Tank/SP and ATG firing differences

[Yoozername]

I have several of the chobham reports on captured German armor.

One of the things that these detailed reports reveals is that weapons like the Sturmgeshutz were superior to turreted tanks as far as weapon aiming. The early StuG with the 75mmL24 gun was actually ranged to 6000m. 0-3000m in 100m increments and 3000-6000m in 50m increments. The Sturmartillerie were actually artillery guys.

The StuGs (all) had the advantage in that the mount was a true gun mount. The same type of control that is used in elevation was used in traverse. This made shooting at moving vehicles much easier than a turreted tank which needs to traverse through turret motion. The panzer IV is mentioned as having a corse type motion to the turret aining. The British report on the panzer IV/long states as much.

In '7000Km in a StuG' the author describes taking T34s under fire at 1700m and getting the range. The only hope for the T34 was to keep moving. the author served in both L24 and L48 StuG.

In the game, I would think the StuGIII/L43 would be the premier AFV as far as threatening armor at range. Its optics included the scissor scope commanders device as standard equipment.

[Yoozername]

Just throwing out some observations I have read in Field Manuals and Reports.

US tank gunnery manuals stress taking up back lash in aiming systems. This is the slop between gears. By taking it up, you will actually elevate the gun beyond the target and then bring it down. I have never read any mention of this in German accounts.

Guns like the US Sherman 76mm long barrel were apparently so sloppy that after firing, the aim would be off 100-200 m on a 1000 m target. That is so bad that I suspect it could not really be zeroed at that range. A fixed gun should be repeatable. That is, you fire it and it will come back to the same aim point (or VERY close). Some accounts claim that you could do chin ups on a Panther tank barrel and it would not move. The same feat on a sherman 76mm would make the barrel oscillate.

The Panzer III long barrel (a VERY accurate medium range weapon) had a torsional bar device on the inside of the turret to steady the weapon. A device like this would also act as a antibacklash compensator.

While many games and grogs focus on muzzle velocity, penetration, etc. There is actually more to the high velocity gun equation. A simple thing like having a very flat trajectory also means that you must have very sensitive and repeatable controls for firing the weapon at range. Superelevation must be controlled over a very small arc in precise amounts.

I suspect that the Soviet guns were also subject to the same slop during this period. The soviet sighting system used on its tanks/SPs/etc in 42 is very similar to the sherman tanks.

[Yoozername]

As far as ATG differences, the Soviets 76mm 'ATG' could also be the F22 gun? This is the long barrel gun the Germans used in the early marders?

[gunny]

very interesting. Then this could be captured in the stats for both rate of fire and accuracy? Retargeting a sloppy second shot would decrease ROF, and walk-in shots would take longer to yield accuracy.

[Yoozername]

You bring up a good point. ROF as a function of range/circumstances. ROF is reduced, when firing at range, for no other reason than it takes longer for a shot to reach the target (and be sensed by the commander and realyed to the gunner).

In some circumstances, especially when the gunner CAN sense the round, he will not wait for the commander to shoot. Once 'UP!' (loader has loaded), he will do his own correction and fire.

But what I would like the designers to model/abstract is the process of WWII tank/gun accuracy. The limitations of the Soviets are so glaring, and the advantage that the Germans were already practising so documented, that I wouyld not want a game dismissed by Grogs because of equilateral modeling. The game is focusing on so few vehciles that its advantage must be in great abstractions or modeling.

[Yoozername]

Will the 37mm ATG have the 'stick-bomb'?

Stielgranade 41:

Germans manufactured about 636,000 Stielgrenade 41 HEAT bombs for 37-mm guns in 1942 - 1943. Compared to German wartime total ammunition production for these at-guns (over 11,2 million rounds) the number was fairly small. But, it was the ammunition model that still allowed these guns to have some change to fight against Soviet medium and heavy tanks, even if it can be considered as an emergency weapon. Basically Stielgrenade 41 was like a very large HEAT-warhead equipped rifle grenade, which was fired from end of barrel with blank cartridge and could be used both in German 37-mm AT-guns and AA-guns. HEAT warhead was capable of penetrating 180-mm of armour, making it dangerous to any tank. However, as the HEAT-bomb weighted some 8.5 kg and had muzzle velocity of only 110 meters/second, it could be used only from fairly short range. Maximum range was about 600 meters and the effective range only about 300 meters or so.

Already from 250 meter distance the average dispersion was considerable:

Vertical dispersion: 71 cm
Horizontal dispersion: 67 cm

When flight time from that range also was 2,4 seconds hitting a fast moving tank was not exactly easy. Using Stielgrenade 41 demanded one of the crew to go in front of the gun and push the grenade to end of barrel for each shot, so firing rate wasn't exceedingly high either. To make things even worse shooting Stielgrenade 41 could cause barrel raptures, even if this happened only once with Finnish Army, shooting live Stielgranade 41 during training was soon forbidden in Finland and this ammunition type was reserved only for combat use.

[Yoozername]

Two non-German guns that the German Army uses in an antitank role are shown at the left and right. At the left is the French 75 fitted with a muzzle brake and mounted on the Pak 38 carriage. At the right is the Russian Model 1936 field gun rebuilt as the 7.62-cm Pak 36 (r). The gun in the center is the gun with which the Russians intended to replace the Model 1936; it is known as the 76.2-mm Model 1939 field gun. The Germans have fitted it with a muzzle brake, and although they class it as a field gun, they also use it in an antitank role.

Note: The French 75 on the German 50mm carraige was extremely unstable in recoil when firing high velocity AP rounds. The Germans called it 'Mustang' or something similiar due to its kick. It was certainly not repeatable as far as returning to the same pointing condition. Some sources state that it mostly used with HEAT rounds.

The 1936 long barrel gun is the one also used on the early Marders. The early Marders on the 38t chassis may have had the advantage of turning in place (like panthers and tigers and some British tanks). This would have made them a very deadly AT system.

http://forum.axishistory.com/viewtopic. ... 6ce024d65b

The Germans mounted those French 75s on chassis also. I suspect that they could fire AP then with no problems.

[Yoozername]

On another forum a person described going to a AFV museum and checking the 'play' in various afv barrels. He stated that the T34s had significant play in the systems. Other afv he checked did not.

I suspect that the T34s had this play and if they did, it would be further compounded by sights that were not actually mechanically linked to the guns themselves.

An important device needed for long barrel weapons is a travel lock. In cases like the Panzer IV L43 and L48, it was an internal device that could be locked after raising the gun up. In other systems, like the Panther, it was a device external to the turret and acted as a rotation lock and a barrel lock. evidently, the driver or bow gunner would lock/unlock such a device.

The need for this is explained by Carius when he served in JagdTigers at the end of the war. If you drive for any period of time without it, you lose zeroing quickly. Another reason that AFV in defense have an advantage.

If a AFV had no lock whatsoever, I would seriously doubt that it could be an accurate weapon at range. Its first round shot could be a wild card that second and third rounds needed to hem in before bracketing a target. If the actual play in the system is greater than the least amount of sight adjustment, then you are just chasing your tail.

[Yoozername]

I would like to explore the Soviet 45mm Antitank gun since it was a common piece used by both sides....it has some interesting features.

http://www.russianwarrior.com/STMMain.h ... Tgun.htm&1

Here we see the ability of these weapons to be used with the wheels removed. On larger pieces, this would be a pain. On a light piece like this, it could be easily managed and allows a ATG to present a minimal height when quickly deployed. Notice the shield is hinged and can be let down to present an even smaller target. By throwing a small amount of foilage over the weapon, it is quickly camouflaged.

http://www.inert-ord.net/russ02i/mort_at/index.html

This website shows the rounds used. They look typical except that the HE rounds for this weapon had an unusual feature...

Muzzle Velocity
FRAG-Tracer (OT-033) - 2,890 fps (880 mps)
FRAG-Tracer (OR-73A) - 2,490 fps (760 mps)
HE (O-240) - 1,100 fps (335 mps)


The O-240 HE round has a remarkably low muzzle velocity. One might (wrongly) assume that means it was inneffective or innacurate.

Elevation With 4.7 lbs. (2.14 kg) HE (O-240) Shell
Range @ 45 degrees 5,470 yards (5,000 m)
payload HE (O-240) - 0.26 lbs. (118 g)

http://www.geocities.com/Pentagon/Base/1852/57mm.html






Note the rather long length of the HE shell. It has a unique thick-walled/thin-walled section. Note the hollow area that shows the absense of propellent. This might actually allow the projectile to experience a 'soft-launch' as opposed to the massive G accleration most projectiles experience.

Perhaps the best testament to ATG firing as support weapons is that panzergrenadiers disliked assaulting them intensely. As a further testament, the GI's in Korea ran into them...

In front of Seoul 2/5 from the 104 fights without a single heavy (machine) gun in action. We'd run into a swarm of 45mm AT guns, and they had sniped our heavy guns out of existence. Those 45mm AT guns fired a round that you could see leave the barrel and proceeded along like a red hot baseball. You could see them coming if they weren't aimed straight at you. Chilling.

My opinion is that firing a low velocity projectile from a long barreled weapon makes for some repeatable shooting. Part of the dispersion from firing HV weapons is the actual physical 'jump' of the weapon as it responds to the projectile engaging the rifling and the physical movement of the whole system. Some designs forego rifling the last part of the barrel for this reason.

The 45mm had a high rate of fire and would have been a fearsome weapon, just like a FLAK gun, when engaging softer targets. It actually should be compared with something like a 37mm HE round for effect. A US 37mm ATG HE round only has a 1.34 pound weight projectile with 1/10 pound HE. Even a 40mm (AA) gun has only a 2 pound projectile and 0.130 pound HE. The Soviet 45mm actually weighs more than a German 50mm HE shell I believe.

Here is a pic of a German 50mm HE shell that has exploded and the fragments recovered. I would estimate the Soviet 45mm to be more powerful by approx 10-15%. I suspect that the thin wall section is designed to throw out a superfast spray smaller fragments while the rear thick walled section will mostly generate larger fragments that will travel further. There must be some reason that the HE shell is laid out the way it is.