Bharat Rakshak

Against tanks, smoothbore (AFPDS/HEAT) is a better (cheaper) weapon

While the sabot spins, the KE penetrator itself does not

Are there methods to impart a spin on round fired from a smoothbore cannon? Against tanks, smoothbore (AFPDS/HEAT) is a better (cheaper) weapon while against buildings and light skinned vehicles, rifled (HESH) seems to be better.

MPAT (M830, M830A1), MPAT-OR (M908) round target effects:
Depend on chemical energy and not striking velocity.

Used primarily against lightly armored targets, field fortifications, and personnel. Are secondary armor-defeating ammunition.

Due to slower muzzle velocity, these rounds are not as accurate as APFSDS rounds at ranges beyond 2,000 meters.

Rounds arm approximately 60-100 feet from the muzzle of the gun. Because of the shape and metal components of the projectiles, however, this ammunition remains effective at ranges of less than 100 feet.

Heavy Armor. Because of a relatively small explosive warhead, MPAT effectiveness against heavy armor (tanks) is limited to attacks from the side and rear. Mobility kills of heavy armor can be achieved when fired at from these orientations (especially if tracks and or road wheels are struck); however, the vehicle armament is likely to remain operational.

Light Armored Vehicles (LAVs). The heavy nose of the MPAT projectile makes it extremely effective against LAVs. Vehicle kills can be achieved with an impact on varying locations on the hull or (if so equipped) the turret. Mobility kills can be achieved if the wheels or tracks are struck, and it is likely that a road wheel or track impact will also produce penetration of the hull structure. MPAT is effective when it impacts targets from perpendicular to highly oblique, but will function with a reduced reliability when striking excessively oblique surfaces (nearing that of a graze impact).

Bunkers. The heavy nose of the MPAT projectile makes it extremely effective against earthen, timber, and or sandbag bunkers with the projectile "burying" itself into the bunker structure before warhead detonation. When this occurs, the projectile detonation produces not only lethal effects to personnel within, but a highly-destructive effect to the bunker structure itself.

Buildings. MPAT is effective against buildings with wooden walls over 1 inch thick. Impact against a thinner wall structure (plywood sheathing without striking supporting members) may produce only a small hole as the projectile passes through the wall without detonating. Impact against a supporting structure (roof rafter, wall stud) causes detonation of the warhead and a subsequent hole and lethal fragmentation effects to personnel located inside. Impact against concrete walls yield holes of about 24 inches in diameter, but reinforcing bars embedded within the concrete are not likely to be cleared from the hole, unless struck directly. One MPAT round normally creates a breach hole in all but the thickest masonry construction - a single round demolishes brick veneer and wood-framed constructions. The round is large enough to displace enough spall to inflict casualties inside a building.

Helicopters - M830A1. The M830A1 MPAT, when switched to the "A" or "air" mode, is effective against attack helicopters because of its proximity switch, which can produce mission abort kills without actually impacting the aircraft. The design of the proximity switch is such that if the projectile (set in the "A" mode) is fired against a helicopter, and is on a direct impact flight path, the projectile warhead will not function in the proximity mode, but will be detonated when the projectile strikes the target. If the projectile, however, strikes lightly armored parts of the structure (such as windows or the aluminum skin of the aircraft), it is likely to pass directly through the aircraft without detonating. Impact with heavier structures, such as the engine or transmission components, will cause detonation of the warhead.

Concrete Obstacles - M908. The M908 HE-OR-T projectile, because of its steel nose, is effective against large concrete obstacles. This effectiveness comes from the projectile's striking the face of the obstacle and penetrating several inches before the warhead is detonated. This penetration fractures the concrete obstacle from within, breaking it into smaller blocks, which can be cleared with an M9 Armored Combat Earthmover (ACE). A concrete block 6 feet in diameter and 6 feet long is broken up into rubble, which can be cleared by a tank equipped with a bulldozer blade.

HESH was the old solution, it is not needed anymore. Better solutions to HESH exist.

MPAT (M830, M830A1), MPAT-OR (M908) round target effects:
Depend on chemical energy and not striking velocity.

Used primarily against lightly armored targets, field fortifications, and personnel. Are secondary armor-defeating ammunition.

Take a look here
http://www.inetres.com/gp/military/cv/weapon/M256.html

Due to slower muzzle velocity, these rounds are not as accurate as APFSDS rounds at ranges beyond 2,000 meters.

Now compare that with the picture of a HESH and HE-Frag round fired from a rifled gun and you immediately notice the bulbous ogival nose that is FULL caliber and obviously packs a far greater amount of explosive than the sub caliber round.

Vina, your "what the 99% of worlds tank do and what India and 500 challys need is different" would even have been a excuse before Arjun decided to switch to smooth bore.

Well, the videos that the folks posted here on mods that are going into MKII feature the same gun as far as I can see! . Unless of course you so clairvoyant that you already see MkIV and V and probably a future tank that is also named Arjun, I think we should go with what is there in front of our eyes!

On changing nature of tank ammunition.

http://www.thefreelibrary.com/Changing+ ... a096696884

Without many of the personnel involved appreciating or liking the fact, the main battle tank is reverting to its original role, that of being a mobile protected gun platform. As tanks evolved historically, the main opponent of the tank emerged as other tanks; therefore, they became the primary targets to be engaged. Entire ammunition loads of many battle tanks were devoted to armour penetration in some form or another, with little or no provision made for other natures (that is what the rifled to smooth bore switch is. both primary and secondary ammo as Anti Tank!). That situation has now been altered, as high explosive projectiles are once again becoming familiar to tank crews, along with other ammunition novelties. (indeed it is. Once you went smooth bore, you have to make do with the best of what you have and hence new ammo, making the best out of a suboptimal choice)

Blunt-nosed Heat fin-stabilised projectiles are fired at low muzzle velocities and are thus prone to side wind and other in-flight influences so may not be particularly accurate other than at short ranges. .haa haa. but we are spin stabilized and NOT fin stabilized like the smooth bores! Hesh, also known as high explosive plastic (Hep) by the US Army and others, is frequently not to hand as many nations have chosen not to adopt the type, usually on perceived ammunition safety grounds. On the other hand, many armed forces, such as those of Britain and Pakistan, have always highly regarded Hesh for its long-range accuracy and on-target effects. More on this later.

In particular read the various types of HE rounds (non HESH) that exist and the roles they play in tank battles.

There is also the advantage that the provision of HE enables, at times, the host tank to act as a mobile artillery platform.

This was exactly the role for which the South African Denel 105 mm HE-T round was developed, to be fired from 105 mm L7/M68 series tank guns. During the South African border campaigns of the 1980s, armoured columns supported by tanks often operated deep within what was then enemy territory. Towed or other artillery was frequently at a premium during such operations, so if artillery support was needed it repeatedly had to be provided by the tanks. Although much of the HE fire provided by the South African Olifant (Centurion) tanks was delivered at direct fire ranges, it was possible to engage indirect targets up to 10,000 metres away .

Armies with artillery assets rarely need tanks to deliver indirect fire but they do need to back up soldiers on the ground, often at very short ranges. HE projectiles are therefore becoming increasingly more commonplace; even if few newly developed examples are yet available.

Here, the former Warsaw Pact nations have the advantage over their Nato and other Western counterparts in that they have always regarded 100, 115 and 125 mm HE as practical, all-round projectiles with numerous applications. They have long been able to deploy HE as a (relatively) low cost means of demolishing obstacles or knocking holes in walls for infantry to crawl through. They can also deal economically with soft vehicle and comparable high combat value targets. There is also the advantage that the provision of HE enables, at times, the host tank to act as a mobile artillery platform.

It appears that Warsaw pact could have a effective multi-role platform with smooth bores -- and they did not use HESH

Dude. This is beyond belief! The Warsaw pacts CAN have an "effective" multi-role platform .. note they DONT .

Here, the former Warsaw Pact nations have the advantage over their Nato and other Western counterparts in that they have always regarded 100, 115 and 125 mm HE as practical, all-round projectiles with numerous applications. They have long been able to deploy HE as a (relatively) low cost means of demolishing obstacles or knocking holes in walls for infantry to crawl through. They can also deal economically with soft vehicle and comparable high combat value targets.

How exactly is a rifled gun of this type meaningless

Because Sanku Maharaj Ji thinks so ?

Oh well. He does have reading comprehension problems, especially when the references he posts say exactly the opposite of what he claims supports his view !

once sabots were made, rifling on tanks was meaningless. .

Actually that is not true and mixes cause with effect. Objects of high length to diameter ratio cannot be spin stabilized and they need tk be fin stabilized. longer thinner penetrators needed fins for stabilization and a way to be fired as sub caliber rounds. that is why sabots were developed - a way to hold and fire sub caliber rounds from guns. sabots would also be needed to fire penetrators from rifled guns because they are sub caliber there too. On the other hand fat short projectiles still need spin stabilization. Pray tell me how sabots have subsumed rifling?

The debate whether HESH is needed at all and consideration of gun similarity is valid. But saying somehow sabots have rendered rifling useless is nonsense and completely meaningless.

When did SABOTs really pick up, after they got long or before they that?

How are you so sure that I havent been reading this thread?

My point is, Arjun might very well become smoothbore, even share a barrel with the T90, not because smoothbores are inherently superior, but because we bought a boatload of tanks which have smoothbores.

My other point is, Arjun got a rifled barrel because it was in the GSQR and the army wanted it.

If they want to go smooth bore on Arjun will the claiber match the existing inventory for commonallity or will it be uniquely different?

At the DEFEXPO, Tata Motors displayed scaled models of its concept Futuristic Infantry Combat Vehicle (FICV) (Tracked & Wheeled), including the turret. In addition, the proposed layout of the production facility was also displayed. Tata Motors is one of the four Indian companies, which has been issued the Expression of Interest (EoI) by the Indian Army, for the FICV - a 'Make Indian' project. Tata Motors has accordingly responded to the EoI based on indigenous design and development in association with key technology partners and submitted their response in October 2010.

Sanku and Anujan while you are arguing about "rifling of barrels", the politicians-arms merchants are rifling the military procurements.

The Arjun MkII isn't getting a new gun. In fact I cannot remember any news about the Arjun getting a 120mm smoothbore gun at all. The only smoothbore talk we have heard about is on the FMBT which is not even a paper tank yet. The only person who seems confident that the Arjun will get a 120mm smoothbore gun is Sanku. I'll appreciate it if he can point us to a news item stating the same.

3) The advantages of a smooth bore gun are well understood, now that Indian Mil-Ind complex has necessary know-how, they are shifting to smooth bore for Arjun.

HEAT is not effective when fired from rifled barrels unless you add slip rings. This is because the HEAT jets get dispersed due to spin. HEAT has to be stabilized somehow. This can be done by making them long, making them sub-caliber and adding fins and a Sabot. But that reduces effectiveness of HEAT because the penetration is proportional to the diameter of the HEAT metal liner. (That is why you have the bulbous head in hand-held anti-tank rounds). You can make HEAT bulbous and stick out of the front of the tank somehow and fire it, but for enough range, it should be rocket propelled rather than an explosive cartridge propelled. Which suits hand-held anti-tank weapons but not tanks.

d. The reality is that we are stuck with thousands of tanks with smoothbores and that is the direction we probably have to go.

You may not know, but I was probably the first on the forum to predict that Arjun will move to smooth-bores, and why. And this was much (2 years?) before the news came out

Of course, but then GSQRs were primarily written in 70s, by which the clear advantages of smooth bores were not fully understood all over the world. Also the GSQRs were closely on lines of "previous and old" experience with British tanks which were rifled. (added later --> ok before you jump on me again, the tanks were not rifled, their gun barrels were)

Sanku and Anujan while you are arguing about "rifling of barrels", the politicians-arms merchants are rifling the military procurements.

The Arjun MkII isn't getting a new gun. In fact I cannot remember any news about the Arjun getting a 120mm smoothbore gun at all. The only smoothbore talk we have heard about is on the FMBT which is not even a paper tank yet. The only person who seems confident that the Arjun will get a 120mm smoothbore gun is Sanku. I'll appreciate it if he can point us to a news item stating the same.