Panzer IV

[Logan Hartke]

My understanding is that they were for weight and torsion distribution.  The greater number of contact points on the track meant for a more even weight distribution on the track itself, which meant it was less likely to get "tracked" and that it would have lower ground pressure (the Panther had better flotation than an M4 VVSS with extended end connectors!).  This should have resulted in more even wear on the tracks, but this advantage was thrown away when they ran out of synthetic rubber and went with steel roadwheels.  This also meant for less torsion per torsion bar because there were significantly more of them.  You have to remember, too, that the tank was a lot wider than a PzKpfw III, which also increases torsion.

The Panther had notoriously thin side armor.  Frontally, it had the armor equivalent of a Tiger I, but from the side it was considerably more vulnerable.  That's because it was originally a lighter, more reasonable medium tank that Hitler ordered the frontal armor to be increased on.  This cannot entirely be criticized, for without that uparmoring, the glacis plate would have been vulnerable to normal AP from the US 76mm and Soviet 85mm at normal combat ranges.  In the event, it was not vulnerable and that caused many a headache for the Allies, so you can't fault Hitler entirely for doing that.  You can't get something for nothing, however, and that now uneven weight distribution on the suspension caused the front torsion bar to break more frequently, which caused a domino effect on the rest of the torsion bars if not immediately replaced.  Unlike the Sherman, which could quickly exchange its entire suspension in a single day of work in the field, the Panther needed to get back to a depot or factory to have torsion bars replaced, so more often than not, they were just driven until two or three broke, then they were stripped, blown up, and left.  This didn't happen as often as one would expect, since most Panthers broke down mechanically, were burnt out from an engine compartment fire, or suffered a final drive failure before they ever got to that point.  The Panther was really a flawed design, automotively.

Cheers,

Logan

[dy031101]

So...... is it safe for me to assume that the idea of "German M26" on enlarged Geschützwagen III/IV chassis should be no problem otherwise? 

[Logan Hartke]

I really doubt it, to be honest.  The M26 was over 45 tons and I don't know a single German vehicle built on the PzKpfw III or IV suspension that was over 30 tons.  You're talking about 50% heavier than that chassis was ever rated to take.  The Jagdpanzer IV stressed the chassis enough as it was (though primarily because it was off-balance, but it still applies).  On top of that, you'd have to have a completely different hull and turret construction.  The Pershing was all cast and the Germans couldn't cast at that size.  It would all have to be welded.  In an effort to keep weight down, the biggest gun you could have would be the 7.5cm KwK 42 on that suspension and your armor couldn't be more than maybe ~70mm on the glacis.  Basically, you'd be aiming for a slimmed down Panther, what it was originally meant to be before it got all porked up.  That's as much as you could do on that suspension and you'd be pushing it.  Not only that, but what track would you use?  At 35+ tons, it would AT LEAST take Ostketten to not have awful ground pressure.

I think you could do a tough vehicle on a modified PzKpfw III/IV chassis, but I wouldn't use the M26 as inspiration, I'd look to the T-44.  It had an 85mm gun, 120mm armor, and the layout you'll need.  Like the Soviets, you'll need to get rid of that fifth man, but it's worth it.  The Soviets had a lot of reliability issues with the automotive components, but these were eventually corrected as the design matured as the T-54.

Logan

[dy031101]

T-44 is said to have used some innovative re-arrangement of engine and other components that allowed for even the 122mm gun in a 30-tonne-class package...... I don't know if I'll miss that bow MG, either.

Armament-wise I'd most likely not be asking for anything with a calibre larger than 100mm, but if the T-44 is to be looked to, would taking the 88mm (thinking KwK 36 here) or US 90mm gun as the turret armament have been possible?  Or would a welded turret with guns of such calibres definitely push the weight past the 35-tonne mark?

[Logan Hartke]

If you do it right, you might be able to.  I wouldn't recommend the KwK 36, though.  Too much weight for too little firepower.  If you can do the KwK 36, you may as well just do the KwK 43.  I'd recommend the 7.5cm KwK 42.  It worked quite well in small packages (AMX-13, M50 Super Sherman) and has just as good penetration.  US 90mm should be fine in that size package, too.  Get past that and you have to worry about gun recoil and turret ring issues, too.  The Russians would also cram people into tanks far worse than the Germans or Western Allies.  If you're doing a German tank, it's unlikely you can have vehicle quite as good as the T-44 for that weight.  The T-44 sacrificed some to get to that point, but it was still a great design.

The M18 Super Hellcat put a 90mm gun in a 20 ton turreted vehicle, but had paper-thin armor on the hull and no overhead protection.  It also needed a good muzzle brake before you could safely fire the weapon.

The welded vs. cast turrets have a lot of differences, but weight isn't usually one of them, so that's not a concern in and of itself.

Cheers,

Logan

[dy031101]

US 90mm should be fine in that size package, too.

The welded vs. cast turrets have a lot of differences, but weight isn't usually one of them, so that's not a concern in and of itself.

Then the US 90mm gun for possible post-war variant would be okay......  

What exactly doomed the Super Hellcat?  The 90mm gun without a muzzle brake is too powerful for the M18 hull and chassis...... so is it that they just couldn't find a good-enough muzzle brake quickly enough?

[Logan Hartke]

No need.  That's what doomed it.  It came too late.  Had the war gone on to 1946 or 1947 it would have made it to the battlefield.  Some authors report that it would never have worked, but reports show that it was considered perfectly adequate once a muzzle brake was installed.

Logan

[rickshaw]

Countries THOUGHT they wanted something different.  In the end, however, they all came around to the same basic ideas.  Not AP (British & Germans) or HE (US), but BOTH.  The Russians were actually in the BOTH camp before the war, not the HE.  That's why you saw the Russian 45mm as the only light tank gun with a useful HE round.  Nobody else had that at the time.

The US 37mm, the German 37mm, the British/Commonwealth 2 Pdr all had HE rounds.  I am unsure what critaria you're using for "useful" but all had them developed for those weapons and while the 2 Pdr HE wasn't issued until 1943, it was available in 1939.  In fact the 2 Pdr was unusual, it had two, seperate HE rounds developed for it - the British and Australian did so semi-independently of each other.  The British round was a nose-fused round while the Australia one was a base-fused round.

I agree that experience eventually showed the inadequacy of all the major powers' pre-war doctrines on the use of Armour.  The British division between Infantry and Cruiser tanks, the German and Russian concepts of "break through" and "pursuit tanks" and the American concept of "tanks" versus "tank destroyers" were shown to be artificial, which is why in the end the British sought a "universal tank" and produced the Centurion to fulfill it.   However, those artificial divisions did exist and vehicles were designed to fulfill those roles, hence the difference in the sorts of ordnance carried by different nations' vehicles.

They just had a more practical approach in developing an AP weapon.  In fact, the Soviet 122mm gun was chosen for the IS tanks over the 100mm gun for two main reasons.  One was that it was more readily available.  You could build more IS-2/3 tanks faster if they were armed with the 122mm gun than if it were armed with the 100mm gun.  The second reason?  It was better at killing German tanks.  While the 100mm gun was in some cases just as good or better at penetrating thick armor than the 122mm, German armor quality had gone down in the second half of the war and the greater mass of the 122mm gun was causing very, very nasty things to happen to German tanks.  The armor was spalling far worse, welds were breaking and whole armor plates were falling off, plates were cracking like the glass in a window.  It was bad.  The Soviets knew this because they made their decision based on testing against a captured German Panther, not test armor plate.

The 122mm gun was not picked because it had a better HE round (although it did) and the IS-2 was envisioned for "infantry support".  That's a myth.  The SU- and ISU-152 were intended moreso for that role (and heavy tank busting, too).  It was picked because it was the more lethal tank killer and was more readily available.  The Soviets were smart enough to see that a future war would not be fought against countries with brittle armor and they knew the 122mm gun was inefficient for its weight, so they planned for their next tank to have a 100mm gun, not a 122mm gun.  That tank would be the T-54 and it shows the Soviets were on top of their game at the end of WWII when it came to tank design.

That is an interesting story.  However, it runs counter to every account I have read of the choice for the IS-II's maingun.  Where did you find out about it?  The accepted version is that the 122mm was chosen over the 100mm because of the 122mm's superior HE content.  Remembering that the role of the IS series of heavy tanks was that of a "break through" tank, it was felt that it was more important to have a weapon who's rounds would be more useful in destroying strong points than in destroying opposing armoured vehicles.  The 122mm proved happily to be able to do both jobs quite admirably, although one wonders whether or not a purposed designed APCR or APDS round might have been advantagous over the plain AP round that it fired when facing tanks.

Yeah, I agree and I often go back and forth on which suspension is the best.  I will agree that torsion bar suspension has major limitations.  Practically, for a Sherman-size vehicle, HVSS was probably the best.  It allowed for higher top speeds than Horstmann, but was likewise externally mounted and very, very easy to replace.  HVSS isn't optimal when you get into the heavier weights, though.  Horstmann suspension is very durable and externally mounted, but not perfect.  It doesn't give as nice of a ride as torsion bar (important when engaging targets on the move) and doesn't allow for as high speeds.  That's the reason why the Merkava no longer uses Horstmann-style or Horstman-inspired suspension on the Merkava starting with the Merkava 3.  The greatest development of the Centurion, the Olifant 1B and Olifant 2 ditched the Horstmann for torsion-bar.  It's the better suspension.  All things have their good and bad points, however.

The ride, particularly at speed is without a doubt superior on modern hydrobar torsion suspensions but that is only possible with the use of advanced metallurgy.  However, that must be offset against the already mentioned difficulties in producing the torsion bars and the difficulty of maintenance and replacement in the field.  Personally, I'd go with a Horstman design.  It is relatively cheap and easy to manufacture and provides an adequate ride up to speeds of about 50 mph (on roads and about half that cross-country).  Particularly when one considers that during WWII, fire on the move wasn't achievable.

I agree here.  After the PzKpfw III, torsion bar was the wrong choice for the Germans.  Really this was as much due to new metallurgical concerns as anything, but the excessive weight of new German tanks had as much to do with it as anything.  Whatever the reason, you play the hand you're dealt and the Germans played it poorly when it came to tank suspension.  I've read the stories of Panther breaking torsion bars (especially up front) when just sitting around because it wasn't designed to take the Panther's weight (Hitler had it uparmored before it went into production).  Basically, it had no room for growth.  German torsion bars couldn't be as strong as they had to be because they didn't have the quality of metal they had earlier in the war.  For that reason, they just doubled the number of roadwheels and torsion bars, which allowed everything to be weaker, or that was the idea at least.  That's why you saw that overlapping roadwheel style of suspension.  Ridiculous.  That isn't a choice at all.  Americans could build much higher quality torsion bars, as could the Soviets.  The Soviets also had weight control in tank design.  Germans didn't think about that, apparently.  For that reason, you saw Americans and Soviets building high-quality torsion bar suspension for their medium and heavy tanks at the end of the war and sticking with it to this day.  It works and works well.  More maintenance-free than most externally-mounted suspension types, too.

I severely doubt that the Panther broke torsion bars "just sitting around".  I am also aware the the MAN design for the Panther always featured the interleaved wheel suspension system so that was not added as an afterthought, either.   I am also unsure where you got the idea that the Germans did not have "weight control" in their design practices as its not something I've read anywhere. As to the amount of maintenance that is required on a torsion bar suspension, its about equal to that as required on most externally mounted systems.  The interleaved wheel design had a great deal more to do with ground pressure and weight distribution along the tracks than anything else.  The Germans deliberately chose it for its superior ride quality as well.   However, they were planning to partially abandone it with the E-series which utilised Bellville Washers.

I also find your concern about the barrel life on high velocity guns quite interesting.  Considering that the service life of most German tanks late in WWII was shorter than the barrel life of their guns, its not a great concern.   Interestingly, the German introduction of sintered-iron driving bands on most of their artillery shells, actually improved the barrel life of their ordnance, over the conventional copper ones which they had used previously and which was used extensively by the Allies, both Western and Eastern.   Sintered-Iron also tended to improve the accuracy, producing more consistent "throw" of the rounds.  Copper however is easier to work with and doesn't require quite the same tolerances, so its generally chosen by most ordnance designers.

As you note, torsion bars require better metallurgy to produce consistent results.  Because of the German loss of Finland, by the end of the war, their access to Nickel - required for high tensile strength steels was also lost, with the resulting loss in quality.   This was, BTW, also the major reason why the Me-262 was delayed into production and why the Jumo-004 jet engine was so unreliable.   

[Sauragnmon]

Very interesting information presented, Rick.  I can't help but find myself wondering if the Sintered Iron Driving Bands on a rifled round would allow higher grade propellants to be used as well - I know when Bull redesigned the rifled artillery bore and managed to do away entirely with driving bands he could amp up the strength of propellants used, which in previous guns would simply have resulted in blowing the driving bands off the rounds and the round going in effect nowhere.

One could wonder at the increased effectiveness that the IS-2 could have gained in its 122mm gun if it had used an APDS round, or even an APC round with a base fuse and a slightly shaped charge to increase blast effectiveness against the target.

[Logan Hartke]

The US 37mm, the German 37mm, the British/Commonwealth 2 Pdr all had HE rounds.  I am unsure what critaria you're using for "useful" but all had them developed for those weapons and while the 2 Pdr HE wasn't issued until 1943, it was available in 1939.  In fact the 2 Pdr was unusual, it had two, seperate HE rounds developed for it - the British and Australian did so semi-independently of each other.  The British round was a nose-fused round while the Australia one was a base-fused round.

I didn't say the 37mm and 2pdr guns didn't have an HE round.  I'm well-aware that they did.  That's why I used the qualifier "useful".  The Soviet 45mm fired an HE round about twice the weight of a 37mm HE round.  After German tanks got thicker armor, Russians still lugged around the 45mm AT gun for the rest of the war as HE fire support.  It was like a bazooka for the Soviets (since they didn't have nearly as many bazookas as the US, for example).  By comparison, the HE content of the 37mm and 2pdr guns was so low that once they were no longer useful in the AT role, they were discarded.  Only the US still found a use for the 37mm gun with its canister round in the Pacific.  The Soviet 45mm gun had a heavier HE round than the German 5cm Pak 38/KwK 38/39!

The Soviets placed real value in that gun's ability to support the infantry and therefore the ability of their tanks to support the infantry as a whole.  Compare that with the British, whose use of tanks in the desert was oftentimes a one man show.  Heck, they had to make "Jock Columns" just to give the infantry something to do.  As you noted, the late issue of British HE rounds for the 2pdr
show how little importance they placed on direct fire HE support for their infantry.  There were the 3inch howitzer-armed tanks, but those were rare on the battlefield due to the low level of importance given to them.

I agree that experience eventually showed the inadequacy of all the major powers' pre-war doctrines on the use of Armour.  The British division between Infantry and Cruiser tanks, the German and Russian concepts of "break through" and "pursuit tanks" and the American concept of "tanks" versus "tank destroyers" were shown to be artificial, which is why in the end the British sought a "universal tank" and produced the Centurion to fulfill it.   However, those artificial divisions did exist and vehicles were designed to fulfill those roles, hence the difference in the sorts of ordnance carried by different nations' vehicles.

The Centurion wasn't designed as a Universal tank.  It was designed as a Cruiser with compromises.  The FV200 failed.  The Centurion was good enough to fill the role, though.  Really a great, adaptable tank for all its flaws and odd development.

That is an interesting story.  However, it runs counter to every account I have read of the choice for the IS-II's maingun.  Where did you find out about it?  The accepted version is that the 122mm was chosen over the 100mm because of the 122mm's superior HE content.  Remembering that the role of the IS series of heavy tanks was that of a "break through" tank, it was felt that it was more important to have a weapon who's rounds would be more useful in destroying strong points than in destroying opposing armoured vehicles.  The 122mm proved happily to be able to do both jobs quite admirably, although one wonders whether or not a purposed designed APCR or APDS round might have been advantagous over the plain AP round that it fired when facing tanks.

I misread part of the account, so I will agree that HE content was one of the deciding factors.  The 122mm gun's incredible performance in trials against a captured Panther, however, is what really made it the only choice for the role.  If Germany had had the ore required to keep good quality welds and less brittle, less defective armor plate, the 122mm gun would likely have been less effective than the 100mm gun in the AT role.  As it was, however, the sheer weight of the round proved devastating to German tanks.  In the trials, it ripped right through an armor plate, breaking the welds holding it in place.  The 100mm gun would put a nice hole in your armor and do awful damage to the insides.  A 122mm round would turn the inside into the outside.

I am well aware that the 122mm gun had wonderful HE performance, though.  That's what it was designed for originally.  It was a great gun in both roles and the Russians are about the only country to field tanks throughout the war armed with guns that were just as much at home firing HE as AP.  The 45mm, the 76mm, the 85mm, and the 122mm were all great dual-role guns.

The ride, particularly at speed is without a doubt superior on modern hydrobar torsion suspensions but that is only possible with the use of advanced metallurgy.  However, that must be offset against the already mentioned difficulties in producing the torsion bars and the difficulty of maintenance and replacement in the field.  Personally, I'd go with a Horstman design.  It is relatively cheap and easy to manufacture and provides an adequate ride up to speeds of about 50 mph (on roads and about half that cross-country).  Particularly when one considers that during WWII, fire on the move wasn't achievable.

Up to 50 mph?  I don't doubt it, although again, "adequate" is subjective, but I wasn't aware of a vehicle heavier than a Universal Carrier (hardly applicable) that's ever gone over 30.  Which Horstmann-suspension tank has?

I severely doubt that the Panther broke torsion bars "just sitting around".  I am also aware the the MAN design for the Panther always featured the interleaved wheel suspension system so that was not added as an afterthought, either.   I am also unsure where you got the idea that the Germans did not have "weight control" in their design practices as its not something I've read anywhere. As to the amount of maintenance that is required on a torsion bar suspension, its about equal to that as required on most externally mounted systems.  The interleaved wheel design had a great deal more to do with ground pressure and weight distribution along the tracks than anything else.  The Germans deliberately chose it for its superior ride quality as well.   However, they were planning to partially abandone it with the E-series which utilised Bellville Washers.

By "just sitting around" I meant they weren't dropped from a crane, fell off a cliff, or something similar that one would expect to cause undue stress.  Normal driving was enough, driving in the mountains such as those in Italy were much harder on it.



Now this is an Ausf D, so it's probably only about a year and a half old at the time of this photo, which is not too old for a tank, but ancient for the average Panther, since you could measure the lives of most of them in weeks.  Again, that's why you didn't see it that often, but I'd love to have seen Panther try to serve in the Israeli Army for 50 years.  You'd either be replacing those torsion bars in depot all the time or you'd give up trying after not too long.

I wasn't saying the Germans didn't do any weight control, just that they seemed to not always do as good of a job or--more likely--make it as important to them as the Soviets did.  Eventually, some of this would come back to bite them with the T-64, but it paid off quite well overall.  They were able to get the IS-2 for the same weight as a Panther and have a great, wonderfully reliable torsion-bar suspension to go with it.  I wasn't saying it was an afterthought to do the interleaved roadwheels in German tank construction, but as far as tank design goes, it was a design choice they made as a compromise to allow for the increase in weight of their new vehicles.  Look at the Tiger I.  It was a great tank, I'll grant you, and ahead of its time in many ways.  But there you had a tank with only 110 mm effective armor at best, a main gun that could penetrate 100mm at 1000m, and it tipped the scales at 60 tons.  Less than two years later the Russians had a tank with nearly half again as thick armor at most, a much better performing gun, and it weighed 15 tons less.  The Soviets and Americans rightly decided to leave the monsters at home until they could get their weight under control.  The Germans had no problems with putting a 60ton tank on the battlefield, at least in theory.  Actually getting it there and getting it back again would prove to be nearly impossible in many cases.

The Germans either couldn't or didn't try to get the weight of their tanks under control and so they paid for it.  Tanks were more expensive and difficult to build, sucking up more resources.  That made for far fewer of them on the battlefield.  They were too heavy for many bridges, making it harder and even dangerous to get them to a battlefield.  They were too heavy for their automotive components, leading to more common breakdowns and failures of engines, final drives, transmissions, and torsion bars.  Finally, once broken down, they were too heavy to recover, causing many breakdowns to result in total losses.

I also find your concern about the barrel life on high velocity guns quite interesting.  Considering that the service life of most German tanks late in WWII was shorter than the barrel life of their guns, its not a great concern.   Interestingly, the German introduction of sintered-iron driving bands on most of their artillery shells, actually improved the barrel life of their ordnance, over the conventional copper ones which they had used previously and which was used extensively by the Allies, both Western and Eastern.   Sintered-Iron also tended to improve the accuracy, producing more consistent "throw" of the rounds.  Copper however is easier to work with and doesn't require quite the same tolerances, so its generally chosen by most ordnance designers.

Again, it wasn't a huge issue for the Germans since the service life of German tanks was indeed shorter than many of their components.  Ammunition was scarce, too, so it's not like they were training with the guns when not in combat.  That being said, it's not something I'd want in my ideal tank.

As you note, torsion bars require better metallurgy to produce consistent results.  Because of the German loss of Finland, by the end of the war, their access to Nickel - required for high tensile strength steels was also lost, with the resulting loss in quality.   This was, BTW, also the major reason why the Me-262 was delayed into production and why the Jumo-004 jet engine was so unreliable.

All true.  They put the horse in front of the cart, in a way.  It's like trying to build atomic weapons without plutonium or uranium.  You may as well not waste your time.

Cheers,

Logan

[buzzbomb]

Hi folks, new here.. well posting wise anyway after a many moons lurking.. Blame Puddingwrestler
Thought I should kick off with a post and as a Mk IV fan, if have had this around for a while

I noticed the Pz IV Rakette has been talked about in this thread, so here is my idea on this vehicle



Plastic card work

This vehicle really had every chance to exist, the missile the Rot Kappchen (Little Red Riding Hood) did exist
info can be found here
http://www.geocities.com/Augusta/8172/panzerfaust12.htm
and the stretch for Panzerwaffe '46 to have a ATGM vehicle mount is not that much

Anyway hope to add some more shortly.. the next PZ IV plan is for a mobile AA Guided Missile mount with a Mk IV with the Rheintochter missile

Cheers
Brian

[ChernayaAkula]

^ Wow! What a cool build!  And the link on ATGMs is also very interesting.

Good to have you here!  We need more tankers.

[Doc Yo]

 Hey, Brian-Welcome aboard! Splendid build with the Mk IV/Rotkappchen...and I have to ask-where did you
find a 1/35 Rheintochter? Or are you scratchbuilding it?

[NARSES2]

That is very interesting and plausable - wellcome aboard.

[buzzbomb]

I have to ask-where did you  find a 1/35 Rheintochter? Or are you scratchbuilding it?

Cromwell models make a very nice Rheintochter on the late 88mm mount, but being far too cheap for that I am going to attempt a scratch build, I have found some dimensions that appear reliable.
It is a big missile, over 5m long so should look impressive. Another possibility is to use the Enzian type missile as an alternative, it is smaller, but does not have all the fins that makes the Rheintocter look so sexy.

This is still an in the box and on paper build so nothing started yet.. but stay tuned
One page of many on the Rheintochter
http://www.cloudster.com/RealHardware/Rheintochter/RheintochterTop.htm

Enzian
http://www.walter-rockets.i12.com/missiles/enzian2.htm


Oh, and thanks for the welcome folks