A question regarding Pak's

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Korbius
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A question regarding Pak's

Post by Korbius » 21 May 2003 19:37

Whenever I see the different Pak guns or guns mounted in tanks, every version has a L/?? and the question marks mean the different numbers present. What does that number mean? Such as for example 20mm KwK 30 L/55, 50mm KwK 39 L/60, 75mm PaK 40 L/46 etc.

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Besian

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David Lehmann
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Post by David Lehmann » 21 May 2003 19:39

That's for the Barrel length expressed in "calibers" I guess ... that's why the 88L71 of the Tiger II is superior to the 88L56 of the Tiger I.
A longer barrel = higher muzzle velocity and often accuracy

David

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Juha Tompuri
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Re: A question regarding Pak's

Post by Juha Tompuri » 21 May 2003 19:50

Korbius wrote:Whenever I see the different Pak guns or guns mounted in tanks, every version has a L/?? and the question marks mean the different numbers present. What does that number mean? Such as for example 20mm KwK 30 L/55, 50mm KwK 39 L/60, 75mm PaK 40 L/46 etc.
Thanks,
Besian


Hi!

As Panzermeyer wrote the "L" means the lenght of the barrel (compared to the caliber).
20mm KwK30 L/55 = 20mm x 55 = 1100mm
50mm KwK39 L/60 = 50mm x 60 = 3000mm
75mm PaK 40 L/46 = 75mm x 46 = 3450mm

Regards, Juha

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Korbius
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Post by Korbius » 21 May 2003 19:56

a ha, so it's multiplying the calibre and the number, isn't it? Thanks guys, through all these years I never took the chance to find out these weird questions that are lingering in the back of my head :D

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Post by gabriel pagliarani » 22 May 2003 16:00

Exactly: it is a simple ratio. Es. 128mm/76 means a barrel 0.128x76=9.728 mt

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Korbius
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Post by Korbius » 22 May 2003 16:57

Grazie per l'informazione Gabriele, and thanks to everyone :)

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Von_Mannteufel
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Post by Von_Mannteufel » 23 May 2003 05:44

it's the lenght of the barrel, for eg. the 50mm L/60 has a barrel lenght of 50mmx60 which is 3000mm or 3m. the 88L/71 has a leghnt of 88mmx71 or 6248mm, 6,248m

it's like this.. the calliber of the gun is it's lenght (L) divided by some number. Cal. = L/N so in a 50L/60 it's like 50=L/60

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Redbaron1908
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Post by Redbaron1908 » 23 May 2003 23:52

So does this mean if the lenght of the barrel is longer that the gun is more powerful or not really?

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David Lehmann
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Post by David Lehmann » 23 May 2003 23:59

Well indeed, with a longer barrel the velocity of the shell will be increased and also the accuracy.
This is very important for AP shells not especially for HE or HEAT rounds. An AP rounds uses the velocity, the kinetical energy to penetrate its taget, especially APCR shells.
That's why for a 50 mm gun on a PzIII for exemple, the short barrel will not achieve easy kills against ennemy tanks but the long barrel version had better chances to destroy a tank and at longer range.

just my 2 cents.

David

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admfisher
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L/??

Post by admfisher » 24 May 2003 01:01

The longer the barrel the more of charge to launch the shot out of the gun.

Thus a longer gun barrel a larger breech to contain the larger explosion of the charge, thus a heavier gun.

When measuring gun barrels by the above equations remember that some countries would include the length of the breech also.

admfisher

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Redbaron1908
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Post by Redbaron1908 » 24 May 2003 01:29

Thank you admfisher and Panzermeyer so it would not really matter on He shots but mainly on the armor piercing shots.

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admfisher
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redbaron

Post by admfisher » 24 May 2003 16:44

Hi Redbaron

The HE, SAP, and such did not need the high muzzle velocity, thus the field guns and howitzers usually weighed much less.

We have a great visual here where I live. There is a 17 pdr, and a 25 pdr at the park.

The 25 pdr has the bigger size of barrel, the but the 17 pdr almost drawfs the 25 pdr.

It is really something to look at, the 17 pdr which was an excellant weapon has a massive breech compared to the 25 pdr. The 25 pdr could fit into the 17 pdr's position if it were in a emplacement. Where the 17 pdr would never even come close to fitting.
The guns are totally different in length, hight, weight and every other catagory.

With a field gun the charge is much smaller thus the less recoil thus the smallers size.

If you want I can send you a pic of each to compare.

admfisher :D

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Von_Mannteufel
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Post by Von_Mannteufel » 24 May 2003 19:27

redbaron1908 wrote:So does this mean if the lenght of the barrel is longer that the gun is more powerful or not really?


It mostly depends on the caliber and how much powder there is in the cartrige. Longer barrels allow more propellant burnt and so a faster mooving bullet, also helps on the accuracy because it guides the project for a longer way through the "riffling" (when there is one) of the gun. But too long barrels are bad because when the whole propellant burns there is no more things to push the bullet on, so the bullet just looses mechanical energy and as so speed.

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