Ready for El Alamein: ideal British tanks

[Juha]

Hello
did some checking on 1 Sept 39 WM had 211 Pz IVs but only 98 Pz IIIs.
At Kursk on 4 July 43 WM had 711 Pz IIIs, the most numerous panzer there was Pz IV (784) and 3rd most numerous was Pz V (200)

On British might be tanks. One answer might have been that WC and War Cabined would have been less enthusiastic to Bomber Campaign and so with less heavy bomber production there would have been opportunity to earlier production of Meteor engines, so a Cruiser with Meteor engine ie something like a Cromwell with 6pdr or 3" for the CS version.

Also Valentine as a backup if the new tank run into technical problems, at least the Valentine was very reliable and was the only British tank which Soviets wanted more, partly because they classified it as a light tank and as such it was well protected and reasonably well armed. And Valentine would have needed a version which would have been able to fire effective HE shell. A better version of Bishop?

Juha

 

[Shortround6]

Even the Germans only got a 128 in a rotating turret in the Maus which is the embodiment of quality over quantity taken to the extreme. A total waste of money man-hours and material.
The Russians did better with the 122mm armed tanks. The 152 was a Howitzer which didn't have the recoil stresses of a high velocity gun.

For an idea of what is involved with WW II guns we can look at the weights of some AA guns
American 90mm, this one was turned into a tank gun, 2445lbs for the barrel and breech for 2700fps with a 23.4lb shell
British 3.7in. 3,931lbs for 2600fps with a 28lb shell.
American 105mm, again this one was modified into a tank gun, never issued. 6575lbs for 2800lbs with a 32.75lb shell

It amy have been used a few prototypes and this;
http://fc05.deviantart.net/fs28/i/2008/083/4/d/T_28_Tank_by_ElectronKing.jpg

1943 gun technology was not the same as 1955 gun technology.

 

[parsifal]

i agree, as stated above the nearest the brits came to this sort of lunacy was the a-39 tortoise. 6 built, weight 78 tonnes, main armament 94mm (32 pounder, a development of the 3.9in HAA gun). Developed 1942, but not progressed with any urgency, could have been ready 1943. Was an SPG rather than a tank. probable deployment, if given priority early 1944. in the context of WWII requirements, a total waste of resources

 

[davebender]

German tank doctrine in early part of the WWII called for both Pz III armed with light gun with good penetration power but also capable to fire HE shells and a support tank with heavier gun for more powerful HE (Pz IV). What killed this was the impact of Soviet T-34s and KVs

Let's refer to the historical timeline.
1935.
Germany funds development of the Panzer Mk III and Panzer Mk IV. This is a slow process as Germany has essentially no tank design or production capability during 1935.

9 Sep 1938.
Germany funds development of the 32 ton VK3001 tank. Intended to replace both the Panzer Mk III and Panzer Mk IV.

September 1939. Britain and France declare war on Germany.
This changes priorities. Germany needs weapons ASAP. They cannot wait for the 32 ton VK3001 main battle tank.

September 1939. Panzer Mk III ausf F enters production.
This is the first mass production German medium tank. 435 produced Sep 1939 to July 1940.

October 1939. Panzer Mk IV ausf D, E and F enter production.
Similiar vehicles so I have lumped them together
229 Panzer IV D. Oct 1939 to May 1941.
233 Panzer IV E. Sep 1940 to April 1941.
487 Panzer IV F1. April 1941 to March 1942.

1941. Four VK3001 tank prototypes produced.

25 Nov 1941. Germany orders development of the Panther tank.

1942. VK3001 tank cancelled in favor of the larger Panther tank. The advanced VK3001 suspension is carried forward in the Panther design. Consequently Panther tank development is relatively fast.

Aug 1943. Panther ausf A enters mass production. Only 21 months after development began! (850 pre-production Panther ausf D were rushed into service even sooner. As one would expect, these not fully developed Panther tanks had mechanical reliability problems.)

IMO Germany did not originally intend for the Panzer Mk III and Panzer Mk IV to enter mass production. The 32 ton VK3001 was intended to be the Heer main battle tank. It would have been capable against both soft targets and enemy tanks. WWII derailed these pre-war German tank development plans.

 

[parsifal]

There is little evidence to support that. VK 3001 was a 32 ton prototype, afforded low priority with an expected introduction to service of 1942. It was never intended to fully replace the mk III and mk IV tanks merely to provide a heavier version of the mk Iv and was to act as a support element to the abteilung. It was to be armed with an L24 75mm short gun, the same as the mk IV, with the possibility of fitting a 105 mm L28 howitzer, but this came later. In fact, no armament and no turret of any kind was ever fitted to any of the 6 prototypes.

guderian never thought much of this project. He always thought the main equipment of the panzers should be the mk III/IV combination. it seems that the VK3001 had overlapping roles. it was somewhat heavier than a mk IVand a revised suspension with innovative interleaved wheels. However in general layout it was similar to the earlier VK 2601, multi-turreted tank, eventually designated pzkpfwV, which were pretty much german interpretations of other multi-turreted tanks like the Char b and T-28. These were reasonably successful as a design, but never entered ful scale production, because their low speed precluded their effective use in a fast moving offensive formation like a panzer div. given one of the main problems with the Vk 3001 was the relatively low power and unreliability of its engine, it is likley that its low development priority and ultinate rejection was for similar reasons....it had no role in a mobile all arms formation like a panzer division.

 

[Shortround6]

Let's refer to the historical timeline.

Yes, let's do that.

September 1939. Britain and France declare war on Germany.
This changes priorities. Germany needs weapons ASAP. They cannot wait for the 32 ton VK3001 main battle tank.

September 1939. Panzer Mk III ausf F enters production.
This is the first mass production German medium tank. 435 produced Sep 1939 to July 1940.

I guess that depends on what you mean by mass production. 96 MK IIIE's made from Dec of 1938 until Oct 1939. MK IIIF is basically the same tank and while the first one doesn't role out the door until Sept 1939 that is not when the orders were placed is it? One source even says that the order for 1250 IIIGs was placed in January of 1939 but reduced to 800 in may of 1939 When Czech production of the 38(t) became available. Orders for 759 IIIH's were also placed in Jan of 1939 orders modified as time went on but with well over over 2,000 MK III tanks on order in Jan of 1939 it is a little tough to swallow the idea that it was NOT the Germans choice for their main battle tank or that they had to produce what they could because France and England declared war on them 8 months after they placed the orders.

October 1939. Panzer Mk IV ausf D, E and F enter production.
Similiar vehicles so I have lumped them together
229 Panzer IV D. Oct 1939 to May 1941.
233 Panzer IV E. Sep 1940 to April 1941.
487 Panzer IV F1. April 1941 to March 1942.

That rather conveniently skips over the 42 MK IVBs and 134 MK IVC built before Sept of 1939 and the fact that hundreds more were ordered back in Jan of 1938.

Just like airplanes, it takes many months if not a couple of years to tool up and get a tank factory producing in real numbers after an order is placed.

IMO Germany did not originally intend for the Panzer Mk III and Panzer Mk IV to enter mass production. The 32 ton VK3001 was intended to be the Heer main battle tank. It would have been capable against both soft targets and enemy tanks. WWII derailed these pre-war German tank development plans.

With thousands of MK IIIS and hundreds if not over thousand MK IVs on order Months before WW II started the Germans had a funny way of not intending to mass produce those tanks.

 

[davebender]

Unless you believe that there no advances in barrel forging technology, metallurgy, and propellant technology in the 15 years or so between 1942 and the coming of the 105 L7 gun. The fact that the L7 didn't fire full bore AP rounds might have something to do with it being successful from a 43 ton tank without a muzzle brake.

Achtung Panzer! - Prototypes !
WWII Germany actually produced a prototype high velocity 105mm tank cannon. If it will fit on a 25 ton Panzer IV ausf A chassis I think it could be made to fit in the turret of a 45 ton Panther, 51 ton Centurion or 55 ton Tiger tank.

 

[Juha]

Hello Dave
why to bother
8,8cm L/71 had clearly better penetration power than that 10,5cm gun, even 17pdr (76,2mm) wasn't far off even with APCBC (appr 95 vs 111mm at 30deg from 2000m)

Juha

 

[davebender]

Because 105mm is the ideal size HE shell for supporting infantry operations. And tanks spend more time shooting at infantry then they spend shooting at enemy tanks.

 

[Shortround6]

Achtung Panzer! - Prototypes !
WWII Germany actually produced a prototype high velocity 105mm tank cannon. If it will fit on a 25 ton Panzer IV ausf A chassis I think it could be made to fit in the turret of a 45 ton Panther, 51 ton Centurion or 55 ton Tiger tank.

No, the Germans didn't have a "prototype high velocity 105mm tank cannon". They had a modified 10cm field gun. It used two piece ammunition, shell loaded separately from the cartridge case. Fitting "on" a rather modified 25 ton tank chassis (accounts differ, it might have used only a six cylinder engine) is somewhat different that fitting "inside" a turret. The 10cm field gun barrel was interchangeable (not in the field) with the 15 cm sFH 18 barrel on the same carriage. They fit in Hummels, does that mean they can fit in a Panther turret?
You may also want to look at modern 105 tank gun ammuntion and see the shell weights and MV used.
The German gun used a 15.6kg projectile at about 805m/sec.
105 HESH is about 11.25 kg at 730m/sec.
105 APDS is about 5.9kg at 1470m/sec.
Recoil is proportional to momentum, not energy.
A modern 105 has about 2/3 the recoil impulse of the German WW II 105mm gun. In fact they are about 15% less than the German 88/71.
The barrels are also considerably lighter.

 

[parsifal]

SR

I agree that the germans never had a 105 multi purpose gun in WWII.

I am not challenging you on this, just curious. I am puzzled wher you say the 88mm and WWII artillery gun had greater recoil impulse than the modern 105mm. Exactly what is "recoil impulse".

Also, you say that recoil is a function of momentum, not energy. I would agree with that, but momentum is a measure of work, and work is a function of how much energy you put into an object.

The physics are

P = MV
where
P= momentum
M= Mass
V = Velocity of the object
If we disregard the effect of friction gravity etc, a unit with momentum is neither releasing or absorbing kinetic energy, neither is it releasing or storing any other enrgy, since energy can neither be created or destroyed, but can change from one form to another. But an object with momentum does possess potential energy, since if it decelarates it immediately transforms that latent enrgy that it possesses to some other form of energy. Thats why projectiles that are either accalarating or decelarating cause damage when they hit an object.


For Force, the formula is

F=MA
where
F=Force
M= Mass
A = Accelaration of the object
this is a NM, which is to say that it is a unit of energy x distance

The SI unit of force is the newton (symbol N), which is the force required to accelerate a one kilogram mass at a rate of one meter per second squared, or kg·m·s−2. The corresponding CGS unit is the dyne, the force required to accelerate a one gram mass by one centimeter per second squared, or g·cm·s−2. A newton is thus equal to 100,000 dyne



and Work
W=F.D
where
W=Work
D= Distance Travelled
The SI unit of work is the joule (J), which is defined as the work done by a force of one newton acting over a distance of one meter. This definition is based on Sadi Carnot's 1824 definition of work as "weight lifted through a height", which is based on the fact that early steam engines were principally used to lift buckets of water, through a gravitational height, out of flooded ore mines. The dimensionally equivalent newton-meter (N·m) is sometimes used instead; however, it is also sometimes reserved for torque to distinguish its units from work or energy.


This all suggests that energy plays a big, if indirect part in the amount of recoil that a gun possesses. Since newtons laws are in evidence with recoil issues (for every action their is an equal and opposite reaction) how can a 105mm round be more deadly, and have greater penetration if it has less recoil, and hence less kinetic energy in the projectile. Can you explain that please.

 

[Shortround6]

Kinetic energy is not momentum.
Consider two rifle rounds. The 45/70 with a 405 grain bullet and the .243 Win with a 105 grain bullet.
The 45/70 fires it's 405 grain bullet at 425m/s for 2370 Jules of energy.
The .243 fires it's 405 grain bullet at 425m/s for 2820 Jules of energy.
Close enough but anybody who has fired the two rounds out of similar weight rifles will tell you the recoil is nowhere near the same, the 45/70 being much worse.
If we multiply the weight of the bullet times the velocity to get the momentum (after converting to grams) we get what I will call a figure of merit of 11152 for the 45/70 and 6188 for the .243.
Of interest is that if we take the .30-06 with a 180 grain bullet (11.66grams) and 820 m/s we get 3949 Jules but a figure of merit of 9561.
There are other things that affect the recoil impulse, or the force trying to move the gun rearward.
The weight (mass) of the propellant, now converted to gas going out the barrel, the "rocket" effect if you will. This is multiplied by a constant for velocity of the escaping gas and can be "tweaked" a bit for extremely high or low pressure guns. Depending on the gun this can add just a tiny bit to the recoil (.45ACP) or a significant percentage (6.5/300 Weatherby magnum.)Adding these two numbers together gives you the "force" going out the muzzle which, as you have noted HAS to be balanced (equaled) by the force going backward.
For our rifle example we can take the figure of merit and divide it by the gun weight to get the velocity of the gun going backward (3.18m/s, 1.76m/s, 2.73m/s for the 45/70, .243, and 30-06 using a 3.5kg rifle and ignoring the powder charge) form this we can figure out the actual Jules of energy in the recoil.

As far as the penetrating power of post war 105 guns goes, for kinetic energy rounds they all used sub caliber projectiles. Basic armor penetration is force (ft/lbs or jules) per sq in or sq cm of target. The Higher the force applied to the SAME AREA of target the higher the penetration. This is ignoring little details like shot breakup and what not
An early APDS round used a core of about 4/7ths diameter or about 60mm diameter. The 60mm penetrator is trying to make a hole of 28.26sq/cm area vs the 86.54sq/cm area of the full bore 105 projectile.
even if you change the formula to trying to push out a plug and sheer the armor at the perimeter of the "hole" the perimeter of the 60mm hole is 18.84 cm vs the 32.97cm perimeter of the 105 hole. Any mixture of the two theories/formulas is going to fall between. While the sub caliber projectile may have less total energy it is trying to do a lot less work.
Modern fin stabilized projectiles can be as thin as 40mm or so.

 

[renrich]

If this has been discussed before, please forgive me. Why, in the M4 Sherman, was it equipped with the 75 mm low velocity gun initially, when later on a high velocity 76 mm gun was fitted? It seems like the high velocity gun would have been fitted in the beginning.

 

[Shortround6]

If this has been discussed before, please forgive me. Why, in the M4 Sherman, was it equipped with the 75 mm low velocity gun initially, when later on a high velocity 76 mm gun was fitted? It seems like the high velocity gun would have been fitted in the beginning.

the Sherman's 75mm gun was sort of a medium velocity with about 50% more velocity than the German 75mm in the early MK IV tanks and about 20% less than the long barreled MK IVs.
The 76mm simply wasn't ready yet (at least in 1942) and the 3in gun as used in the M-10 tank destroyer, while it had the same performance, was actually an old cost defense/AA barrel that was both larger in size and much heavier than the 76mm later fitted which made it much harder to fit in the turret.

 

[davebender]

WWII era American technology amazes me. We built the atomic bomb. Yet we couldn't build a decent torpedo, 75mm tank cannon, 20mm aircraft cannon or army light machinegun. Nor did American infantry have proper winter clothing prior to 1944. They froze during the 1943 winter in Italy.

 

[Juha]

Hello Renrich
also it was a question of doctrine, US Army doctrine called tank destroyers to take main burden of panzer destroying, tanks main job was to race deep into enemy's rear and kill infantry and soft targets. The medium velocity 75mm gun had clearly better HE round than the 76mm high velocity gun, so before D-Day for ex. Patton wasn't interested in 76mm armed Shermans. 75mm could handle Pz IVs and IIIs and Allies thought that Panther was an another heavy tank and so not to be encountered too often. Normandy fighting awaked US Army leaders and troops, so the demand of more and still more Shermans with 76mm became loud.

Dave
US had a decent 76mm tank gun why there would have been demand for a decent 75mm tank gun. US 76mm was a accurate weapon and had more penetration power than than German 75mm L/43 and L/46 (the main guns of late Pz IVs) and had almost as good penetration power than Soviet 85mmL/53 tank gun of T-34/85. It wasn't as good A/T weapon than excellent Panther's 75mm L/70 or the British 17pdr (76,2mm) but was more accurate than the latter. So IMHO US 76mm wasa decent gun for its size.

Juha

 

[Shortround6]

US had a decent 76mm tank gun why there would have been demand for a decent 75mm tank gun. US 76mm was a accurate weapon and had more penetration power than than German 75mm L/43 and L/46 (the main guns of late Pz IVs) and had almost as good penetration power than Soviet 85mmL/53 tank gun of T-34/85. It wasn't as good A/T weapon than excellent Panther's 75mm L/70 or the British 17pdr (76,2mm) but was more accurate than the latter. So IMHO US 76mm wasa decent gun for its size.

Juha

The US 76mm gun was also smaller and lighter than the Panther gun and the 17pdr and was an easier fit in the turret. It may also have had a higher rate of fire.

 

[parsifal]

WWII era American technology amazes me. We built the atomic bomb. Yet we couldn't build a decent torpedo, 75mm tank cannon, 20mm aircraft cannon or army light machinegun. Nor did American infantry have proper winter clothing prior to 1944. They froze during the 1943 winter in Italy.

There were variable reasons for a lot of that . in the case of the BAR, there was an unshakeable belief in its capabilities, despite what is plainly an inadequate design. To some extent these inadequacies were compensated either side of the spectrum, with a good support LMG in the 30cal, and a good self loading rifle, in the form of the garand.

In the case of the aircraft cannon, I guess it was the belief that a heavy broadside of 0.50" HMGs was as good as a barrage of 20mm cannon. I dont buy that argument, but a little self delusion goes a long way and anyway, eight fifties is still a fairly formidable amount of firepower.

The saga of the torpedo failures is more a saga of self delusion and outright sloth on the part of the Navy. They convinced themselves, on the basis of faulty test data, in turn the product of abridged ad inadequate testing regimes pre-war that their torpedo exploders were reliable. It takes years to build up stocks of torpedoes, so by the time they realized the problem, the war was half over. In the case of surface warships it was partly based on poor understandiong of ship roles. Well into 1943, there was this mistaken belief that gun armed cruisers were protecting the destroyers, when the truth was that cruisers were essentially targets. What is remarkable is that once the faults of the torpedoes in service were recognized, the US moved very quickly to redesign, produce and stockpile decent replacements.

The 75mm gun was the product of standardization, as regulated by the general Board. and thank goodness they did, because as the allies proved time an again, numbers counted far more than quality in determining victory. And standardization ensured that numbers were maximized, and the 75mm was adequate, if it fell short of outstanding

 

[fastmongrel]

The 75mm gun was the product of standardization, as regulated by the general Board. and thank goodness they did, because as the allies proved time an again, numbers counted far more than quality in determining victory. And standardization ensured that numbers were maximized, and the 75mm was adequate, if it fell short of outstanding

As an anti tank gun when it first went into action the 75mm was outstanding, by the end of its war service as anti tank gun it was barely adequate. However I believe as a infantry support gun which lets face it was the primary job of a tank gun in WWII it was an outstanding gun for the duration.

 

[Shortround6]

As an anti tank gun when it first went into action the 75mm was outstanding, by the end of its war service as anti tank gun it was barely adequate. However I believe as a infantry support gun which lets face it was the primary job of a tank gun in WWII it was an outstanding gun for the duration.

That was pretty much the argument of the time. The lower velocity 75mm shells could be made with thinner walls and carried a noticeable difference in HE content than the 76mm HE shells.
The 75mm was perfectly good against MK IV tanks and worked pretty well against Panthers from the side/rear. Turns out the 76mm didn't work so well against the front of a Panther anyway so maybe the difference wasn't that great. Perhaps the 76mm should have been adopted sooner but they probably would have wanted an even higher percentage of tanks armed with 105 howitzers for HE work.