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Main Gun Ammo - Revisited


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Very nice, thanks.

Looks like 125 mm APFSDS core pierced through, but cavity is filled with remains of projectile body. Crater in back side of plate is very small, not many spalling inside. 100 mm APDS though - real monster vs RHA at this obliquity.

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3 minutes ago, Przezdzieblo said:

Very nice, thanks.

Looks like 125 mm APFSDS core pierced through, but cavity is filled with remains of projectile body. Crater in back side of plate is very small, not many spalling inside. 100 mm APDS though - real monster vs RHA at this obliquity.

yes and 115 is very strange

jZU_3zvNlPc.jpg

 

core look like 3BM21 but i'm not sure...

 

3-WhT-Lg-bg.jpg

 

 

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57 minutes ago, Wiedzmin said:

yes it's known but never seen such results, to bad no info on which round and striking velocity 

Just posted here the finite element method simulation of this case, remarking that the knowledge picked up here was that it should pierce more armor than other rounds because it should turn downwards because the bottom side hits first, brakes first, so it should turn and negate the effect of sloped armor. Both in the simulation and  on the picture posted by Przezdzieblo the projectile "swims up".

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Probably not relevant, because the speeds and materials are so completely different, but aerial bombs dropped into (relatively) soft earth tended to have curved trajectories underground so that if they did not detonate immediately, could emerge at the surface again some distance from the original impact hole.

When performing EOD, it could take some time to realise that an apparent "dud" had tunnelled like a banana and exploded elsewhere.

If these are comparable, perhaps it reflects cases where there are large differences in material strengths?

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2 hours ago, DB said:

 

If these are comparable, perhaps it reflects cases where there are large differences in material strengths?

I don't think the speed or materials make much difference when the mechanics are essentially the same.  I think the two are quite comparable in as much as a moving object will always seek the path of least resistance, even if that means completing a U-turn.

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impact velocity definitely makes a difference. There is a dramatic change when shifting to the erosion regime and higher velocity generally limits the ability to deflect projectiles as the force needed to do so will more likely exceed the yield strength of the material. There is of course still some deflection from asymmetric forces when both the projectile and plate are eroding but it is less pronounced.

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10 hours ago, DKTanker said:

 I think the two are quite comparable in as much as a moving object will always seek the path of least resistance, even if that means completing a U-turn.

Probably as the projectile splits the armor in shallow angle, the significantly less mass on the outer side counters the course change effect of the one-sided braking. 

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I can imagine that the armour closest to the surface would appear "softer" than the deeper part to the other side. The balance of force would tend to push away from the side with more depth to it.

I have seen simulations with long rods that bend towards the normal, but that might get be a mechanism more associated with tip geometry, perhaps. Rotation towards the initial point of contact if it "bites in". Obviously, rotation could snap the rod or at least severely distort it.

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I think that is an error for 1000 or "only" 10 times increase.

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I believe the additive was lead foil.  As a HEAT round was fired a lot of copper residue was left from the rotating band and a build up of copper was the result.  Lead foil was added to the propellant charge to create a copper-lead amalgam that could be swept away with each subsequent round.

The EFC factors for M456A1 HEAT and M392/M728 APDS were both 1.0, the training analogues M490 and M724 also had EFC factors of 1.0 

The EFC life of the M68 is 1000.  

Interestingly there was another inter-round phenomenon that could occur.  If APDS/TPDS is fired and immediately followed by HEP/HESH or Smoke, the first subsequent round would always fly high.  Evidently the nylon driving band of APDS was lubricating the bore enough that the lower MV rounds were greatly affected.  HEAT wasn't affected and subsequent rounds of HEP would experience normal expected trajectories. 

Edited by DKTanker
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22 minutes ago, DKTanker said:

As a HEAT round was fired a lot of copper residue was left from the rotating band and a build up of copper was the result

but they refer to nylon driving band on HEAT, Sweds also have problems with M456 wyth nylon driving bands at low temp, so M456 have coppper bands or nylon ? or both ?

 

Spridningen ökar avsevärt vid låga temp (<-30c) enar nylongördeln är känslig för kyla.

The spread increases significantly at low temp (<-30c) as the nylon belt is sensitive to cold.

 

22 minutes ago, DKTanker said:

Lead foil was added to the propellant charge to create a copper-lead amalgam that could be swept away with each subsequent round.

there is russian word "размеднитель" 

 

_ITXZ1S7Hos.jpg

 

same thing ? 

 

22 minutes ago, DKTanker said:

The EFC factors for M456A1 HEAT and M392/M728 APDS were both 1.0, the training analogues M490 and M724 also had EFC factors of 1.0 

The EFC life of the M68 is 1000.  

but why report gives only 100 rounds of service life ? 

 

or after each 100 APDS shot, you need check and transfer the barrel to another category? 

 

 

Edited by Wiedzmin
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You're absolutely right about the nylon obturator of the M456.  It's been many years and I conflated HEP and Smoke rounds with the HEAT.  HEP and Smoke rounds have copper bands and the lead foil additive.
 

Why did was the EFC life listed as 100, because somebody who obviously didn't know anything about the cannon and ammunition typed the report and made a mistake.

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Another simulation, albeit of 20mm DM43

- Initial yaw away from the surface normal

- Starts to yaw back towards the normal for the yellow materials.

There doesn't seem to be information about the materials in each layer, unfortunately.

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