Conall

Good points all, in addition you could add that the Germans benefitted from the advantage of operating under auftragestaktik at every level. Auftragestaktik translates very roughly as "mission oriented tactics". One key compnent is that anyone with a leadership role (plt cmdr, plt Sgt etc), should know the intent of the commander two echelons higher - therefore a section commander knew at least the full company brief, the plt commander knew at least the full battalion brief etc. In the context of a tank platoon this meant that the loss of the platoon leader was not automatically a cause for complete disfunction. Efficient radios also helped the transition of command if necessary. By contrast the Soviets, to the best of my knowledge, didn't initially operate a system with anything like that degree of tactical flexibility. Until perhaps mid-1943 Soviet units below the battalion level at least operated a major disadvantage in terms of command flexibility. I look forward to being proved wrong regards, Conall

Not necessarily the case - this is the subject of some debate, as to whether the Mk III & Mk IV Churchill's had geared or free elevation. The short answer is that no-one knows & it's quite possible that there was an ad-hoc mixture. Confusion arises because nearly all schematics show a geared elevation & a handbook on the III & IV's unequivocally refers to geared elevation, however, Vauxhall Motors (the manufacturers) published a handbook in Jan 1944 which has a cross sectional drawing clearly showinga free elevation system (gunner's shoulder pad etc). It would therefore be useful to know what kind of Churchill IV's were being used in the firing trial. For further reading see: D. Fletcher, Mr Churchill's Tank. The British Infantry Tank Mk IV, Schiffer 1999, ISBN 0-7643-0679-0 Regards, Conall [This message has been edited by Conall (edited 03-14-2001).]

Simon, Perhaps you'd care to expound on what you think are in the Regimental war diaries that are more useful (in the context of gun dispersion/accuracy figures) than the tabulated findings in the WO docs (usually material taken from the AORS data/research). I'm not sure that I understand quite what you're getting at, so a little clarification would be much appreciated. Regards, Conall

Paul, Are you referring to the picture I sent you a awhile ago - if so I resent it to you. If you haven't got it just give me a shout & I'll resend it. Regards, Conall

Claus, my bad for a) expressing myself unclearly & talking about two vehicles at once. As I understood it the M10 series required a weight at the back of the turret to balance the weight of the 3" gun (see Hunnicut, Sherman p.366). The Sherman series (either the 75mm or 76mm) didn't need this as the gun was sufficiently balanced in the turret (not least because the turret was much heavier than the open topped M10). In the case of the Achilles the 17pdr was a lighter gun, which didn't require the rear turret counterweight to such an extent, so rather than remove it, it was easier to fit another counterweight on the barrel. Apologies for creating any confusion - your article explains it rather better. http://www.panser.dk/profiler/achilles/achilles.htm Finally in the case of the Sherman Firefly, the radio in the ad-hoc rear extension to the turret acted to counter-balance the weight of the 17pdr. this appears to have been very successful & anecdotally was reported to have been a better balanced turret than the original 75mm Sherman, which in turn improved the smoothness & ease of the turret traverse. Regards, Conall [This message has been edited by Conall (edited 03-11-2001).]

Agreed it is a better website, & it shows that the object in the middle of the barrel of the Firefly mounted 17pdr was a fake muzzle barrel. No, the source I quoted didn't say that sabotted ammunition couldn't be fired from guns with muzzle brakes. It said that doing so would very likely cause a uneven discard & therefore create an unacceptable degree of round instability. It also pointed out that there was a risk of the muzzle brake being damaged. So one more time, just for you, the British had designed the 17pdr to fire AP, APC, & APCBC, for which the muzzle brake was essential in reducing recoil forces to an acceptable level. Having done so they then developed SVDS, and accepted the pay off of a more inaccurate round & much higher barrel wear because they needed the improved penetration. A simple aspect of wartime expediency & having to make trade-offs. Once the war was over however, they had the luxury of producing new guns specifically designed to fire APDS ammunition (20pdr etc). Note the rather glaring absence of a muzzle brake on the 20pdr. No ****, Sherlock! However, I think you should brush up on your intermediate ballistics. Not only does the shell clear the end of the barrel, so does the precursor blast shock (gases preceding the projectile down the barrel). These are followed by the blast shock & the projectile - the propellant gases rapidly expand, accelerating to velocities much greater than that of the projectile. Even under ideal circumstances the action of the muzzle gas flow can have an adverse effect on the accuracy of the gun by causing abnormal yawing of the projectile. This whole process is made much more complex by the effect of the muzzle brake & in particular exacerbates the effect of the muzzle gas on the sabotted ammo as it discards. I look forward to seeing the finding from your notes. Conall

See above ad nauseam. Nope that's a rather badly modelled fake muzzel brake. I look forward to seeing them, but I'm not holding my breath. Conall

References: Re the sights: A Guide to A.F.V. Telescopes, A.F.V. publications section, A.F.V. School Bovington, War Office AFVP/MSC/64 March 1945 This covers all the British & US sights in use at that time & includes some obsolete sights as well. The document runs to 64 pages & includes schematics & specifications plus some additional notes. The detail specific to the 17pdr is on pages 26 to 33, the 6pdr sights are covered on pages 12 to 19, & the 77mm on pages 34 to 37. Although all these guns were issued SVDS (APDS) ammunition at various times in 1944-45, none of the sights issued had any graticules for this ammunition. This is in stark contrast to APC, APCBC, HE & MG, all of which have range scales marked on the sights. Regarding the problem of muzzle brakes, see: Military Ballistics, ed. G.M. Moss, D.W. Leeming, & C.L. Farrar, RMCS, Brassey's 1983, ISBN 1 85753 084 5. Specifically see chapter 3 "Intermediate Ballistics" page 64-65 The Bovington Fire & Movement pamphlet, 1975 shows schematics of two types of SABOT - the pot type that had a single SABOT, which discarded as a whole axially & the petal SABOT, which discarded radially into several pieces - the latter as Claus has indicated was the more successful post-war design. For the best explanation of the process see: R.M. Ogorkiewicz, Design & Development of Fighting Vehicles, MacDonald & Co 1968, ISBN 356 01461 4, pp 58 & 60-63. He notes that the problems with APDS ammunition (disturbances arising during separation etc) were principally solved in the late 50's & early 60's by the Britsh & Canadians working at the Canadian Armament Research & Development Establishment, at Valcartier, Quebec. The problem for the British was that in 1944 SVDS (APDS) was an experimental technology, wheras APCBC was a proven type of ammunition. The priority was therefore, for the 17pdr to operate best (most accurately with the most efficient recoil forces) with APCBC ammunition. The muzzle brake was therefore, essential to reduce recoil to an acceptable limit, given the restrictions on how difficult it had been to shoe the 17pdr & it's trunnions into a Sherman turret (see David Fletcher, The Universal Tank, London HMSO 1993, ISBN 0 11 290534 X, pp. 81-85). The imperative need was limiting the recoil forces & the subsequent gun jump, a process which required a muzzle brake. See also WO 291/1263 Firing trials with 17pdr in Sherman I using APC & discarding sabot shot, 1944 & WO 291/324 Accuracy of first round of an anti-tank engagement of a stationary target using APCBC & APSV/DS ammunition, 1946. It's also worth noting that most 6pdr guns, mounted on the Churchill MkIII & MkIV either had no muzzle brake or had the muzzle brake removed once the SVDS (APDS) ammo was available. Likewise the 20pdr had no muzzle brake (see WO 342/1 Tanks Battle Performance & Tactics 1951-53 1953 for a discussion of the relative merits of 20pdr APCBC & APDS ammunition) The muzzle weight issue is a complete red herring - on the Achilles it was mounted primarily to balance the gun, as unlike the Sherman the turret was not sufficiently heavy to do so - there was also a counterweight on the back of the turret. The object which appears on the middle of some 17pdr gun barrels is nothing more than a fake muzzle brake, placed in an attempt to camouflage the long 17pdr barrel & make it appear more like a L/40 75mm barrel. For more on this see http://www.activevr.com/afv/muzzle.html#dragon & http://www.activevr.com/afv/camouflage/shrmic.html & http://www.activevr.com/afv/camouflage/shrvc1.html I look forward to seeing other sources on the subject. The one's I have quoted are by no means exhaustive, but they do represent a reasonable survey of the subject. For more on the Firefly specifically I would suggest David Fletcher: Sherman VC M4A4 Firefly, Militayr Ordnance Special Number 19, Darlington Productions 1997. regards, Conall [This message has been edited by Conall (edited 03-11-2001).]

Simon, I suggest you take a look through the gunsights which were issued to British tanks equipped with the 17pdr during WW2. Whether you look at the: No. 43 x3 L Mk.I (Sherman C only - Firefly) No. 43 x3 ML Mk.I (1st 23 A30 Challengers only) No. 43 x3 ML Mk.3 (A30 Challenger) No. 43 x3 ML Mk.3/1 (Sherman C - Firefly) you will see one common feature. None of these sights have any markings/graticules/range scales for APDS ammunition. Therefore your suggestion that proper calibration of the gunsight would improve APDS accuracy falls a little flat. I think the testing you are refering to concerns APCBC rounds in use with the AT gun & then the tank mounted 17pdr - the problem was one of the sight becoming rapidly misaligned due to the heavy recoil (a problem not unique to the 17pdr). I agree that experience with APDS would help but in my opinion only marginally at best & would vary from the experience of one individual to another (therefore a little hard to teach, standardise & even model for a computer game/simulation). I hope this helps a little - more to follow with references tomorrow(ish). Regards, Conall

I think a lot of people here are missing the point about the supposed slowness of the Panther's turret. The Panther A & G used a variable speed hydraulic turret, so that it could rotate it's turret 360deg in 15 seconds at 3000 rpm & 360deg in 18secs at 2500rpm. Only the Panther D was at a serious disadvantage as it's hydraulic motor only rotated 360deg in 60 secs. Therefore a Panther A or G in the hands of an experienced crew could rotate their turret almost as fast a Sherman (360deg in 12 secs) - not really a significant difference. Of course the disadvantage of such a hydraulic system was that you were f**ked if your engine stalled & it was much more flammable than an electric system. Best regards, Conall [This message has been edited by Conall (edited 01-31-2001).]

What I would be interested to know is how your model deals with the following factors: 1. The manner in which it treats aspects of fluid dynamics (drag etc), principally calculation of mach numbers & the transition from subsonic to transonic region & from there to supersonic & hypersonic (typically above Mach 5, equating very approximately to projectile speeds above 1000m/s). This area may help explain the difficulty you've had with low velocity guns the 75mmL24 for example. 2. Projectile shape (length, weight, ogive, skin etc), especially with regard to the calculation of the drag coefficient & therefore the ballistic coefficient. 3. How does it treat velocity loss, as a constant or otherwise? 4. Spin induced Yaw & aerodynamic lift. 5. External factors, notably crosswinds, air density & temperature. 6. Gun jump & barrel droop. 7. Treatment of subcalibre rounds - APDS etc. Given that you are trying to produce a simplified model from a very complex subject I'd be fascinated to know how you've incorporated these factors, or alternatively felt confident that for your purposes you can safely ignore them. Having read your posts my greatest concern would be with a) the treatment of different shaped rounds (especially sub-calibre) & the impact of external factors. Anyway thanks for all your material, it's been a really interesting way to start the New Year. I look forward to hearing from you. Best regards, Conall

<BLOCKQUOTE>quote:</font><HR>Originally posted by aka_tom_w: GREAT reference!! Is there any chance Charles and Steve can get a copy of this as it may come in handy when attempting to determine some long range optics advantage to for gunnery accuracy to be modeled in the up coming CM2?? That sounds like a VERY detailed and informative articel there! How can Steve and Charles get a copy of it? Or do they have it already? <HR></BLOCKQUOTE> If they ask me nicely & feel they need them, then I'll happily scan them my copy. regards, Conall [This message has been edited by Conall (edited 01-07-2001).]

<BLOCKQUOTE>quote:</font><HR>Originally posted by rexford: (aside: Firefly had 3x/6x interchangeale gun sight, makes sense to easily see and target long range targets) <HR></BLOCKQUOTE> Just to clarify this the Firefly was equipped with the No. 43 Mk3/1 telescope which had a x3 eyepiece or a x6 eyepiece. These were not interchangeable in combat - nor could the higher magnification be selected in the same way as the dual magnification German telescopes (Tzf9d etc). A Guide to A.F.V. Telescopes Author: A.F.V. Publications Section, A.F.V. School, Bovington Camp Date of publication: March 1945 Publisher: War Office, A.F.V. Publications Section Page number(s): 6 On the subject of the Firefly's HE shell here is a little more information: The 17pdr fired two types of HE shells- the HE Mk 1 T shell (HE-T), weight 34.2 pounds (complete round), 15.4 pounds (projectile). During 1944 a reduced charge round (1,800 fps MV instead of 2,950 fps) was produced which allowed thinner walls for the shell & therefore a higher HE filler. See War Office Document 291/1268 for details of ranging, dispersion & bracketing procedure for 17pdr gun with HE ammo mks IT & IIT reduced charge, date 1944. Also see Hunnicut's "Sherman" p.565 <BLOCKQUOTE>quote:</font><HR> For those who are interested in ballistics, William Jurens wrote a paper entitled EXTERIOR BALLISTICS WITH BALLISTICS that is the single best work on the subject, in our opinion. Has drag coefficients, equations and a computer program in BASIC that computes elevation, angle, etc. for shots and prints out results every 50m or so. The paper ran in a naval magazine, and an internet search on Mr. Jurens' name might identify a current source (we haven't had time to do this). The paper covers naval rounds and it is easy to apply findings to WW II anti-tank stuff. <HR></BLOCKQUOTE> You need to order a backcopy of Warship International produced by the International Naval Research Organization www.primenet.com/~inro I have a feeling that the article on Exterior Ballistics with Microcomputers is in Issue No 1 1984 & is still available. Hope that helps Best regards, Conall

This is a slightly gratuitous bump, mainly because I though this thread was relevant to Rexford's recent musings. <BLOCKQUOTE>quote:</font><HR>Originally posted by Big Time Software: But how much more difficult when all things are considdered? I mean, a sniper's scope on a Springfield or Kar98k has a much more limited field of vision than tank scopes, right? Yet they can hit smaller targets at great distances (1000m with a rifle is probably like 2000-3000m with a tank gun) with one shot in the hands of a very skilled gunner. Steve [This message has been edited by Big Time Software (edited 11-22-2000).]<HR></BLOCKQUOTE> Anyway Steve back to your point - I meant to respond to this but forgot. You're endulging in a wicked bit of sophistry here I'm sure you know perfectly well that most snipers/competative marksmen use binos first to identify the location of the target. In addition most snipers work in teams of two, so that one scans with low power, wide FOV binos & having spotted a target his partner shoots, using a rifle equipped with a high power narrow FOV scope - actually not a bad analogy for the relationship between a tank commander & the gunner. Hope you had a good Christmas & all my best wishes to the CM team for the New Year. Best regards, Conall

<BLOCKQUOTE>quote:</font><HR>Originally posted by Schugger: Conall?!? Are you, by any chance, the Conall from the PE board with the distinguished service career in the famous "Fallschirmpanzer" online regiment? If so, do you still remember Lt. Schuggerbaby ( me ) who rather foolishly tried to stop a german tank offensive with his Greyhound ? Anyway, a very warm welcome to the board. Markus<HR></BLOCKQUOTE> Hey Schuggerbaby good to hear from you - it's been a while. Yup certainly remember the Greyhound incident - did the same last night tying to take on a pair of Panthers with a bog standard M4 - messy very messy (did bag two Panthers though). regards, Conall