AP vs HE - Short barrel vs Long

[:USERNAME:]

Lewis said:

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Horseshoes and handgrenades son. Where are you coming up with a 15m to 20 m jump in lethality? Are you claiming this for a same calibre (mm) diameter shell? Do you know the approximate content improvement you would need?

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Jeffy said:

No, cannot say that I do. I was speculating. Do you? Or are you just good at blanket refutations?

Well heres my answer to Jeff "Hide"man's question:

Yes I do. Since Blast falls off at 1/(R-cubed) by most peoples modeling, you would require about 2.37 times more explosive to attain the same performance at 20 meters than you were getting at 15 meters. If you cant do the math I will give you a big hint: surface of a sphere is a good starting point.

If you had a 10 pound shell with 1 pound of explosive (I am just normalizing here, 1 pound of explosive shouldnt kill you in the open at 15 meters), then you would need a ten pound shell with 2.37 pounds of explosive. Walls would be getting pretty thin, me thinks.

Lewis

[This message has been edited by :USERNAME: (edited 08-09-2000).]

[Jeff Heidman]

Lewis, why don't you stick it where the sun doesn't shine.

I am not hiding from you, I am just uninterested in discussing anything with someone who is a pinhead.

Have a nice day.

Jeff Heidman

[cward]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

So I still stand by the following statements:

Velocity adds an appreciable effect to both the AP and Blast effects of HE shells.

Velocity adds to the accuracy of HE shells as any other shell

Velocity decreases flight time and allows qucker adjustment of fire.

Hardened targets are best attacked by blast effects than 'shrapnel' effect.

Hardened targets mean bunkers, buildings, pillboxes, trenches, caves, etc.

Direct fire Blast effects require hits to be most effective.

Direct fire infantry support HINGES on stealth (since you are operating at fairly close quarters to the enemy), QUICKLY engaging targets and HITTING them with minimal rounds and changing positions. Weapons like the soviet JSU122s give me the willys. Big HE with a kicking velocity. CM2 look out.

Lewis<HR></BLOCKQUOTE>

Another thing that makes me cringe when I read about it is the Supersonic nature of the 88mm.. It was designed for flak, so lots of fast moving shrapnel, and the rounds travelled supersonically.. so the shrapnel was flying even before the muzzle report was heard.. Shudder.. that had to be terrifying..

Not to make this more bizarre, but isnt the relationship to the caliber and the length of the barrell important to its accuracy, like fine tuning a piano, there is a perfect ratio that makes it the most accurate?

Chris

Oh and IS THERE AN ARTILLERY OFFICER IN THE HOUSE!

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Heidman:

Lewis, why don't you stick it where the sun doesn't shine.

I am not hiding from you, I am just uninterested in discussing anything with someone who is a pinhead.

Have a nice day.

Jeff Heidman<HR></BLOCKQUOTE>

If you cant stand the HEAT get out of the kitchen. Besides I never said you had to discuss anything with me. You called me on something and I am just following through. Try it, it builds character.

You are a big baby jeffy. Think you got ALL the answers and decide to pontificate here and got called out on something and humiliated. It happens.

LOL

Lewis

[Dan Weaver]

Perhaps I'm wrong here but don't nearly all gun rounds travel supersonically?

Dan

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by cward:

Another thing that makes me cringe when I read about it is the Supersonic nature of the 88mm.. It was designed for flak, so lots of fast moving shrapnel, and the rounds travelled supersonically.. so the shrapnel was flying even before the muzzle report was heard.. Shudder.. that had to be terrifying..

Not to make this more bizarre, but isnt the relationship to the caliber and the length of the barrell important to its accuracy, like fine tuning a piano, there is a perfect ratio that makes it the most accurate?

Chris

Oh and IS THERE AN ARTILLERY OFFICER IN THE HOUSE!

<HR></BLOCKQUOTE>

The germans did ALOT of studies on FLAk and found out that HE is not very important (at high altitude the air is thin and therefore the blast wave cannot propagate through the atmosphere) but shrapnel/splinters ARE important (maybe jeffy is correct about shooting high altitude bunkers-heheheh) because less air means that the splinters wont slow down. They even were studying hollow charge AA rockets that would take a whole ****load of HEAT charges up to the bombers and "shoot" them towards the bombers. The shaped charge projectiles would extend out to 100 meters.

There is a relationship for the diameter and length and shape of a projectile and a maximum shape is something like the 50 cal bullet. They even based that X15 supersonic plane around that shape.

Lewis

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Heidman:

[b

This is why, historically, the 75mm gun on the early Shermans was considered superior to the 76mm gun on later Shermans when it came to infantry support. The 75mm shell carried more HE, and was smaller and easier to handle, resulting in a higher rate of fire.

Jeff Heidman<HR></BLOCKQUOTE>

OH I AM JUST SO SICK AND TIRED OF THIS OFT QUOTED BS!!!!!!!!!!

The 75mm HE shell weighed more. 6.67 Kg. The 76mm weighed 5.9 Kg.

http://www.history.enjoy.ru/guns/defin_1.html

It was bigger and weighed more. Everyone assumes that they were the same size because the diameter was so close?

Anyone have some useful data like what was the WEIGHT of filling in each of these? Both of these weigh more than a german 75mm BTW.

JEEESSSHHH!!!!

Lewis

[Rattus]

Hogg gives:

76mm gun as used in Sherman & M18 TD (originally designed as AT gun) used same ammo as 3" AT (but different chamber sizes so different mv's) as used in M10 TD & towed equipments, which in turn used same ammo as 3" AA gun. As such thick - walled & small burster:

HE M42A1, wt projectile 12.87lb, wt burter 0.86lb TNT.

Note: The projectile design originated for the old 3" AA gun so was designed for maximum mv (of course the round wasn't designed to hit anything solid!). Both HE and APC (M79) rounds used similar charges (4.56lb & 4.62lb respectively) but the APC round weighed 15lb so had lower mv (2800f/s & 2600f/s respectively)! Despited the extra m/v of the HE round, its smaller burter & tendency to bury itself resulted in overall(Bold & italics!) ( that is for most purposes) a less efficient HE round. This was the price of standardisation of ammo production & that on a type of HE round suited for AA fire not ground fire. Later a slightly better HE was produced.

HE for 75mm M2 (for M3 Tk) & M3 (for M4) Tk same as for 75mm field guns. Originated from moderate velocity field gun so thin walled & large burster:

HE M48, wt projectile 14.7lb, wt burster 1,5ln TNT or 1.36lb Amatol.

Normal propellant charge 1.05lb.

viz APC round M61 of 14.96lb used 2.16lb propellant charge.

Note significantly larger burster of 75mm round and disproportionately reduced propellant charges for 75mm HE rounds to give lower velocity in Tk gun.

I think I posted the burster info previously but it's a looong thread.

[Rattus]

And further to my last...

Weight of fixed round (Projectile + cartridge case) of 3" HE was roughly 24-26lb depending on chamber size (see previous post). [The Brass/Steel/Alloy (whatever!) cartridge cases are heavy.]

Weight of fixed round of 75mm HE was ?!!! From memory about 20lb or less.

The fixed round shell illustration I have shows a cartridge case about 1/2 the length of that for the 3" HE fixed round. That is 350mm long (the diagram is in French!) for the 75mm cartridge case as opposed to 23" (weighing 6.6lb) to 26.7" (weighing 8.5lb)for the 3" cartidge case. Again, variation is due to slightly different chamber size.

The 75mm fixed round is therefore lighter and smaller. So ceteris paribus, higher ROF.

Eh Voila!

[:USERNAME:]

Thank you Rattus

The german 75mm type34 weighed 5.74Kg and packed 0.68Kg of HE. I am quoting from "The Sturmgeshuetz in WWII" Fleischer. This was the same projectile that was used in most german 75mm weapons with different barrel lengths (ie different velocitys).

This works out to 12.62 lbs and 1.5 lbs respectively. This is 11.85 % by weight HE.

Lewis

PS

1. Compare rounds of similar diameter and weight.

2. Lets let the velocity be the main variable.

So:

US HE M42A1, wt projectile 12.87lb, wt burter 0.86lb TNT.

HE M48, wt projectile 14.7lb, wt burster 1,5ln TNT or 1.36lb Amatol.

German 75mm type34 weighed 5.74Kg and packed 0.68Kg of HE. This works out to 12.62 lbs and 1.5 lbs respectively. This is 11.85 % by weight HE.

Lewis' Conclusions:

I believe the german HE shell kicks ass. This is the same shell used in the L24 AND L48 and L70. Notice that these german guns are all weapons of different velocitys. They all used different cartridge cases, of course, but shot out the same HE projectile. It had a great HE payload and velocity(s). Its about time BTS addressed this WWII falacy.

The US 76mm HE seems to be a design that needed to get up to high altitude and therefore had as high a velocity as possible. As I have pointed out previously, HE takes a back seat to splinter effects at ALTITUDE. So the US 76mm was a good FLAK shell by design and perhaps inadvertantly a GREAT pillbox/bunker buster shell by serendipity.

The germans had a variable fuze on the 75mm HEs as standard equipment. Did the US weapons? Anyone have any data on the ability of US direct fire weapons having this? The benefit of such a variable fuze (from point detonating up to 0.15 seconds in the german case) has been discussed previously here and can be found with a search.

Lewis

[This message has been edited by :USERNAME: (edited 08-10-2000).]