Reason for Panzer Mk IV mass production

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Dave Bender
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Reason for Panzer Mk IV mass production

#1

Post by Dave Bender » 01 Jan 2011, 05:16

Everything I have read suggests Panzer Mk III suspension was superior to the Panzer Mk IV. Both tanks were similiar in size. So why was the Panzer Mk IV chosen over the Panzer Mk III for mass production armed with a high velocity 7.5cm/43 main gun?

Some suggest it was due to the Panzer Mk IV having a larger turret ring. But the turret ring can be changed. For instance the Kugelblitz AA turret required a 1900mm turret ring from the Tiger I. There were plans to mount the Kugelblitz turret on vehicles as small as the Hetzer. Modiflying the Panzer Mk III with the Panzer Mk IV turret ring should be simple by comparison.

Kocur
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Re: Reason for Panzer Mk IV mass production

#2

Post by Kocur » 01 Jan 2011, 16:55

Dave Bender wrote: Some suggest it was due to the Panzer Mk IV having a larger turret ring. But the turret ring can be changed.
It can, but it would take no less than designing a new superstructure for Pz. III chassis, while in case of Pz. IV the upgunning with KwK 40 was basically just a tube change (and recoil mechanism plus gun ammunition stowage arrangement perhaps and such details). So I guess it was a matter of delivery time of upgunned tanks.


Dave Bender
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designing a new superstructure for Pz. III chassis

#3

Post by Dave Bender » 01 Jan 2011, 18:18

A bunch of such superstructure changes were made for other German armored vehicles. For instance:

Beobachtungswagen III (observation vehicle)
Bergepanzer III (recovery vehicle)
Sturmgeschutz III (7.5cm assault artillery)
Sturmhaubitze 42 (10.5cm assault artillery)
Stug 33 (15cm howitzer carrier)
Munitionspanzerwagen III (ammo carrier)
Pionier Panzerwagen III (pioneer vehicle)

So why not install a larger turret ring and turret for the 7.5cm/43 high velocity cannon? It cannot be more difficult then the above design changes to the Panzer Mk III.

Kocur
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Re: Reason for Panzer Mk IV mass production

#4

Post by Kocur » 01 Jan 2011, 18:27

I guess they were in hurry much more in case of KwK 40 armed tank than in other cases.

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peeved
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Re: Reason for Panzer Mk IV mass production

#5

Post by peeved » 01 Jan 2011, 20:37

It doesn't appear to have been just a simple case of changing the turret ring and turret size. As you can see from the pics below from Der Panzerkampfwagen III und seine Abarten by Walter J. Spielberger the Pz. IV hull superstructure (on the right) was over half a meter wider than the Pz. III equivalent and thus could comfortably be modified to take e.g. the 1900 mm Kugelblitz turret race. It would OTOH probably have been possible to e.g. mate the Pz. III lower hull with modified Pz. IV hull superstructure to introduce a bigger turret to the Pz. III since the lower hull dimensions (apart for the ca. 100 mm height increase in Pz. III; Possibly necessary to accomodate torsion bars) were quite similar.

Markus

P.S. The Pz. III hull superstructure length dimension appears to be a misprint.
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Dave Bender
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pics below

#6

Post by Dave Bender » 02 Jan 2011, 01:19

Thanks for the drawing!

Turret Ring Size.
1,520mm Panzer Mk III
1,680mm Panzer Mk IV
1,900mm Tiger I
I envision increasing Panzer Mk III turret ring size only to 1,680mm. At least that would be the plan during 1941 to 1942. The modified Panzer Mk III would get the turret and main gun historically mounted on the Panzer Mk IVG.

Stug III Auf G. 23,900kg. Heaviest vehicle to use the Panzer Mk III Chassis.
Panzer IV Auf G. 23,500kg.
The Panzer Mk III chassis can accomodate the weight of the larger turret.

Hull Armor. Front / Side / Rear.
50mm / 30mm / 20mm. Panzer Mk IV Auf G.
50mm / 30mm / 50mm. Panzer Mk III Auf L.
Similiar armor except on the rear. I wonder why Panzer Mk III rear armor was so thick?

The Panzer Mk IV had a bit more hp (300hp vs 265hp). However I suspect the Panzer Mk III was faster when moving cross country due to superior suspension. Which is my primary reason for preferring the Panzer Mk III over the Panzer Mk IV.

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Re: Reason for Panzer Mk IV mass production

#7

Post by nebelwerferXXX » 02 Jan 2011, 03:09

@peeved
Nice drawings, Are you an Engineer? Just asking...Thanks!

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peeved
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Re: Reason for Panzer Mk IV mass production

#8

Post by peeved » 02 Jan 2011, 23:37

Hi nebelwerferXXX,

To give credit where it's due, the drawings though unsigned are probably Hilary L. Doyle's who was Spielberger's scale illustrator.

Regards,
Markus

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peeved
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Re: Reason for Panzer Mk IV mass production

#9

Post by peeved » 03 Jan 2011, 00:14

According to Spielberger the conversion of Panzer III to Panzer IV turret was discussed in March 1942. In light of the difficulties thereof like a significant increase in total weigh, new suspension, new tracks and change in CoG Hitler vetoed this development.

Maybe the answer to Pz. IV's suspension troubles could have been deepening the IV's lower hull somewhat and installing a Pz. III type suspension. Due to the IV hull's full length side walls seven pairs of torsion bars could probably have been fitted.

Markus

Dave Bender
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Re: Reason for Panzer Mk IV mass production

#10

Post by Dave Bender » 03 Jan 2011, 04:44

Maybe the answer to Pz. IV's suspension troubles could have been deepening the IV's lower hull somewhat and installing a Pz. III type suspension.
That sounds like more work then increasing the Panzer Mk III turret ring size.

Perhaps putting the 32 ton VK3001 tank into mass production would be the best solution of all. Development started during September 1938 so it should be close to production ready by late 1941. The historical Panzer IVG turret shoud be a perfect fit for a tank of this size.

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Re: Reason for Panzer Mk IV mass production

#11

Post by Dubliner » 03 Jan 2011, 05:02

The transition to using a torsion bar suspension in the Pz.Kpfw.III Ausf. E was not painless for Daimler-Benz. The change in suspension, along with a untested transmission and steering units, was the brain child of a outside engineer, Kniepkamp at Waffenamt. When things went wrong with these new untested automotive components in the field, Daimler-Benz had to scramble to prevent disaster. The situation caused a great deal of bad blood and had a significant impact on future development work at Daimler-Benz, so much so, that DB's offering for the Panther in 1942 had a leaf spring suspension.

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John Hilly
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Re: Reason for Panzer Mk IV mass production

#12

Post by John Hilly » 03 Jan 2011, 13:04

I'm no expert of engineering in any ways.
But the Finnish experience of StuG 40G and StuG III was, that the first two ground wheels and suspension wore out very quickly because of the front weight increased by the 7,5 cm/L48 gun.
Maybe this was the reason of reducing the use of Pz III chassis for heavier weaponry? :?

With best
Juha-Pekka :milwink:
"Die Blechtrommel trommelt noch!"

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Re: Reason for Panzer Mk IV mass production

#13

Post by nebelwerferXXX » 03 Jan 2011, 13:34

@peeved
thanks!

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Re: Reason for Panzer Mk IV mass production

#14

Post by barbarossa28 » 03 Jan 2011, 16:23

Hello Pekka,

The Panzer III chassis production was not reduced caused by heavier weapons! The opposite is true. The production of the Panzerkampfwagen III was stoped in 1943 but the Sturmgeschütz III G production was significantly increased. In the first time, Panzer III chasis were used to increase the Stug III production. Later, the Panzer III chasis production was changed to Stug III chassis.

Regards,

Holger.

Dave Bender
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Re: Reason for Panzer Mk IV mass production

#15

Post by Dave Bender » 03 Jan 2011, 17:41

Panzerkampfwagen III was stoped in 1943 but the Sturmgeschütz III G production was significantly increased.
That's what happened historically. But to me it makes more sense for the Panzer III to become the German main battle tank armed with a 7.5cm high velocity cannon. You take advantage of the superior torsion bar suspension.

StuGs, SP artillery, SP AA etc. could be built on the low tech Panzer IV chassis. I don't think cross country speed is as important for those vehicles.

Alternately place the 32 ton VK3001 into mass production during 1942 ILO both the Panzer III and Panzer IV. Build 10s of thousands of them including chassis for SP artillery, SP flak, StuG (with 8.8cm main gun) etc. A German equivalent to the American Sherman and Soviet T-34.

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