Rattus

I've done a search but no luck. What happend to artillery observation vehicles (ideally with "demountable" FAO's)? Throw me a thread please!

Thanks - and yes sign me up as a supporter too! I wonder if the H39 in Norway was left behind by the Anglo-French expeditionary force in 1940. I know the French took some tanks and chenillettes(?) with them and the tanks at least saw action.

I was looking for the H39(?) to make a QB but could not find it in the German OB. Is there a particular time frame for it (not 39-40!). At least the comander/gunner would not have to woory about the Radio.. (except maybe in Platoon/Cmpy leaders. I need to practice before slaughtering the fascists with the 3eme DLM from Prioux's cavalry corps! (Actually I don't think they used H35's or H39's but you take what you can get!) "Allons enfants de la Patrie..."

Only data I could find was for 7.2". For a very/very rough comparison... The 7.2" "Wallbuuster" projectile wieghed 135ln & contained 39lb of PE The 7.2" HEAT projectile (also for the Burney gun - not 7.2" howitzer!)weighed 40lb & contained 9.8lb of RDX/TNT (Penetration was 3" diameter hole in 6" plate @ 30 degrees). This indicates the "Wallburster" rounds had roughly 4 times the PE of equivalent HEAT rounds. Taking US 57mm RCL as example: It fired 2.75lb HEAT projectile containing 0.4lb of composition B. An equivalent Wallbuster round might have 1.6lb of HEAT... Given that a) Physics of explosions gives (I think!) increase in force of the ratio of weights to the 1/3 to 2/3 power... A true HESH round would be much more effctive than equivalent sized "wallbuster" round. Even a 57mm HESH round could be very effective - and much more effective than its quivalent HEAT round. I know this is very rough!

I think there were also some "shoot through" rifle grenades but this too might be a modern invention. With the old system of using special cartridges there was always the danger in the heat of action, through carelessness or poor training of firing a ball round into your rifle grenade - ugly! I think the British No. 68 cup rifle grenade was a HEAT round but it doesn't seem to appear in CM. Was it little used? - or usually only vs inf? Maybe the squads thought they had enough to carry with ammo for the 2" mortar!

I have found some "penetration" info on the "wallburster" shell - but only for the 7.2" version containing 39lb of PE. A true HESH shell would be much more effective. [from Hogg] "At a trial in August 1944, against a 6" armour plate... ...the shell blew a 117lb scab, 19" by 24", off the back of the target plate at an estimated 600f/s" Ouch! Hogg notes the 2pdr HE as not issued to tanks - (It was the job of the Besa MG to engage the inf!). Given the feeble HE content it was pretty hopeless anyway. Will CM4 see Matildas at Arras? (Heh Heh!)

The HESH rounds were a development of the "wallburster" rounds (for concrete busting)which were designed for the experimental recoiless guns devised by Sir Dennis Burney during the war. None saw service. My understanding of HESH is that penetration as such of armour is not acheived (except on thin plates) but causes a scab of armour to be thrown off inside with catastrophic consequences for the crew. It is essentially defeated by spaced/laminated armours. There may be a limiting thickness (I think it would have to be extremely thick - several calibres of round) which prevents the scab being thrown off but I have no idea what it might be.

I was joking about the POW mine clearing units! I know it's not entirely ahistorical to use them this way but I usually send them to the care of bailed crews at the rear for extra points.

Mine detectors!

Yes, ground snow in/of itslef not a problwm - Battle of the Bulge, ground snow covered - clear skies on Dec.25(?) & US Airforce force flew support ops.

Bugger - that means my copy must have gone to Austria!

Weight of projectile for most 3" projectiles is about 7kg. Bursters (fillers)forming 0% (for monobloc AP shot) to 10% (for HE High capacity). Suffice to say that against face hardened armour plate at high velocities at which an HE round might otherwise be expected to perform as an increased capacity APHE round, the deformation of the HE shell nose and damage to the fuse will probably result in either partial or no detonation and because of loss of projectile weight and nose deformation, greatly reduced penetration. The greater the burster charge the greater the cavity=weaker shell the worse the problem. At close range and extremely high velocities it really does matter what you fire - even a non-detonating nose shattered round will penetrate some/some armour - but no where near as much as an intact round. Maybe I post something on armour piercing caps and decapping?

Damn! - the equals sign - If i'd realised that I could have done without the other terms!

34 - and a senile delinquent to boot

Unless I went to really bad school (possible) Kinetic Energy = 1/2 mass * velocity squared. Momentum = mass * velocity. Velocity is common term so yes related. Bed time now!

What! no illumination - that means I'll have no use for my Matilda and Grant CDL tanks! Seriously - some representation of IR rounds etc would be visually stunning! How about it BTS?

You lucky, lucky, b@%$&! Since you're in Finland you can visit the Panssarimuseo in Parola any time! My brother went there a few years ago & took volumes of pictures so I would love to get there. One day when I'm in Europe (sigh!) Michael

Concurr, I understood it was largely the excellent cooperation & long association with the marine air wings that made CAS so effective in Korea & the pacific by the US. Certainly having FAC's who did not specifically work either with the same army units or the same air force units greatly hindered effectivenes in Europe. Nevertheless, despite its failing this was the system they used so I tink CM should model it?

Still only have demo (weep) Can't wait to use registered fire! CM2 here we come! And now a little poem! "On sea and land the fighting raged; The sceaming shells contested in the air. Then from the forest little Kate would come, To some familiar landmark, bathed in fire. Out she creeps, her rockets loaded up, Against our homeland's dread assailant, And screams: a comapny is gone. And howls again: no regiment." Anatoli Skoblo in "Red God of War" by Chris Bellamy. Katyushas to beat the bloated fascist beast!

Ah - got the smilies working now! The first round I would fire at any target would be whatever was loaded! After that whatever would make the targt ineffective - which may not mean destroying the ordnance or killing the crew. Note the comments on bunker busting refer to a very particular situation. In some cases & if plaentiful supplie, APCR/HVAP/APDS may be a better choice than APHE given much higher impact velocity and much faster (more energetic (lit.) splinters - slight flaw in that - the tungsten projectile is extermely unlikey to generate any splinters from itself (though they would still come from whtever it hit) so APHE probably still best. I have a 20pdr sabot round which has been all the way through a churchill turret - only a few tiny chips of the base!) Against concrete a good HEAT round is usually very effctive since peneteration of concrete is oftrn an order of magnitude more than steel.

For taking out bunkers/pillboxes (that is concret etc emplacements with steel shutters to the embrassures) you would fire AP as an HE round hit on the shutter (and the chance of slipping a round through the slit is virtually nil) would have little effect - most likely the fuze and shell would be severely damaged/destroeyed on impact. AP round would penetrate the shutters and the splinters flying arounf inside would wipe out eveyone inside. Ideally you would use the APHE round (though still often designated APC)(if you had one) which has a tiny burster - eg. the APC, M62A1 round for 3in AA gun (and others) which had a 0.14lb burster of Explosive D in the 15.5lb projectile. Where the construction of the the bunker is less strong or the shutters are missing go for HE. In practice people had to use what they had! At the Meuse crossings in 1940 many of the French Pillboxes were incomplete & did not have the shutters. The Germans had taken the precaution of bringing up some 88's to deal with them but without the shutters the pillboxes were death traps. On another point, the larger the filling for a givn weight of shell the thinner the walls & the less acceleraton (& hence mv) the shell can stand. If this thin walled shell hits something very hard - it is more likely to break up than a thicker walled shell with smaller burster. A similar analagy might be between "Common" and "High Capacity" naval shells with burtsers of about 5% & 10% respectivly. So sometimes less (fillin) is more (useful) Comments on use of AP/APHE for dealing with pillboxes welcome.

Shouldn't there be a Forward Air Controller calling A/c from the cab rank to strike particular targets? - or same in an Airborne Observation Post (Auster or Lysander) marking targets with coloured smoke for the A/C to attack. Otherwise it seems CM is just simulating free range FB missions over a tactical battle - which is begging for mistaken air attacks...

BTW I'm using Hogg's Brit & Ami Arty as my source here. Filler for US 3in round above is 0.86lb of TNT. That for 75mm (French 75 as used by US) has filling of 1.5lb TNT or 1.36lb of Amatol.

Yes - sorry charge weights are for propellant. Hence lighter HE round uses reduced charge to minimise (within reason) mv/barrel wear etc. Obviously if designers had thought mv was critical they could have used same charge as for AP round for higher mv. Don't have the weight of filler to hand - but unlikely more than 10%? of projectile weight. Even the type of filler is important here (RDX vs TNT or Amatol) Total weight of fixed AP round was 35 1/2 lb (includes weight of cartidge case). By way of comparison the US 3in M5 AT gun (also used in some US TDs') fired 12.875lb HE round with 4.56lb propelling charge. Again filler unknown. Curiously mv is given as 2800f/s - which is 200f/s more than for AP round. This is because the round used was that for the 3in AA gun - for which MV is critical. BTW the 25lber round (exactly 25lb) had a filling of 1lb 2oz of originally Amatol.

I have some data on the 17lbr which bears this out: 15.4lb HE shell @2875f/s with 7lb2oz chge 16lb15oz AP shot @2900f/s with 8lb20z chge 7lb10z APDS round @3950f/s with 6lb10z chge All fixed rounds I don't have the shell weight for the 75mm to hand - but I think it is about 13lb-14lb. Bearing in mind once the gun is built the chamber size is fixed - which limits variation in charge & round sized for fixed rounds when developing new ammo. There are limits on how far the shell (projectile)can be lengthened for a given degree of twist in the rifling so there is not such an easy trade off between shell/proppellant. Of course ideally this was sorted out when the gun was designed. Michael Rattus