Question about the shell size of the 88mm

Thanks Walter, it may well go back to the origins of the designs. The Ordnance Department was often not know for creativity but one must admit they did push production of known things extremely well.

I did look at the pictures and think this is the parent site for lots of them.

http://www.quarry.nildram.co.uk/tankammo2.htm

When I look at the Sherman 75 I wonder how it obtained the velocity it did !

Gaines

 

UK Warrant Office Reports WO 291/1263 and WO 165/135, dated 22 Sept 1944.

US 12th Army Group firing tests conducted at Isigny on 20-21 August, 1944, also noticed the rather lackluster accuracy of the British 17-pounder APDS round(57% hits - 24 out of 42 fired - on a tank-sized stationary target at ranges from 200 yards to 600 yards). However, the US personnel were assured by Colonel A. G. Cole, Deputy Director of Artillery, Ministry of Supply, that the 17-pounder rounds used during the test had not been proof-fired, and that the lot was sub-standard.

 

Just for those not familiar with Mr. Williams and his work, here is a link to his website: http://www.quarry.nildram.co.uk/
All I can saw is WOW!

 

Takao, I totally agree, wonderful site. I was a ballistic buff 55-60 odd years ago and found Mr. Williams site using Google of all things. Been reading it and his constant updates for years. the wife just assumes I am crazy !! LOL Or easily entertained.

Gaines

 

A good discussion. I would like to add that according to Ian Hogg the Germans experimented with the discarding sabot idea but couldn't get past the accuracy problem so they "discarded" the idea in favor of a penetrator encased in a light shell. It didn't penetrate as well as the discarding sabot but it had better accuracy. It penetrated better at the shorter ranges but at longer ones physics dictates that projectiles with lighter mass will lose their velocity faster than heavier projectiles. Also, we must also remember that the metallurgy and design of the projectile also need to be figured into the mix. Can anyone site any study that compares the metallurgy of American, British and German shells? I know that the original AT rounds we took into Africa were junk.

 

Oh boy. This is turning out to be an all time favorite thread already...Thanks for the link to that excellent site Mr Takao. Good input from everybody...
Shell size. Wonder if the British machine guns used in their bombers were very effective? Seeing as the Germans were using low velocity, large chemical rounds...Could the .303 fire an effective round- able to bring down an a fighter consistently? -Yes the Hurricane/Spit did well- can't compare ...And how did the US 50 caliber compare to the British .303?

 

Thanks for the salute, a topic I enjoy as well.
This should answer many of your questions, reads as if it were written for you !!!

http://www.quarry.nildram.co.uk/WW2guneffect.htm

 

HA, thanks G. .. Got lazy and didn't look far enough. Cheers.

 

[SIZE=9pt]I will look up the relevant War Office files in the [/SIZE][SIZE=9pt]NAM[/SIZE][SIZE=9pt]. Please forgive my scepticism about a report which appears on three wargame forums, each interpreting WO as Warrant Office! [/SIZE]

[SIZE=9pt]The second quote illustrates some of the problems with accepting a statement that "17 pdr APDS would hit a target x % of the time at y range. This is what wargamers want to hear, but isn't the language of military technology, as it ignores other variables such as test conditions, quality of the ammunition, ammunition used to zero the weapon sites, skills of the tank crews etc. [/SIZE]

[SIZE=9pt]One of the reports summarised by John D Salt for wargamers http://mr-home.staff.shef.ac.uk/hobbies/ww2eff2.pdf illustrates some of the points which raise my curiosity about WO291/1263(?) and 291 /135. WO291/324 "Accuracy of First round in Anti Tank Engagements" is very closely related to the topic under discussion [/SIZE]This paper, very properly, uses the terms dispersion in minutes (1/60ths of a degree) of arc + or - of the target and then relates these into inches (one minute of arc = 4.2" at 400yds and 10.4" at 1000 yards. This can be converted into a theoretical hit % by superimposing a dispersion pattern onto target area the same size as the vulnerable area of the target.

The report shows that 6 Pdr APCBC has less dispersion +/- 2.9" arc than 6 pdr APDS (+/-3.6" arc if zeroed with APDS and 3.7" arc if zeroed with APCBC ) and no significant difference in mean variation for 17 Pdr ABPC (+/-6.1" arc) and APDS (+/- 5.1" arc zeroed with APDS and +/-5.2 with APCBC) at 1000yds. In other words there is twice as much dispersion for the 17 Pdr at 1000 yards as there is for a 6pdr regardless of the ammunition type and the type of ammunition used to zero the gun sight.

John D Salt does not make it clear exactly what this +/- dispersion means. Is the is the dispersion into which ALL of the shots would be expected to fall? Or is it the standard deviation of the dispersion? Or, more likely, is "Expected range error" what post war gunners might refer to as "Probable Error in Range" and the dispersion into which 50% of rounds will fall. Assuming the latter, the figure for 17 pdr APDS of +/- 5.2 mins of dispersion @ 1000 yds = +/- 54 inches, which means that a 17 Pdr firing at a 108" tall tank will hit it about half the time. There is an explantion on the section on this page under "probability" http://nigelef.tripod.com/errorsmistakes.htm which explains some of these terms.

[SIZE=9pt]The conclusion of the paper is that the key issue is determining first round accuracy is range estimation. We know that armies accepted that this really mattered and post war a lot of effort was spent improving range estimation including ranging MG, coincidence, stereoscopic and laser range finders. There may well have been greater variation in the trajectory of APDS ammunition than AP shot, but the main factor may well be the skill of the gunner and the quality of range cards, whether there has been an opportunity to set up range markers and the target obliging to park on one of them. [/SIZE]

[SIZE=9pt]A first round hit about half the time is pretty much what would be expected of trained gunners using Ww2 vintage sights at 1000 yards range, and not very different to the the results achieved by 76mm US or Soviet guns or German 75 mm Pak 40 ort 88mm Pak 43.. it certainly fits with my own observations watching 105mm and 155mm field gunners undertaking antio tank shoots with anto tank telescope sights. [/SIZE]

 

Oh heck! We don't need rocket science here. One could compare accuracy of AT guns just like you would any other rifle. Fire them all at the same given, known range and compare the groups. Shooters do the same by firing their rifles from a bench rest. To give it some validity one would have to have several examples of each AT gun so that the size of their groups could be averaged. I suspect Britain, the USA and the USSR all did this after, or even during, the war. Perhaps some of that research is still in existence.

 

Harold,

Hmm isn't ballistics based on the same maths and physics as, err, rocket science?

You are quite correct to point out that armies test the dispersion of rounds from artillery pieces in the same way that small arms are tested on a bench rest. These are carefully controlled experiments to factor out other 12+ variable which could affect the trajectory, This leaves the round to round variation from the ammunition filling and variations through imperfections in the design of the gun. Firing guns on other occasions may be affected by factors including the gunner's skill in estimating the range, laying the weapon for elevation and azimuth, target altitude, sight alignment, wind speed and direction, charge temperature, jump, droop, barrel wear, rotation of the earth etc.

However, it was clear from some of the discussion on this thread that there is some confusion between the difference between dispersion of the rounds around the MPI achieved on a proof range and the other factors affecting the likely hood of hitting the target. The field tests listed in the WO 291 series of reports mentioned on the wargame forums were not necessarily undertaken under proof conditions, and cannot be used to claim that the 17 Pdr gun was inherently inaccurate.

The conclusion from WO291/324 is that estimating an accurate opening range has the biggest effect on the likely hood of a first round hit and why accuracy falls off with range between 400yds and 1000yds. This is more important than whether the gun is a 6 Pdr or a 17 pdr or whether the gun fires APDS or APSBC and what ammunition nature was used to zero the gun.

If a wargamer wants to claim that a 88mm gun (or a Sherman 76mm gun) is more likely to hit the target with a first round than a 17 Pdr gunner, then the argument needs to be based on the relative qualities of the gunner and the sights and not the ordnance.

 

Holy crapola!!!
What an awesome read!
I know I am engaging in thread necro here but I just wanted to thank everyone who contributed to what I found to be an insightful and fascinating discussion. And I couldn't think of a better way to do so than creating an account here just to say so.
I love diving into rabbit holes of learning on the web and geeking out about ballistics and thanks to you guys I have a bunch of new links bookmarked to read, Which is very technical end result to a quick diversion to the browser to suss out the coolest way that Larry Correia's Monster Hunters Inc. could take on Harry Dreden's reanimated T-Rex.
I know, I'm a nerd. :v4victory:

 

I love these...

Ordnance refers to ALL "material" - Guns AND munitions

Ordnance corp deals with the munitions...Artillery deals with the gun. As an example...

 

Yep. Each to their own, but jest sews ya nose.
This is my all time favorite thread on this forum. Five Star Rated - for sure!

One look at Otto's image of those shells and all the spit and vinegar built up in you pours out at the upper echelons that let the allies fight a war so thoroughly outclassed by Axis technology and innovation.

All those stories about the Sherman's with their close range howitzer's being so out classed - well that image truly puts it in perspective.
Some of those shells were so obviously so un-aerodynamic it just leaves your head shaking in wonder...

 

As stated I disagree. For instance I remember a thread (not sure where it was unfortunatly) which discussed sabot rounds for the 17lber apparently there was a problem with seperation that effected accuracy. It even came down to which plant manufactured the rounds. From what I recall there were 3 and one stood out from the other two but I don't recall which one or the direction. At close enough ranges it's probably allthe gunner as range increases then other factors come into play although gunner skill is still important.

 

I don't think the evidence from the WW2 OR study supports this.

Even if the variation in MPI/ Zone of the gun may be more significant at longer ranges, the ability of gunners to correctly estimate the opening range drops away even more, significantly enough to account for the decrease in accuracy between 400 and 1000yds,

If you wish to war game this, of course you can build a complex model differentiating between the zone of a APSBC and APDS rounds at different ranges. But unless you also accurately model the soft factors affecting range estimation such as the skills of individual gunners, the stress they are under when they are in action, the presence or absence of range marks, smoke and other obscuration you are likely to end up with random factors dwarfing the subtleties which you have built in - and the same results as WO291/324.

 

Range estimation also makes less difference with higher velocity guns though. An extreme example of this is with modern APDS anything out to about 1.5 km is essentially point blank. If for instance the target is 2m high and one aims center of mass then the projectile will drop enough to miss in ~.44 sec. The distance that the projectile can cover in that time is of little import to hitting the target (it may be critical to killing it however). Looking at:
http://www.quarry.nildram.co.uk/ammotable9.htm
and comparing the US 3"gun and the 17 pounder for instance we see muzzle velocities of 790 vs 884 m/s. In the example above the 17 lber could be off by 395m and still hit the target when the 76mm gun would miss if over 353m. That gives the 17 lber an edge of over 10%

 

There were also some stability problems with the 17 pounder due to compromises that had to be made in the mount to get it into the Sherman turret which affected accuracy. The cradle was shortened so much that the barrel had to be made heavier by reducing its taper. And getting off a second shot from a Firefly was a lenghty process