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tanks

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  • godzillapaul <paulcrane1@aol.com>
    could someone tell me the difference between the typical 75mm sherman and the British firefly sherman with the 17pounder gun and why was it more
    Message 1 of 13 , Dec 25, 2002
      could someone tell me the difference between the typical 75mm
      sherman and the British firefly sherman with the 17pounder gun
      and why was it more effective against german armour i.e. panthers
      and tiger1 +2? thank you and the more i read about the
      typical sherman the army seemed to want it to be more of a mobile
      artillery piece and they preffered the m-36 tank destroyers to go
      head to head with tigers and panthers!?! thanks for your time!!
      paul
    • Paul Roberts
      ... The 75mm gun of the standard Sherman was of medium velocity. Its performance was optimised for the delivery of 75mm high explosive for supporting the
      Message 2 of 13 , Dec 25, 2002
        godzillapaul wrote:

        > could someone tell me the difference between the typical 75mm
        > sherman and the British firefly sherman with the 17pounder gun
        > and why was it more effective against german armour i.e. panthers
        > and tiger1 +2?

        The 75mm gun of the standard Sherman was of medium velocity. Its
        performance was optimised for the delivery of 75mm high explosive for
        supporting the infantry and for shooting up support vehicles in the
        enemy's rear areas after the breakthrough.

        The 76.2mm 17 pdr was a high velocity gun optimised for punching holes
        in enemy tanks. It was little, if any, use as a HE, infantry support weapon.

        The performance of any weapon that uses kinetic energy (i.e. the impact
        of a moving object) to punch holes is directly proportional to the
        square of the velocity, that is, twice the velocity equals four times
        the impact forces. The 17 pdr had a muzzle velocity of about 50% more
        than the 75mm using standard shot and almost two times the 75mm using
        discarding sabot shot. The discarding sabot shot was also considerably
        smaller in diameter thus permitting it to retain more velocity at the
        target (less drag) and have a smaller diameter to try to punch through
        the enemy's armour. Its performance was significantly higher than the
        75mm gun.

        > and the more i read about the
        > typical sherman the army seemed to want it to be more of a mobile
        > artillery piece and they preferred the m-36 tank destroyers to go
        > head to head with tigers and panthers!?!

        Exactly. It was a flawed doctrine, but it was official in the US Army at
        the time. Shermans were to break through and exploit, but not deal with
        enemy tanks. Enemy tanks were to be engaged by thinly armoured but well
        armed tank destroyers. How that was supposed to work in real life has
        never been adequately explained to me.

        >
        HTH

        Paul

        --
        Paul Roberts
        tankmodeler@...

        Scale Tech Distributing
        Scale Model Builders
        http://members.rogers.com/tankmodeler/
      • Mike Canaday
        Having given this a lot of thought, it occurred to me that the WWII doctrine wasn t too far off. In the current mechanized unit the tank (Abrams) acts like
        Message 3 of 13 , Dec 26, 2002
          Having given this a lot of thought, it occurred to me that the WWII doctrine wasn't too far off. In the current mechanized unit the tank (Abrams) acts like the WWII tank destroyer, and the Infantry fighting vehicle (Bradley) acts as the WWII tank, as a fire support vehicle. The basic doctrine wasn't so wrong, its implementation was. The tanks, TDs, and infantry needed to be integrated into one combined team, like it is now.

          The big technological difference I see is that the Tank Destroyer needs to be impervious, or nearly so, to enemy tanks, not just by mobility, but with armor as well. This obviously wasn't the case in WWII. If we had had M4A3E2s armed with 17 pounders equipping Tank destroyer units and operated the Fighter bombers, TDs, tanks, and infantry as a team (as the successful infantry and armored units did) I don't think anyone would have had too much of a problem with the doctrine, which of all the major combatants came the closest in theory to current practice.

          I guess the whole problem is that by misguessing about the design requirements of the Tank Destroyer, (i.e. stressing mobility over armor) the Tank Destroyer didn't do very well in combat and the whole idea collapsed, and was disregarded. Inadequate/wrong/incorrect requirements for a major subcomponent of the system lead to failure of the whole concept. Of course that's still the problem, how do you test a "system" like that?

          Mike Canaday

          ----- Original Message -----
          From: Paul Roberts
          To: G104@yahoogroups.com
          Sent: Wednesday, December 25, 2002 1:07 PM
          Subject: Re: [G104] tanks


          godzillapaul wrote:

          > could someone tell me the difference between the typical 75mm
          > sherman and the British firefly sherman with the 17pounder gun
          > and why was it more effective against german armour i.e. panthers
          > and tiger1 +2?

          The 75mm gun of the standard Sherman was of medium velocity. Its
          performance was optimised for the delivery of 75mm high explosive for
          supporting the infantry and for shooting up support vehicles in the
          enemy's rear areas after the breakthrough.

          The 76.2mm 17 pdr was a high velocity gun optimised for punching holes
          in enemy tanks. It was little, if any, use as a HE, infantry support weapon.

          The performance of any weapon that uses kinetic energy (i.e. the impact
          of a moving object) to punch holes is directly proportional to the
          square of the velocity, that is, twice the velocity equals four times
          the impact forces. The 17 pdr had a muzzle velocity of about 50% more
          than the 75mm using standard shot and almost two times the 75mm using
          discarding sabot shot. The discarding sabot shot was also considerably
          smaller in diameter thus permitting it to retain more velocity at the
          target (less drag) and have a smaller diameter to try to punch through
          the enemy's armour. Its performance was significantly higher than the
          75mm gun.

          > and the more i read about the
          > typical sherman the army seemed to want it to be more of a mobile
          > artillery piece and they preferred the m-36 tank destroyers to go
          > head to head with tigers and panthers!?!

          Exactly. It was a flawed doctrine, but it was official in the US Army at
          the time. Shermans were to break through and exploit, but not deal with
          enemy tanks. Enemy tanks were to be engaged by thinly armoured but well
          armed tank destroyers. How that was supposed to work in real life has
          never been adequately explained to me.

          >
          HTH

          Paul

          --
          Paul Roberts
          tankmodeler@...

          Scale Tech Distributing
          Scale Model Builders
          http://members.rogers.com/tankmodeler/




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          [Non-text portions of this message have been removed]
        • Kurt Laughlin
          I d say the WW II doctrine _was_ far off simply because it split things into offensive (tanks) and defensive (AT guns, whether towed or SP [*]) components.
          Message 4 of 13 , Dec 26, 2002
            I'd say the WW II doctrine _was_ far off simply because it split things into
            offensive (tanks) and defensive (AT guns, whether towed or SP [*])
            components. The integration into a team of "60-minute men" was the big
            change. Having M1A1s and Soviet 125mm dual purpose towed guns in the WW II
            TD system - let alone M4A3E2s - would not have helped.

            The doctrine was created as a result of the fall of France. Much of the
            thinking and technology of the Defense Period (7/40-12/41) was directed
            toward getting the doctrine and equipment necessary to protect North America
            from a German invasion. Once the US went on the offensive (which was
            always) the doctrine was flawed.

            [*] The contemporary nomenclature is revealing, I think. The advantage of
            SP over towed AT guns (it was claimed) was the speed in which they could be
            moved to stem an enemy breakthrough.

            KL

            ----- Original Message -----
            From: "Mike Canaday" <mmcalc@...>
            To: <G104@yahoogroups.com>
            Sent: Thursday, December 26, 2002 9:07 AM
            Subject: Re: [G104] tanks

            > Having given this a lot of thought, it occurred to me that the WWII
            doctrine wasn't too far off. In the current mechanized unit the tank
            (Abrams) acts like the WWII tank destroyer, and the Infantry fighting
            vehicle (Bradley) acts as the WWII tank, as a fire support vehicle. The
            basic doctrine wasn't so wrong, its implementation was. The tanks, TDs, and
            infantry needed to be integrated into one combined team, like it is now.
          • Mike Canaday
            Weren t the TD s to be used in a defensive role even during a strategic offensive? Protecting the flanks of an Armored thrust from counter attack and that
            Message 5 of 13 , Dec 26, 2002
              Weren't the TD's to be used in a defensive role even during a strategic offensive? Protecting the flanks of an Armored thrust from counter attack and that sort of thing? I guess in practice they wound being used up front because of the larger guns. The sucessful US units did actually wind up teaming TDs, tanks, and infantry, as is always the case, doctrine gets pitched if it doesn't work when the bullets start flying. Open order assaults during the Civil War even though doctrine called for shoulder to shoulder assaults etc.

              Mike
              ----- Original Message -----
              From: Kurt Laughlin
              To: G104@yahoogroups.com
              Sent: Thursday, December 26, 2002 11:11 AM
              Subject: Re: [G104] tanks


              I'd say the WW II doctrine _was_ far off simply because it split things into
              offensive (tanks) and defensive (AT guns, whether towed or SP [*])
              components. The integration into a team of "60-minute men" was the big
              change. Having M1A1s and Soviet 125mm dual purpose towed guns in the WW II
              TD system - let alone M4A3E2s - would not have helped.

              The doctrine was created as a result of the fall of France. Much of the
              thinking and technology of the Defense Period (7/40-12/41) was directed
              toward getting the doctrine and equipment necessary to protect North America
              from a German invasion. Once the US went on the offensive (which was
              always) the doctrine was flawed.

              [*] The contemporary nomenclature is revealing, I think. The advantage of
              SP over towed AT guns (it was claimed) was the speed in which they could be
              moved to stem an enemy breakthrough.

              KL

              ----- Original Message -----
              From: "Mike Canaday" <mmcalc@...>
              To: <G104@yahoogroups.com>
              Sent: Thursday, December 26, 2002 9:07 AM
              Subject: Re: [G104] tanks

              > Having given this a lot of thought, it occurred to me that the WWII
              doctrine wasn't too far off. In the current mechanized unit the tank
              (Abrams) acts like the WWII tank destroyer, and the Infantry fighting
              vehicle (Bradley) acts as the WWII tank, as a fire support vehicle. The
              basic doctrine wasn't so wrong, its implementation was. The tanks, TDs, and
              infantry needed to be integrated into one combined team, like it is now.




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              [Non-text portions of this message have been removed]
            • Rexford179@cs.com
              In a message dated 12/25/2002 1:08:54 PM Eastern Standard Time, ... The penetrating capability of a round is roughly proportional to the velocity raised to the
              Message 6 of 13 , Dec 26, 2002
                In a message dated 12/25/2002 1:08:54 PM Eastern Standard Time,
                tankmodeler@... writes:
                > The performance of any weapon that uses kinetic energy (i.e. the impact
                > of a moving object) to punch holes is directly proportional to the
                > square of the velocity, that is, twice the velocity equals four times
                > the impact forces.

                The penetrating capability of a round is roughly proportional to the velocity
                raised to the 1.43 power, 50% increase in velocity raises penetration by
                about 79%.

                17 pdr APCBC gains another advantage over U.S. 75mm and 76mm rounds because
                17 pdr is heavier, and it is solid shot. HE burster cavity in 75mm rounds
                weakens structure and decreases penetration.

                At 2030 fps impact, same as 75mm L40 APCBC at point blank, 17 pdr APCBC would
                penetrate about 106mm while U.S. 75mm APCBC penetrates about 91mm. U.S.
                solid shot AP penetrates about 114mm at 2030 fps (armor piercing and
                windscreen caps on 17 pdr APCBC reduce penetration against homogeneous armor,
                which is why U.S. M72 75mm AP outpenetrates 17 pdr APCBC).


                [Non-text portions of this message have been removed]
              • Gordon Roach
                Which is why the Brits introduced Sabot, and then there was no comparable gun in the western armies. Gordon Roach [Non-text portions of this message have been
                Message 7 of 13 , Dec 26, 2002
                  Which is why the Brits introduced Sabot, and then there was no comparable gun in the western armies.


                  Gordon Roach



                  [Non-text portions of this message have been removed]
                • Carey Erickson
                  Lorrin I think you might be confused if you think US M72 out performs 17lber APCBC.... US M72 (at muzzle) its velocity is 2030 fps...at 500 yards against 30
                  Message 8 of 13 , Dec 26, 2002
                    Lorrin
                    I think you might be confused if you think US M72 out performs 17lber APCBC....
                    US M72 (at muzzle) its velocity is 2030 fps...at 500 yards against 30 degree RHA, it will penetrate 3 inches, fired out of a M3 gun...from M2 gun, 2.4 inches...from M6 gun 2.6 inches

                    Compare that with 17lber APCBC....muzzle velocity 2900 fps
                    At 2000 yds...I repeat 2000 yds....It will penetrate 4.4 inches of RHA at 30 degrees...
                    At 500 yds...It will penetrate 5.5 inches....

                    Regards C.G.


                    ----- Original Message -----
                    From: Rexford179@...
                    Sent: Thursday, December 26, 2002 3:07 PM
                    To: G104@yahoogroups.com
                    Subject: Re: [G104] tanks

                    In a message dated 12/25/2002 1:08:54 PM Eastern Standard Time,
                    tankmodeler@... writes:
                    > The performance of any weapon that uses kinetic energy (i.e. the impact
                    > of a moving object) to punch holes is directly proportional to the
                    > square of the velocity, that is, twice the velocity equals four times
                    > the impact forces.

                    The penetrating capability of a round is roughly proportional to the velocity
                    raised to the 1.43 power, 50% increase in velocity raises penetration by
                    about 79%.

                    17 pdr APCBC gains another advantage over U.S. 75mm and 76mm rounds because
                    17 pdr is heavier, and it is solid shot. HE burster cavity in 75mm rounds
                    weakens structure and decreases penetration.

                    At 2030 fps impact, same as 75mm L40 APCBC at point blank, 17 pdr APCBC would
                    penetrate about 106mm while U.S. 75mm APCBC penetrates about 91mm. U.S.
                    solid shot AP penetrates about 114mm at 2030 fps (armor piercing and
                    windscreen caps on 17 pdr APCBC reduce penetration against homogeneous armor,
                    which is why U.S. M72 75mm AP outpenetrates 17 pdr APCBC).


                    [Non-text portions of this message have been removed]


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                    [Non-text portions of this message have been removed]
                  • Rexford179@cs.com
                    In a message dated 12/26/2002 11:10:04 PM Eastern Standard Time, ... Read my post more carefully, I was comparing the two rounds at the same velocity, namely
                    Message 9 of 13 , Dec 27, 2002
                      In a message dated 12/26/2002 11:10:04 PM Eastern Standard Time,
                      PACKFANONE@... writes:
                      > I think you might be confused if you think US M72 out performs 17lber
                      > APCBC....

                      Read my post more carefully, I was comparing the two rounds at the same
                      velocity, namely 2030 fps. 75mm M72 AP outperforms 17 pdr APCBC at 2030 fps
                      and 0 degrees, mostly due to the absence of armor piercing and ballistic caps
                      which sap energy. M72 was also more pointed than 17 Pounder APCBC, which
                      would also contribute to better penetration (at the same velocity).


                      [Non-text portions of this message have been removed]
                    • Gordon Roach
                      But is the point not that they did not fire at the same, and that the Brit solid shot was far more effective at punching holes than the US round ? G [Non-text
                      Message 10 of 13 , Dec 27, 2002
                        But is the point not that they did not fire at the same, and that the Brit solid shot was far more effective at punching holes than the US round ?

                        G


                        [Non-text portions of this message have been removed]
                      • Rexford179@cs.com
                        In a message dated 12/27/2002 9:14:40 PM Eastern Standard Time, ... As noted in my post this morning, WW II 17 pounder SABOT was better than U.S. ammo against
                        Message 11 of 13 , Dec 28, 2002
                          In a message dated 12/27/2002 9:14:40 PM Eastern Standard Time,
                          gordon.roach@... writes:
                          > But is the point not that they did not fire at the same, and that the Brit
                          > solid shot was far more effective at punching holes than the US round ?

                          As noted in my post this morning, WW II 17 pounder SABOT was better than U.S.
                          ammo against steeply sloped armor, but 90mm HVAP could outpenetrate the APDS
                          if the angle were not too steep.

                          Comparison with 128mm APCBC seemed interesting and placed 17 pounder SABOT in
                          perspective. It could outpenetrate just about every other WW II weapon, but
                          not all of them and not at all armor impact angles.

                          One other note regarding WW II SABOT was that the gunsights did not have
                          range lines especially calibrated for APDS, and gunners appear to have used
                          the APCBC gun sight elevation lines and a 2/3 multiplier with 17 pounder
                          weapons. Something like that might lead to additional inaccuracies due to an
                          extra step.


                          [Non-text portions of this message have been removed]
                        • Carey Erickson
                          ... Lorrin.. I did read your post...very carefully...I found it to be confusing...some people may misconstrue your post as saying the M72 out performs the 17
                          Message 12 of 13 , Dec 28, 2002
                            >From: Rexford179@...
                            >Reply-To: G104@yahoogroups.com
                            >To: G104@yahoogroups.com
                            >Subject: Re: [G104] tanks
                            >Date: Fri, 27 Dec 2002 18:26:12 EST
                            >
                            Lorrin..

                            I did read your post...very carefully...I found it to be confusing...some
                            people may misconstrue your post as saying the M72 out performs the 17
                            lber....You didnt mention the fact that you were comparing 0 degree
                            obliquity shots...

                            Why were you comparing the 2 anyway? M72 at point blank range and 17lber at
                            over 3000 yards velocities? Anyway in trying to keep this from turning into
                            a flame war on this great site....I will only say one thing, my Aberdeen
                            documents say something different..

                            regards C.G.

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                            [Non-text portions of this message have been removed]
                          • Rexford179@cs.com
                            In a message dated 12/28/2002 6:40:59 PM Eastern Standard Time, ... Just to show that the M72 appears to outpenetrate 17 pdr APCBC at the same velocity, where
                            Message 13 of 13 , Dec 30, 2002
                              In a message dated 12/28/2002 6:40:59 PM Eastern Standard Time,
                              PACKFANONE@... writes:
                              > Why were you comparing the 2 anyway? M72 at point blank range and 17lber at
                              > over 3000 yards velocities?

                              Just to show that the M72 appears to outpenetrate 17 pdr APCBC at the same
                              velocity, where the difference is due to caps that absorb energy.


                              [Non-text portions of this message have been removed]
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