mOBIUS
Member
I'm trying to make a spreadsheet of that chart but I can't make out many of the numbers.
CMFB patch released
- Thread starter Elvis
- Start date
mOBIUS
Member
It's curious that this subject has come up simultaneously on different tank forums. Is it the same people doing this?
http://forum.warthunder.com/index.php?/topic/145281-jagdpanzerpanzer
NUTTERNAME
Member
Apparently, they mean the actual deviation from flight axis. It might come from the overspinning of the early M1A1C barrels. The rifling was changed in the M1A2 barrel. If you look at the velocity curves, and realize that it starts at the same velocity, and use the same ammo, then something is scrubbing velocity.
Almost all projectiles come out at less than perfect orientation to the axis of motion. This is damped out as the projectile flies and 'feels' a push on one side to another as its ass-end gets inline with the flight path. The early Tiger I muzzle brake experienced clipping by AP rounds till they figured out that the 88mm FlaK guns actually uncorked the AP at slight deviations. The improved Tiger ammunition solved the issue.
I recently read that even a 1 degree change in change in misalignment could result in a 100 FPS change in critical velocity. Quite a good report concerned with the PzGr 39 as used in the PAK 40.
NUTTERNAME
Member
I have no idea what War Thunder is. It must be like WOT because the same level of discussion occurs.
mOBIUS
Member
Yeah, it is a first person tank shooter arcade-ish game like WOT. But, you have to hand it to them. This is where most of the new historic information and archive digging up is coming from these days.
NUTTERNAME
Member
http://vn-parabellum.com/us/m18-art.html
Some interesting Hellcat info. The Hellcat did not have a muzzle brake at first. Then there were threaded barrels but no muzzle brake, just a thread protector. I wonder if there issues with the brake just like Tiger I had? That is, until the rifling was changed, a muzzle brake had contact issues?
I barely read through that war thunder thread and people were talking about bullet proof vests and shooting cardboard boxes with pellet guns.
Some interesting Hellcat info. The Hellcat did not have a muzzle brake at first. Then there were threaded barrels but no muzzle brake, just a thread protector. I wonder if there issues with the brake just like Tiger I had? That is, until the rifling was changed, a muzzle brake had contact issues?
I barely read through that war thunder thread and people were talking about bullet proof vests and shooting cardboard boxes with pellet guns.
NUTTERNAME
Member
I believe these games have a much greater worldwide popularity than typical tactical games. I would suspect that increase in people 'researching' information, along with the greater languages spoken, can help uncover previously undisclosed 'enemy' information.
Much of the 'Rexford' primary data, and perhaps even more than he ever saw, is available online. I am amazed at the stuff I can read lately.
NUTTERNAME
Member
Very interesting...M62 projectile Stability Factor vs. velocity...
Basically, higher is better. 2 is good enough for artillery fire. A low number, like the M1A1 barrel shows here at 2600 to 1600 FPS, is very telling.
NUTTERNAME
Member
I will hand this to them...they seem to be pilfering both you and me here...
http://forum.worldoftanks.com/index.php?/topic/422853-3-inch-gun-m7-vs-76mm-m1a1/
mOBIUS
Member
On the positive side it is a chance to influence the debate without even having to post on their forums. In fact even better because I don't know many of the languages my 'borrowed' source is found on.
(my website logs where the link is coming from and I find there are russian, german and french forums and of course english linking.)
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mOBIUS
Member
One of the best things in using data from historic tests is that there is no calculations dealing with T/D (armor thickness/shell diameter) like have to be made applying engineering formulas. (Rexford's Demarre or Okun's BL(N) energy equations) That is because if the test says a 3" AP shell will penetrate 1" of armor at x yards that is the answer. In tests the 3" AP penetrated 1" plate at x yards. You don't have to multiply the distance by some factor of 1/3.
NUTTERNAME
Member
I find that thread interesting but kind of don't follow the argument regarding the greater powder charge in the 3 inch gun vs. the 76mm. The drawing clearly shows the 3 inch gun cutaway demonstrating a hollow area the is stuffed with some wadding???? So, while the 3 inch has a greater volume, was it really filled? I suppose I will dig into EOD info or the brass collectors websites for more info. If anything, they could have put more powder in if the weapon recoil mechanism could take it.
It is interesting that the powder issue with these weapons (smoke/flash) was addressed with a longer primer (why not a better powder?) in 1944 Fall.
I always wondered why the Allies never tried using PzGr 39 projectiles in the test shoot in '44. Or even the German powder. They clearly cobbled together US 76mm HVAP projectiles onto 17 pdr. cartridges. In fact, why not just shoot a German tank with a PAK 40 for comparison? They had plenty of those captured. A PAK 40 on a M5 chassis would have been a good filed expedient (same as a Marder for instance). I believe these were actually used in Yugoslavia BTW.
It is interesting that the powder issue with these weapons (smoke/flash) was addressed with a longer primer (why not a better powder?) in 1944 Fall.
I always wondered why the Allies never tried using PzGr 39 projectiles in the test shoot in '44. Or even the German powder. They clearly cobbled together US 76mm HVAP projectiles onto 17 pdr. cartridges. In fact, why not just shoot a German tank with a PAK 40 for comparison? They had plenty of those captured. A PAK 40 on a M5 chassis would have been a good filed expedient (same as a Marder for instance). I believe these were actually used in Yugoslavia BTW.
NUTTERNAME
Member
True but I put the actual field shoots at the top of the list. Actual weapons shooting actual targets. It has its limitations as the number of available targets restrict the data that is meaningful. That is, unless you are some drunk Soviet officers blasting away at hulks that look like Swiss cheese.
NUTTERNAME
Member
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mOBIUS
Member
Yes, I reference it on page36 of my website and I use the tests (figure 4) in one of my computer programs adjusting penetration for hardness.
But, this is always good for a quote:
Not exactly something Rexford would side with.
NUTTERNAME
Member
I liked...
2400 FPS is 731 M/s? At 900 yards? 900 yards is 822 meters? Wouldn't that put the muzzle velocity in the M62 range????
NUTTERNAME
Member
Very true. But in this case, they have chosen wisely...that is, both the PzGr 39 and it's very similar panther PzGr 39/42 were the predominant threat faced by Allied armor in the late war.
It is a good test in that they have varied limited parameters in the search for a simple goal...how to improve survivability to Allied AFV.
mOBIUS
Member
I have no idea what gun they are referring to here. The PAK 40 is not that hot. It would have to be fired at a MV 2730 f/s (832m/s) to have a terminal V of 2400 f/s at 900 yards. While some early 75mm Aberdeen tables were wrong having the Pak 40 MV=2655, they were not that wrong.
NUTTERNAME
Member
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NUTTERNAME
Member
In any case, this report might prove very useful as far as the CMFB demo. The demo shermans appear to be the 47 deg flat glacis types, both 75mm and 76mm. I imagine that the matlet hits on the 76mm might pose a tougher target. i believe the glacis is 64mm@47deg, 250 BHN.
I will line up a bunch of shermans at 1300 meters and let the JgdPzr IV/70 use up the short allotment of AP ammo on them. I will set them flat since the initial set up has them coyly deployed on back slopes.
Edit: i believe a PAK 40 could penetrate a sherman glacis at 1100 meters given the Yugo test data. I am not that sure about the actual penetration criteria, I would suppose getting light through, or perhaps a mix of penetrations and partials. But, in any case, I would expect the 'panther gun" to do better. Stay tuned....
I will line up a bunch of shermans at 1300 meters and let the JgdPzr IV/70 use up the short allotment of AP ammo on them. I will set them flat since the initial set up has them coyly deployed on back slopes.
Edit: i believe a PAK 40 could penetrate a sherman glacis at 1100 meters given the Yugo test data. I am not that sure about the actual penetration criteria, I would suppose getting light through, or perhaps a mix of penetrations and partials. But, in any case, I would expect the 'panther gun" to do better. Stay tuned....
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