That document uses 250-300 BHN armor. The pen curve shows little or no deformation of the round. If the round deformed, the curve would flatten out as the velocity decreased.
T33 APBC
97mm at 55 degrees
T/D ratio = 1.078 (97/90)
1.078 T/D at 55 degrees
That’s 2.185 slope modifier
97 x 2.185 = 212mm
My 2 Pounder AP as reference rates it 215mm
Your calculator would rate the T33 only around 202-204 or so
No, it’s actually 210.
In that case there’s only 2% difference between our figures
That’s reasonable. No one size fits all calculator will work with every round ever fired.
You guys have strayed OFF TOPIC!
My bad, just trying to point out that the data he posted is no good. I don’t see the 105mm clapping T54s.
Type 5 105mm
16kg shell (0.2kg HE filler)
So 105mm AP , 15.8kg penetrator at 1000m/s
I get 303mm which means for you it’s 297mm with 2% less.
To defeat 100mm at 60 degrees
100 / 105 = 0.95 T/D ratio
0.95 T/D at 60 degrees = 2.67 slope modifier
That means you need 267mm vertical pen to clap T-55’s 100mm thick upper plate at 60 degrees
And Ho-Ri production 105mm AP has 297-303mm of vertical penetration (if it didn’t deform)
So if gaijin fixed Ho-Ri Production
The gun would be clapping T-54,T-55,T-62 and IS-3 tanks
You’re comparing solid AP to APHE.
200g inside a 16kg shell is nothing
Anyways AP, APHE. The slope modifier applies either way
It’s not just the weight of the filler, it’s the structure of the shell. German data puts the Soviet 85mm APHE at around 130mm of pen. That would put the Japanese Type 2 at around 215mm. I haven’t seen any data on the Type 2. Was it was well made round? How was the steel quality? Is there any penetration data?
Bro you can literally use the AP slope modifier for M82 APCBC known for its crazy HE filler quantity and you’ll get matching results to the actual official penetration data.
According to this the M77 AP at 822m/s penetrates 191mm.
According to this T33 APBC which is literally M77 AP at 853m/s penetrates 165mm. The T33 APBC was reheated treated M77 AP which ruined the quality of the penetrator so it deformed more and gets ballistic cap.
But it’s sloped pen on T33 APBC is still on par with M77 AP at equal velocities.
Russian AP rounds had blunt noses which made them even worse against thick flat armour. So the tip was already non ideal and due to lack of piercing cap you get deformation on top.
76.2mm M62 APCBC has pretty damn high HE filler relative to its shell size. It’s also an APCBC round but let’s see what happens if we apply AP slope modifier.
127mm (5.0in) @ 0m at 0 degrees
50mm (1.95in) @ 0m at 60 degrees
50mm / 76.2mm = 0.656 T/D ratio
0.656 T/D at 60 degrees = 2.54 slope modifier
50 x 2.54 = 127mm
Also, if I’m not mistaken, Gaijin made up this meaning due to lack of data. At least, I have never seen data on the projectile filler anywhere. If we extrapolate the line of previous projectiles, then both the percent of explosive filling and the type of explosive itself are unusual. Extrapolating the later 75 mm shells to the 105 mm caliber, we get something like 150 grams of a mixture of TNT and hexogen, with a TNT equivalent of 192 grams.
Typical of late Japanese armor-piercing projectiles is the use of tungsten-chromium steel with a fairly high percentage of both alloying metals. In addition, despite the fact that the projectiles are formally sharp-headed, de facto the projectile received a significant increase in the hardness of the front part, as if forming an “armor-piercing cap” from the body of the ammunition itself, this is a fairly well-known and widely used (at least in the navy) technology. This, in fact, explains the absence of armor-piercing caps on shells, despite the obvious presence and mastery of the technology as such by industry.
We only have approximate data. It is known that an early cannon shell (916 m/s) was able to successfully penetrate a 150 mm high grade slab at 1 km, another source “現有対戦車兵器資材効力概見表” talks about 175 mm thick plate at a distance of 1 km during testing. It should be taken into account that Japanese armor penetration standards are considered somewhat more stringent than American ones. During tests Japanese use the armor of different classes, but for critical tests they use heterogeneous armor, simulating the potential best enemy armor. Empirically, the ratio of Japanese high-grade tank armor steel to ordinary American steel is something like 1.2. And, 150 * 1.2 = 180 mm, so I suspect that 150 mm refers to a high-quality heterogeneous plate, and 175 mm refers to a plate simulating the armor of American tanks.
For the new weapon with increased energy, an initial speed of 1005 m/s was expected (versus 916 m/s for the basic version), and management hoped that at this distance it would overcome 200 mm armor plate of the top class slabs at 1 km, which by calculation is equivalent to about 233-240 mm of average American tank armor steel. Sometimes there is information about a ballistic(?) cap are going to install, however there is no comprehensive information about why the cap was needed, but ballistic cap may was required due to the fact that, despite the formal sharpness of the head, they do not have a very high coefficient of ogive for achieve optimal slope effects.
In addition to the armor penetration of the projectile, we are missing the presence of a semi-automatic loader on the vehicle. The rate of fire of the anti-aircraft gun from which the semi-automatic loader was taken is about 20 rounds per minute, while the projectile of the original anti-aircraft gun is 1.5 times heavier.
Spoiler
To understand the effect of its operation: after a shot, using the recoil energy, the gun will independently eject the cartridge case, load the projectile from the tray and again fold the tray back to its original position, without human intervention. Before the tray returns to its original position, a shot is not possible. All the man has to do is place the new projectile in the tray.
This not very cheap system was integrated due to the fact that the weight of the projectile with charge could cause inconvenience to the loader, while the rate of fire was considered a very important parameter. It was expected that for one Ho-Ri there would be at least 5 units of enemy armored vehicles on the front, that in this regard it is conceptually somewhat similar to late German armored vehicles.
Due to the urgency of the work, the semi-automatic loader was not invented “from scratch”, but was taken and adapted from the 120 mm Type 3 anti-aircraft gun
1 Like
200mm @ 1000m is for the 105mm AP round when fired at 1000m/s
105mm AP
Ballistic Factor = 2800
1000m/s at 0m
822m/s at 1000m
Do you know what’s funny?
You know how the Japanese 75mm Tokku Ko AP has
118mm @ 0 yards
100mm @ 500 yards
Penetration when fired from Type 3 75mm
Or how it has 161mm @ point blank range when shot from Type 5 75mm after deforming as I’ve been ranting this entire time?
When I use the Japanese Tokku Kou AP quality as reference, I get 200mm @ 1000m (822m/s) penetration for the 105mm AP
Conclusion
Type 5 105mm
Type 2 APHE
1000m/s at 0m
822m/s at 1000m
Penetration:
264mm @ 0m (0) [302mm if it didn’t deform]
111mm @ 0m (60)
200mm @ 1000m (0) [228mm if it didn’t deform]
87mm @ 1000m (60)
105mm Experimental - 916m/s
Type 2 APHE
Ballistic Factor = 2800
Velocity at 0m = 916m/s
Velocity at 1000m = 753m/s
233mm @ 0m - 916m/s
176mm @ 1000m - 753m/s
As you may know the Japanese have the
Poor quality AP shells such as Type 1 APHE for 75mm and the high quality AP shell such as the Tokku Kou AP
Using the low quality AP 75mm as reference I got 150mm @ 1000m
Using the high quality AP 75mm as reference I get
175mm @ 1000m
When the high quality 105mm AP shell is shot at 1005m/s we get 200mm @ 1000m
I guess the question is do you want the high quality, high pen but at a much higher BR, or the low quality, low pen at the same or lower BR?
Lol the Ho-Ri’s are not even worth their BR.
The current Ho-Ri prototype is literally worse than jagdpanther in every way and yet it’s 0.7BR higher etc
If you give this thing 300mm of pen, it’s going up in BR guaranteed.