Oddball_E8 Posted June 10, 2003 Share Posted June 10, 2003 as som might guess from the title i just wonder why the su-76 has a lower penetration value than the t-34/76... i was under the impression that both vehicles had the same gun... 76mm L/42 afaik :confused: 0 Quote Link to comment Share on other sites More sharing options...
kipanderson Posted June 10, 2003 Share Posted June 10, 2003 Hi, The reason for the difference in penetration figures is that they use the same ammunition, but different guns. The SU76 uses the 76.2mmModel42 gun which has a barrel length of around 37 calibres. The T34 uses a gun which fires the same ammunition, has an identical chamber, but a 42 calibre barrel length. BTW. The Soviets produced around 65,000 76.2mmModel42 guns during WWII. They also tended to be concentrated opposite Panzer and mobile German divisions. In a scenario with a German mobile/Panzer division in attack, if you are after historical accuracy, there should be a generous number of 76.2mmModel42 guns on the Soviet side, in an average/representative game. Anything from four guns, to a mind blowing twenty four guns would be historically credible. All the best, Kip. 0 Quote Link to comment Share on other sites More sharing options...
Oddball_E8 Posted June 10, 2003 Author Share Posted June 10, 2003 thanx for the answer... i just got to thinking when i happened to have the two next to eachother and compared stats... and it sais that the su76 has a L/42 gun just as the t-34 so i got to wondering... 0 Quote Link to comment Share on other sites More sharing options...
Conscript Bagger Posted June 10, 2003 Share Posted June 10, 2003 Originally posted by kipanderson: They also tended to be concentrated opposite Panzer and mobile German divisions. Kip (or anyone else who knows), to me this implies that the Soviets had (a) good enough intelligence/recon to know where the panzers were concentrating and ( time enough to move their AT units to the area. I'm prepared to accept this for the most part, as a panzer division is pretty hard to hide, but were there also instances where, say, the Germans pulled off a deception plan and managed to send an armored force where the Soviets didn't expect it? or expected it but just plain didn't have the AT assets in place? Of course, "everyone knows" that the Soviets had all the time in the world to prepare gun fronts at Kursk, but I'm wondering how the strategy worked in the rest of the war. How much time did it take to find the panzers? How long to get the guns in place? Did they simply have enough guns and the flow of the campaigns was so established that the Germans never surprised them? thanks in advance 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted June 13, 2003 Share Posted June 13, 2003 Originally posted by kipanderson: Hi, The reason for the difference in penetration figures is that they use the same ammunition, but different guns. The SU76 uses the 76.2mmModel42 gun which has a barrel length of around 37 calibres. The T34 uses a gun which fires the same ammunition, has an identical chamber, but a 42 calibre barrel length. BTW. The Soviets produced around 65,000 76.2mmModel42 guns during WWII. All the best, Kip. The ZIS-3 Model 1942 76.2mm field gun had a barrel length of L41.5, based on a German report I have, and was no different from the T34 76.2mm gun in terms of muzzle velocity. Could you share the reference regarding ZIS-3 76.2mm firing APBC at a lower muzzle velocity. The German report I have has the L41.5 and L40 76.2mm field guns firing BR-350A APBC at 662 m/s. Maybe the L37 length for the Model 1942 gun is based on a different definition than the T34 L41.5 length. 0 Quote Link to comment Share on other sites More sharing options...
kipanderson Posted June 13, 2003 Share Posted June 13, 2003 Rexford, hi, You are quite correct. These are the figures. 76.2mmModel42 Gun. Length of Piece, w/muzzle brake 3455mm without/muzzle brake 3169 mm T34s’ gun 76.2mm gun Length of Piece 3168mm Also, they give the same velocity, not for the 350A, but the 350B as 680mps, or 746 mps. Clearly the second is the Super round you have mentioned before. Source is Record of Foreign weapons and Equipment, volume 1, USSR. 1947. I found it in the archives of the Tank Museum in Bovington some years back, copied all 500 pages. It is “by far” the most complete single source for Soviet WWII weapons I have every come across, or even heard of. 500 pages on Soviet WWII ground warfare weapons put together in 1947 by British intelligence. Rexford, why then does the 76.2mmModel42 have lower penetration and velocity, than the F34 gun, in the T34, in CMBB? The 76.2mmModel42 gun was “by far”, the most common gun on the Eastern Front. I think there were around 68,000 produced during the war, from memory. Having the wrong penetration/ velocity figures for it is a terrible shame. “If” BFC have dropped the ball on this one. All the best, Kip. 0 Quote Link to comment Share on other sites More sharing options...
kipanderson Posted June 13, 2003 Share Posted June 13, 2003 Offwhite, hi, You have really already hit the nail on the head. It goes something like this. Number of Panzers. The Germans had between 750 and 1,200 panzers operational on any given day on the Eastern Front. They had between 20-25 Panzer divisions, or the equivalent, on the Eastern Front. Around 20 Panzer divisions in the line. If we assume 1,000 operational Panzers, in 20 Panzer divisions and two Panzer battalions per division, we are talking around 50 operational Panzers per division in two 25 strong battalions. Dedicated, Soviet AT units above divisional level. By January 44 the Soviet had 50 Separate Anti-Tank Brigades. Each with around 74 AT guns in three regiments of 20-24 guns. They also have around 170 Separate Anti-Tank Regiments of around 20- 24 guns. The entire reason for being of these Separate Anti-Tank units was to seal off the Panzer divisions. This was Soviet doctrine. The above Soviet units were clearly not all at full strength at any one time. However, as you can see there was more than enough to go round. And it gets worse for the Germans. Due to the desperate shortage of German infantry units, the Panzer divisions had to be deployed in the line. Hence, the Soviets knew only to well where they were. Added to this, if a Panzer division was holding a section of 15km-20km of line, on any given day it will normally have been the case that both sides were only too well aware of which sectors were the crucial/crisis sectors within the 15km-20km section of front. Thus the Soviets could concentrate their AT assets there. The net result is that a German combat team including a Panzer battalion, at an average strength of 25 tanks, will often have come up against twelve or more Soviet AT guns on a 2km by 2km CMBB map. On a 2km by 2km CMBB map, a Panzer attack could realistically be modelled as coming across anything from 4 Soviet AT guns, to 24 Soviet AT guns. In fact to model it most realistically, you probably want to use a map 2km in width, but 3km in depth. All the above figures come from rock sold sources. Germany records and Soviet records. All the best, Kip. PS. 75% of AT guns in the above Soviet units were the 76.2mModel42 Gun. The other 25% being made up of 45mm AT guns in early 43, then replaced by 57mm AT guns. If you use the 76.2mm Model42 Gun, in the CMBB Editor be sure to increase its loadout of AP rounds from the default which is too low. Most Soviet AT units had the above 75/25 mix of AT guns. 0 Quote Link to comment Share on other sites More sharing options...
Redwolf Posted June 13, 2003 Share Posted June 13, 2003 If the gun is the same except one has a muzzle brake then the gun with the brake should have a lower penetration, shouldn't it? I am surprised they needed a brake on the SP gun but not on the T-34. I was under the impression that the Soviets were not bothering with too good turret ring and other turret mechanisms, so I wonder how the T-34 mount can be stronger than the SU mount. 0 Quote Link to comment Share on other sites More sharing options...
JasonC Posted June 13, 2003 Share Posted June 13, 2003 On penetration differences, I assume they were meant to reflect different ammo availability. More APBC (BR-350B) for the tanks, more of the uncapped rounds for the SUs and towed guns. In 1942 the numbers are low for the tanks, too. BTS has in the past represented mixed ammo with different penetration abilities by a compromise figure, rather than picking the higher or lower value. Then the built in random shot to shot variation (around 10%) is supposed to represent the better ammo on a "good roll", the worse ammo on a "bad roll". 0 Quote Link to comment Share on other sites More sharing options...
John D Salt Posted June 13, 2003 Share Posted June 13, 2003 Originally posted by redwolf: If the gun is the same except one has a muzzle brake then the gun with the brake should have a lower penetration, shouldn't it? No. Indeed, an efficient muzzle-brake may permit the firing of rounds with larger charges, as for example with the 25-pdr, which could use an oofier charge behind its AP round once it was fitted with a muzzle-brake. All the best, John. 0 Quote Link to comment Share on other sites More sharing options...
Redwolf Posted June 13, 2003 Share Posted June 13, 2003 Originally posted by John D Salt: </font><blockquote>quote:</font><hr />Originally posted by redwolf: If the gun is the same except one has a muzzle brake then the gun with the brake should have a lower penetration, shouldn't it? No. Indeed, an efficient muzzle-brake may permit the firing of rounds with larger charges, as for example with the 25-pdr, which could use an oofier charge behind its AP round once it was fitted with a muzzle-brake. </font> 0 Quote Link to comment Share on other sites More sharing options...
kipanderson Posted June 13, 2003 Share Posted June 13, 2003 Hi, Guys, I did not make my post clear enough. If you go back you will find that 76.2mmModel42 gun has a length of 3169mm “without the muzzle brake”. The F34 gun used in the T34 has a length of 3168mm. Note the F34 gun has no muzzle brake. i.e. the two guns have a near identical length, “excluding the muzzle brakes”. I had always assumed that the two guns were the same length, “including” the muzzle brake on the 76.2mmModel42 gun. But I was wrong. In the source I quoted the 350B round is the one used in both. What “may” have happened is this. The source BFC used may have quoted muzzle velocities for “different” rounds for the two guns by mistake. Hence BFC assumed the two guns had different velocities. I think the fact that the two guns were the same length, excluding muzzle brakes, is the clincher. All the best, Kip. 0 Quote Link to comment Share on other sites More sharing options...
Redwolf Posted June 13, 2003 Share Posted June 13, 2003 Originally posted by kipanderson: Guys, I did not make my post clear enough. No, I think it was fine. I think the fact that the two guns were the same length, excluding muzzle brakes, is the clincher. Yes, but firing the same round through the same barrel will result in a slightly slower projectile if a muzzle brake is mounted. The brake is not neutral to the round. You can use the effect of the brake to do two things: 1) fire a more powerful round 2) lessen the stress on the carriage for the same round Seems to be the SU-76 with its fragile chassis had to use a muzzle brake in sense 2. So it would have less penetration with the same round and same barrel as the T-34. The only thing I was suprised about is that the T-34 turret mechanism is stronger than the SU-76 mount (this would be implied by that logic). But given that the chassis is very light I could imagine this is the case. 0 Quote Link to comment Share on other sites More sharing options...
kipanderson Posted June 13, 2003 Share Posted June 13, 2003 redwolf, hi, the 76.2mmModel42 gun is used in the SU76 “as is”. That is why it has a muzzle brake when mounted on the SU76 chassis. The 76.2mmModel42 gun has a muzzle brake as standard. As I understand it the action of most muzzle brakes is not to brake the velocity of the projectile, but to brake/dampen the force of the recoil by virtue of the way the exhaust, blast from the shot is vented by the muzzle brake so as to produce a slight forward, as opposed to backward, force. If the length of barrel of both guns was the same, excluding muzzle brakes, then I would expect similar velocities. All the best, Kip. 0 Quote Link to comment Share on other sites More sharing options...
Redwolf Posted June 13, 2003 Share Posted June 13, 2003 Hi, Kip, Originally posted by kipanderson: As I understand it the action of most muzzle brakes is not to brake the velocity of the projectile, but to brake/dampen the force of the recoil by virtue of the way the exhaust, blast from the shot is vented by the muzzle brake so as to produce a slight forward, as opposed to backward, force. If the length of barrel of both guns was the same, excluding muzzle brakes, then I would expect similar velocities. Yes, the purpose of the muzzle brake is to lessen the recoil, but the projectile is somewhat slowed down by it as an unwanted side effect. The projectile leaves the barrel, with a "pillar" of air in front of it (this is the air which filled the barrel before the shot). Usually this air is "free" to move in any direction when it leaves the barrel, but if there is a muzzle brake then much of the air is compressed against the brake's "wings", producing much bigger counterforce to the projectile's movement than the air which can move away freely without a brake. Most of the force lessening the recoil is from air leaving the barrel after the projectile (which nobody cares about), but some part of the damping energy is taken from the projectile's energy. As I understand the different brake designs try to optimize not only the overall damping effect, but also to get more of the daming out of the post-projectile air and less from the air pushed out in front of the projectile. I am pretty sure I actually learned this on the CMBO forum I have a projectile book at ome which might have this stuff, of you remind me I'll look it up. [ June 13, 2003, 05:01 PM: Message edited by: redwolf ] 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted June 14, 2003 Share Posted June 14, 2003 I have a German translation of a Russian manual for 76.2mm field guns, and the muzzle velocity of the field guns with a muzzle brake is the same as the T34 tank gun with BR-350A ammo. If one wants 662 m/s for BR-350A, and 655 m/s for BR-350B from both field and tank guns, you put a little more charge in the field gun ammo when there is a muzzle brake. Simple. The 680 m/s for T34 APBC is a mistake I am responsible for, Russian Battlefield quotes that velocity for BR-350B and I told the CMBB people it was correct. 680 m/s is for 76.2mm HE, 662 m/s is for BR-350A and 655 m/s is for BR-350B, based on "current thinking" (a select group of folks, myself included, who guess at things with varying accuracy and occasional fits of wild inaccuracy). 0 Quote Link to comment Share on other sites More sharing options...
Redwolf Posted June 14, 2003 Share Posted June 14, 2003 Any working muzzle brake must slow down the projectile somewhat. Of course you can use a larger charge to counter that, but apparently this is not what BFC models in the case of the SU-76 and SU-76i. The SU-76m in CMBB has other penetration data still, slightly less than the T-34 gun (both with blunt-nosed apbc). [ June 13, 2003, 10:47 PM: Message edited by: redwolf ] 0 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.