tag:blogger.com,1999:blog-386077914312449748.post4460354787050881543..comments2024-03-27T20:37:08.065+01:00Comments on Defence and Freedom: Revisiting the ACRAUnknownnoreply@blogger.comBlogger13125tag:blogger.com,1999:blog-386077914312449748.post-83893864890454701222013-10-10T02:39:16.887+02:002013-10-10T02:39:16.887+02:00In theory this resembles a Brummbär-like capabilit...In theory this resembles a Brummbär-like capability, yes. The maximum elevation of a 140 mm gun and the ammunition resupply (indirect fire would rather not make use of HESH) would be issues, though. It would probably be a niche capability.S Ohttps://www.blogger.com/profile/03359796414832859686noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-71241365883244350862013-10-10T02:15:51.305+02:002013-10-10T02:15:51.305+02:00I suppose if you're going to go that route you...I suppose if you're going to go that route you might as well update the ballistic computers so that you can also fire the HE rounds indirect, giving you an expedient heavy mortar capability too.F.noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-82508212088670252812013-10-08T18:07:22.755+02:002013-10-08T18:07:22.755+02:00A 140 mm stub gun needs a HVM, for its AT capabili...A 140 mm stub gun needs a HVM, for its AT capability would otherwise rest on a short range dumb round and a kind of ATGM which is very susceptible to active and reactive defences.<br /><br />Also, a greater diameter helps propulsion not only inside a barrel (pressure * area = force). It can also help rockets, as it provides enough volume for solid rocket fuel without excessive length. The successful HVM developments up to M6.6 used solid fuel rockets without breathing air, which is an additional source for failure in a concept that's still a technology frontier after 30 years of R&D.<br /><br />120 mm automatic guns exist, but you're not going to be able to give them a fine maximum elevation for indirect fire and ShorAD without a very high turret. That and the trouble of reloading 120 mm with elevated barrel are the real restrictions.S Ohttps://www.blogger.com/profile/03359796414832859686noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-45897889911822150152013-10-08T17:35:25.685+02:002013-10-08T17:35:25.685+02:00This blog post should be seen in context to my oth...This blog post should be seen in context to my other pet idea, the medium calibre (~76 mm) rapid fire gun option. A tank battalion with many such 76 mm / 30+ rpm guns would mostly lack raw power of 120 mm guns. A mix of 76 mm / 30+ rpm guns with 140+ mm stub guns on the company level would as a whole possess both specialisation advantages and much greater versatility than a 120 mm-only MBT force.<br /><br />This statement made me calculate a bit.<br />Take the 100mm French naval gun. It has two thirds the diameter area of a 120mm gun and half that of a 140mm gun.<br />Upping rapid fire for 120mm should be within the realm of the possible and a long rod pentrator round with two parts would provide your suggested solution that could be implemented into a 120mm. You have not really explained why a long rod rocket penetrator needs a 140mm tube.<br />As an alternative one might consider the solution of altering the current system by introcuding a two part penetrator rod with matching precision ends and a scramjet, plus an automated rapid fire for the 120mm that can switch to manual loading for special munitions.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-3250213537064643502013-10-08T17:13:40.303+02:002013-10-08T17:13:40.303+02:00Interesting idea. SO
Amount of rocket fuel can be...Interesting idea. SO<br /><br />Amount of rocket fuel can be reduced by having a scramjet that uses oygen from the high volume of air that is being traversed within a short timeframe.<br /><br />Manual loading could be augmented with mechanical aids for the loader. These can help to solve handling problems of length.<br /><br />The two piece amunition process still might be considered. Is it possible to assemble a large pentrator in the barrel? You need to glue one penetrator section onto another. The sarissa is an ancient solution for the task. http://scottthong.files.wordpress.com/2007/05/sarissa1.jpg<br />Something similar can even work today. Its energy transfer capability depends on the high precision of the two matching penetrator ends.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-47605759118255172392013-10-07T04:48:40.575+02:002013-10-07T04:48:40.575+02:00About APFSDS:
The long rod penetrator gets eroded ...About APFSDS:<br />The long rod penetrator gets eroded when it penetrates armour - same as a shaped charge jet.<br />The quest for more penetration wasn't only a quest for better material (tungsten and uranium are necessary because steels shatter at 1200+ m/s impacts). It was also a quest for more length, as more length means more length available for erosion = deeper penetration.<br />Rule of thumb: Fin stabilisation works up to length:width of 6:1, fin stabilisation works at 7:1 and more. So at first APDS was fine, but as penetrators became longer fins became necessary for stabilisation, thus APFSDS. APFSDS became longer over time (DM13 to DM63 was ~463 to ~743 mm: http://www.kotsch88.de/m_120_mm.htm).<br />By the 90's the length of Western APFSDS was greater than the length of the projectile in the Russian 125 mm two-piece ammunition and the Russians were disadvantaged by this restriction of their ammunition's potential.<br />More here http://fofanov.armor.kiev.ua/Tanks/ARM/apfsds/ammo.html<br />But AFAIK they preferred the cheaper HEAT munitions anyway.S Ohttps://www.blogger.com/profile/03359796414832859686noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-26849011813030019982013-10-07T04:36:54.710+02:002013-10-07T04:36:54.710+02:00Refleks isn't so much a missile as it is a gui...Refleks isn't so much a missile as it is a guided round with a sustainer rocket. Its Mach 1 speed requires only 1/36th the kinetic energy as it would with Mach 6. <br />The solid fuel rocket required for a Mach 6 missile with long rod penetrator is different by an order of magnitude. The propellant charge for pushing the missile out of the barrel at Mach 1 is negligible by comparison and the one used with Refleks has been designed that way because of the laser beam receivers and the autoloader dimensions.<br /><br /><br />A HVM is basically a tungsten penetrator, a battery some casing, a simple autopilot and several kilograms of very high quality propellant. There's no expense for a Tantalum liner for the shaped charge and no expense for a non-cooled infrared sensor of 2+ km range as in modern ATGMs. I suppose it's affordable.<br />Its problem isn't price, but its lesser versatility due to no explosive warhead. That's no issue in this case, though.<br /><br /><br />The 140 mm tank guns would have been introduced if the Cold War hadn't ended. It's only the peace dividend which did put a premium on being able to use old 120 mm stocks. Western tank experts were still fixated on frontal MBT-on-MBT combat by the late 90's, but the budgets weren't.S Ohttps://www.blogger.com/profile/03359796414832859686noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-37681782832895540432013-10-07T03:30:22.294+02:002013-10-07T03:30:22.294+02:00. . . But the Russian missiles ARE in two pieces.
.... . . But the Russian missiles ARE in two pieces.<br /><br />I wasn't aware of Russian problems with APFSDS and would be curious to learn more, if you can point me to further reading.<br /><br />I get the desire to shorten tank barrels, but given the expense of current through-barrel missiles, do you really think that a hypervelocity missile would be affordable? Also, at what point do direct-fire systems draw the line between ammo bulk and quantity? I recall that being a problem with the 140mm gun (along with reduced elevation/depression, and a massive increase in weight).F.noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-55997925712311503132013-10-07T00:56:39.095+02:002013-10-07T00:56:39.095+02:00This doesn't work well with long rod penetrato...This doesn't work well with long rod penetrators (Russians have this problem with their APFSDS) and is certainly impractical with a missile body.S Ohttps://www.blogger.com/profile/03359796414832859686noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-2237907502801135322013-10-07T00:12:40.305+02:002013-10-07T00:12:40.305+02:00If you are worried about munitions length, there&#...If you are worried about munitions length, there's always the Soviet/Russian approach of using two-part ammunition. Loading might be marginally slower, but there would be fewer restrictions inside the turret.F.noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-29381172337909512752013-10-06T14:48:44.709+02:002013-10-06T14:48:44.709+02:00Oops, I forgot to make the comparison to the more ...Oops, I forgot to make the comparison to the more relevant HVM instead of with the classic ATGM:<br /><br />CKEM: 1500 mm, "< 45 kg"<br />HATM: 1270 mm, weight unknown.<br /><br />Rockets are less propulsion-efficient than cartridges, so they need more propellant. The high acceleration of a HCM and thermal effects also require a rocket wall of some significant weight.S Ohttps://www.blogger.com/profile/03359796414832859686noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-18038802425822777962013-10-06T14:26:05.167+02:002013-10-06T14:26:05.167+02:00It's a normal rate of fire gun, comparable to ...It's a normal rate of fire gun, comparable to the one used in M41 light tanks or the French Panhard EBR throughout the Cold War.<br />The closest thing is IMHO the 60 mm HVMS used on Chilean light tanks. 60 mm isn't versatile or powerful enough, though.<br /><br /><br />The ACRA's missile weighed 26 kg complete and was 1250 mm long, the dumb round being 20 kg and 900 mm.<br /><br />German wartime cartridges for the 120 mm smoothbore tank gun weight 19-29 kg.<br />The difference is really the length of the missile and the diameter, and not much else.<br />The bulk and length requires a dedicated internal layout of the turret and its basket.S Ohttps://www.blogger.com/profile/03359796414832859686noreply@blogger.comtag:blogger.com,1999:blog-386077914312449748.post-31570592897902654302013-10-06T07:42:52.121+02:002013-10-06T07:42:52.121+02:00Didn't want to necropost on your ARES75 post, ...Didn't want to necropost on your ARES75 post, but I didn't see a mention there of the Rooikat 76 with the Denel GT4. That's the closest I could think of to a current version of that caliber of weapon in current use, although it doesn't seem to have met with any export success. <br /><br />Regarding this post, at its most basic level you add the problem of ammunition handling. A 142mm round/missile would not be lightweight and given most western Atvs continue to use human loaders, you'd be looking at a reduced rof compared to current 120mm systems. Anonymousnoreply@blogger.com