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#41 Stefan Kotsch

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Posted 20 February 2008 - 0714 AM

The problem is indeed with the rifling, but not because of sabot separation issues, it's because of insufficient spin imparted on APDS round to ensure its stability.


Oh, that meets it more exactly. ;)

The Kuerassier gun, on the other hand, requires *specially modified* APFSDS rounds, with reduced charge compared to normal French rounds. It cannot fire standard 105mm APFSDS rounds as far as I understand.


The APFSDS for M-57 of the Kuerassier has shorter cartridge case. The return way had to be kept smaller. The APFSDS projectile is however as with the F1, if I see it correct. The muzzle brake had made problems when shooting with APFSDS, therefore it was changed (two chamber to one chamber muzzle brake).

#42 Vasiliy Fofanov

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Posted 20 February 2008 - 0910 AM

The APFSDS for M-57 of the Kuerassier has shorter cartridge case. The return way had to be kept smaller. The APFSDS projectile is however as with the F1, if I see it correct. The muzzle brake had made problems when shooting with APFSDS, therefore it was changed (two chamber to one chamber muzzle brake).


Right, the projectile does look like F1 (though it may be superficial similarity, I don't believe I ever saw it officially confirmed that it's the same dart). Quite possible what GIAT did is they took F1 projo and put it in a different cartridge. As far as muzzle brake is concerned, I don't know if the change was due indeed to sabot separation problems or for some other reason...

#43 Przezdzieblo

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Posted 20 February 2008 - 1140 AM

Got another pic of Delta arrow round. This one looks more thin.
Posted Image
Additional data - penetrator l/d 8:1, mv=5300 fps (1615 m/s), pen(1920 m)= 300 mm, projectile 17,6 lbs (7,98 kg)

120 mm guns data:
120 mm Delta gun
Lenght of bore: 219,08" (5565 mm) - L/46,4
Length, muzzle to rear face of breech: 230,08" (5844 mm) - L/48,7

120 mm M256
Lenght of bore: 208,7" (5300 mm) - L/44,2
Length, muzzle to rear face of breech: 220,2" (5593 mm) - L/46,6

Still curious if there was any connection between Delta (dropped 1965) and Rh-120 (started 1965) - any knowledge and data flow.

#44 jwduquette1

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Posted 20 February 2008 - 1153 AM

Got another pic of Delta arrow round. This one looks more thin.
Posted Image
Additional data - penetrator l/d 8:1, mv=5300 fps (1615 m/s), pen(1920 m)= 300 mm, projectile 17,6 lbs (7,98 kg)

120 mm guns data:
120 mm Delta gun
Lenght of bore: 219,08" (5565 mm) - L/46,4
Length, muzzle to rear face of breech: 230,08" (5844 mm) - L/48,7


Nice find Pawel. I'm still drawing a blank on images or design drawings for the arrow. But I still have a couple more locations I need to try.

Jeff

#45 Przezdzieblo

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Posted 21 August 2008 - 1620 PM

Quick question for 120 mm M256 gun: does it have concentric recoil mechanism? How this licenced gun differs from the orginal? It is said it got less parts plus maybe new, US made, recoil mechanism. It could be seen mantlet of Leo 2 and combination mount of M1A1 is far from look the same.

#46 dejawolf

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Posted 22 August 2008 - 0648 AM

the M256 differs from the RH-120 mostly because its got a new coilspring recoil system, instead of a hydraulic based on like on the RH-12.
its basically a giant coil wound around the guncradle.
the M256 does not have a stub-catching basket, instead it has an attachment on the rear of the sliding breechlock, and some sort of "basket" on the floor.
it also has a different attachment for the M240 coax, and a huge ammobin on the left side of the gun, along with an ammoguide that goes over the gun, but i'm not sure if that goes as the M256.

#47 Catalan

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Posted 22 August 2008 - 1033 AM

Spain began production of a APDS called the CETME437A; this is an Israeli round produced in Spain, although I'm not sure for which one, mean for Spain's AMX-30Es (EM1s and EM2s) - the gun remained the same, as far as I know.

#48 Przezdzieblo

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Posted 22 August 2008 - 1146 AM

the M256 differs from the RH-120 mostly because its got a new coilspring recoil system, instead of a hydraulic based on like on the RH-12.
its basically a giant coil wound around the guncradle.
the M256 does not have a stub-catching basket, instead it has an attachment on the rear of the sliding breechlock, and some sort of "basket" on the floor.
it also has a different attachment for the M240 coax, and a huge ammobin on the left side of the gun, along with an ammoguide that goes over the gun, but i'm not sure if that goes as the M256.

Thanks! What about barrel itself, no changes to it? Exactly the same performance and barrel life?

#49 Gorka L. Martinez-Mezo

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Posted 22 August 2008 - 1259 PM

Spain began production of a APDS called the CETME437A; this is an Israeli round produced in Spain, although I'm not sure for which one, mean for Spain's AMX-30Es (EM1s and EM2s) - the gun remained the same, as far as I know.


The CETME 437 was/is an APFSDS round, as far as I know Spain never used APDS. This was designed in the mid1980s, supposedly with Israeli assistance (at that time Spian bought M111 and M94 APFSDS rounds from Israel so further cooperation seems natural). This was surely tried aboard the AMX-30EM2 (mentioned on the user`s manual), but we are still not sure if this was series produced.

The M111 was the sole 105mm APFSDS round for many years, later DM33 and DM63 rounds were adquired.

#50 Gorka L. Martinez-Mezo

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Posted 11 January 2009 - 0602 AM

The CN-105F1 in action!

CN-105F1 in action - You tube

#51 Przezdzieblo

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Posted 11 January 2009 - 1045 AM

Nice video. What is that flash, just after ejection of empty cartridge of the 1st round? Some kind of flareback?

#52 Gorka L. Martinez-Mezo

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Posted 11 January 2009 - 1133 AM

Nice video. What is that flash, just after ejection of empty cartridge of the 1st round? Some kind of flareback?


Bore evacuator working backwards? :lol: I also noticed it.

#53 DKTanker

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Posted 11 January 2009 - 1145 AM

Bore evacuator working backwards? :lol: I also noticed it.

Bad seal around the bore evacuator or grease in the holes. I've only seen that much smoke and flash back when either or both of those conditions exist. OTOH, the AMX30b2 doesn't have a bore evacuator so whatever system it does use either doesn't work as well as a bore evacuator or didn't work well in the video.

#54 Stefan Kotsch

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Posted 11 January 2009 - 1212 PM

I also experienced this flashback with the T-55. If one stands beside gun, then looks very enormous... :o Probably the barrel was still oily.
By the way, with the CN105 the gun barel with compressed air is blown out.

#55 Przezdzieblo

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Posted 14 November 2009 - 1731 PM

Ok, Jeff, I see it. But my point is that early Soviet APFSDS looked like thin "arrow", lond rod with fins, while 1950-1960 US army LRPs looked like... an "arrow" which ate too much ;)

Here`s "collage" of that what could be found in Hunnicutt:
Posted Image
Note that proportions of projectile (if I identified it correctly) did not change much (T208 is mid 1950s, Delta gun is from 1960s).
More, ealier projectile seems even thinner (90 round, 40 mm projectile, 37 mm core).
And here is Soviet BM-3 APFSDS, early 1960s (taken from Stefan Kotsch site)
Posted Image



One more "collage":
Posted Image

On the left, Soviet 125 mm APFSDS projectile 3BM-9 (pictures taken from Vasiliy`s site), DOI 1962.
In the middle, US experimental APFSDS penetrator, labbeled T371 (or mislabbeled; I know only one photo from Internet, I got no idea if I draw it correctly, what is it`s construction inside, how long is threaded area, what was WC core shape - bullet-like or elongated teardrop, how thick was balistic cap, etc.), ~1953.
On the right, British 3.0/1.2" (76/30 mm) experimental test-projectile. It looks pretty cool, modern and dangerous, and it is from... ~1947. But no, no British APFSDS at this time - it was used only for sabot evaluation in subcalibre HE-FSDS rounds program.

#56 jwduquette1

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Posted 15 November 2009 - 1145 AM

One more "collage":
Posted Image

On the left, Soviet 125 mm APFSDS projectile 3BM-9 (pictures taken from Vasiliy`s site), DOI 1962.
In the middle, US experimental APFSDS penetrator, labbeled T371 (or mislabbeled; I know only one photo from Internet, I got no idea if I draw it correctly, what is it`s construction inside, how long is threaded area, what was WC core shape - bullet-like or elongated teardrop, how thick was balistic cap, etc.), ~1953.
On the right, British 3.0/1.2" (76/30 mm) experimental test-projectile. It looks pretty cool, modern and dangerous, and it is from... ~1947. But no, no British APFSDS at this time - it was used only for sabot evaluation in subcalibre HE-FSDS rounds program.


Interesting material Pawel -- as usual.

Just so I am clear on this bit -- I assume that is what you are saying -- but the lengths and diameters of each of the three are not drawn to scale relative to each other?

#57 Przezdzieblo

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Posted 15 November 2009 - 1339 PM

Now - same scale:

Posted Image

I added also my attempt to see what is inside. Idea is unsupported - never heard about T371 before, never read if it had WC core at all. But it proportions - 90/40 mm calibre - seems ok, just like in case of T320 family. So I assumed that there was WC core, and it got 37 mm diameter (but I cannot remember where I read about 37 mm core), bullet shape and l/d radio as 3 to 1 (similar to US HVAP and Soviet early APFSDS). However I got some feelings that real ammunition looking like that (with 37 mm core and 40 mm projectile diameter) would breake apart right after pulling the trigger :)

There is one more interesting thing about US arrow projectiles of 1950s - some where fired both from 90 and 105 mm guns. I guess T82E22 for 105 mm gun was slightly different than T82E22 for 90 mm gun (bigger sabot and largers fins), but there seems to be no clear difference in projectile designation.

#58 Vasiliy Fofanov

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Posted 16 November 2009 - 0429 AM

On the right, British 3.0/1.2" (76/30 mm) experimental test-projectile. It looks pretty cool, modern and dangerous, and it is from... ~1947. But no, no British APFSDS at this time - it was used only for sabot evaluation in subcalibre HE-FSDS rounds program.


Very interesting! Such is also the earliest Soviet FSDS design we could find, from the same period - an experimental 100mm AA round.

#59 Stefan Kotsch

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Posted 16 November 2009 - 1124 AM

The projectile has condemned similarity with the "Peenemuender Roechling Projectile" from 1940:

Posted Image

Edited by Stefan Kotsch, 16 November 2009 - 1126 AM.


#60 Przezdzieblo

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Posted 16 November 2009 - 1438 PM

Germen Pfeilgeschoss and British Pfeilgeschoss...
Posted Image
Both were HEFSDS.

My point was it is quite interesting that those experiments did not lead to APFSDS development at this stage. Of course, technology matters, but still seems to be missed opportunity.

Edited by Przezdzieblo, 16 November 2009 - 1448 PM.





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