Armoured Vehicles Discussion Thread

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 09:24

Picklu wrote:This is after Arjun has taken T-90 to task in the comparative trial as came out in the open source.
You won the argument no doubt. You also raised the quality of the debate in the forum to a new height.


Err Sirji, whats your problem with me now? Why are you attacking me personally? What did I do to you?

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Meanwhile on to more meaningful questions?

sameer wrote:Also why smoothbore ? Rifiled gun is more accurate than smoothbore guns.


Sameer, seeing that Austin hasnt replied to some of the questions, let me try and answer the parts I understand (which are open to discussion)

1) The world over all MBTs have shifted to smooth bore, Arjun is the last hold out
The reasons
2) Accuracy for rifled was primarily by spinning the shell, that accuracy advantage goes away with the new ammunition which is finned.
3)In fact for the modern finned ammo and tube fired missiles, the rifled gun is at a disadvantage since it is far more complex to achieve it than from a smooth bore
4) The wearing out of the grooves in a rifled gun makes it more maintenance intensive compared to smooth bore.

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Re: Armoured Vehicles Discussion Thread

Postby Shalav » 29 Apr 2010 09:53

sameer_shelavale wrote:Also why smoothbore ? Rifiled gun is more accurate than smoothbore guns.


Modern AT APFSDS (armour piercing fin stabilsed discarding sabot) ammunition consists of a rod penetrator, which on contact with armour converts to a plasma jet which in turn penetrates the armour. This has to be done at a very high velocity, and the ratio of the rod diameter to the rod lenght is somewhat crucial to the effectiveness of the penetrator.

However this rod is too thin for the barrel of the gun and has a sabot (french:shoe) wrapped around it so the shoe covers the entire inner dia of the barrel. When fired and on leaving the barrel the sabot is discarded (discarding sabot) and the rod penetrator continues on to the target.

There is another twist as the penetrator is most effective if it is not spinning hence it has fins to stabilise it during flight (fin stabilised). To avoid spinning the penetrator and with the expectation that most tank battles will be tank v tank almost all modern tanks have moved to the smoothbore cannon since it does not spin the penetrator.

On rifled cannon the practice is to attach a slip ring to the outside of sabot on the APFSDS shell which neutralises the spin and penetrator and sabot do not spin when travelling down the lenght of the barrel. The slip ring and the sabot are both discarded when exiting the barrel. However this adds a complexity to the ammunition for rifled cannon as compared to APFSDS ammunition for smoothbore cannon.

HESH ammunition OTOH requires spin to stabilise the round, and are ideal bunker busters. AFAIK the IA believes the main problem its will have fighting are the extensive DCB and bunkers on the other side of the border and hence it specified a rifled cannon in its GSQR for the Arjun!

Its just a different philosophy for different needs.

So there you have it.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 10:07

arnab wrote:Well - you were the one who has been claiming that ToT has been absorbed and Tanks are rolling out today. I have produced a report which shows that the extent of indigenisation today is 30 %. So clearly it has not been absorbed - no matter what newspapers or politicians say for soundbites. The devil is always in the details.


I do not understand what your definition of today and absorption is

Tanks with Indian contents are indeed rolling out as we speak.

Today in the year 2010-2011 (check it up on the calendar) where GoI is on the record with 70% Indian content.

ToT absorption and % of Indian components are TWO different things.

ToT absorption happens leading to Indian manufacturing. It is by definition a precursor. You first learn and then you make.

While Indian manufacturing is the final proof of ToT absorption, ToT absorption can very well happen and not be used in manufacturing if the line is abruptly terminated. There have been examples (HDW)

GoI is on the record saying that ToT is sorted out.

I fail to see why such a simple open and shut case is so difficult

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 10:12

2) Accuracy for rifled was primarily by spinning the shell, that accuracy advantage goes away with the new ammunition which is finned.


You have no idea of what you are talking about and keep going on and on like a broken record. I will repeat the technical reasons the one last time and if you are still tone deaf and unwilling to listen to good reason , I give up. My absolute last post on this. Take it for what it is.

Tanks fire 3 types of ammo , FSAPDS(the finned sabot sub caliber round), High Explosive Anti Tank (HEAT, basically an explosive formed penetrator that creates a hypervelocity jet of molten metal, same technique as AT missiles (Nag, Milan, Konkurs, Tow etc) and anti tank IEDs mines etc) and HESH or HEP (basically high explosive plastic good for think skinned vehicles, anti bunker demolition etc).

Out of these 3 weapons, the smooth bore has a potential advantage ONLY for the FSAPDS where it can possible generate a higher initial velocity at the muzzle. Now for HEAT , firing from the cannon of a tank is sub optimal (penetration depenedant on diameter of warhead which is limited by cannon bore, that is the reason why RPGs, AT missiles etc have big bulbous heads / tips/max dia) . That apart, beyond say 100m or so, unless you spin HEAT rounds, the accuracy sucks and pretty much useless beyond that and hence the need for FSAPDS for smoothbore tanks.

Now with a spinning collar/adaptor for the sabot, Arjun can fire a much longer and more modern FSAPDS (L/D is the gold standard for FSAPDS, not the Russian brouchuritis) than a T90S can ever hope to fire at pretty much the same muzzlevelocity of the best in class smooth bore (the Rheinmetall 120mm) and in ADDITION with a spinning collar to keep the heat warhead stationary, can fire a HEAT round to far far higher ranges (upto 6 km like the Challenger 2 did) with far higher accuracy ( any HEAT round from any T series will suck in accuracy beyond 1.5km (basic physics working there) than possible with a T series smoothbore and fire the HESH round (fully spin stabilized to 6 Km. Now , absolutely NO FSAPDS from any tank anywhere in the world can have penetration power at 6 KM (velocity drops off exponentially with distance and it is a KE penetrator) .

For the Russians to have that 6Km kind of range, they need a Rocket to be fired from the barrel of their T-90 and guided by the laser that illuminates the target and homes on to that. And why is that ?. Because they went smooth bore!.

The Arjun on the other hand can easily engage at those kind of ranges with very good accuracy with HEAT and HESH, with a simple gun. Why ? Because it is RIFLED.

Now, the rocket is more expensive, slower, takes a longer time to engage and plus the target needs to be illuminated by the firing tank or another illuminator for the full flight of the missile. Note, for extra long range, if you need the missile , you can still do it from Arjun.

Bottomline, each technical choice has it's pros and cons and based on technology choices, you build solutions. In a smoothbore, you dont need a spinning collar on the FSAPDS. But however, you cant have decent range for HEAT and HEP/HEFRAG kind of ammo and for long range engagement, you need a missile.

Rifling, you can get near smooth bore performance with FSAPDS (but given the T90 design, Arjun FSAPDS will be streets ahead of the T90, probably the FSAPDS in the Rheinmetall will outclass the Arjun minimally), but can do with a far simpler, cheaper and more reliable gun based solution in situations which will call for a missile in the T90.

Unkil's example doesn't count. Unkil will integrally put up a 100 Apaches to give top cover and attack capability over a M1A2 strike unit, not to mention A10s. That is an integrated air land system, that pre supposes tactical /battlefield air dominance. We cant do that, so our tanks will have to take out adversaries tank on tank and higher engagment ranges and accuracy you have, the better you can come off it.

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Re: Armoured Vehicles Discussion Thread

Postby Kersi D » 29 Apr 2010 10:20

Picklu wrote: have one suggestion for a major change to Arjun to rectify shortcomings for it to be adopted in numbers

1. Rename it to T-100

I have a better one, call its new ERA Shikhandi.

This is after Arjun has taken T-90 to task in the comparative trial as came out in the open source.
You won the argument no doubt. You also raised the quality of the debate in the forum to a new height.


One more suggestion.

Make it in Russia !!!

Perhaps all problems solved !!!

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Re: Armoured Vehicles Discussion Thread

Postby arnab » 29 Apr 2010 10:21

Sanku wrote:Today in the year 2010-2011 (check it up on the calendar) where GoI is on the record with 70% Indian content.

ToT absorption and % of Indian components are TWO different things.

ToT absorption happens leading to Indian manufacturing. It is by definition a precursor. You first learn and then you make.

While Indian manufacturing is the final proof of ToT absorption, ToT absorption can very well happen and not be used in manufacturing if the line is abruptly terminated. There have been examples (HDW)

GoI is on the record saying that ToT is sorted out.

I fail to see why such a simple open and shut case is so difficult


Sir, the proof of the pudding is in eating. Currently your assertion that ToT absorption is happenning seems to be based merely on a 'Yes we can' type of statement. GOI is not on record saying there would be 70 % indigenous content by 2010-11 - it uses the words 'expected'. There is no proof (reflected in data) that ToT absorption has happenned in the critical areas of T-90 technology as pointed out by Mrinal.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 10:36

vina wrote:
2) Accuracy for rifled was primarily by spinning the shell, that accuracy advantage goes away with the new ammunition which is finned.


You have no idea of what you are talking about and keep going on and on like a broken record. I will repeat the technical reasons the one last time and if you are still tone deaf and unwilling to listen to good reason , I give up. My absolute last post on this. Take it for what it is.


Boss your smooth bore vs rifled discussion is with T 90 and Arjun as examples.
:lol:

Can we stop this childish length comparison contests?

The reasons I mentioned for Smooth bore have nothing to with T 90 or Arjun. The world has accepted that Smooth bores are the better alternative and has moved on. I would also suggest that you come out of the 60s era sooner than later and update your knowledge base.

Wiki is a good place to start
http://en.wikipedia.org/wiki/High_explo ... nk_warhead

HEAT rounds are less effective if they are spinning, the normal method for giving a shell accuracy. The centrifugal force disperses the jet, so the round needs to be fired from smoothbore weapons, or else modified for use with rifled guns.


There is a VERY good reason the world has moved on from rifled. The new tank ammunition makes Rifled obsolete other than for the purposes of Bunker busting HESH.

Getting into T 90 vs Arjun has NOTHING to do with it.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 10:45

arnab wrote:Sir, the proof of the pudding is in eating. Currently your assertion that ToT absorption is happenning seems to be based merely on a 'Yes we can' type of statement. GOI is not on record saying there would be 70 % indigenous content by 2010-11 - it uses the words 'expected'. There is no proof (reflected in data) that ToT absorption has happenned in the critical areas of T-90 technology as pointed out by Mrinal.


Sure GoI says 70% is expected in 2010-11 in 2010 March. That is not a reliable indicator?

Secondly you may take the PoV that "If the Minister of state of Defence says that ToT has happened I will not believe it till a Parliamentary committee in 2012 states that x% indian components are there"

Fine suit yourself, I WILL take the word of a Indian minister over your characterization that they are saying "yes we can". In any case the point was that we are getting the Tech for T 90 smooth bore canon, its already sorted out (or even if I was to humor you for a moment, will be shortly)

So India should have the know how to make a tank gun which is latest gen for time frames meaningful for Arjun Mk II. It can leverage that understanding to try and design its own smooth bores. That to remind you is the overall point.

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 11:01

HEAT rounds are less effective if they are spinning, the normal method for giving a shell accuracy. The centrifugal force disperses the jet, so the round needs to be fired from smoothbore weapons, or else modified for use with rifled guns


Classic example of reading some factoid and extrapolating without any thought. I wonder if you even read anything I wrote about spinning collar and adaptors. In fact, you cant fire an FSAPDS out of a smoothbore without a collar. Similarly, if you read what I wrote , you will notice I wrote about an a spinning adaptor for HEAT as well.

In fact smooth bore cannons are a throwback to the medieval age. Go to the Delhi fort or any museum closeby (since you seem to be living in Delhi) and put your hand inside a cannon on display and tell me if you can find any rifling at all. They will be as "smooth as Hema Malini's cheeks, if Lalu Prasad were to be believed" .It is for very good reasons, that cannons were given rifling . As of today and in the foreseeable future, every artillery of every caliber is rifled and will continue to be so, becuase only then you can accurately engage in those kind of ranges with normal unguided shells!.

Tank guns followed a "fashion" (sort of like Bell Bottoms, in the 70s, because of the ability to fire missiles). But unlike Bell Bottoms, these "fashions" are very costly (will replace whole sale changes in inventory and stock piles and everything) and you can't throw them away because Bell Bottoms continue out of fashion. Now 40 years later if you are stitching a brand new set of pants and going for a totally new system without legacy issues,you are saying go and stitch Bell Bottoms again! :rotfl:

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 11:13

vina wrote:Classic example of reading some factoid and extrapolating without any thought. I wonder if you even read anything I wrote about spinning collar and adaptors. In fact, you cant fire an FSAPDS out of a smoothbore without a collar. Similarly, if you read what I wrote , you will notice I wrote about an a spinning adaptor for HEAT as well.


No Vina, not reading is a luxury that people, who know everything, seem to have. I have to read In fact I clearly mentioned


2) Accuracy for rifled was primarily by spinning the shell, that accuracy advantage goes away with the new ammunition which is finned.
3)In fact for the modern finned ammo and tube fired missiles, the rifled gun is at a disadvantage since it is far more complex to achieve it than from a smooth bore


So rifled canons have to jump through hoops to fire heats and faspds. For what great advantage?

In fact smooth bore cannons are a throwback to the medieval age. Go to the Delhi fort or any museum closeby (since you seem to be living in Delhi) and put your hand inside a cannon on display and tell me if you can find any rifling at all. They will be as "smooth as Hema Malini's cheeks, if Lalu Prasad were to be believed" .It is for very good reasons, that cannons were given rifling . As of today and in the foreseeable future, every artillery of every caliber is rifled and will continue to be so, becuase only then you can accurately engage in those kind of ranges with normal unguided shells!.


You are beginning to digress Vina. We are talking of tank canons, today which fire finned rounds. We are not talking about
1) Canons firing ancient ammunition without fins
2) Artillery canons.

We are talking Tank canons which have been smooth bore all across the world since Finned projectiles became mainstream, and that is how it is today.

Tank guns followed a "fashion" (sort of like Bell Bottoms, in the 70s, because of the ability to fire missiles). :


Hmm so the entire world Tank industry is blindly following fashion, that is your understanding?

How nice. Did they get YSL for the paint schemes as well?

-------------------------------------

The fact of the matter is today, Smooth bores are the preferred choices because it is better than rifled for the two primary ammunition HEAT and FSAPDS as well as missiles (since you dont have to jump through the hoops to remove the spin, hey if you want to remove the spin why spin the thingy) with the additional advantage of being easier to maintain.

That is how it is backed up by any number of online references. Meanwhile I would look forward to your further posts on the influence of Estee Lauder of mechanized warfare, this truly is a different line of thinking never explored before. :mrgreen:

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Re: Armoured Vehicles Discussion Thread

Postby arnab » 29 Apr 2010 11:22

I thought Shalav and Vina explained it clearly:

'Rifled' can fire HESH, HEATS and fspads (the latter two after modifying the ammo). 'Smooth' can fire Heats and fspads. IA GSQR required firing of HESH for their use in bunker busting. Hence Arjun was made with rifled barrel. Why all this discussion?

Of course one may suggest that it was actually GOI who came up with the suggestion of rifled barrel and asked the Army to go and find out a reason for executing the equipment :lol:

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Re: Armoured Vehicles Discussion Thread

Postby Austin » 29 Apr 2010 11:23

The other day I was watching a video of Abrams they fire the Sabo and HEAT rounds while the former is effective against Tanks , the latter they use it for soft skin targets APC etc and take out hardened position bunker etc.

So HEAT rounds essentially does 90 % what HESH can do , if you hit a bunker with HEAT rounds it will destroy it and kill the guy inside it , HESH may do it slightly better but there is no big advantage in having a HESH shot over HEAT .... one kills the other kills slightly better.

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Re: Armoured Vehicles Discussion Thread

Postby Anujan » 29 Apr 2010 11:26

vina wrote:Tanks fire 3 types of ammo , FSAPDS(the finned sabot sub caliber round), High Explosive Anti Tank (HEAT, basically an explosive formed penetrator that creates a hypervelocity jet of molten metal, same technique as AT missiles (Nag, Milan, Konkurs, Tow etc) and anti tank IEDs mines etc) and HESH or HEP (basically high explosive plastic good for think skinned vehicles, anti bunker demolition etc).


Agree with vina-ji

I have a few things to add.

Bullets from a rifle is stabilized (prevented from tumbling in flight) by spinning them. Hence they are rifled. The stabilization is due to gyroscopic effect and is more pronounced if the round is of a higher diameter. So, spin stabilization works great for a bicycle wheel, but not for a needle (the diameter is important). The rule of thumb is that if Length/Dia goes above 10, spin stabilization does not work anymore.

As vina-ji had mentioned, there are three types of tank ammo.

1. APFSDS - this is the famous rod penetrator. You essentially fire a rod out of the tank barrel. The longer the rod, the better the penetration characteristics. However, typical L/D for these types of ammo is about 20 or so. So there is no way spin stabilization would work. Hence you go for drag stabilization -- that is attach a bunch of fins in the rear, so that it resists tumbling and keeps the business end pointed forward. So smoothbore is ideal to fire this round. However, it can also be fired from a rifled barrel by adding slip rings so that the rod is not spun when fired. Note that for this type of ammo "Gun barrel wear" is a red herring, because the slip rings are usually made of tough plastics (yes plastics!).

2. HEAT. If you recall most shotguns are smooth barrel. Why is this? it is because if the shotgun ammo is spun, the shot disperses and forms a ring pattern and the center has no shot pellets. There is a similar problem for HEAT rounds. If HEAT rounds are spun the metal jet disperses and is not so effective at penetration. vina-ji is right in the sense that a higher dia produces a better HEAT round -- but I think that 120mm dia should suffice (it is the same dia as Javelin missile and RPG-29). I dont know anything vis-a-vis adding things like slip rights for HEAT rounds, but I do know that LAHAT can be fired this way.

3. HESH. This is the round with a plastic high explosive warhead. The round smashes into the target, makes a "pat" of explosive and then sets of off with a delayed fuze. Somewhat like smearing plastic explosives on a wall and then setting it off. Very effective for bunker busting. The problem with smoothbores are that, they cant fire these rounds, because these rounds have to be spin stabilized.

AFAIK, this whole smoothbore vs rifled is a red herring. Arjun can fire APFSDS which can defeat all known NATO targets at 5000m. This is for penetrator rounds. Arjun can also fire the LAHAT - this is for HEAT rounds. And on top of it, can make mincemeat of bunkers using HESH. You should note that Arjun can also fire other types of rounds that are typically fired from rifled guns -- such as airburst rounds with delayed fuze so it has good growth potential. There must be some pretty good reason why IA wanted a gun capable of firing HESH, I think that it is based on the fact that they would encounter bunkers & pill boxes, and armored vehicles can be taken care of by APFSDS anyway.

Now a word on autoloaders. Also note that while "Autoloader" sounds all nice and fancy, in a tank context the advantage is dubious. The reason I say is that it is an engineering challenge to design a simple rugged autoloader. For example, older gen autoloaders could operate only if the gun barrel was horizontal, so after every firing they would have be brought to that position. Secondly, it is hard to design an autoloader to deal with various size ammos. LAHAT for example is longer than typical rounds. And thirdly, the "loader" is also typically a skilled maintenance technician -- IA is not going to hire a guy whose sole job is to simply to shove another round into the tank barrel (which would be a waste of human effort), so that responsibilities are divvied up nicely. One guy to maintain the tank & drive. One gunner, one commander and one more maintenance guy.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 11:32

arnab wrote:I thought Shalav and Vina explained it clearly:

'Rifled' can fire HESH, HEATS and fspads (the latter two after modifying the ammo). 'Smooth' can fire Heats and fspads. IA GSQR required firing of HESH for their use in bunker busting. Hence Arjun was made with rifled barrel. Why all this discussion?


Except that Vina left out the part that modifications were painful and defeated the purpose to rifling. Which I have been saying since first post. (who brought up smoothbores ?)

Of course one may suggest that it was actually GOI who came up with the suggestion of rifled barrel and asked the Army to go and find out a reason for executing the equipment :lol:


Hmm you still need to understand the system it seems like, what the statement should have been "GoI comes with overall reasons which them prompts the forces to form a particular doctrine, which leads to specific acquisitions"

For examples, If the Govt tasks the IA to win East Pakistan back in 10 days, IA will opt for Amphibious assault vehicles and Pt 76 type tanks. If GoI tells IA. Win and hold terriroty in Pakjab in case of conflict, since we will use that for negotiations primarily they will want bunker busters.

If the GoI says, forget pakjab, we want to just be defensive there. But we really want to free up Sindh. We have a govt in waiting there. IA will rush headlong across thar to RYK.

These are the important things which some people seem hyper anxious to avoid.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 11:39

Anujan wrote:AFAIK, this whole smoothbore vs rifled is a red herring.


No its not. The reason is that rifled guns offer NO benefit for the APFSDS and HEATs and Missiles while offering major complexity (in terms of collars) as well as being maintenance extensive. In fact all the complexity to collar etc reduces its performance vis a vis a simple smooth bore.

That is why people have moved away from it. The entire world. Except one tank.

There must be some pretty good reason why IA wanted a gun capable of firing HESH, I think that it is based on the fact that they would encounter bunkers & pill boxes, and armored vehicles can be taken care of by APFSDS anyway.


That is the root of the discussion, is firing HESH a good enough reason to persist with rifled in spite of the extra baggage?

On Autoloaders I will let Austin share his view, at the moment. I would like to understand the tradeoff for sure.

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 11:41

So HEAT rounds essentially does 90 % what HESH can do , if you hit a bunker with HEAT rounds it will destroy it and kill the guy inside it , HESH may do it slightly better but there is no big advantage in having a HESH shot over HEAT .... one kills the other kills slightly better


Problem is HEAT from a smoothbore like the M1A2's accuracy will fall off exponentially with distance , while the Arjun's wont because it is rifled. The M1A2 will never use HEAT to engage an armored target at long range. It cant. Why ? Because HEAT being a full caliber round (120mm in this case) CANNOT be fin stabilized as easily as a sabot.

Remember, Sabots are long thin darts with razor sharp tips, while HEATs by design will have fat sections up front for the jet to be able to penetrate, the HEAT warhead will drop velocity of orders of magnitude more than the dart like sabot (higher frontal cross section) and are subject to more inflight instability that small control surfaces (in relation to frontal area) cannot provide stability without active controls like an aircraft (good luck to anyone who wants to fit moveable control surfaces in a tank shell..just the cost will make you bankrupt).

All this is old hat. Firing sabots from rifled guns and HEATs from rifled guns go back to the 50s and 60s .. Field guns did that all the time for anti tank roles .. Tank main guns were rifled (the only two guns that were smoothbore and became defacto standards in the west and east are the soviet 125 and rheinmetalls) and they always did that. Contrary to Sanku Maharaj's "hoops and loops" this is pretty much old hat and the spinning adapters are as standard as "daal chaawal". We have experience with the Royal Ordnance L7 (one of the best tank guns ever in history) from the Vijayanta. The Arjun's gun is just and updated version incorporating those good experiences. The CVRDE /IA have probably fired literally tens of thousands of rounds (all kinds including HEAT, SABOT, HESH, HE FRAG) from the Vijayanta from it's operating life and would know this stuff like the back of their hands. They are not exactly idiots you know and can easily make out difference between "fashion" and real life capabilities that come from technology choices.

Fact is , with rifling, you can have long range engagement capability with dumb shells (both against armor and non armor) and you can even have pretty decent limited indirect fire role if demanded .. try doing that with a smoothbore. The problem comes from brochure reading and trying to extrapolate US/Soviet concepts into our scenarios without broader understanding. It is for good reason the IA wanted that kind of capability and that is why they got it in the Arjun .

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Re: Armoured Vehicles Discussion Thread

Postby Austin » 29 Apr 2010 11:43

Sanku wrote:Austin, could you please add some thought behind the various items on the wish list.

For example, why would you like to see a auto-loader on Arjun etc?


Ok my thoughts on wish list

>>>>1 ) New 1,500 HP engine to compensate for the increased in weight by couple of Tons

With the adition of ERA , Active protection system or even external fuel tanks the weight of the tank will certainly go up by couple of tons , Ajai shukla mentioned ~ 60 T with ERA for Arjun MK2 ..... if its not matched by powerful engine it will impact tactical mobility , ofcourse how significant it will impact is what IA has to see , if new engine means more $$$$ and time consuming affair a 1,400 HP should be ok.

>>>> 2 ) New 125 mm Smooth Bore which can bring in standardization of ammo that T-90,72 and Arjun can fire

In my view Standardisation is of higher priority even if it means slighlt penalty in performance if at all that happens , there is no point in maintaining two types of MG of different caliber , if we have 3000 Tanks with 125 mm smooth bore , then we may well change the MG of Arjun to 125 mm smooth bore atleast all tanks can fire the same type of ammo and on field logistics and standardization will matter.

>>>>>3 ) ERA , Active Protection System and BMS system

Eventually all will go or adopt a 3 way Tank protection system( main armour , ERA,Active protection ) that T-80/90 have been using for years , in that sense Russians have though this out quite well.

Since the ERA and Active Protection are the modular part and keep getting better , you can always replace the 2 tire of the 3 tier protection and keep the tank current and well protected for a long time.

>>>>> 4 ) Ability to fire F&F type ATGM from its MG

I had a DRDO Journal DSJ where APJ spoke about the ability to fire Nag from main gun of Arjun , so there was some thinking on those line , but not sure if DRDO pursued it or its in the make.

But eventually tank will move towards supersonic , F&F missile fired from MG ..... to over come the weakness of current subsonic , semi active ATGM that they can fire, just a matter of time who does it , wont be surprised if Russia comes out with it , there are russian literature on this matter.

>>>>> 5) Get rid of one guy from that tank ( 3 crew ) and go for a full auto loader .

I do not see a big advantage of having a 4th guy there unless you want to generate additional jobs , the down side is you need to worry about his sal and pension :)

But Autoloader can load the ammo equally well as the well trained 4th guy does , may be if the guy can load 2 rounds faster then its not a big advantage. The French have an autoloader and 3 man crew.

Well in worst case if your tank gets hit , you kill one less guy.

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Re: Armoured Vehicles Discussion Thread

Postby arnab » 29 Apr 2010 11:46

Sanku wrote:Hmm you still need to understand the system it seems like, what the statement should have been "GoI comes with overall reasons which them prompts the forces to form a particular doctrine, which leads to specific acquisitions"

For examples, If the Govt tasks the IA to win East Pakistan back in 10 days, IA will opt for Amphibious assault vehicles and Pt 76 type tanks. If GoI tells IA. Win and hold terriroty in Pakjab in case of conflict, since we will use that for negotiations primarily they will want bunker busters.

If the GoI says, forget pakjab, we want to just be defensive there. But we really want to free up Sindh. We have a govt in waiting there. IA will rush headlong across thar to RYK.

These are the important things which some people seem hyper anxious to avoid.


Well Sir, GOI 'objectives' ar not set in stone and presumably acquisitions are a continuous process designed to take into account all possible GOI options. So even if those examples you give are agreed to (for e.g I don't understand why I would want bunker busters to hold territorry but not to run over defences in 10 days), the point still stands - would I want an equipment which can fire all types of ammo (albeit with modifications to ammo) or would I want a 'smooth bore' which can only fire specific types of ammo.

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Re: Armoured Vehicles Discussion Thread

Postby Misraji » 29 Apr 2010 11:50

Austin wrote:...
HESH may do it slightly better but there is no big advantage in having a HESH shot over HEAT .... one kills the other kills slightly better.


Here is what a discussion on tanknet has to say:

We have learned that we need these rounds more for support roles rather than AT weapons. Heat ammo isn't a very good bunker or house emplacment buster. One task tankers sometimes have to do is make a "new" door to allow the Infantry entry into a building. Heat ammo is so-so on mud brick houses but does poorly on better constructed structures. HESH / HEP rounds are far better. The old American CEV would completely level a bunker with its 152mm HEP round. Sheridans did a better job in Panama.


I think you guys seriously overstimate the protection tanks enjoy from all kinds of attacks!!
back in 85 during training we were on the ranges at lark hill with 105mm L118 light guns, we direct fired 2square L32 fuzed HE and HESH at tank targets at 800m, two hits were scored on the side a comet with he which blew three road wheels off and most of the engine decking up into the air!!

the hesh round hit a centurion target on the front right of the turret and the effect was horrific, every hatch blew open, the turret dislodged and the top plate from glacis to turret ring split!

if you really think a tank and its crew can just shrug off that kind of energy dump right into thier vehicle your kidding yourself!


I was in an ANG tank company (‘Territorials’ I think to British nomenclature) back in the early 1980’s. We trained on M48A5s kept up at Ft Irwin. We were always trained to shoot SABOT vs. tank targets, HEAT vs. BMPs. HEP was to be used vs. bunkers or troops (pseudo-HE), and as a last resort HEP could be used against tanks and BMPs. I never quite understood why HEAT was the preferred round for engaging BMPs – although I suppose that’s a different topic.


put it this way, from my own experience with 105mm HESH, if you hit a T72 with HESH even if the scabbing effect did not occur inside the vehicle the blast and concussion damage wold very probably immobilise it!! at best your optics and external equipment would be damaged, at worst the crew would suffer serious injury!
the blast off a hesh round is pretty horrendous!


So. No. What you have written is most probably incorrect.
Hesh is far more effective on bunkers than Heat.
Not slightly better.

~Ashish.

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Re: Armoured Vehicles Discussion Thread

Postby Singha » 29 Apr 2010 11:52

watching leopard2 videos on youtube, after firing each round, the gun seems to come to a loading position where it points slightly up (or the gunner presses a switch) and then the loader feeds in the next round. can tank guns be manually loaded when the its inclined or depressed at any angle?
one criticism of autoloader was it can only operate by bringing the gun back to a standard position which tells enemy that next few seconds are safe to attack or move around.

in Indian context, a HESH round should cleanly take out/badly damage any IFV like M113, segway-mki, older T-series tanks, trucks, BMPs I feel. only
thing is I dont know how easy it is to engage moving targets with HESH because muzzle velocity is half of APDS rounds and less than HEAT shells.
the tank FCS has to take type of shell into account when calculating the "lead" value for the gunner....more chance of missing target with slower shells.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 12:13

arnab wrote:for e.g I don't understand why I would want bunker busters to hold territorry but not to run over defences in 10 days,


Run over defences in East Pakistan in 10 days means, crossing multiple water bodies, bypassing bunkers etc.

the point still stands - would I want an equipment which can fire all types of ammo (albeit with modifications to ammo) or would I want a 'smooth bore' which can only fire specific types of ammo.


Fine, and I do not deny that. As I said in the outset -- in the end IA/GoI knows this part best.

At this point of time I am only discussing why not put the smooth bore on Arjun, to me the rifled canon appears a artifact of a design choice made 20 years back.

I think this needs to be revisited.

As Vina said the real reason why we have Rifled guns are
We have experience with the Royal Ordnance L7 (one of the best tank guns ever in history) from the Vijayanta. The Arjun's gun is just and updated version incorporating those good experiences


But the world has moved on since then.

Vina wrote:Problem is HEAT from a smoothbore like the M1A2's accuracy will fall off exponentially with distance , while the Arjun's wont because it is rifled. The M1A2 will never use HEAT to engage an armored target at long range. It cant. Why ? Because HEAT being a full caliber round (120mm in this case) CANNOT be fin stabilized as easily as a sabot.


How does this work? Most HEATs are finned today and fly with fins for the large part of their trajectory. In fact their collars make sure they dont spin, how can then they have longer ranges because of rifling? The collar is usually discarded as soon as the round leaves the barrel. So the round itself does not spin, given that only condition then is muzzle velocity.

Or are you saying that Rifled will fire spin stabilized finless HEAT rounds? Do they even exist anymore and are ever used?

And in any case why use HEAT for anti-tank role? Its used these days primarily for other vehicles and bunker bursting, is accuracy really needed here?

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 12:52

How does this work? Most HEATs are finned today and fly with fins for the large part of their trajectory. In fact their collars make sure they dont spin, how can then they have longer ranges because of rifling? The collar is usually discarded as soon as the round leaves the barrel.


HEAT is a full caliber round. It is not sub caliber like a SABOT. Now finned HEAT is because of the design choice of going smooth bore!. See pros and cons of design choices again. You wanted to fire rockets, but with the same choice you made, firing the same shaped charge warhead that you wanted the rocket to carry, but now with a conventional cannon shot suffers.

So the round itself does not spin, given that only condition then is muzzle velocity.

Yeah. A finned heat is a direct fire sabot like weapon. will fly really flat, lose velocity very quickly, have limited range and highly inaccurate over anything reasonably long range. A conventional rifled heat round on the other hand is more like a conventional artillery round. Can be fired at a higher angle/lobbed, stay in the air longer have longer range and more importantly have greater accuracy at longer range ..

Or are you saying that Rifled will fire spin stabilized finless HEAT rounds? Do they even exist anymore and are ever used?

Yes. Sure they will, especially with anti tank guns / older tanks with rifled cannons still in service. In infantry, earlier anti tank roles were by guns, now it is missiles (largely due to man portable ability of missiles).. But now that is sort of swinging back with next gen missiles probably not being very man portable any more at decent ranges like 4 km or so. So the missile advantage is now degraded . Most missiles will now be carried by helicopters/jeeps/IFVs etc.

And in any case why use HEAT for anti-tank role?

Huh :rotfl: .. That is what it exists for and invented for!. Anti Armor is it's primary role.

Its used these days primarily for other vehicles and bunker bursting, is accuracy really needed here?

Without accuracy what is the use of the round ?. If you fire a round and it misses it's target by 2 meters at 4km, what is the big point in firing it in the first place, especially if the target it is even slightly armored like an armored Humvee. Such a miss will be shrugged off. As for using it for "other vehicles", that is basically to find a use for sub optimal weapon because of design choice.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 13:09

vina wrote:
Or are you saying that Rifled will fire spin stabilized finless HEAT rounds? Do they even exist anymore and are ever used?

Yes. Sure they will, especially with anti tank guns / older tanks with rifled cannons still in service. In infantry, earlier anti tank roles were by guns, now it is missiles (largely due to man portable ability of missiles).. But now that is sort of swinging back with next gen missiles probably not being very man portable any more at decent ranges like 4 km or so. So the missile advantage is now degraded . Most missiles will now be carried by helicopters/jeeps/IFVs etc.


Hmm, existing anti tank guns and rifled canons in Indian service? What are those of 120 mm bore? Serious question. I think you are looking at older data. Do we have any 120 mm anti tank guns in practical service?

And the question still remains, for Tank guns, we have APFSDS which are the primary munitions by far. Better with smooth bore by far.

HEAT, you claim that a spinning HEAT round outclasses the most modern Finned rounds, is there a link to support the claim? Remember if its spinning, that means the HEAT efficiency is reduced because a spinning HEAT is far less effective on impact. If it opts for a collar then its no different from a smooth bore.

So what is it, a spinning HEAT or a non spinning one? Most of the world has done this exercise and found that it is better to go with non spinning heat at what ever loss of accuracy (if any, which I doubt with modern rounds)

Meanwhile you are right, the missile advantage is somewhat degraded for infantry, but that is being replaced by smooth-bore RCLs with HEATs like Carl Gustaf

And in any case why use HEAT for anti-tank role?

Huh :rotfl: .. That is what it exists for and invented for!. Anti Armor is it's primary role.


HEAT was in that role only in contexts of infantry weapons, like Panzerfausts, retrofitted on Tanks.

With APFSDS, HEATs are no longer primary AT ammunition for Tanks. As you can see, the standard method is, Sabots for armor, HEAT for other types of vehicles and HESH for bunker bursting.

HEAT has ceded that role as a tank weapon a long time back to newer mutions.

Its used these days primarily for other vehicles and bunker bursting, is accuracy really needed here?

Without accuracy what is the use of the round ?. If you fire a round and it misses it's target by 2 meters at 4km, what is the big point in firing it in the first place, especially if the target it is even slightly armored like an armored Humvee. Such a miss will be shrugged off. As for using it for "other vehicles", that is basically to find a use for sub optimal weapon because of design choice.


So at least for bunkers accuracy does not matter agreed? :)

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 13:37

So what is it, a spinning HEAT or a non spinning one? Most of the world has done this exercise and found that it is better to go with non spinning heat at what ever loss of accuracy (if any, which I doubt with modern rounds)


Reading comprehension problems again ?.I told you there will be an adapter. Fired from a rifled gun, the HEAT shell will spin, but with the adapter, the warhead wont spin. If you don't spin the shell, you will need to stabilize it in some other way. So purpose is lost

Meanwhile you are right, the missile advantage is somewhat degraded for infantry, but that is being replaced by smooth-bore RCLs with HEATs like Carl Gustaf


:rotfl: . RCL, Carl Gustav.. Saar. You are re-inventing the wheel. Carl Gustavs, RCLs predate missiles in Anti Tank role! . They go back to 1940s or so. We used them RCLs in the 1965 and 1971 war against the Pakis. Carl Gustav must be in Indian service since ol blighty. These tend to have pretty short ranges. No way they will compare to a full anti tank gun or a modern anti tank missile in range or effectiveness

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Re: Armoured Vehicles Discussion Thread

Postby bhavik » 29 Apr 2010 13:39

How frequently is cleaning required for smooth bore vs rifled bore?

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Re: Armoured Vehicles Discussion Thread

Postby Austin » 29 Apr 2010 14:22

If Rifle Bore is such a path breaker and must have thing in MBT , why is it that all the modern MBT uses smooth bore .....ok if you make US an exception here since it has too many assets , why arn't modern MBT equipped with Rifle bore ?

More ever if we have to hit a bunker we might use a ATGM with HE to get the longest possible hit with accuracy.

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 14:28

Austin wrote:If Rifle Bore is such a path breaker and must have thing in MBT , why is it that all the modern MBT uses smooth bore .....ok if you make US an exception here since it has too many assets , why arn't modern MBT equipped with Rifle bore ?


Err. Who says "modern MBTs" aren't equipped with rifle bores.. I think Challenger 2 and Arjun are examples of 2 which do have rifle bores!. :mrgreen: :mrgreen:

But seriously, think about it. There were 2 designs basically, the Rheinmetall and the Soviet 125mm that got adopted around the world by nearly all countries (across the east west divide) Russia and Warsaw Pact and US and Nato. Others like France, So Ko , Japan and Isreal preferred buying a gun off the shelf than developing one themselves and they bought the "standard" the Rheinmetall (sort of like everyone buys the "standard" Windows based PC).

The only ones who decided to develop their own guns, namely UK and India went rifle bore!. What does that tell you ?.. Easy thing to conclude that India and UK must be stupid, because Russia and US and Germany went smooth bore. Sort of like, if you bought a Linux or a Mac , you must be stupid because 95% of the entire PC sales in the world is on Windows.

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Re: Armoured Vehicles Discussion Thread

Postby Austin » 29 Apr 2010 15:05

Vina if you look at DRDO own chart it clearly shows Brit and India are into rifle bore and DRDO rates all of them as world class.

But any way even if they use rifled or smooth bore its no great compelling tactical advantage of either just a matter of choice , the reason I would prefer a 125 mm smooth bore is to make it standard across IA inventory and IMO its a big advantage to have standardization as much as possible.

And just because one did not buy a CISCO router does not make one stupid , much like Windows or CISCO has nothing to do with tanks.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 15:10

vina wrote:
So what is it, a spinning HEAT or a non spinning one? Most of the world has done this exercise and found that it is better to go with non spinning heat at what ever loss of accuracy (if any, which I doubt with modern rounds)


Reading comprehension problems again ?.I told you there will be an adapter. Fired from a rifled gun, the HEAT shell will spin, but with the adapter, the warhead wont spin. If you don't spin the shell, you will need to stabilize it in some other way. So purpose is lost


Indeed comprehension issues, on whose part? You have invented a HEAT where the shell spins but the warhead does not? Very nice solution, but do you have a link to back you up?

'Meanwhile here is what is actually used in REAL world

http://www.fas.org/man/dod-101/sys/land/bullets2.htm

If you see there
Image

Its not the shell which rotates, but a small band (which is often discarded as soon as the shell leaves the barrel)

So what I was trying to lead you to is the following gyan "THERE IS NO HEAT shell which both spins and has long range and has HEAT warhead efficiency characteristics"

IT EITHER SPINS OR DOES NOT!!

So decide whether you want your shell to spin or not. In any case people have done this exercise in the past and found it was not worth it to use a band to get there.

Bottom line HEAT works best on smoothbore, in every way.



Meanwhile you are right, the missile advantage is somewhat degraded for infantry, but that is being replaced by smooth-bore RCLs with HEATs like Carl Gustaf


:rotfl: . RCL, Carl Gustav.. Saar. You are re-inventing the wheel. Carl Gustavs, RCLs predate missiles in Anti Tank role! . They go back to 1940s or so. We used them RCLs in the 1965 and 1971 war against the Pakis. Carl Gustav must be in Indian service since ol blighty. These tend to have pretty short ranges. No way they will compare to a full anti tank gun or a modern anti tank missile in range or effectiveness


Yet they are coming back, with increase in Missile weights. What after all is the solution for Manportable Anti-tank mutions which is ultimately limited by weight.

With increase in armor and corresponding increase in missile weight, RCL and plain RCLs with tandem charged warheads are back in fashion you know.

-------------------

vina wrote:Err. Who says "modern MBTs" aren't equipped with rifle bores.. I think Challenger 2 and Arjun are examples of 2 which do have rifle bores!. :mrgreen: :mrgreen:


Vina as I said before, you really are in dire needs to update your tank knowledge from the bygone era.

http://www.army-technology.com/projects/challenger2/
Challenger lethality improvement programme

The Challenger lethality improvement programme aims to upgrade the main gun of Challenger 2 from its current 120mm L30A1 rifled gun to the 120mm Rheinmetall L55 smoothbore gun currently used by the Leopard 2 A6.

The use of a smooth bore allows Challenger 2 to use more lethal rounds developed in Germany and the US. As of January 2006, a single Challenger 2 has been fitted with the L55 and is undergoing trials.


The Brits have wanted to change the gun to smooth bore for the longest time, but given the wonderful state of Brittania, with everything falling apart and subs crashing into each other and what not, they havent gotten it done.

But even they realize that world has changed.

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 15:39

Sanku wrote:Very nice solution, but do you have a link to back you up?


Why dont you do the googling yourself. Dont know, google around for tank cannon fired HEAT shell or tube fired Heat shells.

'
Meanwhile here is what is actually used in REAL world

http://www.fas.org/man/dod-101/sys/land/bullets2.htm

If you see there
http://www.fas.org/man/dod-101/sys/land/fig10-1.gif

Its not the shell which rotates, but a small band (which is often discarded as soon as the shell leaves the barrel)


:rotfl: :rotfl: :rotfl: :rotfl: :rotfl: :rotfl: :rotfl: :rotfl: .. Duude.. You have serious reading comprehension problems , and not to mention totally clueless.. Maybe it is not too late. Why don't you join the NCC in the nearest highs chool and go fire a 0.22 or a the ancient 0.303 rifle and the NCC instructor would englighten you on the difference between a RIFLE and a smooth bore weapon like a Revolver/Pistol.. I still remember my guy from high school.. This is a "Re-Vol-Vah".. This is a RIFLE. This bullet spins this one doesn't.

But anyway, to go your post again, let me post the part about the "rotating band" (also called driving band in other literature).. I think you are confused here between the driving band and the rotating adaptor on a sabot/ rifle fired HEAT. BTW, the picture they have posted is of a standard artillery shell. Go ahead. Google for "Driving band" and satisfy yourself that it is the same "rotating band" in the article.

Rotating Band. The rotating band is a cylindrical ring of comparatively soft metal that is pressed into a knurled, or roughened, groove near the base of the projectile. It mates with the forcing cone of the tube to eliminate gas wash (blow-by) and to provide forward obturation. The rotating band, in conjunction with the rifling of the tube, imparts spin to the moving projectile. A properly rammed separate-loading projectile is held in the tube at all angles of elevation by the wedging action of the rotating band against the forcing cone.


See. I highlighted the part which says it imparts spin to the moving projectile, for ease of comprehension.

So what I was trying to lead you to is the following gyan "THERE IS NO HEAT shell which both spins and has long range and has HEAT warhead efficiency characteristics"

IT EITHER SPINS OR DOES NOT!!

Sure the shell spins, the warhead has a rotating assembly which doesnt spin. There are heaps of examples of British, French , German ammo going back to the 70s that had this kind of ammo. Google around and find out yourself. That is the least you can do yourself.

http://www.army-technology.com/projects/challenger2/
Challenger lethality improvement programme

The Challenger lethality improvement programme aims to upgrade the main gun of Challenger 2 from its current 120mm L30A1 rifled gun to the 120mm Rheinmetall L55 smoothbore gun currently used by the Leopard 2 A6.

The use of a smooth bore allows Challenger 2 to use more lethal rounds developed in Germany and the US. As of January 2006, a single Challenger 2 has been fitted with the L55 and is undergoing trials.



Sure.. That is a fact.

The Brits have wanted to change the gun to smooth bore for the longest time, but given the wonderful state of Brittania, with everything falling apart and subs crashing into each other and what not, they havent gotten it done.

But this part is your spin. In fact, the Brit factories to make the Charm-3 DU rounds are closed for close to 20 years now. They have enough inventory for their own use maybe. But for exports (if they hope to sell the tank at all), they will either have to reopen the line or they will have to go for a off the shelf gun with assured ammo supply.. Guess which "off the shelf gun" is the big enchilada ?

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Re: Armoured Vehicles Discussion Thread

Postby rohitvats » 29 Apr 2010 15:46

With increase in armor and corresponding increase in missile weight, RCL and plain RCLs with tandem charged warheads are back in fashion you know.



Gentlemen, why are we dragging the ATGM and RCL issue here? ATGM have replaced the 106mm RCL even in the Indo-Pak armies....so what is this comeback we're talking about? 84mm Carl Gustaf is hardly an example of RCL in the classic in first place, forget about the 'coming back' in fashion bit. It is used more in anti-personnel/soft-skinned vehicle/bunker busting(build up area) role than AT role - unless in dire straits.

As for the weight bit - you forget that one has man-portable ATGM with tandem warheads now to take on the modern armour? And if push comes to shove and one needs heavier warheads, I'd rather go for something like carrier mounted heavy ATGM. Why take the risk with RCL?

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 16:06

vina wrote:See. I highlighted the part which says it imparts spin to the moving projectile, for ease of comprehension.

So what I was trying to lead you to is the following gyan "THERE IS NO HEAT shell which both spins and has long range and has HEAT warhead efficiency characteristics"




Sirji, you are quoting from a link I gave you, and unlike those who already know I read. I also realize its a general article on shells and not ONLY tank shells, but one has to start you off from some where.

With the rotating band, the spin from the rifling is cut down (for some artillery applications), and that too not accurately and many other issues

http://en.wikipedia.org/wiki/Driving_band
One downside to the driving band is that it must be placed at the widest point on the shell, and also near the balance point. This is not necessarily the best point from an aerodynamic perspective, at high supersonic speeds the widest point should be far to the rear of the balance point. Another issue is that with increasing shell weight it becomes more difficult to engineer the driving band. Instead of the propellant gases driving the shell up the barrel, it can simply blow the driving band right off the shell.


It also says
Freely rotating bands can be used to reduce the amount of spin imparted to the round as is preferable for HEAT warheads or fin stabilised projectiles.


SO if that FREELY ROTATING BAND for HEAT warhead is not transparent enough for you to understand that HEAT shells DO NOT SPIN, I do not know what will be.

Meanwhile go ahead and post LINKS for your fancy spinning shell without spinning warhead design. Also post who uses it.

Meanwhile let me have some more fun -- for your shells which both SPIN and have AT characteristics?
:lol:

http://www.globalsecurity.org/military/ ... -types.htm

There are two problem areas encountered with this method of firing fin-stabilized projectiles from a rifled cannon. Firstly, it is difficult to control the spin reduction in the sliding seat with a degree of repeatability necessary to assure acceptable projectile accuracy over the entire range of operating conditions specified for military employment. Variations in projectile temperature from -40.degree. to +60.degree. C., changes in humidity, finite manufacturing tolerances, contamination by dust, salt and other substances entering between the rotating band and its seat, etc., influence the friction coefficient in the band seat and with it the degree of spin transmission.

Secondly, centrifugal forces acting on sabot components are very effective in initiating the instantaneous and symmetric separation of the sabot from the penetrator upon exit from the muzzle of the gun. With reduced projectile spin the centrifugal forces acting on the sabot components are reduced by the square of the spin ratio. As a result, the sabot separation is neither as rapid nor as precise as with a nonslipping rotating band and is increasingly more dependent on aerodynamic forces.


Spin is BAD as soon as you have fins, BAD.

And note YOU are not telling me this (before you duck back and go yammering about the basics of pistol and rifle) I AM informing you what is really happening.


You SEE THERE IS GOOD REASON THAT RIFILING HAS BEEN DISCARDED FOR TANKS.

PS> Added later -- Vina you claimed that 120 mm Canon will reuse Shells from other weapons. I am still waiting to hear WHICH other weapons.
Last edited by Sanku on 29 Apr 2010 16:30, edited 2 times in total.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 16:12

Rohitvats, was not my intention to drag in that, that was a different discussion which went haywire. Anyway more fun

From another discussion on net.

The rifled barrel isn't really an advantage, and it carries a couple of drawbacks. The most important disadvantage is it slows rounds down. If you load Armor-Piercing Fin-Stabilized Discarding Sabot rounds (the most popular tank killers) into a Challenger 2, an Abrams and a Leopard 2A6, the L2A6's 55-caliber Rheinmetall will fire at 1680m/sec, the Abrams' 44-caliber Rheinmetall will fire at 1580m/sec and the British rifled tube will fire at 1534m/sec. That is why everyone except the British, starting with the Soviets, put smoothbore cannon on their tanks--MORE MUZZLE VELOCITY! You don't lose energy in the rifling, hence the penetrator goes faster when it leaves the tube. Velocity in a tank round equals combat effectiveness--the "penetrator" is a hunk of tungsten that weighs about ten kilos. The faster it goes, the more likely it is to go through the side of the target

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 16:59

Sanku wrote:SO if that FREELY ROTATING BAND for HEAT warhead is not transparent enough for you to understand that HEAT shells DO NOT SPIN, I do not know what will be.


Good.. Now that you have discovered what a driving band is and also probably realized that what the FAS referred to as the "spinning band" is exactly the same, I will enlighten you on further things.

You see Shree Sanku Maharaj ji.. Long long long ago, in a forum called BRF, before you had decided to grace us, there is a certain old timer called Igorr , yes the same igorrs' blog whom Austin posts so copiously about T-90M and Burlak and what not, he used to post on the Armor thread , along with JC a long departed from BR member and Igorr raised a very interesting question.

Like you, the "accepted truth" then at BR was that the muzzle velocity of the AP round in the Arjun HAS to be slower , because it was "Rifled" and .. Igorr, posted a very good logic.. since the round spins, the total translation kinetic energy MUST be less than smooth bore, becuase total KE = translational KE + rotational KE and for smoothbore rotational KE must be zero.

It was yours truly who pointed out the fallacy and explained that contrary to popular "accepted truth" on BR, the Kinetic AP round in the Arjun is FIN and and not spin stabilized. The way to do it is to put a spinning collar that isolates the projectile from the Sabot and since the sabot is discarded and light weight the rotational KE for the Arjun penetrator too is effectively zero and can achieve very high velocity. And yes, figures bear that out.. 1600 m/s is right there in the ball park of the best and mind you, this is the first versions.. That was when it became "an accepted truth" that Arjun APFSDS has a rotating collar. You will find NO DRDO or any brochure which says that. Show me one if you find it. I really know what I am talking about . It is based on strong engineering common sense and also facts on ground.

In fact, I later googled around and found pictures of Bofors rifled tube fired ammo with those kind of rotating collars. Dont have those links. But I do know that there were French, Swedish and maybe even German ammo that had the reverse for HEAT (rotating shell, non rotating warhead) , which is the sensible thing to do. Go ahead and do the Googling yourself and find it.

Meanwhile let me have some more fun -- for your shells which both SPIN and have AT characteristics?


Right.. We have had a lot of fun already with reading comprehension and some absolutely clueless stuff like "rifle bullets dont spin" (backed up Federation of American Scientists, no less), which even a highschool kid will laugh out of the door.


Spin is BAD as soon as you have fins, BAD.

Err. That is why FSAPDS in Arjun doesn't spin and a HEAT round (the Arjun doesn't have one yet I think) if and when it comes on the Arjun will NOT spin.

And note YOU are not telling me this (before you duck back and go yammering about the basics of pistol and rifle) I AM informing you what is really happening

Er.. considering that picked up my own "goli" about spinning collar on the Arjun FSAPDS from BR and giving it back to me, sure, I am all ears.

You SEE THERE IS GOOD REASON THAT RIFILING HAS BEEN DISCARDED FOR TANKS.

Yeah right.. And of course, the 152mm that the Russians wanted to put on their latest ding dong for "commonality" was that Rifled or Smooth bore and why ?

PS> Added later -- Vina you claimed that 120 mm Canon will reuse Shells from other weapons. I am still waiting to hear WHICH other weapons.

Now, you are hallucinating. Where did I say such a thing anywhere ?.You were the one who wanted a 125mm shell in the Arjun for "commonality" with the T-90/T72 fleets..without even realizing that unless you went the exact same T90 /72 architecture like split shells and autoloader, it cant be done.

When I said commonality, I said, go the "Karna" route for the T72 upgrades.. Now google around for what "Karna" is and you will find out why you will have "commonality" if you do that.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 17:25

vina ji you make too many assumptions, such as how long I have been on BRF. In any case that is irrelevant, you bring it up to sidetrack but no matter.


rotational KE for the Arjun penetrator too is effectively zero and can achieve very high velocity.



Sirji, ALL nd APFSDS aHEAT shells have rotating collar/driving band where the aim is to keep the rotation confined to the band and the bearings do not go to the shell. This is not some great knowledge. As you said basics from 60s. Used first when HEAT shells were force fitted in German rifled guns.

But here you go tilting at the Arjun windmill again. I had deliberately posted figures for three top line western tank guns from very similar families They found out that the effective loss was small but not very small. For any similar guns the smooth bore will have some inherent advantages in KE since there is no rolling sholling bizness at all, and no need to worry whether the bearings are well designed to be effective or not.


Right.. We have had a lot of fun already with reading comprehension and some absolutely clueless stuff like "rifle bullets dont spin" (backed up Federation of American Scientists, no less), which even a highschool kid will laugh out of the door.


So you are down to misrepresenting my statements eh?

Spin is BAD as soon as you have fins, BAD.

Err. That is why FSAPDS in Arjun doesn't spin and a HEAT round (the Arjun doesn't have one yet I think) if and when it comes on the Arjun will NOT spin.


CONGRATULATIONS YOU GOT IT!!

This is what I have been trying to say for so long. First you have a rifled gun, then you jump through hoops to make sure your shell does not spin.

YEA!! Bravo!!

Er.. considering that picked up my own "goli" about spinning collar on the Arjun FSAPDS from BR and giving it back to me, sure, I am all ears.


Hee hee, no Sir, basic common knowledge Sir. Well known basics.

You SEE THERE IS GOOD REASON THAT RIFILING HAS BEEN DISCARDED FOR TANKS.

Yeah right.. And of course, the 152mm that the Russians wanted to put on their latest ding dong for "commonality" was that Rifled or Smooth bore and why ?


Yes and thats why its in service right now yeah?

[Added later -- Vina you claimed that 120 mm Canon will reuse Shells from other weapons. I am still waiting to hear WHICH other weapons.[/b]
b]PS>
Now, you are hallucinating. Where did I say such a thing anywhere ?.


I will refresh memory (first post this page viewtopic.php?p=864518#p864518)
vina wrote:
sanku wrote: Or are you saying that Rifled will fire spin stabilized finless HEAT rounds? Do they even exist anymore and are ever used?



Yes. Sure they will, especially with anti tank guns / older tanks with rifled cannons still in service.


You were the one who wanted a 125mm shell in the Arjun for "commonality" with the T-90/T72 fleets..without even realizing that unless you went the exact same T90 /72 architecture like split shells and autoloader, it cant be done.


Yes I want to have commonality and no it HAS NOTHING to do with autoloader. EVEN without a autoloader two piece ammo can be used. No big deal -- you want a example? Guess what your fav chally 2 also has split rounds.

Big deal.

-------------------------------

Meanwhile let me recap for rifled guns
1) APFSDS -- spin bad, use collars with many known problems listed
2) HEAT -- ditto

SO for those two first thing you do is remove the spin, thus negating any spin benefits.

A slow firing HESH round? Yeah ok, you can fire a slow HESH round, but why is the question.

In addition, all the problems with maintenance and what not.

So as we see, Rifled gun is a pain in the ass. That is why even the western world, dropped the Rifled idea as soon as they practically could (with some Dodo's like the British finally getting pushed in)

Today for tank guns Rifled guns are not wanted. And for a very good reason.

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Re: Armoured Vehicles Discussion Thread

Postby aditp » 29 Apr 2010 18:26

Sanku wrote:Indeed comprehension issues, on whose part? You have invented a HEAT where the shell spins but the warhead does not? Very nice solution, but do you have a link to back you up?

'Meanwhile here is what is actually used in REAL world
<pic>
Its not the shell which rotates, but a small band (which is often discarded as soon as the shell leaves the barrel)


The shell IS the warhead. Possibly he mis-spelt

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Re: Armoured Vehicles Discussion Thread

Postby vina » 29 Apr 2010 18:37

CONGRATULATIONS YOU GOT IT!!

This is what I have been trying to say for so long. First you have a rifled gun, then you jump through hoops to make sure your shell does not spin.

YEA!! Bravo!!


Again reading comprehension.. The Shell will spin (the last post was a typo, the earlier ones were correct). The Warhead in the shell will not spin for a potential HEAT round from the Arjun. Too bad for you, if you understood otherwise. That is what I have always been saying. To put a HEAT round in a rifle gun like the Arjuns and to NOT spin it will be colossally bad practice , unless it is a "Kaam chalao" round .

As of "basic" stuff, 60s everyone knows it, dont pretend you knew any of it. You did google around and couldn't find a result jump at you for a Heat round that spun, but the warhead was stationary. Not that it didnt exist. It existed in many armies. For someone who doesn't know that a Rifle bullet spins and points to FAS to "prove" it, it is extremely rich indeed to pretend to know anything about this "common sense" or otherwise.

Sorry. You have made enough of an ass yourself. I am through with you.

The reason why I continued replying is not to educate you or to "enlighten" you on anything. You are simply beyond it. The reason is much larger.

The reason is this. BRF is a much wider audience and a lot of people, hopefully including someone in authority do read into this (they usually do, BRF oldtimers like Shiv etc say the audience that read all this sometimes simply unbelievable) .

For far too long, the Arjun has been a victim of total disinformation from "interested parties " , plainly ignorant people and literally village idiots who pass for journalists in this country. I can go back to mid eighties and quote from magazines of "quality" like India Today and all else quoting blatant falsehoods and disinformation. This is just another way of rebutting it with quality arguments to thinking people.

The "technical" arguments went on these lines.

1) The Arjun is a mis mash of foreign technology , ill integrated and wont work and "not indigenous"
Well, nothing can be further from the truth. It picks and chooses important susbsystems for world leading vendors. All leading Tank programs (be it US, Germany, France, UK, So Ko, Japan etc) went that route . Arjun is far more indigenous than the T90 / T72 which anyway is fully imported!.

2) The Arjun is "slow" cant fight in the deserts.. etc. etc.
Well, the Arjun has a lower ground pressure , has a higher power to weight ratio, has greater power reserve. The recent results prove it.

3) The Arjun is "too big" lacks "strategic mobility".
Well , the Arjun goes on the indian railways everywhre. The Army has operated tanks called Centurion a generation ago that is in the Arjun weight clas..

4) The Arjun has a "rifled gun" . So it cant fire 1) APFSDS 2) Missiles 3) Has lower muzzle velocity 4) Is outdated. This canard ,in addition to journalist village idiots was also spread for long by "Senior Army Sources" based on "fundamental design and physics".

This is what I wanted to answer in these long winded posts.

1) The Arjun does fire world class APFDS, better than anything fielded thus far in any T series variant.

Yes it can and it does. This is old hat. I explained how this comes about much earlier, that the muzzle velocity matches up to the best there is and it is an excellent weapon.

2) The Arjun cannot be fielded becuase a Rifled Gun cannot fire a missle like a smooth bore.
Well, the Isrealis loaned us a LAHAT and we integrated it into the Arjun and there are vidoes of it firing one. That shut the "interested parties" well and good

3) Is "outdated"
I really really wish that the Russians had NOT cancelled their T95 or Black Eagle or whatever. That to any observer, that was a 60 ton tank with a 1500hp engine (unproven), with similar mechanicals (hydropneumatic) as the Arjun (unproven on the Russian tank, proven on Arjun) and most of all a 152mm RIFLED GUN . It would have been total fun to see the village idiots and Natashas and "Senior Army Sources" go all out to claim how "rifled guns were the greatest for tanks" (see, even the Russians went for the Rifled Gun in their latest tank) .. Err. What about 60 tons for which you dissed the Arjun.. Oh.. 60 tons.. no problem, our infrastructure can handle it.. Err. What about "logistics".. Oh, when you induct a new system, you need new logistics ..Err... What about Hydropneumatic suspension for you dissed the Arjun.. Oh.. This is the latest. The Russians have gone for it, so it must be the best choice.

The irony is all too clear to see. Let us not miss the wood for the trees. There are "interested parties", totally ignorant fools and village idiots who have agenda (totally spurious ,ok the ignorant fools are probably plain igorant, but the noise due to their ignorance is plainly dangerous, sort of like a mob).. The village idiots and "interested parties" spread canards and innuendoes . Some of it hilarious . For eg, when the T90s blew their tops in Georgia, the answer somewhere was the Georgians used Russian weapons, of course, the Russians will know how to deal with their own tanks , so that is why. Err. Thanks. At BRF, it our duty to put these canards in their place and expose them for what they are. A solemn duty folks. And may we do it well.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 18:52

vina wrote:
CONGRATULATIONS YOU GOT IT!!

This is what I have been trying to say for so long. First you have a rifled gun, then you jump through hoops to make sure your shell does not spin.

YEA!! Bravo!!


Again reading comprehension.. The Shell will spin (the last post was a typo, the earlier ones were correct). The Warhead in the shell will not spin for a potential HEAT round from the Arjun. Too bad for you, if you understood otherwise. That is what I have always been saying. To put a HEAT round in a rifle gun like the Arjuns and to NOT spin it will be colossally bad practice , unless it is a "Kaam chalao" round .


Reading comprehension but you have a typo?

Can you put up a single source to say that it does? Note that I have put up numerous sources saying that only a band spins and not the full shell, let alone the warhead.

-------------

The rest is A rant about mythical parties being anti Arjun. Total strawmen, whom was that post to? :lol:

Vina I hate to do this to you, but that was really sad really sad, no content and all bluster.

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Re: Armoured Vehicles Discussion Thread

Postby Vivek K » 29 Apr 2010 19:06

vina, wouldn't hurt to put some of these ignoramuses on your ignore list. They show an amaazing lack of coherence and understanding and keep reiterating the same garbage that has been explained over and over to them. This is exactly why I would request that admins either lock this thread or split into separate Arjun and T-90 threads.

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Re: Armoured Vehicles Discussion Thread

Postby Sanku » 29 Apr 2010 19:08

aditp wrote:
Sanku wrote:Indeed comprehension issues, on whose part? You have invented a HEAT where the shell spins but the warhead does not? Very nice solution, but do you have a link to back you up?

'Meanwhile here is what is actually used in REAL world
<pic>
Its not the shell which rotates, but a small band (which is often discarded as soon as the shell leaves the barrel)


The shell IS the warhead. Possibly he mis-spelt


You lost me?

A shell is not the warhead, if you look inside a shell, it will have a body, fins, charge, and a warhead or a shot, or cluster of shots.

In case of rifled guns, the spin has to be some how removed for the APFSDS and HEAT to function well, otherwise their performance characteristics are lost. To this end a small rotating band with ball bearings is placed around the shell. Which is called the rotating or the driving band.

This rotating band spins, but the main shell itself does not, (as far possible, of course some transmission would be there, there is no perfectly fluid system)

The reason why this contraption was first made was because of legacy systems. Most tanks had rifled guns but also needed to fire the above rounds (this is 60s 70s)

This contraption is not needed for smooth bores and gradually everyone did away with that.

The only reason rifled canons exist (for tanks) are the HESH rounds.

Note this is what Shalav also wrote completely independently of what I said.
viewtopic.php?p=864427#p864427

Its just that rather than accept a very simple point that the world has moved on from smooth bores (basic fact no tank uses rifled today) we have
1) You are anti Arjun (???????) :-o
2) Smooth bore is just fashion :-?
3) I have been longer on BRF? :eek:

You cant breath on this thread without "with us or against us" type of thingy.


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