Max Hit Probability

[:USERNAME:]

Originally posted by Ben Galanti:

Ok, I just did some quick hand calculations (which means there probably totally wrong, so someone should check them...) to compare the 75L70 and the 75L24.

I used the following assumptions. Shell velocity was constant throughout flight (ignoring air resistance). Also, that impact was at the same level as firing, so just a simple parabola trajectory. Muzzle velocity for the 75L24 was 450 m/s and for the 75L70 was 925 m/s (please correct those if they are wrong also).

I found the impact angle (as well as the firing angle with the above assumptions) for hitting a spot on the ground 1000 m away. For the 75L24 its ~2.8 degrees, and for the 75L70 it's ~.7 degrees.

I also found the difference in range if the gun was .1 degree above and below the above stated angles (I don't know what kind of resolution could be achieved when setting the vertical angle of WWII guns, the .1 degree delta might not be appropriate.)

For the 75L70:

.6 degrees => 914 m

.8 degrees => 1219 m

spread of 305 m between angles of .6 and .8 degrees

For the 75L24:

2.7 degrees => 972 m

2.9 degrees => 1044 m

spread of 72 m between angles of 2.7 and 2.9 degrees

[This message has been edited by Ben Galanti (edited 01-23-2001).]

I believe the panther gun HE velocity is a little high (maybe 750 m/s). But its somewhat Ok math. I like that you used an angular error and figured its effects.

Vertical scatter or whatever he is calling it is undefined and a little off base.

Lewis

[ASL Veteran]

Originally posted by :USERNAME::

The REASON I posted it is because he references the low angle of fire a weapon of this velocity would have. What you think I posted it for is the mystery. So do you get it? I am sorry but I cant draw pictures here.

Oh, well I figured that you were posting that in a vain attempt to 'prove' that the 75L24 was nearly identical to the 75L48 when it came to firing HE. So what you were really doing was posting a comparison of two identical guns in an attempt to show ... what ... that they were identical? Ah, now I completely understand the relevance of that post.

[:USERNAME:]

Well ASL gets a quirky idea in his head and cant let it go. Whatever. Glad you can amuse yourself. I am pretty sure what a comparison is. The author did not make a comparison. He was just stating that the early stugL24 was very similar to the KWK L24. The point (the part that I was drawing attention to) is that it was a relatively low angle weapon. Its velocity is actually pretty close to the L48 now that you have drawn attention to that fact.

Is that the theme for this thread? People getting things wrong and persisting on them?

What about the guy that was claiming that the L24 was derived from the infantry guns? Why isnt he persisting endlessly? Has he no endurance or just realized that it wasnt true?

Since this vertigo dithering effect is part of our wargaming vernacular; can someone PLEASE define what it is supposed to be? Is it a height differential in a shells flight? Something that can be related to angular error? Is it magically 1 meter for all german weapons somehow?

Boy this is good stuff.

[Bastables]

Originally posted by :USERNAME::

Well ASL gets a quirky idea in his head and cant let it go. Whatever. Glad you can amuse yourself. I am pretty sure what a comparison is. The author did not make a comparison. He was just stating that the early stugL24 was very similar to the KWK L24. The point (the part that I was drawing attention to) is that it was a relatively low angle weapon. Its velocity is actually pretty close to the L48 now that you have drawn attention to that fact.

Is that the theme for this thread? People getting things wrong and persisting on them?

What about the guy that was claiming that the L24 was derived from the infantry guns? Why isnt he persisting endlessly? Has he no endurance or just realized that it wasnt true?

Since this vertigo dithering effect is part of our wargaming vernacular; can someone PLEASE define what it is supposed to be? Is it a height differential in a shells flight? Something that can be related to angular error? Is it magically 1 meter for all german weapons somehow?

Boy this is good stuff.

Included in the IG family was the I.G.37 7,5cm and I.G.42 7,5cm both with a L/24 which was modified and called StuK 37 and PaK 37 when mounted in the early StuG and early PIV. No need to carry on about it user because he's correct.

[Jeff Duquette]

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[This message has been edited by Jeff Duquette (edited 01-27-2001).]

[Jeff Duquette]

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[This message has been edited by Jeff Duquette (edited 01-27-2001).]

[rexford]

75L24 HE was actually fired at 385 m/s and 420 m/s, so the advantages over 75L70 HE noted in my previous studies would be increased.

Previous studies used 450 m/s.

[:USERNAME:]

Originally posted by Bastables:

Included in the IG family was the I.G.37 7,5cm and I.G.42 7,5cm both with a L/24 which was modified and called StuK 37 and PaK 37 when mounted in the early StuG and early PIV. No need to carry on about it user because he's correct.

He wrote:

"As I understood it the 75L24 was developed from the 75mm IG which is known for its accuracy."

I took his saying "the" to mean the common weapon:

As 7.5cm Leichte Infanterie Geschutz 18:

Barrel length: 35.43 inches

Breech mechanism: Shotgun, percussion firing

Projectile & Weight: HE, 13.2lbs

Propelling charge: Five-part; brass-coated steel case

Muzzle velocity: 690 ft per second

Not the:

7.5cm Infanterie Geschutz 37:

Barrel length: 70.75in with muzzle brake

Breech mechanism: Vertical sliding block, semi automatic, percussion

Projectile & Weight: HE 13.2lbs

Propelling charge: Six part charge, separate loading, brass case

Muzzle Velocity: 918 ft per second

Notice the supposedly more accurate weapon has more velocity. Why would that be?

In any case, I think that all weapons that are mounted in panzerkampfwagon are KWK (kampfwagonkanone) not PAK which are antitank guns.

[:USERNAME:]

Originally posted by rexford:

75L24 HE was actually fired at 385 m/s and 420 m/s, so the advantages over 75L70 HE noted in my previous studies would be increased.

Previous studies used 450 m/s.

I see in Panzertruppen2 that the AP was fired at 385 m/sec. The HEAT was fired at 450 M/sec.

What source claims that there was different HE velocitys (actually meaning different shells I suppose)? I see that there was different HE so this is possible. The AP (that fired at 385 M/s) was 6.80 Kg in shell weight. I imagine the HE would weigh the same.

Can you also send Steve information on the US 75mm HE content? I would like to address the uber-sherman weapon also. Is it possible the germans had as good if not better HE? What about their fuzes? Were they better also?

Finally, How is it that all these weapon comparisons are using the magic 1 meter differential? And could you give a definition in technical terms what you think it is and what phenomena is causing it?

Thanks

Lewis

[This message has been edited by :USERNAME: (edited 01-24-2001).]

[Jeff Duquette]

USERNAME SAID: The AP (that fired at 385 M/s) was 6.6 Kg in shell weight. I imagine the HE would weigh the same.

The HE projectile does not weigh the same as the AP projectile. The AP projectile is over a Kg heavier than the HE projectile.

From: "PANZER IV, and its Variants" by W.J. Speilberger.

Secondary source for K.Gr.rot Pz. weight and muzzle velocity, David Honner's Guns vs Armour:

http://www.wargamer.org/GvA/weapons/german_guns5.html

Honner's Info appears consistent with Spielberger.

USERNAME SAID: German 75mm tank weapons all fired the same HE with different cartridges crimped on them. look it up. In fact; do a search here. Nice try though. I admire knee jerk arguments.

Are you sure you dont want to rethink this statement? I'm looking at a source right now that doesn't seem to agree with this. What is Ironic is that it is one of the sources you have quoted earlier.

[This message has been edited by Jeff Duquette (edited 01-24-2001).]

[PzKpfw 1]

Lorrin, I noticed in an earlier post your data, if I understood it corectly, had 7.5 cm KwK.42 SprGr accuracy with an 105m deviation on an shot at 800m even with range known exactly?. Question how did this affect the SprGr. accuracy operationaly?. As an example the French reported in 1947 after LF tests with the Panther; that even fireing SprGr @ 1400 - 2000m that hits were achieved by the 4th or 5th shot.

Regards, John Waters

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

"We've got the finest tanks in the world. We just love to see the

German Royal Tiger come up on the field".

Lt.Gen. George S. Patton, Jr. February 1945.

[This message has been edited by PzKpfw 1 (edited 01-24-2001).]

[rexford]

Will Phelps' PzKpfw IV site losts two muzzle velocities for 75L24 HE, 385 and 420 m/s.

1.0m vertical dispersion for 50% of shots is from German ballistic tables, as I mentioned previously. A careful re-reading of the accuracy analysis will verify this. This is figure for 75L48 HE at 550 m/s.

75L24 HE at 385 m/s would have significantly different trajectory and accuracy from 75L48 HE at 550 m/s.

Never said German HE was superior to Sherman 75mm HE, only that 75L24 HE had heavier explosive weight.

Finally, interesting to note that none of the complainers about absence of trajectory analysis for 75L24 HE accuracy has commented on the Page 7 study that supported our theory.

[rexford]

Received an e-mail that CM accuracy at 2000m is higher than 4.5% for many guns, and follow-up shot accuracy may reach 3 times the initial figure after repeated shots at the same target.

Please note this correction to my earlier e-mail.

[rexford]

In response to John Waters' post, where French trying to hit a vertical or horizontal target.

Earlier analysis based on a ground point target, say tank is trying to drop HE in them middle of a group of soldiers at 800. 75L24 more accurate than 75L70 on this due to curved trajectory of short 75.

Maybe French were firing Panther HE at a vertical target, such as a building or tank, and 700 m/s HE round might hit on 3rd or 4th shot with bracketting.

My earlier posts repeatedly noted that the normal "To Hit" accuracies don't count for HE fire at ground point targets, since slower is actually better if ground is fairly level. Two HE accuracies would be the ultimate, one for ground point targets and one for vertical targets.

75L24 is bad at hitting vertical targets accurately on the fly, but is good at consistently dropping HE close to a target.

If infantry at 800m are on the side of a small hill facing a tank, it might count as a vertical target or ground point target, depending on alot of factors.

Previous posts are based on the distinction between vertical HE targets and ground point HE targets.

[Jeff Duquette]

Oberst Aufklerung John:

Totally off topic, but someone recently posted a great snippet from the French 1947 test indicating that the Panther was capable of astounding rate of fire of 20 round per minute with its main gun. Do you know what the test parameters behind this rate of fire were? Surely this wasn't aimed fire?

Thanks

[Jeff Duquette]

Field Manuals for Artillery Gunnery (ala FM6-40) typically focus dispersion discussions on horizontal dispersion. Burst radius of individual rounds needs to be considered when talking about the effects of dispersion, ideal sheaf sizes, and artillery accuracy\effectiveness. HE doesn't need to directly strike an infantryman in the open to he considered accurate and effective fire.

The opposite is true for Tank Gunnery (ala FM17-12) in which the chief focus is on vertical dispersion. Point accuracy is obviously the main consideration here. A near miss in tank gunnery does not do a tank crew much good…the crew need to hit what they are shoting at for their fire to be effective.

Pretty basic...or so I thought.

When someone makes a statement like the "75L24 was know for its accuracy"…what is that really implying? Are we talking about the fact that it has a relatively small horizontal dispersion zone…or does it have a small vertical dispersion zone? (These are intended as rhetorical questions.)

The differences in trajectory and initial velocity between the 75mmL70 HE round and its AP round should be evident by a simple examination of the weapons gun sights. Range graduations for HE and MG fire are on the left side of the scope. AP range graduations are on the other side of the scope. Same is true of the T.Z.F. 5f1/L48 75mm. HE range scale on left…AP on right. I haven't seen the T.Z.F. 5b/L24 75mm I suspect since HE and AP velocities were so close the sight probably had MG range scale on left, and AP/HE on the right.

This is a photo taken through the gun sight of a 17-pdr. Conell provided the following image to me in order to post of the 88 accuracy thread.

click on the URL if you wish to see the full size version:

http://www.geocities.com/tigervib_2000/Crap/17pdr.jpg

Note the close spacing on range graduations for the AP rounds relative to HE rounds. Look at the 400m and 800m marks for APCBC...than go across to the left side of the sight and look at the same stadia lines for HE. This should be a direct implication of variation in launch angle between high velocity and low velocity rounds. The HE round will fire along a high arc...steep launch angle...steep decent angle. APCBC is the opposite...shallow launch angle....shallow decent angle. Also recall that we're not firing in a vacum, so decent angle will be somewhat steeper than launch angle.

========================================

Side note on turret ergonomics: High velocity range scales for British sights are on the left side of the sight. German tank gun sights have high velocity range scale on the right. It is interesting to note the difference in the way the range scales are laid out between British sights, American sights, and German gun sights. The German TZF sights have aim point that is always the same (assume no lead). On American gun sights the aim point changes with range estimation. I believe modern German tank sites (at least GAS) are arranged where aim point changes with range estimation. What do you reckon prompted the Germans to switch design philosophy?

[This message has been edited by Jeff Duquette (edited 01-24-2001).]

[Jeff Duquette]

This is also way off topic…One additional question on turret ergonomics. German WWII tanks have their gunner and TC positions on the left side of the turret. This has always struck me as a disadvantage to a right-handed loader. Leo-1 and Leo-2 both have the more conventional arrangement of TC & gunner on right, loader on left. Why do reckon there was a change in design philosophy after the war?

[This message has been edited by Jeff Duquette (edited 01-24-2001).]

[Bastables]

Originally posted by Jeff Duquette:

This is also way off topic…One additional question on turret ergonomics. German WWII tanks have their gunner and TC positions on the left side of the turret. This has always struck me as a disadvantage to a right-handed loader. Leo-1 and Leo-2 both have the more conventional arrangement of TC & gunner on right, loader on left. Why do reckon there was a change in design philosophy after the war?

[This message has been edited by Jeff Duquette (edited 01-24-2001).]

Post war West German Army using USA tanks with the loader on the left.

[Bastables]

Originally posted by :USERNAME::

He wrote:

"As I understood it the 75L24 was developed from the 75mm IG which is known for its accuracy."

I took his saying "the" to mean the common weapon:

As 7.5cm Leichte Infanterie Geschutz 18:

Barrel length: 35.43 inches

Breech mechanism: Shotgun, percussion firing

Projectile & Weight: HE, 13.2lbs

Propelling charge: Five-part; brass-coated steel case

Muzzle velocity: 690 ft per second

Not the:

7.5cm Infanterie Geschutz 37:

Barrel length: 70.75in with muzzle brake

Breech mechanism: Vertical sliding block, semi automatic, percussion

Projectile & Weight: HE 13.2lbs

Propelling charge: Six part charge, separate loading, brass case

Muzzle Velocity: 918 ft per second

Notice the supposedly more accurate weapon has more velocity. Why would that be?

In any case, I think that all weapons that are mounted in panzerkampfwagon are KWK (kampfwagonkanone) not PAK which are antitank guns.

I'm sorry who but you stated the I.G.37 was more accurate vs infantry targets than the I.G.18? Rexford was detailing the StuK/I.G.37 vs the Kw.K 42 in engaging infantry targets. It’s quite apparent that there was a reason that the lower velocity I.G.18 was the preferred infantry support weapon and therefore manufactured and issued in greater numbers than the I.G.37 to the 13 Kp of the Infantry regt (I.G. Kompanie). Still trying to muddy the debate as usual eh User?

Quite right about the detail of of Pa.K vs Kw.K still wrong about the actual main argument.

[PzKpfw 1]

Originally posted by Jeff Duquette:

Oberst Aufklerung John:

Totally off topic, but someone recently posted a great snippet from the French 1947 test indicating that the Panther was capable of astounding rate of fire of 20 round per minute with its main gun. Do you know what the test parameters behind this rate of fire were? Surely this wasn't aimed fire?

Thanks

Jeff IIRC they were testing the limits of the KwK.42 & it was not aimed fire just one of those'alright lads lets see what she can do' deals ...

Regards, Joh Waters

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

"We've got the finest tanks in the world. We just love to see the

German Royal Tiger come up on the field".

Lt.Gen. George S. Patton, Jr. February 1945.

[Jeff Duquette]

The Beast Said:

Post war West German Army using USA tanks with the loader on the left.

Dam it Bastables! I wanted the answer to be something complicated and mysterious…not something quit so obvious!!! Presumably the Bundeswher decided they liked the right side gunner slot after playing about in the Walker Bulldog.

Did you get Kitty to make your "dazzle" Panther winter camo scheme yet? Or did I succeed in pissing her off to the point of dumping the whole idea?

John said:

Jeff IIRC they were testing the limits of the KwK.42 & it was not aimed fire just one of those'alright lads lets see what she can do' deals

Gracias John…you don't by chance have the full blown version of the French Test Report?

I cant beleive no one said a darn thing about my John Wayne sound bit I posted. Just click the button and it plays.

[This message has been edited by Jeff Duquette (edited 01-24-2001).]

[PzKpfw 1]

Originally posted by Jeff Duquette:

Gracias John…you don't by chance have the full blown version of the French Test Report?

I cant beleive no one said a darn thing about my John Wayne sound bit I posted. Just click the button and it plays.

No Jeff just snips. I am trying to aquire it. Actualy I was ROFL at both of the waves as they were both fitting ......

Regards, John Waters

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

"We've got the finest tanks in the world. We just love to see the

German Royal Tiger come up on the field".

Lt.Gen. George S. Patton, Jr. February 1945.

[Paul Lakowski]

Just got a great package in the mail from Jeff 'TM9-1907' covering amoungst other things air & ground burst patterns for various Allied [ USA] shells. I had no idea they were that varied. Some are star shaped but most are a long thing side lob type pattern. Only airburst have anything approaching a ellipical pattern. These mostly come in a low angles 10-30°. If any one has seen this type of data , was it compareable for Germans Russian and British HE ammo?

[Jeff Duquette]

More data on the mysterious German 75mm

From: George Parada's "Actung Panzer" Web Site

http://www.achtungpanzer.com/pz3.htm#panzer4

German 75mm KwK40 L/48

Sprgr 39 (HE)

Weight = 5.72kg

Muzzle velocity = 590 m/s

PzGr. 39 (AP)

Weight = 6.8kg

Muzzle velocity = 790 m/s

=============================

Hey Paul:

Figured you'd find that TM of interest.

[:USERNAME:]

Originally posted by Jeff Duquette:

The HE projectile does not weigh the same as the AP projectile. The AP projectile is over a Kg heavier than the HE projectile. Are you sure you dont want to rethink this statement? I'm looking at a source right now that doesn't seem to agree with this. What is Ironic is that it is one of the sources you have quoted earlier.

[This message has been edited by Jeff Duquette (edited 01-24-2001).]

I corrected it to 6.80 before you posted the above info. I believe the L24, L48, L43 and L70 all fired AP rounds weighing 6.8 Kg.

I would suspect they were all the same but who knows.

There seems to be two HE rounds. Rex is stating that one fires at 385 m/s and the other at 440 m/s for the L24? One must be heavier than the other and have a correspondingly higher payload.

Anyway, since the AP is 385 m/s I assumed that if the HE also weighed the same then it would have the same velocity as the AP. This does not really have to be true.

So whats the HE shells weights? I think that the website I posted showed the payloads for the two different types of HE shells but not the weights. Whats the velocities?

If you have the rifling info on the L48 and L70 guns I would appreciate it.

I still say rex is wrong on the 1 meter thing.

Lewis