"Panzer War Research pages" Topic

I've added a few pages to the site showing some of the research I've found in the last few years. Not all of this has made it into the rules at present as gaps remain.

panzer-war.com/page32.html

Interesting.

Thanks.

Mobius, I'm really interested in what you've posted.

I worked as a Scientist on Tank Gun Accuracy at Chertsey in the UK on Challenger 2 firing trials. I had to put together some stats routines to work out chance-of-hit against various targets. This included working out the SDs and MPIs from firing trial results (not just for Chally2).

The first link you gave to the 1969 Naval Research report gives a report which is pretty good. I'd like to read the other report by Robert McCoy but the link for that goes to the same report as in the first link. Is that deliberate?

Anyway, your program to use drag co-efficients etc is really interesting. Is that for working out KE and penetration at the target?

For chance-of-hit you just need the SDs and MPIs.

SD stays constant whatever the range. The chance of hit depends on the amount of target covered by the SD distribution, as I think you've already got. Getting the SD for a firing platform is the key part, and these can vary a lot.

I did use a simple Basic program to sum the strips of the distribution covering the target, including for an off-set MPI, but I did it 25yrs ago and can't remember exactly how I did it :( It's probably classified anyway.

I recently tried using Excel to do the same but the Excel functions couldn't do the summing for off-centre MPIs properly.

However, I do remember that no matter how bad the SD for a firing platform basically anything under 1000m is liable to be hit. Small SDs and good chance of hit only really comes in to play at longer ranges.

Keep up the good work and shout if you think I can be of help.

Cheers,

B

Hint: convert the target size into Mils and express the SD in Mils as well.

The first link you gave to the 1969 Naval Research report gives a report which is pretty good. I'd like to read the other report by Robert McCoy but the link for that goes to the same report as in the first link. Is that deliberate?

No, it's not. That link must of got stuck in my clip board. It is suppose to point to the amazon listing of the book.
link

Anyway, your program to use drag co-efficients etc is really interesting. Is that for working out KE and penetration at the target?

No, I use a different program that averages the normalized armor penetration data from various published sources.

As someone who worked with British dispersion data isn't the term 'average mean' in regard to dispersion redundant?. Or, does that mean something other than mean dispersion?

And, maybe you can tell me the way to get to S.D. from ave. m. d. because my calculations of British and US guns from British data seem too low compared to other countries.

Hi Mobius,

Not quite sure what the term 'average mean' is referring to.

But I can probably give you an idea of why the Brit and US SDs seem different to other countries.

Brits use an SD expressed as an angle at the target and use a term called 'Military Mils', which is slightly different to other definitions of a mil.

The Brits use a definition of 1 Mil = strike co-ords in cm x 10.1859 / range in metres, or
1cm deflection at 1000m = 0.0101859 mils.

I also remember that 1 Military Mil = 0.982 milli-radians.

There is a HMSO publication called 'The Textbook of Ballistics and Gunnery' that was our bible, but I think it'd be very difficult to obtain a copy of this.

Hope this helps,

B

I've never heard the term "military mils" before, but there are 6400 NATO mils to a full circle, 6000 Warsaw Pact mils, and (obviously) 1000 x 2 x pi milliradians, which explains the conversion factor.

I am quite surprised that anybody would bother with differences of less than a tenth of a mil.

All the best,

John.

One strange thing I found is this bit in FOREIGN FIRING TABLES for SOVIET GUN, is the Notes.
link

4. The probable vertical error in this table is computed differently than in U.S. tables. It represents the entire 50% dispersion, hence it is twice as large as a comparable figure shown in U.S. tables.

Does this mean that US (and maybe British) dispersion are understated when compared to German or Russian dispersion?

No – what I think they're saying is that the Sovs are expressing the SD as both sides of the mean, whereas the Brits express the SD as just one side of the distance from the aim point. Hence halve the Sov value.

Think of it as just a simple right-angled triangle with the firer at one vertice, the target at the perpendicular at distance range R, with the shots landing either side of the target a distance measured in SDs. The Brits just use one side, the Sovs use both sides. It's the same, just expressed differently.

JohnD: They express the SD in this way so as to easily convert the distance a round falls from the aim point in centimetres.

When firing in a tank the Brits use a 3m square target with 9 aiming marks on it. They fire 10 rounds at the target (to get a statistically significant set of results and also enough rounds to cover something approaching a realistic engagement (round-to-round variances etc)) and record each shot strike relative to the aiming mark. If the shots are going waaay off then adjust the aiming mark accordingly.

Compute SD and MPI when all shots are done.

Sometimes a round may be statistically wild and be discounted (do an outliers test).

Mobius, your Italian charts have some inaccurate information for the M13/M14. They did not have auto-loaders. The confusion comes because they had semi-automatic breeches, and there's been confusion translation and/or with people not understanding terms. The semi-automatic breech pops open and ejects the shell casing when the gun is fired, leaving it ready for you to slam in another round. This does speed up firing, but you still need a gunner and a loader, so the M13/M14 suffer from having two-man turret crews. Semi-automatic breeches were not entirely uncommon in WWII--the German 75mm infantry gun had one and there's film of a single gunner just slamming in rounds and firing the gun again and again. Remarkably fast, but he's not changing aim at all and the very short shell and casing are moderately light and quick to load.

Find some turret interiors of the M13/M13 and you'll see that there's no sign of an auto-loader (and certainly no space for one).

link

your Italian charts have some inaccurate information for the M13/M14. They did not have auto-loaders.

Thanks,
changes made.

Mobius,
Excellent work.

It looks like your program uses a range estimation error for the second shot. My question is wouldn't crews be using a range adjustment like "Add 200" or "Drop 300" for the second shot? Normally an adjustment of +/- 10-20% after sensing the tracer? This is under the "Average Range Estimation Error".

Do you still have a download link for the program accuracy.zip?

Wolfhag

It looks like your program uses a range estimation error for the second shot. My question is wouldn't crews be using a range adjustment like "Add 200" or "Drop 300" for the second shot?

It's a reduced range estimation error for the second shot. From US "Tank Gunnery Study Number 53"

b. However the manual does not provide a method by which the correct range change can be be determined. Experience in the European Theater indicated need for such a method.

(1) Interviewees emphasized the necessity for getting a hit before the enemy did, particularly when firing at tanks.

(2) Adjustment of tracer height can result in obtaining hits in fewer rounds than by following bracketing principles, when firing at vertical targets.

c. Accurate measurement of the height of tracer above the target is possible only with flat trajectory weapons.

Mobius,
On page 54 of FM 17-12 it shows how do do Burst on Target for a follow up shot. Isn't a crew attempting to estimate range replaced with range adjustment in yards/mils or aim adjustment using BOT because it's quicker for a follow up shot? I'm not disputing your 2nd shot range estimation error. Supposedly it's hard for a gunner to perform range estimation because of magnification but stadiametric RF do help. I know your program can't really take into account all of the variables and nuances of crew performance.

I'm asking if there are any any other ways your program can show 2nd round range estimation errors / hit chance % based on techniques other than range estimation.

Wolfhag

The second and subsequent adjustments are improvements to the original estimation. The limiting factor would be the ability to observe the shot and shot dispersion.

More Research pages added and updated.
panzer-war.com/page40.html