Armoured Vehicles Discussion Thread - Jan 12, 2012

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Sanku
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Prasad wrote:
Sanku wrote:So yes, given a FCS (software+hardware), a moving target, a moving platform, quick reaction times, long range engagements, uncertain winds etc etc etc. -- a high velocity round will always be "better" for accuracy, since the mathematical model being executed by the FCS, will have lesser real life variables whose performance would be different from the model.
Wait, what? I'd like to see something to back this up. I wont dig up facts to back your statement. So before you throw statements like that, please do give us some reference to what variables various FCS' use and how smoothbore uses less variables compared to rifled bores, simply due to a higher velocity round.
It may be difficult to give references for this off the web. I will try, you might want to ask a chaiwalla or some sort working on FCS software in the meantime.

==========================

Added later >> Not exactly what you are looking for but look at this wiki page for example

http://en.wikipedia.org/wiki/External_ballistics


Predictions of several drag resistance modelling and measuring methods
The table shows that the traditional Siacci/Mayevski G1 drag curve model prediction method generally yields more optimistic results compared to the modern Doppler radar test derived drag coefficients (Cd) prediction method.[19] At 300 m (328 yd) range the differences will be hardly noticeable, but at 600 m (656 yd) and beyond the differences grow over 10 m/s (32.8 ft/s) projectile velocity and gradually become significant. At 1,500 m (1,640 yd) range the projectile velocity predictions deviate 25 m/s (82.0 ft/s), which equates to a predicted total drop difference of 125.6 cm (49.4 in) or 0.83 mrad (2.87 MOA) at 50° latitude.
The Pejsa drag analytic closed-form solution prediction method, without slope constant factor fine tuning, yields very similar results in the supersonic flight regime compared to the Doppler radar test derived drag coefficients (Cd) prediction method. At 1,500 m (1,640 yd) range the projectile velocity predictions deviate 10 m/s (32.8 ft/s), which equates to a predicted total drop difference of 23.6 cm (9.3 in) or 0.16 mrad (0.54 MOA) at 50° latitude.
The G7 drag curve model prediction method (recommended by some manufacturers for very-low-drag shaped rifle bullets) when using a G7 ballistic coefficient (BC) of 0.377 yields very similar results in the supersonic flight regime compared to the Doppler radar test derived drag coefficients (Cd) prediction method. At 1,500 m (1,640 yd) range the projectile velocity predictions have their maximum deviation of 10 m/s (32.8 ft/s). The predicted total drop difference at 1,500 m (1,640 yd) is 0.4 cm (0.16 in) at 50° latitude. The predicted total drop difference at 1,800 m (1,969 yd) is 45.0 cm (17.7 in), which equates to 0.25 mrad (0.86 MOA).
Last edited by Sanku on 04 Apr 2012 00:00, edited 1 time in total.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Mihir wrote: Dishonest or illogical? Take your pick :P
Mischievous, on your part. :P
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by kvraghavaiah »

The Arjun development was as follows.

The user did not tell what he wants clearly.
The developer did not question the user sufficiently to know the requirements of the tank.
The developer did not plan sufficiently for at least what he thought of making.
After many reworks and fightings, finally 70% foreign product is out.

As even kid, I had far far better planning and management skills.

I do not know what the government managers in defense sector learned from the modern management funda available everywhere. At least they did not plan to copy the management plans of other successful countries for defense. And this is about management wisdom of a billion strong nation.


On top of these, Indian army does not have a clear vision for the future, which no one will be able to believe, but it is fact. I think it will try to show something now to fool us.
and many army leads and ministry officers had always interests in foreign commissions and always looked for every opportunity to kill the Arjun project.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Anujan wrote:[

Let me put it in mathematical terms. Assume you made a smoothbore as smooth as Hema Malini's cheeks and fired a round at 3000 m/sec. (Which is about twice the muzzle velocity of any modern tank). Over a range of 3km, the drop is about 10 meters. Yes 10 Meters. If you do not correct for that, you will miss a tank by 3 tank heights or more than 5 times the height of the tallest SDRE. And this is for a smoothbore.

Now calculate and tell me how "slow" rifled guns are when compared to smoothbores and what percentage more drop they add? (if at all Arjun's gun is slower?)
First and foremost, you are taking but one variable. Please look at the wiki link on ballistics. There are multiple effects playing of which gravity is one. But it is safe to say, that higher velocity translates to higher momentum and flatter and straighter trajectory.

However let us take your point -- it appears that you agree that velocity difference will make a difference. The question is how much, the gravity drag for a trajectory will be given by (if I remember right)

1/2gt^2 => 1/2g(d/v)^2

Therefore the % drop will be (v1/v2)^2. (v1, v2 are two velocities).

That gives you the drop factor, I am trying to get the speeds for representative smooth bore and rifled tanks.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Anujan »

But it is safe to say, that higher velocity translates to higher momentum and flatter and straighter trajectory.
Please. What has momentum got to do with anything?
the gravity drag for a trajectory
That deserves a ban for posting anything about ballistics.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Anujan wrote:
But it is safe to say, that higher velocity translates to higher momentum and flatter and straighter trajectory.
Please. What has momentum got to do with anything?
the gravity drag for a trajectory
That deserves a ban for posting anything about ballistics.
Gravity drop, sorry, its late in India, but then again you are getting hung up on a few words.

Let me look up a formal reference and send it over, much better that way.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Meanwhile Prasad, here is one document on the web that talks of something as simple as the effect of zeroing policy on the FCS accuracy. This gives an idea of the issues involved in accurately capturing all the real world variables in the model.

http://www.armyconference.org/ACAS00-02 ... bDavid.pdf
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by member_23061 »

Hello,

I wanted to ask the gurus on why the Arena and Drozhd self protection suites were not bought for the T90. Unproven tech at the time?
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by nachiket »

That supposed PSQR in the Business Standard article talks about creating a FMBT with a 1800 HP engine with traditional armor plating plus active protection, yet keeping the weight at 50 tonnes. Setting aside the fact that this smells too much of unobtainium, it still doesn't tell us where Sanku got the idea that the Arjun's gun will be changed.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Sanku wrote:Not only are you ignorant, you are pompous and unwilling to learn.
But Guru Maharj Ji, I am ignorant and so I am indeed trying to learn. However, your sermons are very "Conphoosing" to say the least and totally contradictory , so I don't really know which one to take as the truth and which is fiction.

For Example.

In a later sermon you said,
Smooth bore *always* more accurate than rifled for all kinds of ammo
And you justified this by saying,
2) Drop in trajectory due to gravity is less, since the flight time is less.

The second makes the trajectory "flatter" and hence "more accurate" since the compensation for trajectory during flight is a lesser problem.
In response to a remark by me that the smooth bore is optimized to throwing darts at high speeds, you said, no, it fires all kinds of stuff, including HEAT and some new HE ammo which does wonder Phool things (which were done earlier, but eclipsed by that Mayavi , like the sun was during Mahabharat Yuddh, but I digress), and which now shines in all it's glory.

But some Googal Unkil search and common sense (after all a HEAT round NEEDs a big dia and cant be a needle like a Kinetic penetrator), says that HEAT too goes at comparable speeds out of the gun muzzle at aroun 800 to 900 m/s out of the smooth bore, just like the equivalent shell out of a rifled. And even for KE penetrators, it seems that the muzzle velocities are comparable!

Now the big "prashna" is this Maharaj. Pliss to throw roshni.

How is that if two projectiles come out at nearly the same velocities out of the muzzle (one spinning the other not), does Ma Bhoo Devi recognize that one is from smooth bore and other is from rifle and apply different bhoodevi ka keench (in ghor Kaliyug, in adharmic Physics, they insist it is a Constant of g = 9.8 m/s^2 ! , but, indeed, since Dharma is the true path, that must be wrong of course)
Bad habits.
Indeed. Adharmic fields like Physics, Mechanics ,Mathematics as opposed to "Dharmic" (Bhautik Shaasta, Ganith, and Prakriya Shaastra) intrude in today's Kaliyug and create "distractions" like the Apsaras dancing in front of the Rishis doing "Ghor Tapasya" is the root cause of "Bad Habits".

However, if you can do "gyan prakaash" on how Ma Bhoo Devi in all her wisdom does differential "Kheenchayi" for a equally fast moving or slow moving rounds from smooth bore vs rifle, the "shanka" in my mind will get clear and your true wisdom of "trajectory flatter and hence more accurate" will become "Prakaash" and poor me will be "Un Konphoosed"
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by rohitvats »

^^^^hhehehehehehe
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

ramana wrote:Philip, Bascially the APFSDS is an arrow in flight. So it needs some taper at the aft to give it static stability for the Center of pressure to be aft of the center of gravity. And at the high velocity, all it needs is a small taper.
Ramana garu, the APFSDS is just a high speed dart with a needle like tip and a cylinderical body and a "boat tail" (probably to minimize separation drag there) and most importantly, the fins.

The fins provide lift (and equivalent stabilizing moment about the center of mass, just like an airplane's tail planes does) and prevents it from tumbling.The lift is generated well aft and the penetrators CG will be somewhere in the middle or just ahead and since lift is well behind CG, it is stable. Yes, indeed that is just how the arrow works as well. The steel/stone point in the tip in the nose makes it nose heavy and the fins in the end , give it the necessary lift to stabilize.

Philip --the Chally's charm-3 round. There is also a tungsten version since they are contract bound to keep Oman's fleet upto date wrt penetrators and UK doesn't export DU. Notice that too is not very different. I just picked it out of google. Read that article, it is some ginger group that is for banning depleted uranium muntions , though there are factual errors in some of their assertions, it is an interesting read.
Charm 3
The pics look different, because the Chally uses separate charge and ammo and is not a unitary piece like the Arjun and the Rheinmetall guns.. Chally is more like the T-72 /90 etc.

You can see the shiny slipping driving band on the sabot (unlike Maharaj Ji's assertions, it is simple, it just slips like bangle instead of being fixed to the sabot and works perfectly fine), , the orange cap on the base covers the fins
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Mihir »

nachiket wrote:That supposed PSQR in the Business Standard article talks about creating a FMBT with a 1800 HP engine with traditional armor plating plus active protection, yet keeping the weight at 50 tonnes. Setting aside the fact that this smells too much of unobtainium, it still doesn't tell us where Sanku got the idea that the Arjun's gun will be changed.
If you had spent more time understanding the CONTEXT of what was said rather than nitpicking the words alone, you would have realised that, broadly speaking, the DRDO is laying the groundwork for designing a new tank, and it will sport a cannon as its main armament.

The rounds fired by this tank will have good penetration because the gun will be well stabilised. The gun is also expected to be more accurate because it will fire shells along a flatter trajectory.

Whether this tank is named "Arjun" or "FMBT", whether its main gun is "rifled" or "smooth", is all a question of semantics.

So let us do away with this mischievous line of argument, shall we?
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by shiv »

vina wrote: However, if you can do "gyan prakaash" on how Ma Bhoo Devi in all her wisdom does differential "Kheenchayi" for a equally fast moving or slow moving rounds from smooth bore vs rifle, the "shanka" in my mind will get clear and your true wisdom of "trajectory flatter and hence more accurate" will become "Prakaash" and poor me will be "Un Konphoosed"
Misphortunately you are all adharmic. Ma Bhoo Devi actually does differential khinchayi, but even more misphortunately the khinchayi only helps the spinning shell path stay truer and more dharmic than the smoothbore shell.

See thich bedio about gyroscobe

http://www.youtube.com/watch?v=cquvA_IpEsA
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

nachiket wrote:That supposed PSQR in the Business Standard article talks about creating a FMBT with a 1800 HP engine with traditional armor plating plus active protection, yet keeping the weight at 50 tonnes. Setting aside the fact that this smells too much of unobtainium,
See, there is only ONE highly speculative "article" by Ajai Shukla on FMBT. I read it in his blog first and there too , one particulary erudite person in the comments with handle "GorchaaraGabbar" goes on and on, in detail (seems to be an insider/former army type with firm ideas on how it should be 50 tons and doable with the current kind of specs.. with going for an autoloader , 3 man crew etc), says that the DRDO proposal was for the current Rifled Gun (he says it was "convoluted" because it was a rifled gun proposal) and during deliberations it went to "Smooth Bore" from the Army's side (I wonder why , though, if it just following the Joneses and fashion, it is not well thought of, but if following from a specific op requirement that trumps other choices , perfectly fine) , and DRDO probably went along with it because it is really no big deal to make a smooth bore out of the current gun.. The Army will have a logistical nightmare with FMBT ammo incompatible with the Arjun fleet ammo , but it is their headache , not the DRDO's I suppose.

But whatever it is, the best that the Army's requirements of 50 tons will be is a slightly better armored version (both active and passive defense incorporated) of the Swedish CV90120-T light tank (30 tons or so), which has a 120mm smooth bore (to fire NATO rounds, commonality reasons of course) and a small turrent with autoloader (still has a 4 man crew though, only a part of the ammo is in ready storage in the turrent, rest in hull), but I am not sure, if that will cut the mustard in terms of armor protection that the Army seems to be looking for.
nachiket wrote:it still doesn't tell us where Sanku got the idea that the Arjun's gun will be changed.
From Col Shukla's speculative piece of course. But that can wait, until Guru Maharaj does "spashtikaran" on "dharti maa ki keenchayi"
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

shiv wrote:See thich bedio about gyroscobe

http://www.youtube.com/watch?v=cquvA_IpEsA
Ahh. Athi Sundar, Shivji. Yes, this gyroscobe (angular momentum conservation in Adharmic fyzzics), is what keeps the angular motions that are dharmically called bhatakna (ie.. yawing, adharmically), balti maarna (ie pitching adharmically) and ghoomna (ie rolling, adharmically) in "niyantran" and keeps the projectile in the true dharmic path and makes sure it doesn't do "balti" to hit mushrraf first after doing idhar-udhar bathakna.

But the other three linear motions heave (ie, udna and girna), drift and straight line motion are unconstrained (this is true for fin stabilization as well, pliss to note, Maharaj Ji) and the FCS will have to compensate suitably.

Drift you account for by gun correction to windage, seeda jaana is affected by drag and Udna aur Girna is controlled by Ma Bhoo Devi ki keenchayi , for which Maharj Ji will do "gyaan prakaashan"
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Raja Bose »

Some shades of enqyoob seem to have rubbed off on our resident Yum Bee Aye :lol:

Based on above discussion, from now on IA snipers will only use smooth bored bandook like Chambal ke Daakus and will call their weapons sniper guns.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Vina, you are ranting, in a nutshell, of things that you have attributed to me only 10% is correct, and that too has been made a hash of by paraphrasing and out of context quotation.

Silly behavior.
You can see the shiny slipping driving band on the sabot (unlike Maharaj Ji's assertions, it is simple, it just slips like bangle instead of being fixed to the sabot and works perfectly fine), , the orange cap on the base covers the fins
You can not be serious with this nonsense right? Slips like a bangle? What the hell are you talking of? What travesty of basic physics.
However, if you can do "gyan prakaash" on how Ma Bhoo Devi in all her wisdom does differential "Kheenchayi" for a equally fast moving or slow moving rounds from smooth bore vs rifle, the "shanka" in my mind will get clear and your true wisdom of "trajectory flatter and hence more accurate" will become "Prakaash" and poor me will be "Un Konphoosed"
You really are a specimen. Seems for all your blooming chest beating strutting about physics, you seem to have forgotten the basic equations of motion.

Do you really think some one can talk about different "g" on projectiles? You make me breathless.

No dear, you could at least follow the objection anujan raised, viz, what will be the drop over a large area with velocity. Basic simple 1/2g(d/v)^2 equation.

Come on now, with that posted, you are talking of different g's.

I dont know what is wrong with you, you either dont read anything any one else posts, or are intent on trolling.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Raja Bose wrote:Some shades of enqyoob seem to have rubbed off on our resident Yum Bee Aye :lol:

Based on above discussion, from now on IA snipers will only use smooth bored bandook like Chambal ke Daakus and will call their weapons sniper guns.
Funny you mention sniper guns and smooth bores....
:mrgreen:
http://world.guns.ru/sniper/large-calib ... 000-e.html
(posted before too)

Apparantly Steyr managed to make a Sabot based assault rifle as well, more effective than convention ones.
http://en.wikipedia.org/wiki/Steyr_ACR

:shock:
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Raja Bose wrote:Some shades of enqyoob seem to have rubbed off on our resident Yum Bee Aye :lol: .
BTW thats not necessarily a good thing. For all his erudition, N^3 wouldn't change his opinions even with new data and ended up on the wrong side.

Ego is best given a go by if one wishes to truly discuss.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Sanku wrote:You can not be serious with this nonsense right? Slips like a bangle? What the hell are you talking of? What travesty of basic physics.
Well, Maharaj, why get in Bhuatik Shaastra (adharmic Physics) here ? After all, you hold Kangan (bangle) and twist your hand, your hand turns, or if you prefer, hold the hand still and turn the bangle, it turns innit ? That is exactly what the slipping bands do, they are just like bangles (ok, bangles constrained from moving along the length) and slip around the hand/sabot.
No dear, you could at least follow the objection anujan raised, viz, what will be the drop over a large area with velocity. Basic simple 1/2g(d/v)^2 equation.
But, Guru Maharaj, even more Conphoosed onree. In your sermon, you said, that V drops are different, because the time of flight is shorter for 'flatter trajectory' , because of Bhoo Devi ki keenchayee and hence you concluded that "smooth bore" --> flatter than rifled bore --> hence better.

All I asked you is now given all the data that we have, it seems that both rifled and smooth bore shells have nearly same muzzle velocities. So if you still insist, that smooth bore has a flatter trajectory in such a situation, then the only way it will be so is because Bhoo Devi does "atiktam keenchayi" to a shell from rifled gun and "nyoontam keenchayi" from smooth bore.

Instead of doing 'Gyaan Prakaash', you introduce, more "katin" equations like 1/2g(d/v)^2 , which is beyond someone like me with praathmik siksha onree. :lol: :lol: . So first, praathmik siksha dijiye, and then we will go to Madyamik and Unchi.
I dont know what is wrong with you, you either dont read anything any one else posts, or are intent on trolling.
Not at all, I am only trying to understand some basics.. Very fundamentally, how do the flight times vary, so that one has a flatter trajectory than the other , when both have the same muzzle velocity?
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by nachiket »

Mihir wrote: If you had spent more time understanding the CONTEXT of what was said rather than nitpicking the words alone, you would have realised that, broadly speaking, the DRDO is laying the groundwork for designing a new tank, and it will sport a cannon as its main armament.
Oh is that so? I would have never guessed it had it not been for your truly magnificent intellect. I bow to your extraordinary knowledge in tank design and humbly take my leave.

Cannon armament indeed. As opposed to the water pistols found on all the other tanks ever made I suppose.
Whether this tank is named "Arjun" or "FMBT", whether its main gun is "rifled" or "smooth", is all a question of semantics.
Of course. All semantics. How stupid of me.
Last edited by nachiket on 04 Apr 2012 12:52, edited 1 time in total.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Prasad »

Ok. Lets get some facts into the discussion. The Rheinmetall 120mm gun on the M1A1 Abrams has a muzzle velocity of 5,200 to 5,700 ft/s. The L30 gun on the Challenger is also a 120mm gun (rifled) and has a muzzle velocity of 5,030 ft/s for one of their tungsten long rod AP rounds.

So for any given AP round of mass m, for the Rheinmetall gun, KE at the end of the barrel = 1/2 x m x 5200^2
KE for the L30 = 1/2 x m x 5030^2

So difference in KE in % terms is (5200^2 - 5030^2)/5030^2 is 6.9% roughly.
Assuming a muzzle velocity of 5700 ft/s, the difference is roughly 28%.

More may always be better. But if the rifled gun is causing enough damage, do you need the greater KE? :)
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Prasad wrote: More may always be better. But if the rifled gun is causing enough damage, do you need the greater KE? :)
Its a valid point, however you have chosen the higher figure of the velocity range for rifled (5030) and lower part of the range for smoothbore (5200), what if the velocity is 5700? Clearly the KE difference is far more.

I have been trying to do two things, since our discussion yesterday

1) Get numbers for Arjun APFSDS muzzle velocity (open source)
2) Get a good online reference for velocity related effects (a few simpler one posted)

These two would have enabled us to give answers better. In my understanding the muzzle velocities of APFSDS vary from 1400 to 1900 m/s (significant difference)
Very fundamentally, how do the flight times vary, so that one has a flatter trajectory than the other , when both have the same muzzle velocity?
Of course with the same muzzle velocity the flight times wont vary. However are the muzzle velocities same? The whole point of opting smoothbore is to increase the muzzle velocities. One reference is provided here as 5030 ft/s vs 5700 ft/s. That is a 15% difference in velocity.

Also, the smooth bore APFSDS despite the slip ring, as some spin which produces the spin related drift complications too.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Prasad wrote:Ok. Lets get some facts into the discussion. The Rheinmetall 120mm gun on the M1A1 Abrams has a muzzle velocity of 5,200 to 5,700 ft/s. The L30 gun on the Challenger is also a 120mm gun (rifled) and has a muzzle velocity of 5,030 ft/s for one of their tungsten long rod AP rounds.

So for any given AP round of mass m, for the Rheinmetall gun, KE at the end of the barrel = 1/2 x m x 5200^2
KE for the L30 = 1/2 x m x 5030^2

So difference in KE in % terms is (5200^2 - 5030^2)/5030^2 is 6.9% roughly.
Assuming a muzzle velocity of 5700 ft/s, the difference is roughly 28%.

More may always be better. But if the rifled gun is causing enough damage, do you need the greater KE? :)
Indeed, lets do. So, given DRDO brochure reading (very open source, Ask Unkal Googal, who takes you to the correct website and chamatkaar.. it is right there ), the Arjun APFSDS is 1650 m/s and above.

So that is 1650* 3.28083989501 ~ 5413 f/s , now that is better than the Chally you posted and just about the average speed (5450 fps) of the Rheinmentall.

So if all others are equal, (ie L/D, mass etc) how does Maharaj Ji's Gyaan follow from Bhoo Devi's effects?

Lets do something similar for HEAT rounds, again speeds are similar (they have to be) and anyway, HEAT works with chemical effects and not KE (as Maharaj himself posted), as Shivji posted gyroscobe is good, Maharaj says, smooth bore doesn't work well beyond 2 kms, but Shivji ka gyroscope is good and accurate to easily twice or thrice, again, given Bhoo Devi and all the rest of it, how does Maharaj Ji's Gyaan work here too, after all, he said that smooth bore is *always* better for all equivalent ammo!
Last edited by vina on 04 Apr 2012 13:08, edited 1 time in total.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Sanku wrote:Also, the smooth bore APFSDS despite the slip ring, as some spin which produces the spin related drift complications too.
Ah, Pliss to refer to my Shivji ka Gyroscobe response. There was a "prashna" in that for you as well, especially about linear motion and then think about what you wrote about drift and smooth bore.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

vina wrote:
Sanku wrote:Also, the smooth bore APFSDS despite the slip ring, as some spin which produces the spin related drift complications too.
Ah, Pliss to refer to my Shivji ka Gyroscobe response. There was a "prashna" in that for you as well, especially about linear motion and then think about what you wrote about drift and smooth bore.
I cant understand the gibberish in pinglish. If you post in normal language, or if you want to use hindi, do so with proper grammer and fonts.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

nachiket wrote:Of course. All semantics. How stupid of me.
:rotfl: . He was being sarcastic and responding to Maharaj. Chill
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

vina wrote: Indeed, lets do. So, given DRDO brochure reading (very open source, Ask Unkal Googal, who takes you to the correct website and chamatkaar.. it is right there ), the Arjun APFSDS is 1650 m/s and above.
Well the answer is simple then. The smooth bore is to take that to 1900 m/s and above
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

vina wrote:
nachiket wrote:Of course. All semantics. How stupid of me.
:rotfl: . He was being sarcastic and responding to Maharaj. Chill
Comedy is the last resort of the ignorant?
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Prasad »

Sanku wrote:Also, the smooth bore APFSDS despite the slip ring, as some spin which produces the spin related drift complications too.
I didn't understand this. Could you please put it clearly or explain this/
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Sanku wrote:I cant understand the gibberish in pinglish. If you post in normal language, or if you want to use hindi, do so with proper grammer and fonts.
What !. Ghor Kaliyug and how Adharmic! . But here is the part.
But the other three linear motions heave (ie, udna and girna), drift and straight line motion are unconstrained (this is true for fin stabilization as well, pliss to note, Maharaj Ji) and the FCS will have to compensate suitably.
In Inglees. Whether you use spin or FIN stabilization, what you stabilize the projectile for is angular motions (ie yaw, pitch and roll), but the linear motions (ie, drift (lateral motion), straight line translation and heave (up and down motion) are unconstrained in both. So go back to your post and think again.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Sanku wrote:
vina wrote: Indeed, lets do. So, given DRDO brochure reading (very open source, Ask Unkal Googal, who takes you to the correct website and chamatkaar.. it is right there ), the Arjun APFSDS is 1650 m/s and above.
Well the answer is simple then. The smooth bore is to take that to 1900 m/s and above
.

Okay.How will/did they do it ? By going from a 44 caliber to 55 caliber barrel. So, what prevents the Arjun gun too from going to 55 calibers! Nothing! That knocks the bottom out of your argument.

And notice, even with that, your HEAT and HE rounds will STILL be far slower and experience greater V Drop (higher frontal area, poorer ballistic coeff and all the rest of it.. You think only Bhoomi Devi, but Vayu Dev is equally important) and less accurate than Shivji ka Gyroscobe.

So relax.

What you did smacks of desperation in fudging numbers to fit your worldview. In BRF we call it Shanghai Stats and Madrassa Math ,applied to Lahori Logic. :lol: :lol:
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by VibhavS »

A question here if anyone can point me in the right direction. Rifled vs Smoothbore does anyone have any idea how often the L11 gun on the challenger has to undergo a barrel change as compared to say the M256 of the Abrams or the Russian 2A46M?

The rifled gun ruled the roost till the 60's and even later if you look at the Western Armies (US shifted to Smoothbores only in the late 70's) could it be to do with the cost of maintaining a rilfed gun? Barrel wear would be faster for one of these.. than compared to a smoothbore.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Aditya_V »

To vibhavS post here are 2 links

20 Millimetre MBT Arjun Armament System
Barrel life 500 EFC
Rheinmetall 120 mm gun
Originally the gun had a barrel life of between 400 and 500 rounds, but with recent advances in propellant technology the average life decreased to 260 rounds. In some cases, barrels have had to be replaced after firing only 50 projectiles.[26]
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Aditya_V wrote:To vibhavS post here are 2 links

20 Millimetre MBT Arjun Armament System
Barrel life 500 EFC
Please check again that appears to be only for HESH. Round velocity 735 m/s.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Prasad »

Sanku wrote: Please check again that appears to be only for HESH. Round velocity 735 m/s.
No such correlation. They are two separate columns of data.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

vina wrote:
Sanku wrote:
Well the answer is simple then. The smooth bore is to take that to 1900 m/s and above
.

Okay.How will/did they do it ? By going from a 44 caliber to 55 caliber barrel. So, what prevents the Arjun gun too from going to 55 calibers! Nothing! That knocks the bottom out of your argument.
At which point of time, it might be just better to shift to smooth bores for many of its advantages as well.

Why not, its not a religious theme. Once you have to upgrade, might as well upgrade the full system. No one in the world makes staying on rifled gun an ideological issue.

You take what ever is more optimum, which is smooth bores -- which is precisely what DRDO is doing.
And notice, even with that, your HEAT and HE rounds will STILL be far slower and experience greater V Drop (higher frontal area, poorer ballistic coeff and all the rest of it..
Where did that come from. We are not talking about HE rounds here, HE rounds etc are only for close support, there velocity plays a lesser role as compared to for APFSDS.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by vina »

Sanku wrote:Please check again that appears to be only for HESH. Round velocity 735 m/s.
Come on.. Stop clutching at straws. From that page, it is clear to anyone who can read, it does not say anything specific about any round, just that the Barrel Life is 500 "EFC" which means "Effective Full Charge" , by the way and is the no of firings at full charge before it must be junked.

Oh.. So what do we have here.

1) A rifled gun, at 50 calibers (ie 6000/120) is roughly the same muzzle velocity 1650m/s+ (okay lets take the minimum), of the best Rheinmetall 55 caliber smooth bore that is out there (1750 m/s)

2) It seems to have a "longer life"

3) And that is for the APFSDS

4) For secondary ammo, it fires bigger rounds, lot further more accurately!

So there goes the 'theoretical" smooth bore *always* better for tanks and rifled shorter service life and lesser max velocity for APFSDS theory flushed down the toilet.

Face it. The Arjun main gun is a STUPENDOUS achievement. It is simply brilliant and from all accounts, so is the armor. It is simply a crying shame that the Army played the dirty tricks it did with the Arjun. In fact, the Arjun project is a great success, especially for the 1st indigenous tank. It came late alright, thanks to a variety of factors, but when it did, it simply crushed the best that the Russians can field as of today.

The rest of it all is Lahore-via-kuwait from you.
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Re: Armoured Vehicles Discussion Thread - Jan 12, 2012

Post by Sanku »

Prasad wrote:
Sanku wrote: Please check again that appears to be only for HESH. Round velocity 735 m/s.
No such correlation. They are two separate columns of data.
Does it make sense to talk about barrel life independent of the round type? It is known barrel life would heavily depend on the round being fired (propellant, velocity, pressure etc) since different stress would be put on the barrel for each type of round.

Not all rounds will have same stress on the barrel --> in this case it is the "design" life in generic terms I guess.
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