This is a translation of a Russian post, published on the developer's blog. I think it's actually pretty interesting and related to World of Tanks and it would be a shame not to have something like that in English, so... I hope the author doesn't mind :)
Original link: http://world-of-kwg.livejournal.com/150813.html
Translated and redacted by: Silentstalker (please note it's not a perfect translation, I had to redact some sentences to make sense in English)
Background and development
My friend Lyocha truly believes that the Schmalturm was a stopgap measure - there were few resources, there were even fewer workers available, so it was needed to make the turret as simple and functional as possible without hindering the possibility to actually shoot. And shape-wise, the Schmalturm turret was really simple, compared to the Rheinmetall turret (standard Panther turret) and to the Porsche turrets, used on Tigers, it didn't have too many accessories. But that is the truth only partially.
The ideas to modernize the Panther turret reach back to 1943 for three reasons. The first was to improve the weak turret armor of the Panther turret without actually increasing the weight. The second was that by that time, the Panther II project was already scrapped and the soldiers needed something to fight with. The third was, the Panther turret was too complex and too slow to rotate manually - in order to rotate it fast, the engine had to be switched on and revved, which really messed up the ambush tactics. The turret also acted badly if the vehicle was standing on some kind of a slope. As we can see, the Schmalturm development was not an act of desperation.
And so it was that in 1943 the Germans tried to modernize the Panther turret. The main idea was to reduce the possible space where enemy shells could hit the turret, which implied making the frontal armor of the turret narrower. Even then it was planned to increase the frontal sloped armor effective thickness to 120mm, so the shells don't ricochet into the driver's ass. By 1944, Rheinmetall presented drawn development ideas. The first name of the new turret was to be "Turm Panther (schmaler Blende)" (Panther turret with narrow profile). This turret represented a mixture of good traits of the Porsche turrets from the King Tiger, and the Panther turrets - it was compact, light and had a narrow frontal profile in order to minimize the chance of enemy shell impact. It also respected the demand for new armament, which later allowed the Germans to develop a project of 88mm L/71-armed Schmalturm.
On the top of the turret it was possible to install a rangefinder and there was also the possibility of installing the periscope gun sights. Most of the standard Panther equipment did fit into the Schmalturm turret. So, as we can see, the turret equipment was very, very decent, it cannot be simply called an "ersatz" project.
Later, the turret project was handed over to the Daimler Benz company. Therefore, it's no surprise that the Schmalturm turret has a lot of similiarities with the VK3002DB turret. By that time the order for the turret development was updated: it was ordered to implement the possibility to convert the turret into the command version or the night fighting version by the tank crew itself. An interesting fact: the rear hatch was made from a sheet of metal, that was carved out of the rear armor plate itself. This allowed for better resource savings, resources that the Germany was running out of by then.
The first Panthers with new turrets were supposed to come out of the factory in 1945, but that didn't happen for obviously reasons - when the Allies came to the factories, all they saw were unfinished parts of the vehicles.
Comparing the Schmalturm with the Panther turret
Even so, could the Germans have reached their goal? The turret weight did decrease, while the armor protection increased. The turret weighted only 7,5 tons (Panther turret - 7,6 tons). The machinegun was changed into a newer model. Even though the turret was called "narrow", the effective volume was the same, there was no difference for the crew. The commander's copula was "sunk". The turret ring diameter remained at 1650mm.
The turret was hydraulically powered by the engine, but the manual turret rotation drive was enhanced: if the tank was standing on a slope, the loader could install a spare flywheel and he could help the gunner - and so the turret rotated even faster. But the most important fact was that the turret mechanism, despite this enhancement, got actually smaller and less expensive while the rotation of the turret became easier.
The vertical gun aim mechanism was also changed, allowing to raise the gun to 20 degrees up and lower it to 4 degrees below the horizontal axis. This mechanism has also become lighter, cheaper and more compact. The commander's copula also got lighter and more compact while keeping all its previous properties: it was possible to set up the stereoscopic rangefinder, a night vision device or even an anti-aircraft machinegun.
The loader profitted even more: in the initial version of the project, a special periscope was installed for him. Later this option was removed and the periscope hole was covered with an armored plug. But if the periscope was installed, all three of the turret crewmembers would have very good night and day battlefield overview possibility.
A question arises while reading about all these great properties of the turret: is this really such a great turret? Not at all. If you compare the Schmalturm to the King Tiger turret, the Schmalturm doesn't end up as the winner. It was the original Panther turret that was so bad that in comparison to it, the Schmalturm comes out as the winner.
Schmalturm in World of Tanks
The first problem is the weight: the turret weight should be 7,5 tons. In the game it weights in various versions 10,8 tons, 4,6 tons, 12,5 tons, 13,2 tons... that's bullshit.
Second problem: maximum elevation. In real life, it was 20 degrees. In the game:
- Panzer IV Schmal: 20 degrees (as IRL)
- Panther: 17 degrees
- VK3001(H): 18 degrees
- VK3002(DB): 16 degrees
The turret rotation spead was in real life bigger than the one of the standard turret of the Panther: the turret was lighter and there was the additional flywheel. In the game, it's vice versa: the Schmalturm rotates slower and with different speeds:
- Panzer IV Schmal: 24 degrees
- Panther: 26 degrees
- VK3001(H): 25 degrees
- VK3002(DB): 30 degrees
- Panther II: 28 degrees
View range: In real life it was very good: all the crewmembers had their own viewing devices, night vision devices. In the game:
- Panzer IV Schmal: 370m
- Panther: 380m
- VK3001(H): 370m
- VK3002(DB): 370m
- Panther II: 390m
No complaints about the viewrange, but it's different every time.
Where to install it:
- Panther - as planned in real life
- VK3002DB - it had smaller turret ring, the installation of Schmalturm possible only if the whole hull was re-worked.
- VK3001(H) - I won't even comment on that
- Panzer IV - the Schmalturm was twice as heavy as the usual turret, the suspension wouldn't have survived that, but at least the turret ring is the same - remember the Panzer IV turret installed on the Panther hull.
Schmalturm mit 88mm L/71
Oh, that's a problematic topic. The thing is, in order to provide enough space for the loader to operate with a 88mm gun installed, the turret ring would have to be increased to 1750mm. The weird thing is, in the game the new turret with the new gun weights only like 1 ton more than the early Schmalturm model with the Panther gun.
With the new wider turret ring we can't even talk anymore about the turret installation on the VK3002DB and VK3001H. But the interesting part is, on the aforementioned tanks in the same turret, we have the 88mm. Glory to the great German designer Pasholok & Co.! And so, they glued the Daimler Benz gun mantlet on the short 88 despite the fact the gun mantlet fits only the LONG 88 and the Panther II is running around with the Krupp mantlet for a change. That's how they do it in Omsk. Pasholok wrote himself: there might be inaccuracies and mistakes, but the spirit (TM) is present.