Jeff Duquette

Gorilla: First off thanks for the research\digging and posting the above URL. I have the URL booked marked now. I am glad you are enjoying the CM DEMO. I was not sucked into CM initially by playing the DEMO. On the contrary I couldn’t figure out what all the fuss was about. But I stuck with it, bought the full blown version…now unfortunately I’m hooked. I can’t wait for CM2 East Front to rear its head. I’m a civil engineer by profession. And, although I’m not technically a materials engineer, I do know a fair bit about construction materials and construction material engineering (comes with the territory). I have some military background, but that time was spent in Armour back in the early\mid 80’s. Trained on the old M60A1 and M48A5’s (M48A5 was basically uprgraded to carry a 105mm). I’m guessing from your comments, that you have a fair bit more hands on experience in the handling of artillery than myself…so I will try to limit my answers to your questions via references to Army Field Manual information. Regarding the heat effect of the blast I suspect that your second premise on blast heat being enough to start engine fires, ingnite fuel, etc is probably correct. I am guessing that the time of the blast is such that melting -- or a phase change in the steels structure -- would only occur at the very surface of armor plating. Scorching and blackening of the surface would probably result. With respect to mortar ROF (and hopefully you are on DSL or have a cable modem…the images are really going to slow this thread down) the following table is contained in FM 23-91 MORTAR GUNNERY. I suspect WWII mortar ROF’s were very similar. Mortar Rates of Fire Some of the basics of mortar fire (again derived from FM23-91 Mortar Gunnery <BLOCKQUOTE>quote:</font><HR>SHEAVES The term sheaf denotes the lateral distribution of the bursts of two or more weapons firing at the same target at the same time. The distribution of bursts is the pattern of bursts in the area of the target. Normally, all weapons of the platoon/section fire with the same deflection, charge, and elevation. However, since targets may be of various shapes and sizes and the weapons deployed irregularly, it is best to adjust the pattern of bursts to the shape and size of the target. When mortars fire an open sheaf, the distance between impacts of rounds is half again the distance between mortars. Normally, 120-mm mortars are 60 to 75 meters apart, 81-mm and 4.2-inch mortars are 35 to 40 meters apart; thus, in an open sheaf, rounds should land about 60 meters apart. For the 60-mm mortars, which are normally 25 to 30 meters apart, rounds should land about 45 meters apart. All mortars fire using different deflections. The open sheaf is used when the target is slightly wider than the area a standard sheaf would cover.<HR></BLOCKQUOTE> So to a very great degree sheave size seems to be a function of burst radius or lethal radius around the impact point. Open Sheave Standard Sheave The following is a table detailing ideal sheave geometry for Final Protective Fire type missions (FPF for us laymen). It’s based upon burst radius, mortar caliber, and unit size (i.e. number of tubes firing). Normal FPF Dimensions Firing a 100 meter or 200 meter zone would ideally appear something like the following for burst distribution. Presumably this would entail firing three successive sheafs, with either an increase or decrease in charge to cover the target area. Firing a 100meter Zone Firing a 200meter Zone Hopefully some of the above poop will answer some of your questions.

A quote from one of Gorilla’s above provided URLs. Should shed some light on the subject. <BLOCKQUOTE>quote:</font><HR> From: Military Analysis Network When a high explosive detonates, it is converted almost instantly into a gas at very high pressure and temperature. Under the pressure of the gases thus generated, the weapon case expands and breaks into fragments. The air surrounding the casing is compressed and a shock (blast) wave is transmitted into it. Typical initial values for a high-explosive weapon are 200 kilobars of pressure (1 bar = 1 atmosphere) and 5,000 degrees celsius. <HR></BLOCKQUOTE> For normal folk an atmosphere is better understood as 14.7 psi (pounds per square inch). Sorry for the non-meteric presentation here. In America we are still using that backward English system of units and measurements. Anyway a compression blast from detonating High Explosive is capable of generating a pressure of (see above URL) 200 kilobars. That’s: 200 x 1000 x 14.7 = 2,940,000 psi. To put that blast pressure into perspective, construction grade rebar (reinforcing steel used in concrete for you lay folk), and structural steel typically has yield strength in the range of 30 or 50 ksi…or 30,000 to 50,000 pounds per square inch (psi). This is the applied pressure at which mild steel moves from an elastic state to a plastic state. In other words failure of the steel is initiated at the yield strength. Construction grade steel doesn’t snap or rupture once yield strength is exceeded. Construction grade steel will creep along and deform plastically for awhile until rupture occurs. In buildings and bridges this is a good thing. Deformation and shift about before failure occurs gives folks time to get off the bridge or get out of the building before the thing collapses (or so the theory goes…doesn’t always happen that way in practice). Now in the case of less ductile steel (hardened steel) which would tend to be employed in tank armor … From: Ballistic performance Maps for Thick Metallic Armour by Srivathsa Ramakrishnan (1998), Grade A steel armor plate is rated with a yield strength of about 3 times the yield strength of a mild steel. This equates to about 150,000 psi (that’s some seriously strong steel…take my word for it). The critical item to remember being that hardened steel does not really fail in a ductile manner ala. construction grade steel. It fails in a brittle manner…so as yield strength is approached catastrophic failure tends to occur (i.e. rupture or cracking) with little plastic deformation occurring prior to rupture. So what’s this all mean: Well a compression blast from an exploding high explosive shell weighs in at about 2,940,000 psi. The yield strength for armor plating weighs in at 150,000 psi (and bare in mind the values in Ballistic performance Maps for Thick Metallic Armour, by Srivathsa Ramakrishnan are for modern armor…not WWII armor…and if you think there hasn’t been serious advances in metallurgy over the last 55 years, think again). A is really big compared to B. I leave the rest to your imagination. [This message has been edited by Jeff Duquette (edited 09-29-2000).]

Sorry, couldnt resist. From: Bill Mauldin’s “Up Front”

Olle Petersson: <BLOCKQUOTE>quote:</font><HR>A well known design flaw with the early german 12cm mortars were that they did hit the same crater with all rounds...the dispersion was only one or two metres. This was subsequently corrected.<HR></BLOCKQUOTE> Interesting. I have seen (somewhere) a similar impression of the 4.2 inch chemical mortar. Can't recall if it was something anecdotal or actually a US ARMY or USMC sanctioned study or FM. Anyway, I reckon given testing conditions, and reducing the influence of potential systematic errors, anything is possible. The nasty habit of hitting the same point could simply be eliminated by reducing or increasing charge. If a mortar platoon were employing say an open sheaf pattern, the depth of the impact area might be on the order of 100 to 200 meters and width around a 140 meters (assuming an 81mm Mortar platoon of 4 tubes). To cover the depth required 3 separate fires might be performed, successively increasing or decreasing charge to insure some coverage over the target area. But back to your original point, what could be termed as a relatively small accuracy influence at a range of 2,000 or 3,000 meters really becomes a considerable influence over a range of 10,000 to 12,000 meters. That's really what we're talking about when trying to compare mortars to field artillery. <BLOCKQUOTE>quote:</font><HR>I think most of it was field artillery. The Russians had a habit of placing their 76mm field guns in direct firing positions, just as the Brits did with their 25pdrs in the desert. The 76mm field gun had a fair anti-tank capability.<HR></BLOCKQUOTE> Agreed. Regarding the 25 pounder firing solid shot in a direct fire mode…I have already provided a reference to this in a previous posting on this thread. As with most artillery units during the war solid shot or HEAT type munitions were typically available for firing in direct fire mode. Lets not forget part of the idea behind Blitzkreig was penetration of armour to the rear of enemy combat formations in order to destroy artillery assets. Blizkreig was really somewhat of a continued evolution of German Stosstruppen tactics developed in late war WWI (i.e. highly trained assault infantry teams would avoid strong points with the intention of penetrating to the rear of enemy formations in order to get at a defending formations artillery assets). An infantry division without its artillery has really been reduced considerably in its overall combat effectiveness. It would therefore seem somewhat naive not to outfit WWII artillery with a means of self-defense against being over-run by tanks….thus the availability of AP and HEAT munitions to field artillery. Regarding the Soviet 76mm…agreed again. With the exception that I suspect the Soviet 76mm was employed much more often in a deliberate anti-tank mode relative to that of the British 25 pounder. But again I think we are talking about the 76mm employing solid shot while being employed in an anti-tank role.

39 going on 12, been living in sin for 6 years. Finally gonna make her an honest women in March. Addicted to wargaming since I can remember. Got a German Sherpard (almost a kid

Gorilla: For someone who doesn't post much that was a good read. Thanks for taking the time. Unfortunately as to changing opinions here it is seemingly a case of arguing with the DMV or City Hall. As far as how good this game is, I posted my own personal impression of Combat Mission at another web site…URL is: http://www.clubssi.com/ubb/Forum8/HTML/002457.html It's a good game…reminds me a great deal of the early Squad Leader games (before all the rules books became unbearable). It's Squad Leader with all the visual appeal of a first person shooter. There is a DEMO available, so if you're still unconvinced have a look at it. I think you can download it from this web site somewhere. CM isn't appealing to everybody's tastes in computer games, so have a hard look at the DEMO before spending your hard earned cash. A good 3D card is definitely a plus. My overall impression of CM is one of "watching a war movie, and playing a wargame at the same time".

Jeeze Claus...you are omnipresent. Can you sniff the air and determine what internet forums are having disscussions on armour penetration Great Post by the way. I am betting you are intimately familiar with many of the quality photos presented on the Russian Military Zone showing destroyed AFV’s. I am under the impression that many of the photos bearing the description “Destroyed By Artillery Fire” would be what an American like myself might have detailed with a description of “Destroyed by Anti-tank Artillery fire”. Would this be an incorrect assumption on my part? [This message has been edited by Jeff Duquette (edited 09-27-2000).]

Yo Future: Taking a walk on the wild side? Figured they would have to pry CC from your cold dead hands (sorry...A poor American Joke regarding our obsession with certain things). GO Cathy Freeman! You getting a free copy of V for your tesing services?

It is interesting that there is actually a debate on what the effect of a direct hit by a heavy caliber HE round would be on the upper deck or turret top of a tank. Its got noting to do with kinetic energy. The blast effect of a 105mm HE round alone would rupture 15mm of plate steel like it was a tin can. It’s a case of lack of historical evidence to suggest a large percentage of tanks in WWII combat being damaged by indirect HE fire. Relative to tanks damaged\destroyed by direct fire, anti-tank mines, Air Attacks etc. those kills attributable to indirect HE fire are relatively small. This is a function of the inherent inaccuracy of artillery. Without very heavy concentrations of fire the probability of indirect fire landing smack dab on top of a tank are very low. <BLOCKQUOTE>quote:</font><HR> George Blacburns: The Guns of Normandy. Blackburn served as an F.O.O. in the 2nd Canadian Division, ETO, 1944. They have about a dozen really big tanks (Panthers and Tigers) as well as about fifty Mark IVs in the two or three miles I can observe from our slit trench. But you never see them all at once, and there's a confusing number of derelict tanks lying about, both his and ours, knocked out during Goodwood. For a while we are right between his tanks on the left and ours coming up on the right. One of his with an 88-mm gun (probably a Tiger) is in a copse near the Caen—Falaise highway firing from a hull-down position. He's so bloody close – only about two hundred yards away - that each time he fires, the muzzle blast bangs our ears together and flattens the grain all around us as the shot screeches overhead and a shower of sparks goes up from one of our tanks up on the hill, which he keeps hitting until it brews up. The Typhoons aren't flying because of the rain. Anyway, the Tiger is too close. (Were much afraid of a Typhoon missing its target and hitting us.) So I put a battery of mediums (sic 25 pounder howitzers) on him and hammer him for about half an hour. (I may not have knocked him out, but I'll bet I loosened up the bowels of that crew.) <HR></BLOCKQUOTE>

<BLOCKQUOTE>quote:</font><HR> From: Artillery In The Desert, Prepared by Military Intelligence Service, War Department. This Case study was prepared by the United States Army and is available for review as FMFRP 12-3 United States Marine Corps Historical Publication, 7 November 1988. This study focuses on the employment of both field artillery, and anti-tank artillery tactics and equipment employed by the Germans, Italians, and British during the Campaign in North Africa 1940 – 1942. C. 25-pounder Field Gun-Howitzer Fire from the British 25-pounder (3.45-inch) field gun-howitzer, the basic field piece of the British Army, has been extremely effective for two reasons: (1) the 25-pounder is an excellent field gun, and (2) British artillery was well-trained before the outbreak of war. German tanks when struck by 25-pounder armor-piercing (sic direct fire engagements of German Tanks) shell at ranges less than 1,000 yards have sometimes been knocked-out; some have had turrets completely blown of, and others have been set afire. Indirect 25-pounder fire is, however, not effective for stopping tank attacks, but it can cause the tanks to "button up" their hatches. Reports of indirect fire's stopping tank attacks are believed to be erroneous interpretations of the repulse of reconnaissance’s in force.<HR></BLOCKQUOTE> The inability of a Panther to resist the impact of a direct hit from a 25 pounder on its upper deck or the top of its turret is not, I’m sure, in question by anyone on this thread. However, the question of how often an indirectly fired artillery round will land on the upper deck of a Panther should be answered as “not very often”. There are numerous systematic errors at work, which limit the accuracy of indirect fire. The ability of F.O.’s or F.O.O’s and their associated FDC's to walk rounds onto a pin point target such an individual tank should be considered an unlikely occurrence at best. If a number of rounds of ammunition of the same caliber, lot, and charge are fired from the same position with identical settings used for deflection and quadrant elevation, the rounds will not all impact on a single point but will fall in a scattered random pattern. This phenomenon is called dispersion, and the array of bursts on the ground is called the dispersion pattern. The points of impact of the projectiles will be scattered both in deflection and in range Dispersion is caused by inherent (systemic) errors to include: Conditions in the bore. The muzzle velocity achieved by a given projectile can be affected by minor variations in the weight of the projectile, form of the rotating band, and moisture content and temperature of the propellant grains. Differences in the rate of ignition of the propellant. Variations in the arrangement of the propellant grains. Differences in the rate of ignition of the propellant. Variations in the ramming of the projectile. Variations in the temperature of the bore from round to round. For example, variations in the bourrelet and rotating band may cause inaccurate centering of the projectile, which can result in a loss in achieved range because of instability in flight. Conditions in the carriage. Deflection and elevation are affected by the Conditions during flight. The flight of the projectile may be affected by the difference in air resistance created by variations in the weight, achieved muzzle velocity, and projectile. Also, the projectile may be affected by minor variations in wind, air density or air pressure, and air temperature from round to round, etc etc The ability to destroy tanks via indirect fire is really a function of massing fires of artillery battalions, and even artillery regiments. This is resolved into a question of density of fire within an area. Drop enough rain drops and you are bound to achieve a saturated condition. Combat Mission is typically simulating or modeling a less than saturated condition – so to speak. Scenarios are often limited to off-map artiller assets of single batteries or perhaps two batteries of medium or heavy artillery. We are therefore not really in a position to reasonably say for example: After such and such a historical event involving the concentration of 7 or 8 battalions of heavy artillery a resultant destruction of 4 Panthers occurred, and subsequently compare that historical event to a simulated battle in which the available dedicated artillery support consists of a single battery of 25 pounder howitzers. They are not really the same thing. It is really a matter of being very lucky or very unlucky (depending on weather you are on the receiving end or delivering end) when a tank is destroyed by low-density indirect artillery concentrations. WWII Battlefield studies\statistics of tank casualties and the cause thereof would support this assessment. One such study conducted by the 21st Army Group, ETO, examined the cause of damage of some 333 tanks (Shermans, Crommwells, Fireflys, Comets, Stuarts and Challengers). Damage was defined as: (abbreviated) the tank of concern could no longer participate in the action at hand (so damage really includes out right kills, mobility kills, and other assorted mechanical damage). The following causes and associated percentage for each cause included: AP Shot 41%, Shaped Charge 35%, Anti-Tank Mine 21%, HE Shell 3%. I have not seen similar statistics for German AFV’s in ETO. My gut feeling is that due to the availability of massed concentrations of American and Commonwealth artillery and abundance of ammunition available to Allied artillery, the number AFVs damaged as a result of HE shot would be somewhat higher. However, it is probable a stretch to think that much more than an additional 5 or 6 percent could be tacked onto the British 3% figure. And again to reiterate the higher percentages are more than likely attributable to massed battalion and regimental fires. With respect to the URL posted by KwazyDog (The Russian Military Zone) it would be interesting to hear the authors description of what is implied by “destroyed by artillery”. In the case of many of the photos with artillery listed as the primary cause of destruction it is clearly evident that either front, side, or rearward facing plate perforations have occurred. I suspect that the “destroyed by artillery” description might be an abbreviated version of “destroyed by anti-tank artillery”. Two types of ordnance bearing similar names, but performing very different missions. I would be curious to see similar statistics as those I have indicated above for either German or Soviet AFV’s. If anyone has access to such studies indicating hard numbers I’m sure it would be enlightening to all of us who may be interested in this subject.

ding...ding...ding JoePrivate has got it right. Look at the dates over which the study I refer to above was conducted. The dates should provide some clues as to the nature of the numbers presented. Several things are going on there which could potentially skew the statistics indicated in this document, and therefore skew the conclusions one might draw from it. <LI>One: The situation facing 21st Army Group during this late period of combat in ETO was relatively fluid. Once the Rhine was forced during Varsity organized German resistance was becoming rather scarce. Significant artillery concentrations on the part of the German Army were therefore probably few and far between. <LI>Munitions availability by this late date would probably have been somewhat scant for whatever German Artillery that may still have been functioning within cohesive units. <LI>I have read some indications that German availability of prime movers was severally strained by this point in the war. This would further reduce the ability of a retreating formation to retain their organic artillery, as well as further limit the ability to concentrate whatever artillery may have still been available. From Danny Parkers: The Battle of the Bulge, Hitler’s Ardennes Offensive, 1944-1945 <BLOCKQUOTE>quote:</font><HR> In the immediate battle to rupture the American lines the German artillery was instrumental in the Nazi advance. However, as the battle progressed both the supply for the artillery as well as its transport to the fighting front became problematic. Road conditions and fuel shortages made it extremely difficult to move the artillery forward; the situation was further aggravated by the lack of prime movers. According to the artillery commander for Heeresgruppe B, "There was a shortage of towing mediums and transport space was lacking for ammunition and motor fuel. There were no tractors for the heavy army batteries of 22-35cm and even a chronic shortage of movers for the lighter guns. For instance, in the case of the XLVII Panzerkorps, both the 766th Volkartillerie Korps and the 15th Volkswerfer Brigade were without any prime movers, having "loaned" them to the Panzer Lehr Division which had arrived in the Waxweiler area with no organic transport for its divisional tubes. The web of problems that beset the artillery, particularly the shortage of ammunition and fuel, led to an early decision to leave half of the weapons behind—there clearly was no reason to haul around guns for which there was no ammunition. <HR></BLOCKQUOTE> In spite of the late date of this particular British Army study, it is interesting to note the number of tanks being damaged\destroyed as a result of shaped charges. Presumably this statistic is -- to a great extent – a function of the availability, reliability, and power of Panzerfausts. But what about the question at hand? I think you will find – with a little digging –you will most likely come to the conclusion that tank damage/destruction as a result of indirect artillery fire is most often a function of massed concentrations of artillery i.e. battalion, division, and even corps artillery massed fires. A couple good references are: George Blackburn’s “The Guns of Normandy”. A best seller and a good read. & “FMFRP12-3 “Artillery in the Desert” (A US Army study of German and British Artillery Practices in North Africa 1941 – 1943). Available for viewing on line from the USMC War Fighting and Doctrine web page. Lay down enough High Explosive in a small enough area and your bound to get some AFV kills. Conversely mass enough tanks in a small enough area, subject the area to an FFE and it is probable that you will kill AFV's. However, (and I am relatively new to CM, so correct me if I’m wrong) off map artillery typically consists of one or two batteries of medium or heavy artillery (105mm +). The game scenarios I have seen are not typically modeling massed battalion or regimental fires. What would be the point in playing a scenario of CM with that much artillery available. JoePrivate: I would be curious to see the US ARMY stats you alluded to.

This is part of a report produced by the 21st ARMY Group, ETO. Data was collected from actual tank damage assesments between March - May 1945. You can view part of this document at: http://www.geocities.com/jeffduquette/tank_casualties.html The study included the examination of 333 Commonwealth tanks damaged/destroyed in combat. The following distribution of tank damage and cause of damage was determined: <LI>Biggest tank killer was AP shot...41% <LI>Second biggest killer was shaped charge (or hollow charge)...35% <LI>Third was from anti-tank mines...21% <LI>And last -- with only a 3% share -- tank damage atributable to H.E. 2% of the tanks examined during the study were damaged by unknown causes. [This message has been edited by Jeff Duquette (edited 09-23-2000).]

Renaud: Thanks for the information.

I've been a dyed in the wool CC fan and a loyal poster to several CC forums for a couple years. I was curious as to what all the hub-bub regarding CM was so I broke down and did the mail order thang. Got my copy last week. Wow! What a ton of fun. Now I hear there is an East Front Version in the works. Don't get any better than this (well the mail order could have included a pizza and six pack). So when is the East Front Version of CM due out? Has there been any screen shot releases yet?