Dhanush the Indian Bofors

[pmaitra]

Hey guys I cant get a grip over the advantage of having 52 caliber over 45 caliber the projectile dia is same 155mm and i don't understand how it is impacting on the range of it compared 45 to 52 caliber
2nd. if you can design a 45 caliber gun how in the world it is tough to design a 52 caliber gun its just a matter of 6.95 ~ 8.06 meters different i cant understand the rucks behind a 45 and 52 caliber difference........

Think of the Laws of Motion:

The more force is applied to any body, the more velocity is added to the already existing velocity:

(eq. 1) v = u + at. (see eq. 2 below and substitute a)​

Also, the projectile has some mass. If force is applied to it, then it gains acceleration as below:

(eq. 2) F = ma
=> a = F/m.​

Take m as the mass of the projectile, then a is the acceleration of the projectile, and F is a force applied by the exploding chemicals.

To ensure more time is spent in applying the force, the distance (roughly) has to be increased during which the force is applied, because:

(eq. 3) S = ut + (1/2)at[SUP]2[/SUP].​

In other words, if the projectile spends more time in the barrel, it gains more velocity, and because it is moving at the same time, it needs a longer barrel. Thus longer barrel increases muzzle velocity. This phenomenon continues till the explosive gas stops expanding.

 

[Blood+]

Hey The Fox,are you a Naruto fan buddy??

 

[The Fox]

yes I am a naruto fan

Hey The Fox,are you a Naruto fan buddy??

 

[The Fox]

thanks but how difficult is to manufacture it the way I see it the length and strength of the barrel must b increased n we do have 155 mm 52 caliber guns n we can take a hint from those as well

Think of the Laws of Motion:

The more force is applied to any body, the more velocity is added to the already existing velocity:

(eq. 1) v = u + at. (see eq. 2 below and substitute a)​

Also, the projectile has some mass. If force is applied to it, then it gains acceleration as below:

(eq. 2) F = ma
=> a = F/m.​

Take m as the mass of the projectile, then a is the acceleration of the projectile, and F is a force applied by the exploding chemicals.

To ensure more time is spent in applying the force, the distance (roughly) has to be increased during which the force is applied, because:

(eq. 3) S = ut + (1/2)at[SUP]2[/SUP].​

In other words, if the projectile spends more time in the barrel, it gains more velocity, and because it is moving at the same time, it needs a longer barrel. Thus longer barrel increases muzzle velocity. This phenomenon continues till the explosive gas stops expanding.

 

[Kunal Biswas]

Think of the Laws of Motion:

The more force is applied to any body, the more velocity is added to the already existing velocity:
(eq. 1) v = u + at. (see eq. 2 below and substitute a)

Also, the projectile has some mass. If force is applied to it, then it gains acceleration as below:
(eq. 2) F = ma
=> a = F/m.

Take m as the mass of the projectile, then a is the acceleration of the projectile, and F is a force applied by the exploding chemicals.

To ensure more time is spent in applying the force, the distance (roughly) has to be increased during which the force is applied, because:
(eq. 3) S = ut + (1/2)at2.

In other words, if the projectile spends more time in the barrel, it gains more velocity, and because it is moving at the same time, it needs a longer barrel. Thus longer barrel increases muzzle velocity. This phenomenon continues till the explosive gas stops expanding.

Its like saying we can make Tandoori Chicken, but have a problem with chapathis. Some genius from BR Forums also postulated " its like taking chapathi and reverse engineering to find the composition of water and atta" Over 40 countries build artillery howitzers, including N. Korea, Iran, and Finland, but cannot match us in other areas like space science,supercomputers and fly-by - wire technology. ARDE lab has enough no. of M.Tech and Phd holders, testing facilities, and access to research papers from all over the world. Actual issue maybe bureaucratic inertia prevents open communications between various organizations who have to come together.

^^ This and ===>>

In Simple words, The composition of the barrels are not the same, like 45cal barrel use 40% of titanium and 60% of other metals, In 52cal the composition is different like 55% titanium and rest other metals, That is the mystery which can be solved in continual experiments with metallurgy of the barrels ..

Just increasing 45cal barrel to a 52cal length may cause more tear and very low service life ..

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@ladder

The 400 guns are meant to be 52cal, The addition of 45cal is a stop gap measure and may take place of 52cal guns if the tenders proved useless as always they do, As of 45cal guns are addition to the older 39cal guns, Btw OFB have another prototype of 39cal for mountains which may replace the original bofors 39cals ..

DRDO working on 52cal which will compete or will fill the 52cal need directly in future ( 3 years ) ..

thanks but how difficult is to manufacture it the way I see it the length and strength of the barrel must b increased n we do have 155 mm 52 caliber guns n we can take a hint from those as well

Hey guys I cant get a grip over the advantage of having 52 caliber over 45 caliber the projectile dia is same 155mm and i don't understand how it is impacting on the range of it compared 45 to 52 caliber
2nd. if you can design a 45 caliber gun how in the world it is tough to design a 52 caliber gun its just a matter of 6.95 ~ 8.06 meters different i cant understand the rucks behind a 45 and 52 caliber difference........

Kunal Sir, my understanding was that IA ultimately needs 400 of 45 cal Dhanush to replace the Bofores in the inventory, of that 114/ 100 have been ordered (LOI) issued.
DRDO 52 cal is needed for future projection and requirement of IA.

Even when the original bofors were indicted there was a requirement of around 1600 examples.
So, may be the DRDO 52 cal will cater to those requirement if the ongoing artillery procurement is delayed to 2020.

 

[The Fox]

Thanks Kunal this is exactly i wanted to know and now that you said it there was a project in indian Army to convert the 39 caliber into 45 caliber can you weigh on that

^^ This and ===>>

In Simple words, The composition of the barrels are not the same, like 45cal barrel use 40% of titanium and 60% of other metals, In 52cal the composition is different like 55% titanium and rest other metals, That is the mystery which can be solved in continual experiments with metallurgy of the barrels ..

Just increasing 45cal barrel to a 52cal length may cause more tear and very low service life ..

============================
============================
@ladder

The 400 guns are meant to be 52cal, The addition of 45cal is a stop gap measure and may take place of 52cal guns if the tenders proved useless as always they do, As of 45cal guns are addition to the older 39cal guns, Btw OFB have another prototype of 39cal for mountains which may replace the original bofors 39cals ..

DRDO working on 52cal which will compete or will fill the 52cal need directly in future ( 3 years ) ..

 

[Kunal Biswas]

It was, the plan was to upgrade all older FH-77 of 39cal to 45cal with help of Soltam of Israel, Latter it was found such upgrades are not beneficial as the sub systems and chassis are already old ..

It is better to make new guns based on FH-77 of 45cal, Which is now call Dhanush ..

Thanks Kunal this is exactly i wanted to know and now that you said it there was a project in indian Army to convert the 39 caliber into 45 caliber can you weigh on that

 

[The Fox]

thanks kunal for the insight

 

[ladder]

@Kunal Biswas Sir, any news on the up-gunning of addl. M-46 guns?

It is learnt that while approving the Army's proposal for upgunning of 300 more 130 mm M-46 field guns to a 155 mm gun system, the DAC on April 2 also decided that the request for proposal (RFP) would also go to interested private players. The Ordnance Factory Board, which used to automatically get these orders, will now be one of the contestants.

http://www.indianexpress.com/news/i...firms-can-bid-to-make-artillery-guns/1101211/

 

[arnabmit]

Can anyone explain something to me?

AFAIK, when a shell is fired, a powerful source of drag is the vacuum left behind the shell due to its blunt base, which reduces its range.

Base bleed is one way to reduce this drag, but a small loss of accuracy happens due to the somewhat more turbulent airflow, and a small loss in explosive payload due to some of the shell being taken up by the gas generator.

To overcome this, why can't an aerodynamic spindle shaped shell be used with a discarding sabot?

Green = Shell
Blue = Discarding sabot

 

[Kunal Biswas]

There is unknown no of 155mm M46, The OFB kit is successful and slowly most of the 130mm are under conversion to 155mm ..

 

[Kunal Biswas]

Interesting point, But again even with that modification an Arty shell wont be archiving the accuracy which are archived by guided rounds, though it may be accurate compare to today`s design, But again will it be worth doing in economical sense ?

To overcome this, why can't an aerodynamic spindle shaped shell be used with a discarding sabot?

Green = Shell
Blue = Discarding sabot

 

[Decklander]

Can anyone explain something to me?

AFAIK, when a shell is fired, a powerful source of drag is the vacuum left behind the shell due to its blunt base, which reduces its range.

Base bleed is one way to reduce this drag, but a small loss of accuracy happens due to the somewhat more turbulent airflow, and a small loss in explosive payload due to some of the shell being taken up by the gas generator.

To overcome this, why can't an aerodynamic spindle shaped shell be used with a discarding sabot?

Green = Shell
Blue = Discarding sabot

Why do you need discarding sabot for a round, you can have the normal round shaped this way. The force is provided to the shell in the barell only. The max dia of the round can have the round locking system to ensure that all the energy of the cartridge is applied to the shell.

 

[arnabmit]

Interesting point, But again even with that modification an Arty shell wont be archiving the accuracy which are archived by guided rounds, though it may be accurate compare to today`s design, But again will it be worth doing in economical sense ?

If you are talking about tumbling effect, that can be overcome by 2 things:

1) shells are anyway always nose heavy to mantain its ballistic dynamics.

2) Micro Rifling the shell to make it move through the air like the Americal Football.

Cost wise it should be similar to the 'dumb' shells, much lesser than the expensive base bleed rounds.

 

[arnabmit]

Why do you need discarding sabot for a round, you can have the normal round shaped this way. The force is provided to the shell in the barell only. The max dia of the round can have the round locking system to ensure that all the energy of the cartridge is applied to the shell.

Without the sabot, the pressure of the expanding fluid gas would get distributed to the entire 'U' shaped lower half, which would result in inefficient transfer of kinetic energy to the shell, due to more surface area and the shape.

A sabot being a solid object, the base with lower surface area and flat face, would accept the full pressure of the fluid expanding gas and transfer it to the next solid object with minimal loss.

 

[Decklander]

Without the sabot, the pressure of the expanding fluid gas would get distributed to the entire 'U' shaped lower half, which would result in inefficient transfer of kinetic energy to the shell, due to more surface area and the shape.

A sabot being a solid object, the base with lower surface area and flat face, would accept the full pressure of the fluid expanding gas and transfer it to the next solid object with minimal loss.

Usually a sabot is applied when the shell itself is very small compared to the barrel. But in this case you can block the expanding gases from going ahead of the shell by creating a sealing ring at its max diameter.

 

[arnabmit]

Yeah, but the issue of the spreading of pressure due to the larger surface area, thereby lower energy transfer to the shell, would still remain.

Not to mention the multiple vectors in which the pressure would act because of the shape of the shell base inside the barrel, which would not happen with a flat base.

Usually a sabot is applied when the shell itself is very small compared to the barrel. But in this case you can block the expanding gases from going ahead of the shell by creating a sealing ring at its max diameter.

 

[Decklander]

Yeah, but the issue of the spreading of pressure due to the larger surface area, thereby lower energy transfer to the shell, would still remain.

Not to mention the multiple vectors in which the pressure would act because of the shape of the shell base inside the barrel, which would not happen with a flat base.

Normally the shell skin is made of metals which can heat up quickly and expand to block the barrel even more.

 

[arnabmit]

Hope I am able to explain the fluid dynamics of the expanding gasses better with this diagram.

With the sabot, the barrel and the expanding gasses would act the same way it acts on a normal artillery shell.

However without the sabot, and due to the aerodynamic nature of the base of the shell, there would be extreme pressure built up at the edges where the shell touches the barrel, which might result the barrel to bulge and burst, but at the same time, there would not be enough pressure applied to the center of mass of the shell to propel it far downrange.

This is the basic principle without going into the detailed vector analysis of the expanding gasses.

Normally the shell skin is made of metals which can heat up quickly and expand to block the barrel even more.

 

[Decklander]

Hope I am able to explain the fluid dynamics of the expanding gasses better with this diagram.

With the sabot, the barrel and the expanding gasses would act the same way it acts on a normal artillery shell.

However without the sabot, and due to the aerodynamic nature of the base of the shell, there would be extreme pressure built up at the edges where the shell touches the barrel, which might result the barrel to bulge and burst, but at the same time, there would not be enough pressure applied to the center of mass of the shell to propel it far downrange.

This is the basic principle without going into the detailed vector analysis of the expanding gasses.

The range of barell loading guns got increased and accuracy increased due to expanding bullets under heat. same is true about cannons. The sabot will stop this heat transfer to whole of shell body but if we make the shell the way I stated, we will be able to make the shell heat up much faster as more area is available to absorb that energy and also impart more velocity to the shell as the heated shell will transfer its energy to its surrounding air thereby heating it and accelarating it which will remove the need for base bleed.
I am not an expert in guns as such but just using my knowledge of aerodynamics here.