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Main Gun Ammo - Revisited


Jim Warford

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2 minutes ago, Junior FO said:

t was found a "soft" ignition was needed to mitigate the shatter effect most powders of the era had, which could lead to pressure spikes. F.e. Swiss tests with DM23 @-32C° resulted in an average of 4401 bar, and a spread of 383 bar while a Wimmis powder with similar corn geometry had led to damaged gun in 1980

hm, british ammo also had i think similar problems with german powders during L64 development 

 

There is an embarrassment in that the muzzle velocity which was quoted at the Bourges trials which demonstrated the superiority of L64 over the US M735 round, and which was subsequently requited in documents, is not now likely to be met. Although we remain confident of the superior performance of L64 the extent to which this point will of itself incline potential buyers, such as Belgians and possibly even the Dutch, to other solutions remains to be seen.

2. Shatter. Further trials of the basic WNC propellant had confirmed evidence of shatter at low temperatures. This was unacceptable to the UK. MGO asked whether we were being stupid as the propellant was used in the FRG 120mm KE round.S/GR2 RADHE said that the OB would not accept the situation. DGW(A) said that we knew that the Germans were having more accuracy problems and shatter could have something to do with that. In some batches the pressure at -40C was higher than it should have been. S/GR2 RARDE said that this propensity to shatter could not be «blended» out. Tests with reduced diameter granules had not improved the situation.

3. MV. Each batch of basic WNC propellant had shown a different temperature coefficient(the original was about 4 but the latest had reached 5.8). As a result RARDE had been forced to specify an MV of 1472m/sec. Competitive rounds were set at about 1465 m/sec whereas we had predicted 1505m/sec from the UK propellant at the IEPG competitive trials. It might be possible to blend out the temperature coefficient variation but that would not solve the shatter problem.

13. It is unlikely that, even if a successful development programme could be carried out in the time stated above, the MV will exceed 1470 m/s. This will give little edge over the Israeli M111 round, the only advantage of L64 being its greater shot development potential (W/Ni/Fe core, reduced drag). However, the ROFs have as yet given no indication that they are seeking to pursue the potential offer by W/Ni/Fe cores.

Conclusions

15. The L64 programme has run into serious trouble in the final stages of its development. A difficult decision must be made within a month as to whether it is wise, or indeed possible, to inject further effort to save the project in view of the scarce resources available at RARDE, PERME and DPEE.

THE ROF/SALES DILEMA

8. L64 development is already late. Performance has fallen below that demonstrated at Bourges in 1978 when 1505 m/s mv was announced. (Difficulties with temperature correction for chamber pressure have led to the 1471 m/s figure). Competition from the Israeli M111 round now being manufactured by Diehl in Germany is intense, this round being available in production quantities at very competitive price.

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On 9/23/2023 at 4:46 PM, Junior FO said:

It seems the Pz Kan 61/68 recoil system was having problems with high energy rounds, needing to be checked/serviced after every 100 rounds of APDS/APDSFS. This was fixed with a revised recoil system in the mid 80's.

On 9/23/2023 at 5:24 PM, Wiedzmin said:

is there similar data for L7?

In 1981 the recoil system was initially to be serviced after 60 rounds, this was then later increased to 100. For wartime usage one could continue until one of the two recoil buffers fail. This was expected to be not before at least 200 rounds. Extensive tests to find the limit were not considered worth the cost.

For Pz Kan 61, the Dm23 stressed the recoil system an additional 10% @52°C compared to L52, but the piston rods had a margin of at least 25% over the entire spectrum of -25C° to +52C°. Higher Impulses were only at +32C° and above. However the seals showed strong signs of wear as well as security? elements. With L64 it is noted that the recoil system is at the upper end of what it can handle. From the timing this must apply to the original English, pre WASAG LM1700/1900, powder, since the trials with WASAG powder showed equal or slightly less recoil than the L52 baseline at all temperatures.

For Pz Kan 60, which would be the direct L7 copy mounted in the Centurions, it is merely noted that the recoil pressure is above what is guaranteed by the licencee. Since L64 and DM23 had been the focus up till then, but initial trials were also starting to be held with M111, it's unclear whether this applied to all 3 or maybe only the first two, or again only to L64 with the original English powder.

 

On 10/15/2023 at 2:57 PM, Wiedzmin said:

hm, british ammo also had i think similar problems with german powders during L64 development

It turns out that L64 was the main contender for the Swiss PfeilPat until M111 being chosen at the last moment, so I have some material.

I'll post the stuff when I've gone through everything in a seperate thread.

 

 

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On 5/31/2017 at 4:01 PM, Wiedzmin said:

btw, about L52A2, soviet test(very strange to me) from captured M60A1

rMz8m22ZU7A.jpg

table of сalculated penetration(don't know it there was real firing of L52, or just soviets carried out metallurgical analysis of L52 core, report notes that the L52 has different alloy than L28)

 

i also read some western source about L52, they claimed that new cap and alloy gives good penetration at angles(45-70°)but worse at vertical (0-30°),but i never seen such low 240mm at 1km at 0° for L52, maybe you have something about L52 ?:)

https://ufile.io/fzchf0bn

page 26

The 2000m 120mm@60° L52A2 agrees with the UK document . The 1000m for 120mm@60° for L28 also matches.

page 39

(Probably 1970) UK Ballistic APDS data for 30mm, 105mm, 110mm and 120mm, together with HESH for 105mm/120mm.

The 105mm APDS should be L52A2 as L52A3 was still in trials in December 1970.

 

https://ufile.io/kwnv5h10

105mm L28 against various plates, angles, qualities. The first section with reduced charge is the approx equivalent to a distance of 1600m.

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On 10/16/2023 at 6:05 PM, Junior FO said:

It turns out that L64 was the main contender for the Swiss PfeilPat until M111 being chosen at the last moment, so I have some material.

german report(from british archives) about plate quality vs APFSDS real penetration during trials

agYevMMko3U.jpg?size=2560x1944&quality=9
z1KCEZvIb4U.jpg?size=1566x2160&quality=9
wUBs6tJCVM8.jpg?size=2560x2087&quality=9
oQl6rlmcsP4.jpg?size=2539x2160&quality=9
8gNPPGnC0Sw.jpg?size=1279x2160&quality=9
KYo_F4mM62U.jpg?size=2560x2116&quality=9
kQYDynZ5yAY.jpg?size=2560x2068&quality=9
VmIENreh7CI.jpg?size=1372x2160&quality=9
80ICMXp34gs.jpg?size=2560x2031&quality=9
5VyXHqHGjGw.jpg?size=1412x2160&quality=9
j87srb5PTuM.jpg?size=2560x2027&quality=9
9728TpmLuTg.jpg?size=2560x2143&quality=9
q-MQjC9zZxk.jpg?size=2560x2112&quality=9
7c1kadO3hMU.jpg?size=2560x2021&quality=9
GdrFgMszp-o.jpg?size=1370x2160&quality=9
F5TC_batfRo.jpg?size=2549x2160&quality=9
Cirx7uQ99L0.jpg?size=2560x2092&quality=9
SUYZecII_zs.jpg?size=2560x2110&quality=9

 

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  • 2 weeks later...
On 10/25/2015 at 1:54 AM, Wiedzmin said:

 

amx30-firepower-obus-g-heat-round-page-1

 

amx30-firepower-obus-g-heat-round-page-2

 

 

 

amx30-firepower-obus-g-heat-round-page-3amx30-firepower-obus-g-heat-round-page-4
Obus G = APFSDS ?
300mm at any distance ? it's about HEAT or APFSDS ?

Obus G 105 T59

1960 Switzerland was looking for a HEAT round that could be fired from its 105mm cannons/ howitzers and was also looking at maybe adopting the French 105mm on AMX13 chassis, modified to accept existing Swiss ammo.

French official info was 360mm with fusing up to 70°.

https://ufile.io/e1tqv61f

The original French penetration tests from 1960 to April 1961.

of note:

on page 11, penetration dependant on rotation speed

on page 15, penetration probability, I'm not sure why 360mm is the official figure, when the 100% here is at 384mm, while the 50% perforation chance is at 428mm.

 

Switzerland did comparative trials with the 20pdr and the L7 in first in May 1961 and then again on 1st September 1961, but I don't have the results.

 

Switzerland had it's own low rotation HEAT project in the mid 50's with a company in Geneva, Constructions Mechaniques Du Leman. Not sure if it was connected to the Obus G but one of the two avenues pursued had the identical concept, while the second avenue was a slip ring with fins that extended after exciting the muzzle.

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33 minutes ago, Junior FO said:

on page 15, penetration probability, I'm not sure why 360mm is the official figure, when the 100% here is at 384mm, while the 50% perforation chance is at 428mm.

depends on...are they give penetration as a hole in the armor after which some witness plates was perforated, or full penetration path at which jet stopped in steel completely 

+inconsistency in shell batches and test targets properties  for sure

Edited by Wiedzmin
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Interesting videos about a 3BM22 round, full disassembly and also some little experiments. Worth watching. Its in russian, but if that is a problem for somebody, auto translate works surprisingly well. BTW, the round was expired and was going to be disposed of anyway. 

 

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Interesting is also how hard is powder to ignite with weak heat/flame sources like cigarette.

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  • 2 weeks later...
7 hours ago, Harkonnen said:

New MOD RF patent for APFSDS

There you can read: спиральные каналы ствола орудия [spiral channels of gun barrel]

What do you mean with that? With a smoothbore gun? OK, the fact that there is a slight rotation is helpful when removing the sabot. But spiral channels of gun barrel? There is nothing about this in the patent for the 2A82 gun.

The patent references a US patent that was developed for a rifled tank gun.

@edit
Presumably what is meant is that the APFSDS was developed primarily for smoothbore guns, but it also works in rilfled guns.

@@
I think, iIs it an improved version of the 125mm BM60 SVINETS APFSDS with tungsten penetrator. There must have been some problems with the dispersion with the previous SVINETS.  Above all the centering of the sabot in the gun barrel has been changed. There are now only two guide rings left.

Edited by Stefan Kotsch
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22 hours ago, Stefan Kotsch said:

Presumably what is meant is that the APFSDS was developed primarily for smoothbore guns, but it also works in rilfled guns.

Was about to point this out, the patent says so.
 

22 hours ago, Stefan Kotsch said:

I think, iIs it an improved version of the 125mm BM60 SVINETS APFSDS with tungsten penetrator. There must have been some problems with the dispersion with the previous SVINETS.  Above all the centering of the sabot in the gun barrel has been changed. There are now only two guide rings left.

While outwardly it resembles svinets, especially the ballistic tip (and not enough is theorized about that tip BTW), this is a way bigger projectile. I estimate it to 860mm of total length, with a penetrator of 775x25.5mm. The patent deals mostly with the sabot because "previous designs" (Svinets?) we having inadmisible dispersion when fired with higher energies. The new sabot design produced an improvement of 16 percent less dispersion compared to the prototypes.

*edit: this said, I think its fair to refer to this round as an "upscaled Svinets" with a different sabot to compensate for the difference in energies involved.

Both the dimensions of the projectile and the mention of higher energy to me suggest almost unequivocally the Vacuum series of APFSDS. I recall that at last year´s Army Forum, ammunition mock ups for Armata were displayed and among them a main propellant charge that is 25 percent longer than traditional 125mm propellant charges (500mm vs 400mm).

Now what remains to be known is the muzzle velocity of this thing. 2A82 produces significantly higher muzzle energy than past 125mm main guns, question is if that energy is only enough to maintain a velocity compared to rounds like Svinets or if shoots faster. I think that in 2 years from now at most, Vacuum will be displayed at Army Forum just like Svinets was with good mockups and specifications.

Edited by alanch90
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I came up with these dimensions. The scale 1 pixel corresponds to 1 mm. The objects are proportionally aligned to the scale.

I also experimentally transferred to the 152 mm caliber. Although it seems pretty unlikely. But you never know what's happening behind the scenes.

However, I think it is a 125mm model. The photo of the BM60 is a bit distorted. According to Russian sources, the length is officially given as 740 mm.

The design of the traveling charge on the patented APFSDS is unknown and can only be assumed.

neue-apfsdsoqe1q.jpg

Edited by Stefan Kotsch
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5 hours ago, alanch90 said:

Now what remains to be known is the muzzle velocity of this thing

The patent also writes that the old model did not allow increasing the propellant charge.  Because of the insufficient strength of the guide ring / driving band and other problems with this.

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1 hour ago, Stefan Kotsch said:

I came up with these dimensions.

This is mine. One very useful thing on Fig.1 is that the bottom end of the penetrator is clearly marked (4 represents the begining of the cavity for the tracer). To estimate how far the penetrator reaches into the ballistic tip, I used a CAD model from a few years ago, which you published on your website as well. The resemblance between the CAD model and the drawings on the patent is very telling. For the rod width, I made a separate estimation based on Fig.2 which is a top down, clearer cutaway.

Fig.1
image.thumb.png.80343fb38a705af46af47f01b7ce7a58.png
 

Fig.2image.thumb.png.87ab390f4a3765d7627e7ec714c2eca0.png
 

CAD model
PosibleVacuum.thumb.jpg.cfe2c66c57399226d56ba38ba269299b.jpgPosibleVacuumyotros.png.3ab417d0103ce0106016db5b0be6bdba.png

To sum up.

Projectile total length 867.5mm
Penetrator length 775mm
Penetrator width 25.5mm

49 minutes ago, Stefan Kotsch said:

The patent also writes that the old model did not allow increasing the propellant charge.  Because of the insufficient strength of the guide ring / driving band and other problems with this.

This is the bigger charge shown last year (in orange):
Longerpropellant.png.dda44dc1b3fd01b3233c927338bddb1d.pngimagenamedir.png.c1dc292cb81138b6938c1c800653d956.png

 

59 minutes ago, Przezdzieblo said:

Vakuum maybe? 

I´m 99 percent sure its Vacuum.

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4 hours ago, Przezdzieblo said:

Vakuum is said to achieve 15,3 MJ. 775x25,5 mm rod is huge and heavy. Unless composite sabot is used flying mass might be circa 12 kg, so muzzle velocity would be close to 1600 m/s.

Not Vacuum per se but 2A82 is reported to achieve that muzzle energy. Its completly possible that given the likely weight of this rod, the velocity doesn´t exceed what is achieved by Svinets fired from 2A46 (1660 m/s) but I wouldn´t discard at all much higher velocities in the 1750 m/s range either. After all, 2A82 is just a 152mm gun (APFSDS were claimed to be fired from it at velocities higher than 1900 m/s) scaled to 125mm.

Also I guess that the enlarged dimensions of the projectile produce less drag and hence less velocity loss over distance.

All in all, likely impact velocities at combat ranges (assuming muzzle velocity anywhere between the 1650-1750 m/s range) produce a penetration performance well above 800mm of steel.

Edited by alanch90
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  • 2 weeks later...
On 10/20/2023 at 11:33 PM, Junior FO said:

https://ufile.io/fzchf0bn

page 26

The 2000m 120mm@60° L52A2 agrees with the UK document . The 1000m for 120mm@60° for L28 also matches.

page 39

(Probably 1970) UK Ballistic APDS data for 30mm, 105mm, 110mm and 120mm, together with HESH for 105mm/120mm.

The 105mm APDS should be L52A2 as L52A3 was still in trials in December 1970.

 

https://ufile.io/kwnv5h10

105mm L28 against various plates, angles, qualities. The first section with reduced charge is the approx equivalent to a distance of 1600m.

Can you upload documents again, links doesnt work for me

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On 12/10/2023 at 3:09 AM, old_goat said:

New video from "Shawshank Redemption", this time about OF19/26:

 

Was an enhanced fragmentation HE for 125mm ever produced ? OF19 should produce not very good results at least vs. infantry, given it uses a thick steel casing without any scoring or preformed elements, and so should produce a small number of large fragments.

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