess would be the maximum theoretical range future artillery pieces could achieve? What are the limiting factors preventing further range increases anyway?

Oh, forgot to ask... could liquid propellants, with their inherently higher energy densities than solid ones, significantly enhance range? And if so, by how much?

We got into a debate a while back about liquid propellants. United Defense (UDLP) years ago was developing an LP gun (there was an article in Popular Mechanics back in the mid-to-late 1990s.) The claims were a 22 percent increase in range. The test gun was a modified US "Long Tom" M59 155mm gun (the infamous WW2 shooter with its easily-identified carriage), and a 22 percent increase on its range of about 24,000yards/22km would be about 29280 yards/26.84km from its 45 caliber barrel. Considering modern 45 caliber guns (the GC-45 family, including the South African G5) can reach about 38km with base-bleed ammo, then "theoretically" about 46.3 km could be reached if converted to liquid propellant. The 52 caliber guns which currently reach about 42km could theoretically reach 51.25km (using the 22 percent increase.) Liquid propellants were studied because, like a car engine, the fuel can be tuned to burn at a more ideal mixture/rate, which offers greater "horsepower" at the muzzle, and more favorable launch stresses on the projectiles: solid grain burns at a set rate, whereas LP can be, like a gasoline engine, made lean or rich to get differing launch envelopes (instead of adding more charges, just pump in the right amount and mixture of liquid propellant.) Further developments certainly should afford greater than a 22 percent increase in range, as the best efficiencies per ratio are figured out. The Crusader SPG was considered to be equipped with an LP system at a later date. That Al Fao 210mm gun I mentioned supposedly could reach 57km with base bleed ammo, so the theoretical range there could easily be 69.5km. Gerry Bull designed several ballistically-impressive weapons, and his Iraqi Project Babylon Supergun was supposed to reach Israel from a hillside in Iraq. At a bore diameter of 1 meter (1000mm), the gun would have fired a sabot round: a sub caliber, possibly fin-steered, projectile that could gain great velocity like tank KE ammo, and reaching into the upper atmosphere, could reach the range of 1000km. More info is over at: http://www.fas.org/nuke/guide/iraq/other/supergun.htm Although such massive weapons (a 1000mm supergun and the Gustav 800mm railway weapon of WW2 fame) are wholly impractical from a US standpoint, certainly long range tube artillery will be around for years to come. The idea of gun range needs to be considered for your area of operation: no point sending in a gun system capable of 25-30 mile range when your enemy is only within 5-15 miles of you. Range is nothing without terminal lethality: the South Africans used a CAD program to design the fragmentation pattern of the 105mm shell for their 30km LEO prototype, and claim its lethality is on par with many 155mm airburst rounds. So logically, using the same technology in 155mm guns would increase their lethality even more. And as electronics improve, we will see even more artillery launched PGMs. Adding rocket assistance also allows for more maneuvering in flight to compensate for a target changing location. Years ago some defense contractors were expirementing with ramjet-powered artillery shells designed to reach higher velocities, higher altitudes, and corresponding longer ranges. I haven't seen much on this for the past few years, though. But certainly there are technical hurdles here as well, as the shell would have to sit inside a shoe or sabot so no gun gases vented up through the shell's hollow ramjet chamber on launch. But the catch here is: the more "stuff" we pack into artillery projectiles (such as ramjet fuel and electronics), the less room for explosives. The US does seem over-dependent on the MLRS and USAF/USN CAS aircraft. But certainly we should not be putting all our faith in just these platforms. I do agree we have fallen behind in the capabilities of our tube artillery. (case in point: we've purchased and "Americanized" the UK light towed 105mm gun instead of designing our own, and just about everybody but the US and Canada has incorporated some of the newer long-range 155mm guns into their inventory. (perhaps that's how the US DoD justifies spending billions on aircraft programs, to do the job of the artillery we don't have?). Perhaps such sub-caliber rounds could be developed for standard tube artillery: one of Bull's "paper projects" was such a round for the 16inch rifles of the Iowa class battleships. He anticipated a roughly 8"/200mm subcaliber round with a range of 200-240km (I'll look around and see if I can find more info.) But without an effective guidance system for that kind of range, the CEP of the shells would've been horrid. As for maximum unassited ranges for a gun... It is doubtful that we will see anything approaching 100miles without a rocket boost. But if the shells could be made extremely smooth aerodynamically to reduce air friction (maybe even dimpled like those long range golf balls?), and the shells could withstand higher muzzle velocities approa

A bit of theory and practical considerations. Starting with internal ballistics range is a product of shell weight and muzzle velocity squared. This means that for a given MV the heavier unassisted projectile goes further. Of course for a given MV a heavier shell needs more propellant. MV is mainly determined by the amount of propellant. The maximum amount of propellant is a function of chamber size. Of course there are differences in the energy produced by the same amount of different propellant types but they are not huge. The next design consideration is that all the propellant should be burnt before the shell leaves the barrel (otherwise its wasted). In fact its also desirable that 'all burnt' is well inside the barrel because the gas pressure keeps pushing the shell albeit it at a slowing rate of acceleration. This is the effect exploited by longer barrels. Of course a highly energetic propellant is usually hot burning and this means the chamber and barrel wear faster. Wear gradually reduces MV. Ignoring shell weight, this invites the question as to what is the highest MV than can be produced using chemical propellant. One indicator may be tank guns firing KE projectiles. This leads to a consideration, these are solid metal, no need to worry about the high acceleration and rotation having adverse effects on HE filling or fuze mechanism (or other payload - remember Copperhead and M483 bomblet are range limited because of this problem). This leads to other constraints, obviously 5000 tons of ship is not too bothered by a lot of recoil force or a long barrel. Not so field artillery. There are obvious size and weight constraints, some actual (eg bridge loads) others more subjective, such as practical barrel length in the field. Then there are stability issues for the mounting/carriage. For towed guns the amount of traverse is a stability issue, but it also affects some SPs (eg 175mm M107 had a reduced traverse when firing at top charge, G6 needs stabilisers and undercarriage spades). Tactical concepts/doctrine and other technology also come into play. For example, if you think your artillery will always operate by changing positions after each target, and your guns have automated location and pointing, then you don't need much traverse because you can 'always' align the vehicle with the target. However, it's extremely doubtful if this is a viable tactic. In some situations you might want to dig in and maximise protection including top cover. And given that the world is increasing urban things like factory buildings offer excellant concealment, they also screen against sensor fuzed munitions and keep bomblets at bay. However, parking in the doorway tends to require a lot of traverse. They also have concrete floors so you can forget any gun that needs spades. Actually this is also a problem in the country, the need to fire from roads when there is a mine threat, deep ditches (unless you carry fascines), wet padi on either side, etc. It's not clear if guns like Ceasar can fire from hard surfaces. Of course guns that need to deploy spades, outriggers and the like for stability are not well suited to the tactic of 'stop, fire a burst, move', although in these circumstances you can also accept a certain amount of sliding back. However, if you're on a narrow road and have to align the vehicle with the target you've got a problem unless the road points at the target. It's these sorts of tactical considerations that actually limit the options in gun design (and also call into question some of the new guns being touted around by salesman and purchased by armies who confuse the field firing training areas with possible battlefield reality). Moving back on subject, after internal ballistics come external ballistics. The main concerns for range here are projectile stability and streamlining. Stability tends to decrease as barrel wear increases (the shells get a slight wobble). However, streamlining is the big consideration, the feature of Bull's 'solutions' is not really gun design, its shell streamlining. The S African designs were highly streamlined (so much so that they have 'nubs' on the ogive to keep the shell straight in the barrel), this streamlining may reduce the amount of HE fill (depending on shell length) but it certainly decreases the cargo capacity for things like bomblets. This leads to target end considerations, notably dispersion (ie probable error in range). First it's worth pointing out that modern ammo improves PE. For example L15 shells with L8/L10 charges have about half the PE of M107 HE and white/green bag. To this you can add the technology of MV prediction (MV radar on every gun providing data for the next round fired), which roughly halves PE. The problem is increased dispersion means you usually need to fire more shells for the same effect on a given target. Current thinking seems to be that about 40km is the limit for acceptable

Actually nobody has 'americanised' the Light Gun. There were in fact 3 versions designed, L118 which is the real thing, a version for the Swiss firing their ammo but did not go beyond prototype and L119. UK only acquired about 15 L119 which fires the US type M1 round (L41 105mm How in UK terminology) and were built to make use of existing ammo stocks for training. The US took the L119 as the M119. Aust also built a few dozen L119 and L118 for own and NZ use, exactly as per the technical data packs provided by ROF, although the first few guns were built in the UK and most of the rest used many UK built assemblies, this local assembly and limited manufacture was in the name of 'self sufficiency'. The only differnce is that L119 uses the L20 ordnance, L118 uses L19 ordnance for the '105mm Fd' ammo, to be really pedantic this is actually the Mk 2 105mm Fd. Mk 1 was only used in training during the first few years of Abbot while Mk2 ammo stocks were built up, it used the L41 type shell for a 15 km max range. Interestingly this option of a cheaper shell seems to have passed Aust by when they decided range was unimportant and stopped using L118, but perhaps the cost of modern triple base propellant was also unaffordable. Interestingly Aust trialled both M198 and FH70 in the early 80s. M198 was selected and the Army Minister at the time claimed it was the 'best gun in the world' (clearly his speech writer didn't know his arse from his elbow). It seems that weight was the deciding issue and the ability to move M198 by heli! Again Aust missed the opportunity to adopt high lethality ammo.

Ah yes, liquid propellants. A long and sad story were a lot of people (but not all) who should have known better ignored the obvious and believed their own hype. Liquid propellants have been experimented with since soon after WW2. In the late 70s some people decided that enough progress was being made that they would soon be viable as a gun propellant. Crusader was originally intended to use LP! Oops. The problem that was persistently ignored ('hoped away') was what a propellant needs 2 things, fuel and oxidant. The fuel problems were steadily worked through, but the oxidant proved too difficult. Some experts had said this all along.

doggtag and neutralizer - these were incredible posts - I am truly in awe and thankful for you sharing your knowledge with me. :) BTW: Sorry for my belated responses - I had a sudden surge of workload... Neturalizer, you mentioned that liquid propellants (well, the oxidizers) proved unviable in the 1970s, but it has been 30 years since - has technology advanced far enough to make them viable now? You also mention that beyond about 40km dispersion becomes too great to use non-guided munitions - can this be circumvented somehow? Once you begin using guided munitions, the price per shell (I believe guided shells cost about $30,000 per round and although I do not know how much unguided ones cost, I would guess no more than $300 including propellant charges - 100 times less) goes up enormously thus negating one of the main advantages of artillery. I would also like to ask, what are the desirable characteristics for artillery to have apart from range (which is part of my original question), price (this is pretty obvious), traverse (explained very well by neutralizer already), flexibility of fire and move (again brilliantly explained by neutralizer how some guns cannot fire well on all surfaces and how fire and move depends on other artillery characteristics). Perhaps maintainablility and durability, or mobility and weight, or the rapidity of fire and ability to fire many types of artillery shells or armoured protection and lethality of fire something else entirely is crucial? What else can be used to judge artillery? The fire and move flexibility brings me to another question... why cannot some self-propelled (I can see why this does not work with towed, carried, or other types of artillery) artillery fire when moving? Tanks can do it, so I am wondering why even best self-propelled artillery has to at least stop. Also, would it be possible to combine tanks and self-propelled artillery into one platform? And a final question - how much do modern artillery pieces (carried [in case of mortars], towed, self-propelled and ship based) generally cost? Yes, it depends on the type, but a general ballpark figure would suffice.

LP, if there has been any breakthrough no one is saying. I've always suspected another problem, precise 100% guaranteed failsafe measurement and injection of the fuel into the chamber. The problem is during training not so much in war. Particularly in W Europe where the live firing areas are small with not much margin for error. I've always wondered (in the LP Crusader context) how on earth the US Army was going to convince the German officers who run the ranges in that country and have a legal responsibility to ensure that no shells land outside the training area that there would be no malfunctions. The problem with guidance is that its cost needs to be related to the value of the effects of the payload. However, low cost methods have been developed, for example probable error is a range problem, but you don't need fancy flight controls to fix this, just aim to overshoot, use GPS and a few smarts to control 'pop-out' (from the fuze body) spoilers to reduce range at the right time. There's probably all sorts of features that artillery could/should have. What priority is given to which depends on doctrine, what sort of enemy you expect to fight, tactics, strategic needs, operational concepts, how much arty you have, the capabilites of different elements, environment, terrain, etc. It's also useful to remember that the gun is not the weapon, the shell is. But that the arty system is far more than just shells and guns, the whole thing has to adressed as a system (its now fashionable to talk about arty as a 'system of systems', a nonsensical term to anyone who understands systems as a science). During the Cold War things were simple, most armies knew what to expect with some degree of confidence and where they expected to fight. Its still fairly simple if you limit yourself to narrowly defined national defence of own territory and you have a fair idea of your neighbours' capabilities. If you envisage expeditionary operations anywhere against an undefined enemy then it gets a lot more difficult. It's a question with no right answers in advance and no consensus. Apart from added complexity and the need for heavier mechanical gear to keep the unclamped elevating mass under control while moving there's no real reason why SP guns couldn't fire on the move, ships do. The question is 'for what benefit'. Stop, shoot, move seems OK for the moment. Moving isn't going to stop a RPV following you, as an Iraqi 130mm bty discovered last year (they tried a 'shoot and scoot' action against the Brits, who located them then directed an RPV on to them, the snag was the time it took to get an aircraft to attack them because they were out of arty range).