Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
That's right. The KaJaPa mainly fired HEAT and HESH, MV not mattering much.I would be very careful about that.
The gun certainly used US ammo but using old barrels seems a little much. Re-manufactured perhaps?
The US guns were good for 700 EFC rounds (Effective Full Charge) so depending on training might have had a fair amount of wear. Not sure if a different recoil system was used.
Rheinmetall also developed new ammo for the gun. Two different HEAT rounds and a HESH round. Apparently kinetic energy rounds were not used (or quickly replaced) in the Kanonenjagdpanzer as the primary AT rounds meaning a shorter barrel could be used. The HEAT projectiles being 5.74kg and the HESH projectile 7.45kg. The WW II 90mm AP projectile weighed 10,9kg.
Do you have the actual test results for these numbers or did you derive them from some sort of engineering formula? Real tests don't seem to agree. For example the US Aberdeen data Pak40 Pgr.39 ~635m/s @ 1500yds penetration=109mm.Armour in this period for tanks was homogenious rolled or cast armour. In some cases, units may according to these trials the british reports attributed the 75mm APCBC at 610m/s and normal impact with a penetration of
at 610m/s:
75mm Pgr.39 --- 115mm penetration
3" M79 AP --- 102mm penetration
SU 76mm APC:-- 85mm penetration
-----
Do you have the actual test results for these numbers or did you derive them from some sort of engineering formula? Real tests don't seem to agree. For example the US Aberdeen data Pak40 Pgr.39 ~635m/s @ 1500yds penetration=109mm.
Unfortunately, this conception has turned out as incomplete. While much testing was indeed done in this region, different BHN values were trialed, too (corresponding to 215BHN min and 265BHN max). I have almost all data for the M72 AP from Dr. Allan Hershey´s records at the USNPG and can identify the plate properties from these trials.US tests were done vs. 230-250 BHN armor.
The effect of tensile strength (correlated with BHN hardness as long as ductile under impact) is most significant for normal impact (0 deg in british, 90 deg in german definition) but reduces with obliquity. As an example, trials conducted 1942 with 2cm model shots (Ss and SK) on 50kg/mm^2, 100kg/mm^2 and 150kg/mm^2 plates respectively showed that at 90 deg impact tripling the tensile strength resulted in a quadruple of resistence compard to soft plates while at 60 deg obliquity the difference between 50kg/mm^2 and a 150Kg/mm^2 plate was just 6%-almost identical.
I have quite a bit. I use it to test my ballistics program.What is needed is a ballistic datafile for the various 75mm gun´s firing this projectile with the drop of velocity plotted against range.
British tests against homogeneous armor at 610 m/s impact velocity, which are documented in Miles Krogfus' AFV News article, resulted in:
102mm penetration for German 75mm APCBC
90mm penetration for U.S. 76mm M62 APCBC
75mm penetration for Russian 76mm APBC
I only have a document on the M79 giving two points of NBL penetration. The velocity of 4' and 3' penetration. I would like a document on the M79 with more data points. Maybe we can do some document horse trading?I have almost all data for the M72 AP from Dr. Allan Hershey´s records at the USNPG and can identify the plate properties from these trials.
That must be a different report on the same subject, BHN vs. Penetration, that I have:
Watertown Arsenal Laboratory
Report Number 710/607
Problem Number J-1.2
Principles of Armor Protection
Partial Report, no 1
14 April 1944
For the German 75mm/L48:
RANGE..75L48
0m......750
100m....738
500m....691
800m....659
1000m...637
1500m...585
Weight..6.8
I start out with something like this:
BHN adjustments
My Baseline BHN=270 (1.0)
German=275 (1.0182)
British=263.5 (0.9866)
US=240(230-250) (0.941)
That's why I didn't include Russians or cast armor. Russian hardened RHA acts well vs. undermatched projectiles. For overmatched not so much: 350 BHN acts like 260 BHN. From yugo tests cast hardened rounded 444 BHN T-34 turret acts like 260 BHN. But then from the same test 230 BHN cast rounded M4A3 turret also acts like 260 BHN.Ok, I understand. However, I have some issues here.
[3] using 270BHN as a guideline, some of the russian turret armour would be roughly 60% more resistent (at normal impact) than those mentioned above but this isn´t supported by sources.