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Autor Thema: Admiral Scheer vs. Admiral Hipper  (Gelesen 12573 mal)

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Offline delcyros

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Re: Admiral Scheer vs. Admiral Hipper
« Antwort #30 am: 07 Juni 2016, 15:52:07 »
Dear Neil,

LÜTZOW´s armour was mostly not made of Wh grade materials. It was made of high percent nickel-steel, such as used in ww1 for turret tops where full homogenious armour protection was desirable.

Altough research in the improvement of homogenious armour was well under way the time DEUTSCHLAND was ordered, not enough practical results existed to base and formulate new specifications for the manufacture and ballistic acceptance of homogenious armour.

This ww1 based material (also KC/a.A. for barbettes, turret front and Ct side plates) had lower ballistic properties compared to the new Wh./n.A. introduced shortly after LÜTZOW was launched and specified as armour for both SCHEER and GRAF SPEE.

GKdos100 does omit these differences but when You pay attention, these differences re-appear in the tabulations, as You have noticed.

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the quality of projectiles of the L/3.7 Psgr. and L/4.4 Psgr. family of AP was very different. The former was an evolution of ww1 period APCBC-projectiles with 1.5crh headshape (38cm L/3.5 Psgr.> 35cm L/3.6 Psgr > 15cm L/3.7 Psgr), but changed in the 28cm L/3.7 Psgr. the shape of the cap (both AP-cap and balltistic cap) in the late 20´s when production of AP-projectiles recommenced for the PBB´s.
The old, ww1 style 28cm projectiles with 2crh nose shape and hollow AP-cap (Firth-type) were discontinued because tests in 1916 demonstrated that these projectiles with this cap type frequently suffer nose-only shatter striking improved, post 1906 KC/a.A. (28cm and 30cm L/3.2 and -L/3.4 Psgr. vs 28cm and 30cm KC/a.A. plate). This resulted in an elevated perforation velocity, even though the projectile- thanks to it´s sheath hardedning- stayed intact in a condition fit to burst -over wide ranges of obliquity (a very low raise in penetration velocity over obliquity).

Altough superior 2crh AP-projectiles (indestructible) could be made with fuller cap over the nose (and indeed were made by Krupp as early as 1900 as our 1902 Meppen trials demonstrate), they required a very small cavity and low HE effect, and had inferior characteristics if striking obliquily.

Krupp then reduced the nose radius shape from 2.0 crh down to 1.5crh and also reduced slightly the capacity for the HE-cavity, and added a cap with more metal in front of the nose for the newest 38cm, 35cm and 15cm AP during ww1.
This removed the problem of nose-only breakage, giving the shells a drastic improvement in low to mid obliquity perforation because the shells stayed intact more regularely striking KC/a.A. It´s possible that the high obliquity perforation capability was slightly inferior to the older ones.

The introduction of deeply chilled KC/n.A. shortly afterwards greatly added to the KC plates ability to damage these 15cm and 28cm L/3.7 AP projectiles. Again, damage would usually not render the projectiles ineffective but nose only breakage increased the velocity required for successful penetration.
In response, the same parameters were applied: The cap over the nose was thickened and deeper hardened, the projectile nose was further blunted to 1.3crh and the HE capacity was further reduced in addition to minor improvements in the hardening and tempering contours, resulting in a projectile which would be even better against this type of deep chill armour at normal impact (virtually no damage) and generally better against all types of KC at mid and high obliquity than those of the previous 2.0 crh or 1.5crh AP bullets.

Comparing 20.3cm L/4.4 with 28.3cm L/3.7 Psgr. is therefore beset with a series of issues biasing against the older projectile.


hope this helped,
delc

 

Offline Neil Robertson

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Re: Admiral Scheer vs. Admiral Hipper
« Antwort #31 am: 07 Juni 2016, 20:49:29 »
Thanks for this outline of the contest between German shells and armor.

The Hkdos 100 document for Lutzow shows Wh deck armor of 30 and 45 mm thick. According to secondary sources this is correct for thickness but wrong for armor type (it should have been the older WW1 material as you say). Even official documents can have errors.

Neil