Jump to content
Sign in to follow this  
rexford

U.S. 76mm Shatter Failure vs Panther and Tiger

Recommended Posts

The following presents the latest research findings regarding the shatter failure of U.S. 76mm APCBC against heavy German armor (80mm and thicker):

SHATTER GAP FAILURE OF U.S. 3” CHEVROLET APCBC

Firing trials and combat reports from WW II suggest that the Chevrolet 3” APCBC round was susceptible to shatter gap failure, where hits which should have penetrated resulted in defeats. The following summarizes all of the research conducted by this writer on the subject of U.S. 76mm APCBC shatter gap and refines past estimates.

1. Report in Faint Praise book that U.S. 76mm penetrated front of Tiger at 50 yards in France but failed at further ranges

2. U.S. firing trials against captured Panthers in France (First U.S. Army, July 1944) where penetration range against Panther mantlet is limited to 200 yards (183m)

3. U.S. Navy firing tests against American 3.8” and 3” plate result in two distinct velocities for 50% success separated by a wide band of failure velocities with extensive projectile damage

Analysis of the above information results in the following shatter gap characteristics:

3.82” at 20 deg, U.S. Navy, 1.124 shatter gap penetration ratio

3.84” at 30 deg, U.S. Navy, 1.125

3.00” at 20 deg, U.S. Navy, none (no shatter gap exhibited)

3.00” at 30 deg, U.S. Navy, 1.229

3.00” at 40 deg, U.S. Navy, 1.193

102mm at 10 deg, Faint Praise, 1.210

100mm cast at 0 deg, U.S. First Army, 1.323

100mm cast at 10 deg, U.S. First Army, 1.284

100mm cast at 20 deg, U.S. First Army, 1.160

Notes:

1. The Shatter Gap Penetration Ratio is the ratio of the higher penetration figure for 50% success divided by the lower limit (based on computed effective armor resistance), where the figures in between would result in a high failure probability due to projectile shatter

2. The First Army tests against the Panther mantlet did not indicate or suggest an impact angle, so three possible angles are analyzed where the lower angles may be more likely

Applying the above results to the Tiger effective armor resistances results in the following ranges for potential shatter gap failure by Chevrolet 76mm APCBC (50% penetration probability at listed ranges, zero percentage in between and normal penetration probabilities outside the range):

102mm plate hit at 10 degrees, 46m to 1050m

102mm plate hit at 20 degrees, 100m to 750m

102mm plate hit at 30 degrees, 25m

84.5mm side armor resistance at 20 degrees, no shatter gap possibility

84.5mm side armor resistance at 30 degrees, 0m to 1100m

84.5mm side armor resistance at 40 degrees, no shatter gap possibility, no 50% intact penetration limit

For the Panther mantlet, the upper and lower penetration ranges appear to occur at 183mm and 1500m.

Research by Miles Krogfus has found that the Chevrolet M62 3” round was susceptible to a variety of problems due to a relatively rapid decrease in hardness from nose to main body, which could lead to bulging out of the projectile shoulder after impact. There were two other manufacturers of U.S. 76mm APCBC and the other makers used a slower variation than Chevrolet for the hardness from nose to main body.

Share this post


Link to post
Share on other sites

The following presents the latest research findings regarding the shatter failure of U.S. 76mm APCBC against heavy German armor (80mm and thicker):

SHATTER GAP FAILURE OF U.S. 3” CHEVROLET APCBC

Firing trials and combat reports from WW II suggest that the Chevrolet 3” APCBC round was susceptible to shatter gap failure, where hits which should have penetrated resulted in defeats. The following summarizes all of the research conducted by this writer on the subject of U.S. 76mm APCBC shatter gap and refines past estimates.

1. Report in Faint Praise book that U.S. 76mm penetrated front of Tiger at 50 yards in France but failed at further ranges

2. U.S. firing trials against captured Panthers in France (First U.S. Army, July 1944) where penetration range against Panther mantlet is limited to 200 yards (183m)

3. U.S. Navy firing tests against American 3.8” and 3” plate result in two distinct velocities for 50% success separated by a wide band of failure velocities with extensive projectile damage

Analysis of the above information results in the following shatter gap characteristics:

3.82” at 20 deg, U.S. Navy, 1.124 shatter gap penetration ratio

3.84” at 30 deg, U.S. Navy, 1.125

3.00” at 20 deg, U.S. Navy, none (no shatter gap exhibited)

3.00” at 30 deg, U.S. Navy, 1.229

3.00” at 40 deg, U.S. Navy, 1.193

102mm at 10 deg, Faint Praise, 1.210

100mm cast at 0 deg, U.S. First Army, 1.323

100mm cast at 10 deg, U.S. First Army, 1.284

100mm cast at 20 deg, U.S. First Army, 1.160

Notes:

1. The Shatter Gap Penetration Ratio is the ratio of the higher penetration figure for 50% success divided by the lower limit (based on computed effective armor resistance), where the figures in between would result in a high failure probability due to projectile shatter

2. The First Army tests against the Panther mantlet did not indicate or suggest an impact angle, so three possible angles are analyzed where the lower angles may be more likely

Applying the above results to the Tiger effective armor resistances results in the following ranges for potential shatter gap failure by Chevrolet 76mm APCBC (50% penetration probability at listed ranges, zero percentage in between and normal penetration probabilities outside the range):

102mm plate hit at 10 degrees, 46m to 1050m

102mm plate hit at 20 degrees, 100m to 750m

102mm plate hit at 30 degrees, 25m

84.5mm side armor resistance at 20 degrees, no shatter gap possibility

84.5mm side armor resistance at 30 degrees, 0m to 1100m

84.5mm side armor resistance at 40 degrees, no shatter gap possibility, no 50% intact penetration limit

For the Panther mantlet, the upper and lower penetration ranges appear to occur at 183mm and 1500m.

Research by Miles Krogfus has found that the Chevrolet M62 3” round was susceptible to a variety of problems due to a relatively rapid decrease in hardness from nose to main body, which could lead to bulging out of the projectile shoulder after impact. There were two other manufacturers of U.S. 76mm APCBC and the other makers used a slower variation than Chevrolet for the hardness from nose to main body.

Id love to know what Tiger he supposedly engaged, given that there were no Tigers on the American front in france....

 

Also, those mantle hits mean nothing. For all we know, the penetration might have been limited due to the failure rounds hitting the upper or lower sections of the mantlet. 

 

As for the Navy tests: Id like to see those....and see if they make any mention of shatter gap. Funny how this problem never came up in the original testing of these guns. 

 

What is more, with this being only one of the 2 manufactures, you wouldnt expect it to happen 75% of the time like it does now

Share this post


Link to post
Share on other sites

 

Report in Faint Praise book that U.S. 76mm penetrated front of Tiger at 50 yards in France but failed at further ranges

 

 

Id love to know what Tiger he supposedly engaged, given that there were no Tigers on the American front in france....

 

Don't have the book (£365.98!) to hand but does it specify if that result was found out from combat or subsequent allied testing on say captured Tiggers conducted in France after the battles in Normandy moved on. 

 

http://www.amazon.co.uk/Faint-Praise-American-Destroyers-During/dp/0208020063

Share this post


Link to post
Share on other sites

Don't have the book (£365.98!) to hand but does it specify if that result was found out from combat or subsequent allied testing on say captured Tiggers conducted in France after the battles in Normandy moved on. 

 

http://www.amazon.co.uk/Faint-Praise-American-Destroyers-During/dp/0208020063

There were ZERO, I say again:--ZERO-Tigers on the American sector in Normandy. Any accounts Faint Praise uses are just good examples of Americans reporting everything as a Tiger. From the descriptions in Rexfords own book, they appear to combat accounts. I have never seen any 1944 tests on Tigers done by the United States. The tests on German tanks done after and during the battle are well known, specifically the isigny tests, which involved no Tigers. On the subject of those tests, they did test the 76mm gun on a 100mm armor plate at 30 degrees, and it penetrated just fine---a fact Rexford dismisses in his book. In CMx1, the Shatter gap for the 76mm gun was fairly rare, but in CMx2 it is all over the place. Even German tests claim the 76mm gun could Kill the Tiger from 400-600M. 

 

Outside of Rexford and Bailey, I havent been able to find anyone else claiming "Shatter Gap" was a thing aside from people quoting either Rexford or Bailey. Anything used in Baileys book should be taken with a large grain of salt in particular----since it is one of those "The shermans are death trap, oh my, how stupid the Army was to not have 90mm guns," sort of narratives. 

Edited by shift8

Share this post


Link to post
Share on other sites

^ No wonder a jagdpanther turns into a hetzer and tiger is actually a panzer iv. I don't think they knew one enemy tank from the next and what they were up against in the war. Tons of Drafties.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...