BTS and Troops, Info on Military Ballistics: Resources

[John Kettler]

Many moons ago I asked about how the fragment spray patterns were modeled in Combat Mission, after observing they weren't even close to the ones I'd seen in the official Joint Munitions Effectiveness Manual volumes. Seems like Steve said if I found better info on the actual frag pattern shapes and it didn't kill the CPU, then he'd look into it.

Well, I was making my occasional visit to the Panzer Elite board and happened to look at a response I got from Conall about rexford's post on frag density and velocity for the U.S.

75mm, 76mm and 105mm HE shells when I happened to see something which might help. Conall

cited two books which address such matters, and I thought I'd list them here. Has anyone seen or used either one?

Regards,

John Kettler

Military Ballistics, A Basic Manual, by G.M.Moss, D.W.Leeming & C.L.Farrar, Brassey's 1983, 1995

&

Modern Exterior Ballistics by Robert L. McCoy, Schiffer Military History 1999

Also you could read the article on Exterior Ballistics with Microcomputers is in Issue No 1 1984 of Warship International produced by the International Naval Research Organization www.primenet.com~inro. This is the article that Rexford has based his work on.

[John Kettler]

Hmm. Not even rexford has responded.

John Kettler

[Guest JonS]

Hi John,

I have the notesd given to me during a FOs course, which covers terminal ballistics and the shape of fragmentation patterns at various incident angles. Do you think that might be of use?

Jon

********

Ubique

[kipanderson]

Hi,

I have got the Brassey's book. A very fine book and not that expensive, probably around $30. It is one of a series of books written by the staff at The Royal Military College of Science for use by visiting service personal. Its a text book. Great series of books for anyone that really wants to know a subject.

All the best,

Kip.

[Jeff Duquette]

From a WWII field manual 23 September 1944.

Larger Version for the far sighted:

http://www.geocities.com/tigervib_2000/75mmM48_Shell_Fragmentation.jpg

Also Included are burst patterns for:

3" Shell M42A1

81mm Shell M56

90mm Shell M71

105mm Shell M1

4.5" Shell M65

120mm Shell M73

155mm Shell M107

Burst pattern of various fragmentation bombs is also included in the same manual.

Why not include realistic dispersion patterns for Indirect Artillery Fire as well. Range Probable Error and Deflection Probable Error for any type of gun, howitzer or mortar is available in common tabular firing tables.

[John Kettler]

Now, we're getting somewhere!

The various materials you all describe seem to be exactly what we need to improve the frag pattern modeling in CM and successors.

JonS,

Is there any way you could copy the info and get it to Madmatt or Steve? I'm sure it would be useful.

kipanderson,

So, you have one of the two, and it's great. That's good to know. I think I got a look at it years ago in Stanley Kramer's bookstore in Washington, D.C. A smallish book, yes?

Jeff Duquette,

You have presented exactly the kind of material I was hoping to see. Does anyone have data like this for German, Russian and British projectiles and bombs? What you show is fantastic. How difficult would it be to copy the manual and get it to Steve or Madmatt?

Presumably, the patterns are from static detonations instead of live fire?

Ideally, we should be seeing two separate phenomena in CM when a projectile detonates--fragmentation, which can carry quite some distance, especially for heavy artillery fragments, and blast, which is typically modeled by approximating a spherical charge of TNT and falls off as one over Range cubed.

Back when I had access to the JMEMs, there simply wasn't enough computational horsepower out there to model multiple effects. Even the JMEMs treated kill probability separately by kill mechanism type. Blast effects were in one section and frag effects in another, with blast modeled as described above and fragmentation effects handled through highly

detailed shotline modeling of fragment paths through the target from a series of elevations and azimuths.

I'd say we're emphatically on track.

Thanks, guys!

Sincerely,

John Kettler

[Guest JonS]

Sorry John,

I don't have the material to hand - and won't until May. <shrug> Unfortunatly that's the best I can do. Bad case of Real Life

Jon

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

*******

Quo fas et vino de femme

[kipanderson]

John, hi,

If you want a copy of the Brassey's book, or any others in the series, then Foyles, in London, is the place. They have a huge military history department, twice the size of any specialized book shop I have come across.

http://www.foyles.co.uk

Best to ring and talk to the staff in the military history department.

All the best,

Kip.

PS. Brassey's Land Warfare Series is what you need.

[:USERNAME:]

Originally posted by Jeff Duquette:

From a WWII field manual 23 September 1944.

Larger Version for the far sighted:

http://www.geocities.com/tigervib_2000/75mmM48_Shell_Fragmentation.jpg

B]

This data is certainly interesting in that it invalidates alot of what rambling wrecksford has been putting out as fact.

If you go to the websites and study the data closely, the shell that is landing at an angle of 30 degrees (on the right) spreads its effects to the sides predominately. This requires that the range be accurate in distance. The shell on the left (the one landing at a very shallow angle) spreads its effects to both the sides, front and rear. This is certainly more forgiving in range than is thought.

Rexford in his "vertical dispersion" pontifications does not seem to take this into account.

Lewis

PS Imagine a shell that has just kissed the ground at a shallow angle like a tank weapon could achieve and the shell bursts a few feet off the ground after ricocheting. The effects would be very deadly. In effect, the sides of the HE shell are focused towards more target area and less ground and sky.

[Jeff Duquette]

John Kettler Said:

How difficult would it be to copy the manual and get it to Steve or Madmatt?

I have been under the impression that BTS felt that contemporary (ie Circa WWII) Tech Manuals and Field Manuals were not considered accurate\reliable information for game design. It would however be interesting if actual artillery firing tables were considered in determination of indirect fire dispersion (or what wargamer’s like to call scatter). For example Range Probable Error is an indication of the probability of rounds falling a certain distance short of over from the mean range line (or from a gamers perspective your intended target). The values for range probable error at various ranges are typically laid out in tabular firing tables (TFT's). These values may be used as an index of the precision of the artillery piece or mortar tube at a particular powder charge and range. TFT values are determined on the basis of actual firing of ammunition under controlled conditions. For example, TFT for a 155mm M107 shows that the value of range probable error for charge 5 green bag at a range of 6,000 meters is 15 meters. On the basis of a 100 percent impact zone rectangle, 50 percent of the rounds will impact within 15 meters (over and short) of the mean range line, 82 percent will impact within 30 meters (over and short), 96 percent will impact within 45-meters (over and short), and 100 percent will impact within 60 meters. Deflection Probable Error (scatter to the left or right of a gun\mortars line of fire) is also detailed in TFT’s. But than again, one could simply approach wargame design from the perspective of what “feels” right rather than wading through the monotonous details of TFT’s or burst patterns.