As we all know, the United States and the Soviet Union are completely different in the development route of armor-piercing bullets, the Germans insist on strong artillery, with moderate armor-piercing bullets, which have the greatest penetrating effect on the large-inclination armor, while the United States and the Soviet Union emphasize the performance of the shells themselves, taking the United States as an example, the T33 cut-off armor-piercing bullet born in the autumn of 1944 as the best full-caliber armor-piercing bullet known to mankind, can freely penetrate the Panther's first armor at a distance of 1100 yards (3.32in/ 55), while the Soviets used flat-headed bullets (with hoods).
(Left) flathead bullet FAP, (center) interception bullet AP (BC), (right) hood/flathead bullet FAPT
First of all, we must find out what is a flathead bullet, what is a truncated bullet, what is a hood / flathead bullet, in general, the armor-piercing warhead tends to be flattened, or the AP armor-piercing bullet with a sleek convexity, which can be called a "flathead bullet", that is, FAP, and the truncated bullet specifically refers to the warhead is tapered (not sleek protrusion), with a hood or not, can be called a truncated bullet (AP/APBC), a hood/flathead bullet, a copper-containing "small hood" welded on the tip of the flathead bullet, generally called FAPT, These three shells were tested by the US military in turn, and finally won as apBC's T33, while FAP/T33 and FAPT/T33 (the Americans gave the three test bombs the name T33...). The Soviet Union adopted a bold hoodless flathead bullet, and the Germans had almost no such design, which corrected a widely circulated rumor: "the hat armor-piercing bullet is suitable for large inclination", on the contrary, when dealing with large T/D large inclination or mid-inclination armor, the hat-piercing armor-piercing bullet APC is the worst, and only needs > 50 degrees of inclination to make the APC produce a terrible "negative turn positive" (warhead facing the sky), which greatly affects the oblique penetration of the armor-piercing bullet, and the so-called "make the warhead penetrate downwards", That is, the complete positive turn can not be achieved at all, under normal circumstances, full-caliber armor-piercing shells in the treatment of inclined armor, is simply unable to suppress the equivalent protection < trigonometric data, the mad T33 and BR471D can penetrate the panther head at a distance of more than 1000 meters, T33 is a truncated bullet, the confrontation with the tilt armor is naturally excellent, and the BR471D is stained with large-caliber light, these two shells can only suppress the equivalent value on the panther's head to about 6in, regardless of wind speed, In a better case, it can even be pressed to 150mm (almost impossible in reality), while the "horizontal thickness" obtained by The Panther based on the trigonometric data is 130-140mm, which is far lower than the actual equivalent, especially for the medium-caliber hood being impersonated by armor-piercing bullets, which will be as high as 190mm.
APBC-T33
Here is another question, how to calculate the equivalent protection? To calculate the equivalent, you must be able to calculate the T/D value, I will give a simple example.
According to the above table, I take the head of the panther (there is an 85/55 panther, I pick a good calculation here) as an example (80/55), first of all, we want to use the vertical thickness of the tank armor / gun caliber, I will use the data of the 90mm gun T33, 80/90≈0.89, and then according to this table, find the interval of 0.89 (those who have learned the function should know), that is, 0.5-1, 0.89 is about 1.9, and then use the tank armor thickness × 1.9, that is, 80 × 1.9=152, the equivalent is out! Although it may not be very accurate, but it is almost 150-160 or so, the impact is not large, if it is the 85mm APBC launched by the T-34/85 tank, facing the Panther head, it has a horror equivalent of about 176mm, while the 85 gun is only 139mm, that is, it cannot be penetrated at all, which shows how good the Yankee's black technology shells are! If you want to calculate a more accurate equivalent protection, you need to use the penetration curve, which is very troublesome, and will be talked about later...
Soviet 45mm flathead bullet
In 1944, the Americans did a special study of 90mm FAP, APBC and FATT in Aberdeen, and finally came to a convincing conclusion: in the fight against small T/D armor, flathead bullets have absolute advantages, at the same time, in the face of super inclination > 65 degrees, the flathead bullet performance is better than APBC and APFT, however, when the T/D value rises, FAP will "pull the crotch", facing any angle of armor above 0.75 values, FAP is embarrassed to shoulder the heavy responsibility, in the middle T/D value, FAP effect is the worst, and FATT has a multi-angle advantage, although the advantage is not large, when T / D is raised to the critical point of 1, FAPT also began to appear oblique wear deficiency problem, FAP at this time and the hat armor-piercing bullet is almost the same (all rotten), at this time, APBC has a better effect, in the face of large T / D value vertical armor, APBC effect is the best, but not as good as AP, in the face of large T / D value, large inclination, APBC and FATpt is very bad.
Description of the American
In this regard, the Americans immediately kicked the FAP out of the test, because the main purpose of developing the T33 was to attack the first armor of the Panther tank, but when attacking the large inclination, APBC had good fragmentation, and did not need a strong impact force to smash the copper hood, so, based on many considerations, the Americans chose APBC to design the T33 for the blueprint. The Soviet BR-412B 100mm FAPT is quite different from the T33, in the face of such bullets, the Panther has only a 150mm equivalent on the head, the T33 initial speed is 3000fps, while the BR-412B is 895mps, and the BR-412B fired from the 100mm BS3 gun has a larger muzzle kinetic energy than the T33, and the T/D value is more dominant.
Su standard PSP+V80
It is not difficult to see from this table that in the face of vertical or small inclination armor, the T33 has a crushing advantage, after all, the warhead is tapered.
In the face of large inclination, T33 and BR-412B are almost equally divided, each has its own advantages, on the whole, in the face of an inclination of more than 55 degrees, T33 and BR-412B are comparable, and in the face of 0-30 degrees of inclination, T33 is completely better than BR-412B. 0-10 degrees: T33 is dominant at full distance. 10-20 degrees: 0-500 meters equal, > 500 meters T33 is dominant. 20-30 degrees: 0-1500 meters equal, > 1500 meters T33 is dominant. 30-40 degrees: 0-1000 meters equal, > 1000 meters T33 is dominant. 45-50 degrees: BR-412B has a slight advantage over full range. 50-55 degrees: T33 has a slight advantage over full distance. 55-60 degrees: BR-412B is dominant at full range. > 60 degrees: T33 is dominant at full range. After the end of World War II, the Soviets gave up the flat-headed bullet, chose to continue to develop the hood and hat armor-piercing bullet, although this behavior buried the flat-headed bullet excellent oblique wear, but the Soviets had to rely on the large caliber, this disadvantage was pressed back, but the Choice of the Soviets was also the upper book, throughout the Entire World War II, the Soviet Armor-piercing elasticity, to the Zis-5 gun BR-350A and BR-350B as an example, the Soviets' small-caliber bullets are almost known for rot, and the 85mm BR-356 performance is mediocre, The BR-412B and BR-471D of the 100 and 122 guns were extremely highly effective, which demonstrated the limitations of Soviet artillery shells, and when faced with large T/D shells, the penetration depth also plummeted. The Americans continued to develop the interceptile, the most famous and the best of which was the M358 120mmAPBC, which became one of the main ammunition of the M103 heavy tank.
Common bullet types (left to right): armor-piercing bullets, hat-piercing bullets, hood-hat armor-piercing bullets, hood-piercing bullets
As for the main German armor-piercing bullets, my evaluation is: moderate but not bad, all the German full-caliber armor-piercing bullets are called Pzgr.39, taking the main threat of the Pershing tank Kwk42 as an example, Pzgr.39/42 Although the hanging is better than the T33, the oblique wear is unbearable, the T33 can easily penetrate the Panther's head at a distance of 1100 yards, while the Panther can only penetrate itself at 150 meters.