HVAP ammo availabilty

[SadSack]

Hello to all. I'm a newbie here at this site. I have heard many good things about the CM game over at a wargaming club that I am a member of. I hope to some day soon get involved with the CM game. All my PC wargaming experience has been with the older Campaign Series games done originaly by the the Talonsoft company. I have a question regarding the availability and allocation of HVAP ammunition to US tank and tank destroyer crews during WWII. Was it normal practice for say an M18 Hellcat TD to have a hefty amount of 76mm HVAP ammo ? .. Would it be more than was provided for crews the of 76mm armed Shermans ?, I'm figuring on the time frame being very late 1944 and onward. And my other question. The US Army refitted a number of M4A3E2 Jumbo Assault Tanks with the 76mm gun in early 1945. Seeing that the original 75mm gun armed in those Jumbo's had a better HE shot, Would I be somewhat correct in assuming their role changed a bit ? .. Being rearmed with the 76mm gun and taking into account that it was now 1945. Were these Jumbo's so armed with the expectations that they could engage German tanks like the Panther or Tiger I head on and win ? .. Obviously they were far better protected than your average Sherman, Or most any other allied tank for that matter. This protection allowed them to survive hits that would have surely knocked out other Sherman types and would have allowed them to close the distance with their foe. So was there a shift in the uses of these up armed Jumbo's from a true assault tank to a tank killer ? .. Would these 76mm armed Jumbo's have a greater amount of HVAP ammunition than found with other 76mm Sherman types ? .. Could it have possibly been that they were allocated the amounts that one would expect to find in a tank destroyer ?

Thanks for any input !

[roqf77]

1. hvap was first produced by the us from september 1944.

2. It was issued at a rate of 1-3 rounds a month per sherman tank. And 5-10 for each TD. So a hellcat would not have alot of hvap, although they did tend to pool Hvap i.e pass it to units that would stay in positions whilst others would flank.

3. The rearming of the 75mm to 76mm was in shock of the normandy and mid 44 engagments(not that us had no tank wins mind).

Where the m3 75mm proved totaly ineffective against the german heavies frontaly. And in some cases marginal to the sides.

4. Problem with m62 apc ammo was it was prone to shatter gap failures, search for posts by rexford for a better explanation. But the 76mm only penetrated the tiger from 50m and the panther mantlet from 200m. The nose was only able to be penetrated if it were a 50mm model.

This was fixed in about september i think when longer primers were issued with the round.

and i believe the cap was hardend to increase performence, but the us 76mm was inferior to the l56 88mm on the tiger and 17 pounder.

Hvap improved this but was only availble in incredibly small quantities.

5.

The shift in tactics was more like to use where possible(only about 250 jumbo's were made and only about 100 were rearmed with 76mm guns)to lead the front of a column as it was frontlay invunerable to l48 75mm fire.

However engaging tigers and panthers was not easy as it did not have the firepower to deal with them.

6.

As for hvap i realy have no idea how much they would get.

[JasonC]

Anecdotally, I've seen reports from tank commanders in early 1945 to Ike, discussing equipment differences with the Germans, weak spots, etc. Only about a quarter of their Shermans were 76mm even then, and they typically had 4 rounds of HVAP per 76mm tank. They had been screaming for more for ages and knew it worked, but never got enough.

[SadSack]

Thanks for your input roqf77 .. What you have said regarding HVAP ammo distribution for the US tanks and tank destroyers appears to fall pretty much in line with what I have read in the past. But it has been helpful none the less. I have had the impression that the 76mm HVAP shot could defeat the Tiger I's vertical armor plate at fairly decent ranges along with the Panthers turret front and gun mantlet. The well sloped face plates of the Panther was a real problem though. As it's my understanding that HVAP shot did not do particularily well against well sloped plate. Where it really shined was against armor hit pretty much at the vertical. It's interesting about how bad the situation was for the US armored forces in regards to dealing with heavy armor shortly after Normandy. I've even read a few times about the M12 SP guns mounting the WWI vintage 155mm gun, being pressed into direct fire missions against heavy German tanks. This gun had an AP shot available to it that weighed 100lbs!!. Thats a shot that was nearly twice the weight of fired from the Russian 122mm gun. In those readings of mine, It mentioned that those M12's performed reasonibly well against those heavies and it's shot could demolish a tank. Even read of an M12 that rounded a street corner with the intentions of taking out a bunker with a concrete piercing shot that was allready ready to be fired. It then suddenly came face to face with a King Tiger that was down the other end of the city street, at what amounted to just about point blank range. That M12 got the first shot off and that was all that was needed. It's shot hit the front face of the King Tigers turret but did not penetrate. What it did though .. was it literally tore off that King Tigers turret and killed the entire crew !. I guess there is something to be said about the weight of an incoming shot.

Regarding the Jumbo assault tanks. I've also read that they were virtually invulnerable from a frontal attack by a German L/48 75mm AT gun. From what I've also read is that the 88mm gun had major difficulties trying to take this tank out frontally too, And would have to be dangerously close to a Jumbo to succeed. I've seen several photos of a few Jumbos that had been knocked out by German 88's. Both had been attacked at a range of 800 meters. Of the 12 shots that struck those Jumbo's, only 2 managed to penetrate. One shot penetrated the hull side of the first Jumbo. And the other Jumbo was taken out by a freak shot that actually entered that Jumbo's periscope opening in the mantlet. The shots that struck those Jumbo's front plate and transmission cover looked like nothing more than mere scratches. But the shots that struck those Jumbo's turrets left some deep gouges. However all looked no where's near a penetration, And that included a few shots to the side of one of those Jumbos turret. Not to sure very many tanks could withstand that kind of punishment. I also saw a site somewhere on the internet that listed all the Jumbo's that were put out of action. And to my surprise their losses were remarkably low in comparison with other Sherman types. Even more remarkable when one takes into consideration the type of role they had to take on ! ..

[roqf77]

well the problewm with the jumbo is, it couldnt penetrate the tiger at much range either.

I have read one acount at a range of 500 yards about 5-6 sherman 76's and 4 75mm managed 23 hits against a tiger.

0 penetrations, and the 2 tigers knocked out all the shermans.

A jumbo was tough but the 88mm must of been the l56 flak 88mm, not the pak 43 88mm.

Also the l70 75mm off the panther would have a good chance.

[SadSack]

Yes no doubt about it. The Tiger with it's powerful L/56 88mm gun could blast holes strait thru any Sherman type even at extreme ranges with the exception of only the Jumbo. The Sherman was clearly over matched by both gun and armor. The Tiger I's frontal armor was around 100mm and 110mm thick set at the vertical. But it's armor quality and construction was outstanding. The mere thickness and hardness of it, allowed it to withstand a serious amount of punishment. Had the 76mm Shermans been able to hit those Tigers with HVAP shot at ranges that were not in the extreme or at to high of an angle, those Tigers would have probably meet there end. The big problem was. There wasn't enough of that ammo to go around. And subsequently, many Shermans meet their end.

In regards to the 88's that had attacked and eventually knocked out those Jumbo's. I believe it was the FlaK 88 type that attacked them. From my understanding the Jumbo's were built to withstand a frontal attack from either the L/48 75mm AT gun or the L/56 88mm type. These were I guess the most likely German type to be encountered at that time. The PaK 43 L/71 88mm gun was a real monster of a gun, and I'm fairly certain no tank type could withstand to many hits from it. However after taking a good close look at the armor specs for the Jumbo. Even the PaK 43 was not certain to penetrate a Jumbo frontally from that range unless it was firing the heavily rationed APCR shot. If a Pak 43 was to be firing it's standard AP shot it could in theory I guess penetrate the Jumbos turret at up to 1500 meters and the mantlet up to 1000 meters. However it would have to be much closer ( anywhere between 100 and 500 meters ) to have a chance against the transmission cover or the upper front plate of the Jumbo. And those would have to be attacks at no angle. I don't believe the L/70 75mm gun would have had even a fair chance at that range unless it was firing APCR shot at the turret. The Jumbo's turret had 152mm thick armor plate on the front, sides and rear. And it's gun mantlet was 178mm thick. But even with all that armor, it's turret front was the softest part on that tank. If one considers the effective thickness of the Jumbo's front plate and transmission cover based on it's actual thickness and degree of slope. Those areas were far harder to achieve a penetration on than even that very thick turret. I haven't seen how well these tanks hold up in the game against the German AT guns. But my guess is that unless their firing APCR shot or they are one of the extreme pieces. A King Tiger or Jagd Tiger, It should be pretty tough.

[roqf77]

er the sherman jumbo,s front hull was 92mm sloped to 55 degree's.

So about a vertical equivalent of 190mm, us tests put the penetration of the l70 75mm at 210mm at 100 yards with a apcbc round. So it could penetrate the upper hull at close range maybe medium.

Its important to compare test methods when comparing digures.

German guns were tested against higher quality armour than that used by us armoured vehicles.

But your pretty much there, Hvap put the us 76mm on the same level with 17 pounder apcbc.

[SadSack]

Actually the Jumbo's hull front was 102mm thick and sloped at 47 degrees for a 193mm effective thickness. The transmission cover was much harder for an incoming AP projectile to overcome. It's thickness went from 140mm and gradually reduced to 114.5mm thick at the upper most portion of the cover. Also sloped at 47 degrees the transmission covers average effective thickness would work out to something like 238mm. The difficulty in breaching that kind of armor could be compounded greatly if the incoming shot at the tank was taken from any angle other than strait on. The turret armor protection on the Jumbo's had to be unquestionably the best of any tank used in WWII. With a 152mm of thickness front, side and rear. followed by a 178mm thick gun shield.

Tanks were usually alot more difficult to take out on the battlefield than on paper. How difficult the CM game makes it to take out this tank, I really have no idea ? .. But in real life it was very difficult. I can only see the King Tiger surpassing it in terms of protection.

[roqf77]

well if you compare armour qaulity, i.e bhn etc

You will see that the churchills 152mm(bhn average of 315, compared to about 250 of the jumbo) that it probably isnt the toughest.

(by my calculations 102mm by 47 degree's should be 183mm).

The transmission was very tough, and the sherman jumbo was a tough tank, but i think that the churchill and russian js tanks were atleast very similar.

[SadSack]

Hi roqf77

It's true the Jumbo's turret armor was on the soft side. Around 250 bhn was the lowest measured for it. So we can assume the others had simular numbers. It's my understabding, the gun mantle and particuarily the transmission cover along with the face plate were quite a bit harder. Why the turret was cast that soft I don't know?

The Churchill VII's and VIII's were well armored. 152mm frontally and around 95mm for side armor. That's darn good no doubt about that. It's frontal armor was set at the vertical however. Which did not promote deflection nearly as much as with a Jumbo. Turret protection still well in the Jumbo's favor.

The Russian IS-2 and IS-2 model 1944 tanks were well protected all around. And the model 1944 IS-2 had an incredibly well protected front upper glacius. However the it's lower hull was not well sloped at all. And even though the front, side and rear protection offered by it's turret was good. IMO it was no where near as protected as with the Jumbo. An armor calculator will bear that out if you have one. On another note with these IS-2 tanks. The quality of the armor was absolutly terrible !! .. Due to shortages of good quality metals, the Russians made due with poor materials. The armor was extremely brittle.

I'd have to say the Jumbo was tops as far as protection goes. My order would be

1. Jumbo

2. IS-2 model 1944

3. Churchill VII's and VIII's

4. IS-2 and Pershing

I'm probably using a different armor calculator than you are .. 183 and 193 are pretty close though.

[roqf77]

as far as i know, all us rha was a bhn of 250.

The resistance difference is about 25% between the churchill and the jumbo(by bhn).

152mm at 315 bhn equals about 190mm by bhn 250,

So i would say they were similar.

Plus us rha plates over 124mm were at bhn of 220.

http://www.onwar.com/tanks/usa/fm4a3e2.htm

turret and the 114-140mm section were not massivly sloped.

Im not using an armour calculater, im uding a ww2 british war office armour curve.

Normaly the mantel calculation i.e thickness includes the turret behind it, so i dont think it is 152 + 178mm of armour.

Other wise the 17 pounder could not penetrate the panthers mantlet and it could do to over 1,000 yards quite easily.

Also in real life the integrity of the internal structure, i think in the case of the churchill. It could take a great deal of punishment.

But yes i do think that the jumbo was a very tough tank.

Its a shame the us didnt produce more. Im not sure if a jumbo firefly would of been possible but it would of been a great tank to have.

[SadSack]

As far as bhn of the US tanks, I'm pretty certain it was greater than 250 on the average. I have read previously somewhere that the Jumbo's turrets were cast with fairly soft. But just taking a good look at the photos of those two destroyed Jumbo's. It's turret easily handled those hits to it's turret by those 88mm gun. The Jumbo turrets were cast with 6 inch thick walls on " all "" sides. The gun mantlet was a completely seperate piece and is not factored in any way with the front turret thickness. The Jumbo's mantlets were very large and thick. It included an extremely thick band around the base of the gun and the mantlet so as to make it very difficult to take the gun out of action from a hit there. It was not completely uncommon for guns to be taken out with hits in that area. As far as calculating both the Gun mantlets armor and turret front armor togather. That would be incorrect, exept only in the case if an incoming shot were to hit the very most outer edges of the gun mantlets head on. In that case they might have to also travel thru a portion of the turret fronts armor. Otherwise and in the case of both the Panther and Jumbo, There was a large opening in the front of the turret. This was to provide an area for the tanks gun to be mounted. For the most part the only protection offered to the tanks gun mechanism's and crew inside the turret was from the tanks gun mantlet. In the case of the Jumbo a bit more becouse of the overall coverage provided at the front by its gun mantlet as compared with a Panther. A direct hit to a Panthers turret front is quite a bit more likely as would be with a Jumbo. The Jumbo's mantlet looks as though it has almost complete coverage from end to end at the front of the turret. As far as the transmission cover 114mm to 140mm thickness not being massivly sloped ? .. massivly no. But well sloped yes !. 47 degrees at the upper side of the cover and 56 degrees at the lower side of the cover. This was extemely hard for even the largest German guns to overcome. The nose was rounded and was 140mm thick at the outer most edge and gradually reduced to 114mm thickness at the upper most and lower most portions of the transmission cover. One look at the layout of the Shermans transmission cover. It is clear that the rounded nose encompases only about 10% to 15% of the overall area to be hit by an incoming German shot. The remaining area is primarily sloped at 47 degrees and the remaining at 56 degrees. Given it's thickness there and the degree of slope. It was extremely well protected in that area. Frontally and along with it's entire turret the Jumbo's were extremely well protected, Even by German standards. As superior as say a Panther or Tiger I was in many ways to it. Those tanks were not designed to be assault tanks. Based on previous experince with German AT guns, Primarily the L/48 75mm, L/56 88mm of the Tiger I and Flak 88's. The Jumbo's were designed

from the outset to resist hits from these weapons, And they did ! .. And just imagine if the US forces had to try and knock out their own Jumbo's with the same stuff they had to throw at the Germans ? .. It would have been next to impossible I think !. Just like the King Tiger, It would have almost been impossible to take out frontally by US and UK guns. What kind of reputation would that tank have had if it had been a German design with that kind of armor protection I wonder ? .. The Germans simply had tons and tons of very deadly AT guns to throw at it. And those Jumbo's were often set out to actually attract German AT fire so as to disclose their location!. More than likely a rain of US artillery fire would then come next. Like any other tank the Jumbo's had their Achilles heel. The hull side armor was only 75mm thick. And allthough that was not bad. It was not nearly good enough to withstand most German AT guns around that time. When they were taken out of action, I would suspect it was primarily from shots around that location.

Alltough I'm American. I think the US was really dumb for not accepting at least some of the 17pdr guns for use in their tanks. It is said that the Brits claimed there were not enough of those guns to go around and the Americans said it would be a longistics nightmare ? .. There was the plan in late 1944 to make the Jumbo's a massed produced tank outfitted with the 76mm gun with muzzle brake and HVSS suspension system like the M4A3E8's had. And later even the possibilty of mounting the Pershings turret with it's 90mm gun on that HVSS Jumbo. Had the war been longer fought in Europe, I think it may have been possible to see at least the 76mm HVSS Jumbo's as a regular piece motoring around.

I have also thought about the 17pdr in the Jumbo. The 17pdr would have been able to mount in the Jumbo's turret. And what an awsome piece that would have been for the allies to have. The ultimate Sherman !! .. Jumbo with a 17pdr and an HVSS suspension system. It could have happened and should have happened IMO.

[roqf77]

just a note, the url i posted above says in the german fashion the 114mm-140mm hull was sloped 34-90°. 90 being considered no slope by western allied calculations.

The bhn was 250 for sure, it was the us standard produced at the time for all vehicles, it is possible that it was better on the jumbo but it would of been a higer standard than any other tank including the pershing.

The churchills in france and some in italy got new cast turrets that were 152mm(190mm by 250 bhn) all the way around.

So were its front hull and its lower hull 140mm(173mm by 250 bhn).

As for the 17 pounder it was offered as early as march 43 and again in december. Both were early enough for the us to overcome the logistical problems, Bradley asked for firefly's and achilles after normandy.

This was turned down as the british army had grown accustome to a certain number of these vehicles.

Had the us army taken the 17 pounder on board when offered they would have had just as long to work the guin into the sherman as the uk did.

This could of been very good, lots n lots of firefly's and achilles,

Possibly the saving in industrial capacity in the uk could of lead to the development of the centurian/comet possibly even the black prince(churchill with the 17 pounder sooner).

But i think we are in general agreement, th jumbo was one of the toughest tanks in the war. But even with a us 76mm with hvap at least in terms of fire fight it was no match for a king tiger.

[SadSack]

The 90 degrees does infact represents no slope. But have you ever looked at the transmission cover on a Sherman ? .. If you do or have. That 90 degrees only accounts for the area at the very tip of the nose of that transmission cover. That tip is actually rounded and only accounts for a fraction of the overall area of the transmission cover. The 34 degrees is for the slope taken from the opposite angle. From the perspective that we would be looking at it head on. It is 56 degrees set back from the vertical. That 56 degree acounts for the area just below the rounded tip of the nose they are saying is at 90 degrees ? ( in theore correct. But it's misleading in some ways )while the upper portion of that transmission cover below the face plate was set at 47 degrees just like the Shermans face plate. That armor went from 140mm thick and gradually reduced to 114mm thick at the top. So half way up the upper portion of that transmission cover it was bassically 127mm thickness set at 47 degrees. Were as those heavily armored MK VII and VIII Churchilles had 152mm thickness set at the vertical completely " top to bottom " ! .. Those Churchills did not have 152mm thickness all around as with the Jumbos. Their thickness was less than 100mm on the side of the turret. Still very good though.

I agree in terms of a firefight the Jumbo was no match for the King Tiger. The Tigers gun was absolutly awsome and it's frontal armor equally so. The Jumbo would need to get a shot to the Tigers side. The King Tiger could deal with a Jumbo frontally. But not a long range. And more than likely it would have to be on the short end of medium range or even close range. Penetration tables for guns no matter how good they might be, don't allways show the whole picture.

Just on an added note. The Campaign Series games give currently give these tanks the following armor protection values.

JagdTiger front - 48

side - 12

rear - 12

King Tiger front - 36

side - 12

rear - 12

Tiger I front - 16

side - 10

rear - 10

Panther front - 21

side - 8

rear - 7

Jumbo front - 26

side - 14

rear - 12

Pershing front - 21

side - 9

rear - 9

M4(76)W front - 9

side - 5

rear - 5

Churchill

MK VII & VIII front - 17

side - 11

rear - 7

IS-2 front - 20

side - 13

rear - 12

IS-2m front - 30

side - 13

rear - 12

KV-1 M42 front - 16

side - 11

rear - 9

T34/85 front - 12

side - 8

rear - 7

Using my own formula, I had come up with numbers extremely close to the values Talonsofts designers originaly gave these tanks. actually exact in most cases. However I believe the Churchill MK VII's and VIII's were shorted a bit.( it should have been more like 20 for the frontal value ) This will be changed with up and coming expansion disc. I wanted the Tiger I's values increased by at least 10% to 15% to reflect the excellent materials/metals used in its armor construction. The best in the whole war!. That has not been decided on yet. IMO the IS-2 should have had a frontal protection value of 23 instead of 20 and the IS-2m's a value of 27 instead of 30. No decissions on that as yet. And I'm not really pushing for it either. The Jumbos factored to a 30 frontal value and not a 26 as the original designers had it. That will be up dated with the project disc. Alot of new equipement will appear on these updates including M4(76)W Shermans with applique armor kits, The rare Sherman Crocodille tanks and even the T26E4-1 Super Pershing !

[stoat]

90 degrees represents an infinite slope. 0 degrees equals no slope.

[SadSack]

Yes stoat thats correct .. But for the sake of the conversation we were having and that the site as to where roqf77 got his info. They stated 90 degrees for the trans cover. The site had the slope backwards. It obviously does not have an infinate slope. But rather o degrees at the nose which was actually rounded. Also the cover has no place where the slope is at 34 degrees. But on the lower portion of the cover it's at 56 degrees just like any other sherman model. The numbers used at the site used for slope were backwards for some reason ?

[roqf77]

this may be correct, but the german used 90 degree's as no slope. I.e the round would impact the armour at a right angle, i.e 0 angle of impact.

The western allies refered to it differnently, so obviously the site is mistaken, But in the german way which this site is using 90 degree's is no slope.

[roqf77]

and yes the churchills did hve 152mm all the way round.

According to both osprey's d-day and churchill infantry tank book.

The turrets were added prior to normandy.

Although they were used in france and italy.

But like i said by bhn 250 as used on all us tanks from 44-45 that would be like 190mm or so.

Like i said the jumbo was a tough tank, but i dont think it is tougher than the churchill. Not the uparmoured marks for it.

Battlefront dont seem to think so either, from my memory in cmbo the churchill was tougher than the jumbo.

One of the most confusing points ive heard against , the us constructing more jumbo's was infact 2 part.

1. Not enough steel could be located.

2. They were to big for us landing craft.

To me this sounds like a load of old cobblers.

you seeem to be very informed on us afv's could you shed any light?

[ October 07, 2005, 05:11 AM: Message edited by: roqf77 ]

[SadSack]

I kinda like those late model Churchills too. They were defianetly tough. But their turret armor positively was not 152mm thick on all sides! .. Even the site you passed earlier at www.onwar.com has its frontal turret thickness at 152mm and the sides and rear thickness at 95mm?..

Those numbers are mot wrong either. The hull was 140mm thick and the superstructure is at 152mm thick. A the hull sides were at 57mm thick. all this armor was set at the vertical too. These figures fall right in line with all other reliable sources I have seen. I never heard anything different. What was your source of information on that 152mm thickness all around for the Churchill? ... the Churchill MK VII's and VIII's were very tough just like the Jumbo. But even if the bhn were to be factored in. Still not as tough as a Jumbo. The Jumbo offered far better protection on the most exposed area of the tank, The turret. The front armor of the Jumbo was both thick and well sloped. Churchills was very thick but no slope and did not promote deflection nearly as much as the Jumbo. I still give advantage to the Jumbo there too. And it's side armor is not quite as thick as the Jumbo's.

I would be curious to the defense factors the CM game has given to these two tanks? ... Lets say either one is under attack from a German Tiger I tank from a range of 750 yards. I wonder what tank would have a better chance of survival in the CM game?

The designers for Campaign Series turn based games done by Talonsoft, Felt the Jumbo was more than a bit tougher too. Those fellas really did their research and that is one reason those CS turned based games are considered one of the all time great PC wargames. maybe it's not your cup of tea. But you should check them out sometime. Also as a flash news piece. It looks as though Matrix games has just purchased all the rights to those old Talonsoft games !

[roqf77]

It's simply clear we dont see eye to eye on this.

But it is nice to have a discusion with someone willing to think through there argument.

If you could please answer the two questions i asked you previously.

We may get this conversation going somewhere again.

[ October 07, 2005, 09:23 AM: Message edited by: roqf77 ]

[SadSack]

OK .. There's no problem with having different views roqf77.

To answer your questions :

1. I can't believe for a second that the USA had any real shortage of steel as you stated. It's my understanding that the USA out produced all other combative nations combined !! .. If there was really a case to be made about shortages. I figure they could have built a few less barges and built more Jumbo's hahahaha

2. There was a small issue with transport I believe. It had to do with what the shipyard cranes were rated to lift. Pershings and Jumbos being a bit to heavy for them. But as we can see. They found some way to load them up and ship them over !!

The only shame about the Jumbo tank, was that they did not build them in mass. They also could have built some with 17pdr guns and the HVSS suspension setup. All the stuff was there for the taking and would drop right in. A tank like this could have been introduced alot sooner than the Pershing, And actually could have had a far greater impact against German armor IMO.

[SadSack]

I have taken another and rather simplistic approach to this discussion about which tank may have been tougher. The U.K. Churchill MK VII or the U.S. M4A3E2 Jumbo .. We for the moment will just consider the frontal protection of both tanks. I will also take into consideration the bhn of the steel for either tank. I will approach it from the perspective that the bhn of the steel will directly relate one for one with the overall effectiveness of each tank.

M4A3E2 Jumbo

Turret front - 152mm at 12 degrees = 157.713mm effective. bhn is 220

Gun Mantlet - 178mm at 0 degrees = 178.00mm effective. bhn is 250 ( they were 79mm plates welded togather.

Upper hull - 102mm at 47 degrees = 193.278mm effective. bhn is 250

Lower hull or Transmission cover varied. But as follows.

Upper most - 114mm at 47 degrees = 216.016 effective

Upper middle - 127mm at 47 degrees = 240.65mm effective

Upper lowest - 140mm at 47 degrees = 265.83mm effective

The rounded nose - 140mm at 0 degrees = 140mm effective

Lower upper - 140mm at 56 degrees = 369.573mm effective

lower lowest - 114mm at 56 degrees = 300.938mm effective

I will now average what we have for the Jumbo's turret and upper and lower hulls.

Turret average is 167.8565mm effective with an average bhn of 235

Upper and lower hull averages combined is 246.612mm effective with an average bhn of 235

--------------------------------------------------

Churchill MK. VII

Turret front - 152mm at 0 degrees = 152mm effective. bhn is 315

Upper hull - 152mm at 0 degrees = 152mm effective. bhn is 315

Lower hull - 140mm at 0 degrees = 140mm effective. bhn is 315

Turret effective average is 152mm with a 315 bhn

Upper and Lower hull effective average is 146mm with a 315 bhn.

--------------------------------------------------

So with the Churchills 315 bhn being a full 34% more than that found on the Jumbo. I'll for arguments sake calculate the Jumbo's armor as 34% less than what I calculated.

Jumbo's Turret front overall = 110.7852mm effect.

Churchill's Turret front overall = 152mm effect.

Jumbo's Hull front overall = 162.764mm effective

Churchill's Hull front overall = 146mm effective

With this generous style of trying to figure out which tank may have been tougher. I think I have been more than willing to try and see your point about the Churchill. I do not see that the bhn had as great an effect than I have actually given it. But I have done done it none the less. If this were truely the way to calculate effectiveness based also on bhn. I'd have to say that the Churchill's turret front was the clear winner. But on the flip side, The Jumbo's upper and lower hulls would win. But aside from that. And all what degrees of slope due to change a tanks overall effectiveness. It also promotes shot deflection. Where as vertical set armor does not. The 47 degree slope of the Jumbo's hull would cause an incoming shot that struck it to waste alot of it's energy trying to overcome that slope. Where as the Churchill did not have that effect on an incoming round. This makes an absolutly huge difference weather or not a shot will even have a chance to penetrate. A Jumbo's frontal hull area was almost completely invulnerable to any German AT weapon firing standard AP shot. ( except for Pak 43 88mm L/71 )

And the German APCR shot much like the US HVAP shot, did not perform particularily well against thick sloped surfaces. That is what the Jumbo had. The Churchill did thick plate. But it was all set at the vertical ! .. A German APCR shot was tailored made to defeat thick vertical plate. So even though I really like the Churchill myself. It just does not seem to me that it could hold up to AT fire as well as the Jumbo. The one big advantage I'd give to the Churchill was it's lower profile or silluette.

BTU roqf77

[roqf77]

tuue but standard armour curves included the chance of defelction within the relative armour value.

Bhn is a rating of pressure a point of armour can take. i think 1 bhn is equal to 10kg per square inch. So it is kinda relative to armour effectiveness. The only real problem with bhn is it doesnt show up flaws.

my armour curvce figure is...

102mm at 47 degrees = 183mm.

140mm = 250mm.

127mm = 227mm.

But id say there about the same.

ill ask more questions later. gonna go play coduo.

[roqf77]

by removing 25% i.e difference in bhn.

you get.

102mm at 47 dg = 137mm.

114mm at 47 degree's is 153mm.

127mm at 47 = 170mm.

140mm at 47 degrees = 188mm.

So by me the turret and upper hul ar weaker, but the jumbo's lower hull is stronger. but they are very similar. i.e side turret is 105mm equivalent at bhn 315.

side hulls, 76mm unsloped.

The 57mm side hull of the churchill is covered by tracks.

the hull you would hit with a gun is 95mm, equivalent about119mm of armour at bhn 250.

I cant remeber where i got the 152mm all around for the churchills turret. So i conceed.

Basicaly, the churchill has a tougher upper hull and frontal turret.

The jjumbo has a tougher frontaly lower hull and side turret, but is weaker to the side hull and rear hull too.

Even if the difference's were not massive.

[ October 07, 2005, 03:16 PM: Message edited by: roqf77 ]

[SadSack]

I'm pleasing to see two fellas can have a good discussion on this subject. I rolled in those numbers of mine previously to simply check effectiveness based on your bhn numbers and to see though this discussion in some manner. However the bhn numbers simply do not work in the fashion that I did it. It would be like saying a Tiger I's large 110mm thick gun shield was just as much if not more effective at resisting an incoming AP shot as the massive 178mm thick gun shield on the Jumbo based almost soley on bhn?. That is what would happen if we tried to factor in bhn. And that would be flat out ridiculous. It simply does not work out that simple.

I think the armor calculators do factor in for slope well and can only try to emulate chance of deflection. If an incoming 88mm AP shot comes strait at and smacks right into a 152mm thick vertical plate. It's going to dig as deep a hole as possible into it. On the other hand. If that same 88mm AP shot hits the 102mm thick upper glacius of the Jumbo thats angled at 47 degress from the vertical, it's going to very likely richochette becouse the size of the 88mm shot is overcomed by the thickness of the 102mm plate coupled with the angle of that plate. The 88mm

AP shot simply does not have enough energy to overcome that. On the other hand, If that 88mm AP shot were to strike a standard Sherman glacius that only had 62mm thickness. Becouse of the diameter of the 88mm shot and the area that it was directly applying that force/energy over was less thick 62mm. That AP shot would have a far greater chance of getting to dig in and punch a hole strait thru a standard Sherman. Infact it would easily from 800 yards. But one look at what those 88mm hits did to that Jumbo's glacius from 800 yards tells and shows the big picture as to what I'm talking about here. Those hits were from dead strait on, and they are mere dents and scratches on those Jumbos faceplates. That is becouse the shell even flying in from just 800 yards away could not overcome the thickness combined with the angle of the plate. Those German 88's were clearly light years away from doing any damage to the faceplates of either Jumbo. However the hits that struck those Jumbos huge 178mm thick gun mantle did not look to take the least travel of resistance and richochette. What those 88mm AP shots did was leave some huge deep holes in those Jumbo's gun mantlets. And that was all becouse the gun mantlets are set at the vertical. There was no place for those AP shots to go but strait forward. That is the same effect those 88mm shots would have had on a Churchill MK. VII front, Top to bottom ! ..

IMO and becouse of layout .. I would still say a Jumbo's turret offered better protection for the crew. And as for the upper and lower hulls. No comparison there IMO. Infact not even close. A huge advantage for the Jumbo