120mm Smoothbore. Why?

[coonan357]

and all this time I though it was because the fine folks at barsto said " you want us to rifle a WHAT???"

 

[EMDII]

The HESH (high explosive squash head) projectile does not use a PIBD fuze, it uses a straight base detonating fuze. PIBD fuzes are used in HEAT projectiles.

Rich

!

I am corrected, and THANKS! Isn't HESH similar to our old HEP round? Can you tell I used to live on an M60? But I did graduate as far as the M1A1!


Me, I'm waiting for X-Rod. As far as spin/length goes, the problem probably comes from initial effortsto get a clean release. A FS round separates nicely from its bourrelettes (petals), and so retains ballistic form/truth. A spin-stabilized round has not nasties in it's physics when using LRPs (Long Rod Penetrators). Suffice it to say FINS work!

 

[Tamara]

The problem may come from finding an optimal twist rate to stabilize both long/dense long-rod penetrators and short/less-dense HEAT rounds, no? Fins stabilize anything...

 

[Thumper]

Fins stabilize anything...

Pshaw...tell that to the Ruskies buried on the Karelian isthmus.

 

[Frohickey]

The fins are for stability, not for spinning the projectile. Its really there to add a little drag to the projectile so that the front stays at front, and the rear stays at the rear (no tumbling)

Now, when Rheinmetal making the 120mm smoothbore, will the US start making its own, since Rheinmetal is a German company?

 

[Detritus]

Isn't HESH similar to our old HEP

not a tanker, but the sources i can find say No.

HESH is still an Anti-armor round, HEP (if you;re referring to High Explosive Plastiqe, the one that is basicly a semi-aerodynamic chunk of C4??) is a soft target, or breaching round.

 

[EMDII]

Now, when Rheinmetal making the 120mm smoothbore, will the US start making its own, since Rheinmetal is a German company?

We've been making our own M256 cannon for over 15 years. the gun is a German design, but no longer an import.

HEP was used as an anti-armor round (just not the primary one) and yes it is a large flying blob of C4. The detonation caused large scabs and spalling to occur on the inside of the AFV. Not pretty.

Now I'm back on the PIBD issue:

High Explosive Squash-Head. Use plastic explosives and a ballistically capped round. The round strikes a hard surface and the cap flattens the round evenly onto the surface. A piezoelectric crystal in the base shatters on striking the armor surface, detonating the plastic explosive. Really effective against armor, but not so effective against soft-skinned targets.

And this from the Indian MBT Arjun technical data:

High Explosive Squash Head (HESH) is the secondary ammunition for Arjun and is effective against a variety of soft targets, tanks, fortifications, etc. The complete HESH round consists of a semi-combustible cartridge case, primer with steel obturating cup, and a single-base propellant. The optimised explosive composition of HESH defeats rolled homogenous armour plate detaching a scab of about 9 kg mass moving with a velocity of 100 to 120 m/s. Besides the scabbing effect, blast and shock imparts a tremendous jolt to the enemy tank stripping off explosive reactive armour and incapacitating the crew severely, thereby affecting their fighting capabilities. The accuracy of the HESH is of the order of 0.25 mil standard deviation.

And this from a monologue on Soviet (sic) Armor-defeating rounds:

'base-detonating fuze"

Ah well,I won't wonder at my confusion: it's been 15+ years since I had to fire a HEP round. Seems as if only HEAT used the piezo-electric PIBD fuze. Tada! And my last SABOT and HEAT were fired in 1997. I never got to crawl on the new Challenger 2. Interesting how the Brits apparently treat this as a common Anti-Armor round, where we Americans use the APFSDS-T.

 

[EOD Guy]

I am corrected, and THANKS! Isn't HESH similar to our old HEP round? Can you tell I used to live on an M60? But I did graduate as far as the M1A1!

not a tanker, but the sources i can find say No.

HEP (high explosive plastic) rounds and HESH round are exactly the same thing. HESH is British nomenclature and HEP is US nomenclature.

 

[EOD Guy]

High Explosive Squash-Head. Use plastic explosives and a ballistically capped round. The round strikes
a hard surface and the cap flattens the round evenly onto the surface. A piezoelectric crystal in the
base shatters on striking the armor surface, detonating the plastic explosive. Really effective against
armor, but not so effective against soft-skinned targets.

Unless something new was developed since I left the service, piezoelectric elements were not used in base detonating fuzes. The normal application was as the point initiating element for an electical base detonating element in PIBD fuzing. The piezoelectric crystal generated an electrical charge when stressed by impact. The electrical charge was transmitted to the base element via a wire.

PIBD fuzing is used in HEAT (shaped charges) rounds, not in HEP (HESH) projectiles. HEP Projectiles used conventional striker/detonator base fuzing.

Rich

 

[EMDII]

Gracias!

The several articles I read on HESH said only BD IIRC. I recall clearly the LIBD arrangement on HEAT from AOBC classes, and even earlier when I took 11E class in 1970.

They (and their surrogates AND the Russians) still use this as an anti-armor round. Weird. I guess we make interesting Silver Bullets, too.