German discarding sabot rounds

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critical mass
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Re: German discarding sabot rounds

Post by critical mass » 22 Oct 2017 08:27

Zünder wrote:@Critical mass: you are referring to the 10,5 cm/4,5 cm UKP/Peenemünde Pfeilgeschoss for 10,5 cm Flak 39 ?
I am not sure that was a AP round, i examined a complete specimen and own remains of another one and there was no indication that they were AP.
The tip unscrewed and was not hardened, the projectile itself filled with tar.
I know this shell was fired from a 10,5 cm Flak 39 smooth bore, but i recently acquired 1 of the ringsegments for this shelltype and it clearly was shot through a rifled barrel.

@Yoozername: i think the idea behind the sub HE-round was the longer range, the same reason why so many sub-cal were developed for the Flak guns.

Zünder,

http://www.wk2ammo.com
See attchment. Is it this one?

I am sure this was only a test projectile to obtain information about satisfying terminal ballistic attributes of fin and centre of gravity, there were multiple reports about slightly different deflection of the fin conducted for this item.

Production:
I found a productionsheet for the 10,5 cm Spgr. 42 Ts: 4500 produced in December 1943 and no other shells in stock.
Similar numbers for the 15 cm Spgr. 42 Ts, with 5100 produced in January 1944 of which only 4000 were eventually accepted, no other shells in stock.
Thanks for it. It independently confirms that monthly production for 15cm Psgr42 TS was scheduled to 20.000 specimen per month from mid1944. The sheet is dated early 1944, it would be very interesting to get another dating to early 1945 in order to get an overview about actual production (as opposed to intended production).
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critical mass
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Re: German discarding sabot rounds

Post by critical mass » 22 Oct 2017 08:30

stg 44 wrote:Awesome!!! Thank you so much for all of these. Where did you get them?
The engeneering drawings seem to be carefully made and translated copies of original german blueprints contained in BAMA RH8-1326, the photos are new, we are dealing with one of the post war technical reports on german items No.361, obtainable via NARA.

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Re: German discarding sabot rounds

Post by Radar » 22 Oct 2017 09:36

The drawings and pictures are from a Technical Intelligence report.
The ammunition was found on a German proving Ground. See report. Not from BAMA.
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critical mass
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Re: German discarding sabot rounds

Post by critical mass » 22 Oct 2017 10:55

Radar,

Some of the notes in BAMA RH8-1326 are short transcripts and translations, typically made by hand- into english, which tells me that the german material was also captured postwar and used to extract information for another report to be written in english. I had always been guessing that the technical report No.361 is involved but hadn´t had opportunity to fetch my own copy from NARA yet. However, the drawings seem to confirm ths presumption.
Can You elaborate the archival signature of the report for full reference?

thanks in advance

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Re: German discarding sabot rounds

Post by Ulater » 22 Oct 2017 12:33

This ammunition is quite obscure on the internet, and I keep seeing claims that tests of this DS ammo yielded dissapointing results. Are there any penetration charts?
awful 'Archive Awareness' website
Ah yes, the owner of that blog engages in quite a bit of "creative" writing in every other post.

Quite sad that it is widely being taken at face value.

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Re: German discarding sabot rounds

Post by critical mass » 22 Oct 2017 18:05

Are there any penetration charts
All discarding sabot rounds for le.Fh., s.Fh. and PAK44 are based upon the standart mass produced 75mm Pzgr39 and 88mm Pzgr39 series AP ammunition and converted with discarding sabots to fit 105mm, 128mm or 150mm barrels to be discharged at an elevated velocity. There are plenty of penetration curves available on this side for these AP bullets, which show You the relationship at which velocity what penetration can be expected. For this reason I refer to those posted previously in the various threads here (see attchment). From my perspective, there is absolutely no conspiracy or mystery about these shells AP-performances and no surprises were encountered in the Hillersleben prooving ground trials in this regard.

10.5cm le.FH.18: The elevated velocity virtually transferred the 10.5cm l.Fh.18 firing 10.5cm Pzgr39TS performancewise into a PAK40, firing a 7.5cm Pzgr 39 in it´s sabot at a muzzle velocity of 765m/s. 30° penetration at 100m: 99mm RHA; 500m: 88mm RHA; 1000m: 76mm RHA.

15cm s.FH.18: The elevated velocity virtually transferred the 15cm s.Fh.18 firing 15cm Pzgr39TS performancewise into an high performance anti tank gun, right in the middle between the 88mm KWK36 & 88mm PAK43 but with somehow worse accuracy, firing a 8.8cm Pzgr 39 in it´s sabot at a muzzle velocity of 880m/s.
30° penetration at 100m: 155mm RHA; 500m: 140mm RHA; 1000m: 126mm RHA

12.8cm PAK44/KWK44: The elevated velocity finally significantly enhanced the 12.8cm PAK44/Kwk44 firing 12.8cm Pzgr39TS, firing a 8.8cm Pzgr 39 in it´s sabot at a muzzle velocity of 1230m/s. Initially, problems were encountered with the 8.8cm Pzgr39 used here and the very high striking velocities against plates thicker than 200mm (some of the projectiles broke up). This occurance of unexpected projectile break up in this specific case is probably the source of all accounts claiming that little improvement was to be gained by these shells.

In fact, the increases of low range break up events at extreme velocity (the 88mm pzgr39 ammo stocks used in the 1st trials were falling into some kind of shatter gap here) indeed caused something of a discussion in WaPrüf whether or not the penetration does increase ever on linearely with velocity or plateaued off at very high velocities due to break up. A second series of trials in Hillersleben in autumn 1944 showed that the problem was the worse quality 88mm Pzgr39 ammunition used in the first set of projectiles, which did not gave the best performance obtainable (8.8cm Pzgr39 from the Bochumer Verein in the 2nd trials stayed intact at up to 1250m/s and started to break up at >1300m/s when fired in sabots). Notice that these extreme velocities were, of course, far beyond any proof specifications for these projectiles and entered a new terretory. Projectiles to be fired for these velocities would have required updated proof specifications in order to guarantee intact penetration. These improved -DS projectiles also seem to have been fitted with a somehow thicker and blunter type of cap with the fwd sabot rings attached to the cap- unlikethe lower velocity 15cm/8.8cm Pzgr39TS, which used & converted the complete 8.8cmPzgr39 with it´s thinner, and sombrero-shaped cap. I would suppose that the thicker cap (compare attachments: NOTICE, I edited the graph to show the line between cap and projectile body, which is not shown for security reasons in it) does help a great deal in negotiating more severe conditions of impact (e.g. elevated velocity) for mass produced shells. The same result could probably be obtained with more careful heat treatment and thinner caps -as evidenced by the shells made by Bochumer Verein- but these results would be less reliable in mass production than for thicker capped AP.
30° penetration at 1000m: 264mm RHA*; 2000m: 230mm RHA*
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Re: German discarding sabot rounds

Post by Ulater » 22 Oct 2017 18:33

12.8cm PAK44/KWK44: The elevated velocity finally significantly enhanced the 12.8cm PAK44/Kwk44 firing 12.8cm Pzgr39TS, firing a 8.8cm Pzgr 39 in it´s sabot at a muzzle velocity of 1230m/s. Initially, problems were encountered with the 8.8cm Pzgr39 used here and the very high striking velocities against plates thicker than 200mm (some of the projectiles broke up). This occurance of unexpected projectile break up in this specific case is probably the source of all accounts claiming that little improvement was to be gained by these shells.

Hmm, I just wanted to ask whether the 12.8 cm TS shell had indeed just a plain PzGr.39 core, because the muzzle velocity seemed too high to tolerate for a steel projectile.

Edit: And I was not indicating any conspiracy, just wondering. Are there any more data on the penetration of 128 mm TS projectile ? 100, 500 and other ranges?

Would (and could) this projectile be eventually used, with Jagdtiger or Maus?

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Re: German discarding sabot rounds

Post by critical mass » 22 Oct 2017 19:57

The AP projectile body of the 12.8cm Pzgr.Ts. was indeed a plaín vanilla 8.8cm Pzgr39, sans cap, windscreen and driving bands cut.
Unlike the Pzgr39, it had a different cap (similar to 12.8cm and 10.5cm Pzgr.43 series and the 7.5cm Pzgr39). The thicker cap takes away some mm penetration compared to the 8.8cmPzgr39 but offers better high velocity impact attributes (remember, it was mandatory for the projectile to stay intact in german AP specifications). Problems encountered in frequent projectile break up during the first set of trials against plates thicker than 200mm RHA @ 30° have been already mentioned. Initially, WaPrüf, mentioned that the limit for 8.8cm Pzgr39 used there was at 200mm, and higher, theoretical penetration figures were without practical relevance (compare asterics in attachment below). During the 2nd trial at Hillersleben with better quality ammunition, and acc. to the account of Dr. Wagenknecht by Bochumer Verein, his 8.8cm Pzgr39 fired in sabot penetrated a high quality homogenious armor plate 305mm thick at a velocity of 1280m/s under 30° obliquity without suffering projectile break up (he claimed these 8.8cmPzgr39 to have been taken from ordinary mass production stock and converted).

There are no data for 100m or 500m but for 3000m and 4000m:
3000m: 176mm RHA @ 30°
4000m: 140mm RHA @ 30°

This projectile was intended for vehicles armed with 12.8cm L/55 KWK44 according to the sources and was always directly compared with the 12.8cm Pzgr 43 fired by 12.8cm L/55 KWK44. While no specifications are made explicitely mentioning JAGDTIGER or MAUS in the tabulations I have seen, it stands to reason that these two vehicles were the only vehicles armed with this 12.8cm L/55 gun and they were also the only ones to fire the 12.8cm Pzgr43 by the 12.8cm L/55.

A related, but in details different 12.8cm Pzgr.Ts.Mbs. to be fired by 12.8cm PAK80 and 12.8cm K81 is also mentioned as "under development" by 1944 (as opposed to "fertig entwickelt / development completed" for the aforementioned -Ts). Due to manufacturing, the 12.8cm Pzgr.Ts. was also to receive further simplification development in sabot design in order to simplify conversion.
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Re: German discarding sabot rounds

Post by Ulater » 24 Oct 2017 12:47

What was the difference between the developed and "developing" projectile?

I see that one that was developed had a steel sabot, If I am reading it right. What is the other one? Translator is not very helpful in this case.

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Re: German discarding sabot rounds

Post by Zünder » 24 Oct 2017 13:13

The second one (in development) had a simplified 3 part supportring and a 1 piece sabot with pressurechamber.

Here are 2 Ts shells from the MTM museum collection in Landhorst (Netherlands)
As you can see, there's a difference in the support ring, 1 flange/ 2 flanges.

The pressurechamber sabot design can be seen in the 8,8/7,5 cm Spgr. TS L4.1. drawing Radar posted earlier.

Zünder,


http://www.wk2ammo.com
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Re: German discarding sabot rounds

Post by critical mass » 24 Oct 2017 13:16

Zünder just beat me to it. It´s a production detail, concerning the simplification of the sabot rings ad the lower sabot ring, whether or not it should be made as a single piece or three-piece assembly. The single piece base sabot ring would have been preferred from the point of view of mass production while the three-piece version had already successfully passed all development and stood ready for service if a decision for mass production was to be made. The single piece base sabot ring would still await some of the flight tests, dispersion tests and pass of the mass firing test. There is no difference in armor piercing performance between both.
Notice that prior to the advent of the IS-4/-6 /-7 there was no urgent need for such a powerful penetrator, so optimization of manufacturing details was believed to be worthwhile.

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Re: German discarding sabot rounds

Post by Zünder » 24 Oct 2017 13:21

critical mass wrote:Zünder just beat me to it. It´s a production detail, concerning the simplification of the sabot rings ad the lower sabot ring, whether or not it should be made as a single piece or three-piece assembly. The single piece base sabot ring would have been preferred from the point of view of mass production while the three-piece version had already successfully passed all development and stood ready for service if a decision for mass production was to be made. The single piece base sabot ring would still await some of the flight tests, dispersion tests and pass of the mass firing test. There is no difference in armor piercing performance between both.
Notice that prior to the advent of the IS-4/-6 /-7 there was no urgent need for such a powerful penetrator, so optimization of manufacturing details was believed to be worthwhile.
I vaguely remember there was also an issue with damage to muzzle brakes after the 3 piece rings broke up.
Can you confirm ?

The page you showed, found in Freiburg ? If so, do you have a filenumber ?

Zünder,

www.wk2ammo.com

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Re: German discarding sabot rounds

Post by critical mass » 24 Oct 2017 21:04

I am not entirely sure which of the posted images is meant but I have recently posted pages using two sources, BAMA RH8-1326 and BAMA RH1319, both from Freiburg.

According to BAMA RH8-1326, the fouling of the muzzle break by premature loosing of a three piece sabot ring was reported to WaPrüf during operational field trials on the eastern front during the period 20th of oct. to 1st of nov. 1944 with 10,000 15cm Spgr. 42 Ts. Ausf. I to be fired by 15cm sFh18.
This caused the development of the muzzle break proof Ausf. II with changes in the sabotring and flange. 800 such 15cm Spgr 42 Ts. Ausf. II were expanded without muzzle break fouling on the prooving ground and 10,000 further 15cm Psgr 42 Ts. were cleared for another field trial for february 1945. Delivery of 50,000 further specimen was almost finnished by then but these were hold back from service until the operational field trials cleared them. A drawing of these longer range HE projectiles (range is reported with 18100-18300m when fired by sFh18) is attached to this memo.
I suppose that You are having these issues with 15cm Spgr 42 Ts. in mind because they are related technically.

No such difficulties are mentioned in context with the 12.8cm Pzgr Ts. -which was only to be fired by KWK44, which on MAUS and JAGDTIGER were esspecially specified to be planned without muzzle break in order to be able to fire discarding sabot projectiles in the future (unlike 12.8cm PAK44 which always (?) were fitted with muzzlebreak). However, the mode of changes to the flange and sabotring suggest at least that all experienes with the 15cm Spgr 42 Ts. were taken into account (a muzzle break proof variant for K44 and Pak 80/81 field guns/ anti tank guns was planned). But the reason for the change of the sabot ring and flange itselfe on the 12.8cm Pzgr Ts. was always given as related to simplification of manufacture / conversion.
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Re: German discarding sabot rounds

Post by Ulater » 26 Oct 2017 07:22

Is there also any info on the second test?

Because, well, this one was ... a failure?

Were the mroe durable projectiles capable of meeting the calculated penetration?

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Re: German discarding sabot rounds

Post by critical mass » 26 Oct 2017 10:26

By what standart would You describe them as failure?
I am not convinced that this interpretation can be extracted from the primary sources dealt with here.
Information on the 2nd Hillersleben trials have been referred to already previously. Unfortunately, I have only the results of the trials based upon the account of one of the participants (Dr. Wagenknecht by Bochumer Verein, whose lot of 88mmPzgr39 were used to fire the 88mm set of trials), but not all the details nor the complete report. Relevant is that their 88mm Pzgr39 did not break up striking at 1280m/s when engaging a 12" thick RHA plate @30° while some of the 88mmPzgr39 in the original trials did when striking plates thicker than 200mm @30°

note: keep in mind that the standart of penetration in all official rated penetration figures such as those reproduced above was a "worst case standart" in Germany. For a penetration to be counted successfully therein, five out of five projectiles had to completely perforate -without damage- the test plate in a narrow velocity band, so even a single projectile breaking up, will render the penetration attempt negative, even if all five projectiles completely penetrate the plate.

Break up at such extreme velocities has to be expected with steel AP, and no other service would care about the criterium whether or not the projectile stays intact, not the soviets, nor the british nor the US.
The optimum of penetration performance -at least for good quality 8.8cm Pzgr39- was determined to lie in between 1250m/s and 1300m/s, an this velocity was therefore also choosen to limit the validity of the Gercke penetration formula and is in good agreement with the 12.8cm Pzgr Ts fired by 12.8cm L/55 at 1230m/s initial velocity. Higher velocities (tested up to 1800m/s in this trial) would always cause complete break up and have lower actual penetration.
There was a variance in the quality of 88mm (and for that matter 75mm as well) projectiles from mass production. The variance is correlated with the critical velocity at which break up sets in. This is why WaPrüf would need to change specifications for the 12.8cm/8.8cm Pzgr Ts. in order to ensure that only high quality Pzgr39 ammunition -with a higher critical velocity where break up sets in- is to be converted into -Ts ammunition. This can be done by specifying a higher velocity for penetration test with a correspondingly thicker plate and/or higher obliquity.
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