Tiger Fibel Notes on Tiger Accuracy

[rexford]

The final adjustment to the range estimate brings the shot placement from the target contact with ground to the approximate midpoint, and is accomplished by measuring the height of the observed target in mils (using the gunsight triangles), and then adding twice that number times 100m.

If a tank target was 3 mils high on the gun sight, half would be 1.5 and the adjustment would be an addition of 150m.

If a Tiger was firing on a hulldown T34 and the turret appeared to be 0.50 mils high, the range would be estimated and the modified by an addition of 0.50 x 1/2 x 100m or 25m.

I did some ballistic studies using a trajectory computer program and the method works very well.

The Tiger crew would not have to remember an equation for the final adjustment, they would measure the approximate height on the sight and add half the height times 100m.

[rexford]

If a 20mm spaced plate on the front of the PzKpfw III will detonate the HE burster on a 75mm Sherman round before the round reaches the main armor, and will do the same to the 122mm AP, it does not take much to set off the burster.

There are a few inches between the spaced 20mm plate and the 50mm main armor on PzKpfw III, so AP rounds with HE bursters don't last long after the initial impact.

In British firing tests, the Sherman 75mm APCBC-HE hits the PzKPfw III spaced 20mm plate at about 100 yards, say 2000 fps. It takes very little energy to pierce a 20mm hard plate at 30 degrees, say 822 fps. Which means the round leaves the 20mm plate going 1823 fps.

There is about a 6" space before the round hits the main armor, so the time for the burster detonation is less than 0.5'/1823 fps, or 0.00027 seconds. Not a whole lot of time.

[ June 26, 2004, 10:06 PM: Message edited by: rexford ]

[Mr. Tittles]

The real question is does the small HE charge in a APHE destroy the solid round?

But the sherman HE was prone to predetonation, so for rexford to claim it is a benchmark is wrong minded.

Striking plate is much more a G force shock than hitting soft ground and changing the angle of the shot.

[ June 26, 2004, 10:52 PM: Message edited by: Mr. Tittles ]

[rexford]

Originally posted by Mr. Tittles:

The real question is does the small HE charge in a APHE destroy the solid round?

But the sherman HE was prone to predetonation, so for rexford to claim it is a benchmark is wrong minded.

Striking plate is much more a G force shock than hitting soft ground and changing the angle of the shot.

Not true, sir, on all points. The 90mm APCBC_HE was prone to detonating upon contact. The 75mm APCBC-HE worked just fine in the British tests and exploded between the plates.

You also disregarded my reference to Russian tests where the 122mm APHE round detonated between the 20mm spaced plate and the 50mm main armor. I did not attempt to use the 75mm Sherman APHE round as a benchmark but presented two completely different projectiles.

A 20mm plate is nothing to a 75mm APCBC round, whereas hitting the ground radically changes the flight path.

The 75mm Sherman APCBC round carries 1.7 POUNDS of high explosive, which would seem to be enough to rip the round apart. That is the purpose of HE fillers in armor piercing rounds, to turn the ammo into a grenade that explodes in the tank and send fragments flying about.

[Mr. Tittles]

Pzgr. 39 FES

APCBC

RDX

83 gm.

90% PETN

Bd. Z. 5103

black w/red marking

-

Pzgr. 39 Kw. K. 40

APCBC

Cyclonite

82 gm.

90% PETN

Bd. Z. 5103

black w/red band/marking

These 75mmL48 APCBC rounds carry 83 grams or so of HE. I HIGHLY doubt that the detonation of this HE in the back of a hardened AP shell would shatter it beyond the very small cavity area (if that). What is your source of a Sherman AP round having over a pound of HE?

[ June 27, 2004, 09:28 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

As far as what constitutes a radical physical change, skipping a round off typical ground cover at a steep angle is NOT as bad as striking 20mm of armor plate! G forces result from change in velocity/direction. Rexford talks like a 75mm AP round is going through a 20mm plate like its a sheet of paper.

[rexford]

Originally posted by Mr. Tittles:

As far as what constitutes a radical physical change, skipping a round off typical ground cover at a steep angle is NOT as bad as striking 20mm of armor plate! G forces result from change in velocity/direction. Rexford talks like a 75mm AP round is going through a 20mm plate like its a sheet of paper.

Both conditions cause an impact which may set off the HE burster. Why don't you do a research project with regard to whether bouncing an APCBC-HE round off the ground will set off the burster, and get back to us.

[rexford]

Mr. Tittles asked:

"These 75mmL48 APCBC rounds carry 83 grams or so of HE. I HIGHLY doubt that the detonation of this HE in the back of a hardened AP shell would shatter it beyond the very small cavity area (if that). What is your source of a Sherman AP round having over a pound of HE?"

Accidentally quoted the weight of HE in an HE shell. 1.7 pounds is 75mm Sherman HE.

Regardless of what you doubt or think, British and Russian tests showed that when 75mm APCBC-HE and Russian 122mm APHE penetrated the 20mm spaced plate on the PzKpfw III the HE burster in the round detonated before it reached the 50mm main armor, and the hit was defeated.

The British showed that the defeat was due to the HE burster detonation because when they took out the HE and replaced it with an inert filler, the rounds penetrated the 20mm spaced plate and the 50mm main armor.

So what was left of the projectile, in terms of fragments and pieces, did not have enough penetration left to get through a 50mm face-hardened plate a few inches beyond the detonation. Sounds like the round was fairly damaged if it failed against a 50mm plate.

[ June 27, 2004, 03:07 PM: Message edited by: rexford ]

[Mr. Tittles]

The 75mm Sherman APCBC round carries 1.7 POUNDS of high explosive, which would seem to be enough to rip the round apart.

Are you sure you havent confused the AP with the HE? Why don't you research that?

[rexford]

Mr. Tittles said:

"Are you sure you havent confused the AP with the HE? Why don't you research that?"

Already responded.

[rexford]

Originally posted by Mr. Tittles:

Pzgr. 39 FES

APCBC

RDX

83 gm.

90% PETN

Bd. Z. 5103

black w/red marking

-

Pzgr. 39 Kw. K. 40

APCBC

Cyclonite

82 gm.

90% PETN

Bd. Z. 5103

black w/red band/marking

These 75mmL48 APCBC rounds carry 83 grams or so of HE. I HIGHLY doubt that the detonation of this HE in the back of a hardened AP shell would shatter it beyond the very small cavity area (if that). What is your source of a Sherman AP round having over a pound of HE?

First off, the German 75mm APCBC-HE round is not a good comparison to the American 75mm APCBC-HE, for two reasons:

1. German 75mm has one of the smallest HE bursters for a WW II round on a percentage basis, Sherman 75mm APCBC burster is quite a bit larger

2. German 75mm APCBC is one of the hardest steel armor piercing projectiles of WW II, Sherman 75mm APCBC is one of the softest.

Sherman 75mm APCBC with HE burster is going to detonate with a bigger bang, and the metal will tear apart easier, than the German 75mm APCBC.

Suggest you go to following site and click on U.S. Army Test #1 for a discussion of the tests regarding detonation effects when 75mm APCBC is fired against spaced plates:

http://www.geocities.com/mycenius

Regarding ground hits and burster detonation, the Sherman gunnery manual suggests that HE ricochet fire be used against troops in trenches where the round is bounced off the ground and explodes in the air. The HE round burster is set to delay so it won't go off as it hits the ground.

If an HE round will detonate on a glancing hit against the ground, why wouldn't APCBC?

I don't have the time or interest to research any of this anymore but would be interested in hearing what others come up with.

[ June 27, 2004, 03:58 PM: Message edited by: rexford ]

[Mr. Tittles]

The HE has a point activated fuze that is set on delay. The AP round has a base activated fuze that needs a severe G event to det it off. Why are you comparing apples to oranges?

[ladoga]

Originally posted by Griffin 36th:

You can quote all the stats you like really but that all goes to crap in a combat situation, as mikeyd's contribution fully illustrates. What I imagine happened in the illustrated scenario is that the tiger traversed the turrent and lowered it as fast as they could and fired without aiming in a situation like that, since the turret speed of a tiger was notoriously slow fine tuning on the gunners part would surely take much to long. That being said I loved the tables despite what I said earlier, very informative and very accurate in my opinion. The main doctrine of the German armor was to engage at geat distance due to their better sites and shells.

I just read article of finnish Stug commander Börje Brotell. He says that 1st round hits in combat were a norm. Also he mentions that they could hit black center area of 300m rifle target from 600m.

So i guess it depends much of the crew. With careful aim these guns were VERY accurate.

[ June 27, 2004, 05:16 PM: Message edited by: ladoga ]

[rexford]

British report M.69144/4 No.1 analyzes German 75mm and 88mm APCBC ammo:

75mm APCBC fired by Kwk 40

14 grams HE burster, minimum armor thickness to set off burster is 12mm

88mm APCBC fired by Pak 43

60 grams HE burster, minimum armor thickness to set off burster is 6mm

German 75mm APCBC had one of the smallest HE bursters by percent weight of any WW II ammo, 0.2% of projectile weight.

Suggest that Mr. Tittles recheck his source for the 82 gram to 83 gram HE burster in 75mm APCBC. Looks terribly high.

[ June 27, 2004, 09:29 PM: Message edited by: rexford ]

[Mr. Tittles]

So whats the point?

[rexford]

Originally posted by Mr. Tittles:

The HE has a point activated fuze that is set on delay. The AP round has a base activated fuze that needs a severe G event to det it off. Why are you comparing apples to oranges?

You missed the point of my statements on HE shells, and need to correct your statement about HE shells being fuzed for delay detonation.

First, I discussed HE shells to show you that a glancing blow on the ground can set off an HE shell fuze, which shows that bouncing off the ground can generate enough of a force to detonate a round. Sufficient G's from a bounce off the ground, which appears to be "severe enough" to set off the burster.

Which suggests that your opinion may not be correct.

Secondly, HE shells can be set for instantaneous detonation. Suggest you get access to ARMORED FORCE MANUAL, TANK GUNNERY, April 22, 1943, which is U.S. FM 17-12.

Pages 19 and 20 of the FM disprove your above statement and suggest that you should do more research on projectiles:

"The PD fuze M48 used with the 75mm shell, HE M48, is a combination superquick and delay point-detonating duze. The shell comes at superquick".

"It may be set to burst 0.05 seconds after impact by turning the slotted key on the side of the fuze so that the slot points to the word DELAY stamped on the bidy of the fuze. Always set the fuze at DELAY before stowing the ammunition."

Superquick action: is so sensitive that the shell detonates immediately upon impact. Therefore, when striking armor plate, a gun shield or a building the shell will burst before it can penetrate.

Delay action: 0.05 second delay before bursting when it strikes light armor, gun shields or buildings.

Based on my analysis of the Sherman 75mm APCBC=HE going through the 20mm spaced plate and detonating before it reaches the 50mm main armor, the delay for armor piercing ammo is very short.

[rexford]

Originally posted by Mr. Tittles:

So whats the point?

Last response to your posts on this thread for me.

British say German 75mm APCBC had a 14 gram HE burster based on their analysis of actual combat rounds, data which you previously quoted had 82 to 83 grams.

Your data looks incorrect. That's the point. I thought you would compare your previously quoted numbers to the figures I had posted but I guessed wrong.

[Mr. Tittles]

check panzer IV website.

As for your meandering into nose fuzes, its still has nothing to do with the topic. So what if they have settings? They are entirely different than base fuzes????

I think your posts may bring interesting data to the forefront, but your logic and technical skills are not up to the level needed to discuss these topics.

[Panzer76]

Originally posted by Mr. Tittles:

I think your posts may bring interesting data to the forefront, but your logic and technical skills are not up to the level needed to discuss these topics.

I think you are the one that is found lacking Tittles. I rather take his word over yours, seeing he has written a book on WWII armour etc. What are your qualifications again?

[flamingknives]

It usually looks like a diploma in Google. Mr. Tittles can find masses of information, but he's not always that good at analysing it.

I'll have a look in my textbooks later to see if I can figure out the delta V for an 88mm going through a 6mm plate. I'd guess that it's pretty small, meaning that an AP shell would have to only lose a tiny amount of energy to avoid going off when it skips.

rexford, you're such a prima donna

[Mr. Tittles]

It would be a delta G but let me sort out all the rexforditus first.

I made the statement that a short round still has the potential to skip and do damage (I have read of accounts of both German AP rounds skipping off the ground and KOing armored targets AND penetrating earth/building/etc and doing extensive damage). rexford goes on about a skipping round would detonate before hitting target. He then misapplys HE data regarding non-german AP rounds. He claims that AP rounds shatter like grenades (!). He then seems to want to prove that German AP rounds had even less HE than I am stating (???).

The real facts are that perhaps US and Soviet APHE would start the HE charge detonation train when striking something AND that they had sufficient HE to actually take sufficient mass off the back of the AP round to decrease its penetration once through the first plate. The German rounds did not have enough HE in the AP projectiles to do this. Theres accounts of Panther rounds completely penetrating a sherman and hitting another sherman that was directly behind the first. Niether the passage through the front armor, rear armor or internals of the first sherman (and the detonation of its base HE) shattered the AP round or stopped it from striking the next sherman.

A base HE charge in a AP round should have sufficient designed delay in its detonation train so that it will not go off till it has penetrated its maximum potential. In the case of 90mm US, it is so minimal that it goes off when striking a 20mm plate. Let me emphasize that it is both initiated AND the delay is SO short that it goes off AND destroys the 90mm AP round (its HE burster is too large). In the case of the 75mm US and Soviet 122mm (both have large HE?), the train is slow enough to last the time to penetrate the 20mm but by the time they strike/start to penetrate following plate, the detonate and have sufficient HE to decrease mass.

The really pertinent data is how long is the detonation train AND how long does it take to actually penetrate the armor. Both very small amounts of time but critical ESPECIALLY if the HE charge is over sized and has the potential to decrease the mass of the AP round.

When firing real HE rounds against armor, the HE is always put on delay. If it isnt (or can only be set for superquick), it will blow its mass to small pieces and have very little penetrating ability. Theres a good pic of a cromwell tank around that shows what a HV 75mm or 88mm HE round does to the turret.

I don't care if rexford compiled data in a pamphlet. Whats important is what he states here and how it is possibly involved in game design decisions.

[ June 28, 2004, 11:10 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Originally posted by flamingknives:

It usually looks like a diploma in Google. Mr. Tittles can find masses of information, but he's not always that good at analysing it.

I'll have a look in my textbooks later to see if I can figure out the delta V for an 88mm going through a 6mm plate. I'd guess that it's pretty small, meaning that an AP shell would have to only lose a tiny amount of energy to avoid going off when it skips.

No you are thinking incorrectly and you are probably a student with very little real world experience.

The AP round has both a forward velocity component AND a rotational V component. A designer COULD use either to design a mechanism for starting the HE train. But again, its critical to know the amount of time that the train requires.

Are your textbooks just your own version of 'Googling'?

[flamingknives]

Are your textbooks just your own version of 'Googling'?

In a manner of speaking, yes, although I tend to trust them more than internet sites.

The timing on an APHE shell is important because it is intended to detonate inside the tank. To skip a shell into a tank would require:

* That the ground is hard enough for the round to skip off

* That the angle is acute enough that the round will skip without being too damaged or the trajectory be altered too much (i.e. if the direction of travel is still along the long axis of the shell

* That the target tank is close enough that the shell will not detonate prior to hitting it. OR

* That the impact with the ground is not sufficient to trip the fuse. OR

* That even if detonated, the charge does not significantly alter the shell mass/shape/trajectory

As to whether the HE in an APHE shell is sufficient to reduce the shell so that it is not capable of further penetration, one would need to know the proportion of shell mass that is HE. If it is comparable to the US 75mm APCBC-HE, then one can conclude that the detonation would radically alter the shells mass.

No you are thinking incorrectly and you are probably a student with very little real world experience.

Real world experience? Of skipping 88mm APHE shells into tanks, no. I have no experience of that. Am I probably a student, or probably have little real world experience. As we're working with theory and history, it will suffice to prove me wrong rather than say that I'm wrong because I'm inexperienced.

[John D Salt]

Originally posted by Mr. Tittles:

[snips]

The German rounds did not have enough HE in the AP projectiles to do this. Theres accounts of Panther rounds completely penetrating a sherman and hitting another sherman that was directly behind the first. Niether the passage through the front armor, rear armor or internals of the first sherman (and the detonation of its base HE) shattered the AP round or stopped it from striking the next sherman.

You seem to be claiming that the HE burster in German 7.5cm PzGr 39 is insufficient to actually burst the shell.

If this is not what you are claiming, then please explain exactly what you are claiming.

If this is what you are claiming, then please explain what earthly point there would be to having an HE burster in the first place.

You can also explain why the Panther gun over-penetrations you refer to could not be attributed to simple fuze failures.

All the best,

John.

[Mr. Tittles]

Theres a couple of earthly reasons to have a HE in the back of an AP shell. One is to have an explosive go off inside a confined space. Namely the interior of a AFV. It would be very dangerous (even if small HE) and if the hatches were closed, especially so. The AP round would also be reaccelerated by having the detonation take place in its rear. Any fragments blown off the end or having the fuze blow out the back would be gravy.

A german 75mmL48 has such a small cavity that it is less than a 1/3 of the diameter and most of this small space is occupied by the fuze! These are AP (read very hard) shells. I doubt that the small HE would do more than break the back of the AP shells rear into more than a few pieces.