Paul Lakowski

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1: I have a question was the transitional velocity effect on projectiles traveling over 2800m/s even known about in 1950?. As Robert pointed out IIRC the error in the British report concerning slope/angle equasions was because they hadn't discovered an efect at that time that was later discovered. The report was based on all they knew about penetration to that date. <HR></BLOCKQUOTE> John the answer is yes and no. They new that something was happening but not exactly what. You have to remember most stuff back then was done by trial and error, initially the idea of APDS was rejected on the grounds as being 'unproven and too complex'. Most work that covers the transition from plugging type penetration to erosion penetration was done with APDS tech after the war. The works that I'm looking at now is late 60s early 70s and alot of it was done in Canada.

The idea of dismissing test data cause they don't quite match up is wrong.Ballistic researchers use test data all the time its called 'normalizing the data to a single reference point'. Thats why they need to know plate hardness , lateral confinement and depth confinement etc for each test. But you'll find that they all treat test data as king to determine if there sim works or not.If they it doesn't they go back to the drawing board. Transitional velocity comes into all penetration of all projectiles its just a question of what striking velocity.

<BLOCKQUOTE>quote:</font><HR>Originally posted by The DesertFox: LOL! The test results don´t fit the formula, ergo the test results are wrong ? Actually I would see it vice versa. Formulas are a sorry substitute for hard data and this example clearly shows the problems involved when trying to fit the real world hard data into a formula. The non ability to describe a phenomenon with a certain formula not necessaryly means that the phenomenon doesn´t exist. Try to do the comparison I did just for fun with David Honners formula with 2 other guns. Or compare the data like Charles did. Try to compare the 75L/24 with the 75L/70 and see how silly the outcome is. Does that mean the data for the 75/L70 are faulty ? BTW: If you use the very rough formula at David Honners site you have to use the velocity of the shell in the moment of IMPACT and NOT the muzzle velocity. <G> Velocity drops from the moment the projectile leaves the muzzle, so unless you know the velocity at 100m, 500m, 1000m etc. you cannot use the formula. Anyone who has these data ? No this question wasn´t serious <HR></BLOCKQUOTE> Helge is ofcourse right hear...if the facts don't fit the theory , you don't chuck the facts , you modidfy the theory to inculde the facts or you chuck the theory. For more info on 88mm velocity see the thread '88mm ballistics' [url="http://www.tanknet.org/ubb/Forum1/HTML/000314.html"]http://www.tanknet.org/ubb/Forum1/HTML/000314.html[/url] [/HTML] At this point I need more time to study the results, but several things are clear....the shape and hardness of the ogive has a direct baring on penetration perfromance more so than velocity. The narrower and harder the tip the longer the delay in the onset of the 'transitional velocity'. It seems the this is the division between 'modern erosion' type penetration and 'normal' penetration. I can post Jpegs to that site so I'll focuse on working some thing out there.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Big Time Software: This is a simplified example, of course, and one cannot expect purely linear results. But this clearly demonstrates that Jentz' 88/71 numbers are not even in the right ballpark. Note also that Jentz' figures for the 88/71 are greater than those for the Jagdtiger's massive high-velocity 128mm gun! This just does not square with reality. Charles [This message has been edited by Big Time Software (edited 08-22-2000).]<HR></BLOCKQUOTE> Well if you don't believe Jentz try Ivan Hogg his figures are within a couple of mm of Jentz's figures, and if you don't believe them we have a problem here. The problem with formulas is that the more you simplify data presentation the more info you lose. The ordnance board report covers APCBC up to around 2800 f/s while the 88L71 reaches 3300 f/s . You old timers on this forum like to tell every one to 'search'. Well alot of us research , so I will point you in the right direction. The search word is called " Transitional Velocity" or "hydro dynamic Transitional Velocity" and its impact on the "plastic wave velocity" of the material and the mode of penetration . Believe me the difference of if penetration is above or below the Transitional velocity is critical!

<BLOCKQUOTE>quote:</font><HR>Originally posted by Fionn: Time, You get an "almost grognard" sticker insofar as you've spotted one interesting datum BUT have failed to research and check relevant related facts. The answer is simple. The JagdTiger was the only WW2 German tank gun to fire separate ammunition BUT it also had TWO loaders. One for the charge and one for the projectile. End result.. Loading speed wasn't compromised as much as you'd think. Nice try though.<HR></BLOCKQUOTE> I thought the Jagd Panther also had two loaders? Whats a 'normal ROF' 7-8 RPM ?

The 88 L71 should be able to penetrate 60mm RHA @ 60o @ 2km range, more than enought to penetrate the T-34 Glacis. Why where the 88 figures reduced when , as I understand it , German penetration figures were used as the standard?

The Sherman , for all the critisim had one of the fastest ROF of any tank in WW-II ~ 12-20 RPM .Pz III & IV were in the same range but Panther and Tiger were only 7-8 RPM , a draw back to be sure. When you get to CM-2 youyr going to have to make some changes cause T-34/85 could only manage about 3-4 RPM as did JS-2 while T-34 76 could do 3-6 RPM . The Germans found in france they could out shoot the one and two man turret tanks by at least 2:1 , while in Russia it was 3-4:1 .This is critical cause it was one of the main reasons they prevailed over there opponents tactically.

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1: I'm confused here as Jentz lists the mantlet on page 12 under 'armor protection' as being 120mm @ 0^ . The 100 - 200mm figure was from the British LF tests which a portable poldi was set up, IIRC. also Robert told us that British Poldi results were 10% higher then US results. Do we know how they obtained this figure and why no firm mm thickness was settled on for the mantlet ?. <HR></BLOCKQUOTE> If you look at helge's pic of the cutaway mamtle on page 1 of this topic youll see the mantle thickness is far from uniform instead it thickens towards the middle where the mantle comes through the front turret <BLOCKQUOTE>quote:</font><HR> Looks to me like ~ 11cm mantle and 10cm FT. <HR></BLOCKQUOTE> So thats 110mm mantlet & 100mm TF?.

Germany's Tiger Tanks, pp 21 "Mantlet 100-200mm 280BHN" and Helge's picture clearly shows the thickenin of the mantle in the area where the mantle goes through the front turret!So you've either got to go through 200mm cast turret or two 100mm plates, since the free edge plays a roll here the value of 15cm seems reasonable and works Vs the 122mm AP shell. Panthers Mantle : The front is listed as 100mm on the mantle,I think you should always atleast include a 20° angle bringing this upto ~ 12cm. Robert told me that the mantle near the extreme edge [top & bottom] is only 25mm @ 70° ~ 7cm effective but then theres the overlap with the front turret [100mm] . The free edge will reduce the mantle edge effectiveness by 0.6 to ~ 5cm while the Front turret should be down only 0.8 to 8cm for a total of 12cm. The gradual thinning of the mantle suggest this is cast reducing the mantle by 90% to ~ 11cm. But we have a problem , I was looking at the 'Panther in Detail" and it shows the gun cradle as armor box which covers most of the mantle area.This is a box with 4cm thick casing which probably 0.6 for the free edge and 0.7 t/d or 2-3cm total The free edge on the mantle is ~ 3-4 projectile diameters or about 0.75 x 12cm = 9cm, for a total of 11cm effective resistance . The FT is listed at 250 BHN and 110mm @ 10° thats x 1.04[angle] x 0.97[hardness] or 11cm. but this is a cast so the resistance should be ~ 10cm. [url="http://www.mobilixnet.dk/~mob75281/gunsarm.htm"]http://www.mobilixnet.dk/~mob75281/gunsarm.htm[/url] [/HTML] Looks to me like ~ 11cm mantle and 10cm FT.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Mr. Johnson-<THC>-: Wow thanks, very cool info. Guess Hitler picked a fight too soon with Poland to ever start mounting this weapon on SPW-250s or PSWs. Or could these chassies even handle the weight of this 1,300 pound gun.<HR></BLOCKQUOTE> Since the 37mm AT gun [ >950 lb] was mounted from the beginning and 75L24 mounted later, I don't see why the PAW couldn't be mounted on a SPW.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Vanir: Does anyone know exactly what the value will be when BTS changes it? Is Charles going to do the 100+ 25% of 100? It sounds like an interesting idea, but I wonder where he got the 25% from. The mantlet obviously covers a heck of a lot more of the front plate than 25%. I'm starting to think it would be best if it was just set at 120mm. I know you think it should be more, Paul, and you know more about the mathematics than me, but that matches Jentz's (revised) number and most of the values in the game seem to be based on his numbers. I think maybe we're over analysing this.<HR></BLOCKQUOTE> No if anything this is under analysed. When shooting at the front turret from straight on do you ever get ricochet off the side turret , if so then that part is covered[ > 200mm]. But the latest Jentz work puts the front turret at 100mm and mantle at 100-200mm and Helge's drawing clearly shows the extent of the over lap....so across the front the LOS thickness is 200mm. But if you think this is over analysed then lets look at some other tanks to see if the same mistake is being made.

You miss understand me cause I didn't expand on the point[ thats from talking on too many boards ] I use these as simulations, playing the computer against its self- thus 'evening out the playing field'. With SP I can edit the scenario as I see fit....I dumped all the game scenarios and made my own ....there maps and OB are/were appalling and then I edited the weapons to be more realistic . Now most battles- when run as sims- work out to the historical result [ averaged out over several runs]. The problem is simple one I encountered with board games back in the early 80s.Unless you're simulating one on one, the actions of each unit should be 'out of your hands'. You issue commands but the units/troops don't do what you want thats historical....If you've ever tried minitures with an umpire, you'll know what I mean.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Germanboy: Why? And what would the effect of this on PBEM games be? <HR></BLOCKQUOTE> To correct any errors , I don't PBEM so thats not an issue for me

<BLOCKQUOTE>quote:</font><HR>Originally posted by Simon Fox: Is the resistance to penetration of two 100mm armour plates spaced apart effectively identical or sufficiently similar to one homogeneous plate 200mm thick? <HR></BLOCKQUOTE> Vs shaped Charges yes , infact given sufficent gap the spaced plate should offer a bit more. Vs AP shots the gap will reduce the efficency by about 3-5% in this case[ 1-2 projectile diameters] In the case of the Tiger mantle the 'free edge effect' will reduce this even more and the mantle is cast which should offer ~ 90% resistance of Rolled plate of the same hardness. All told the Tiger -1 front turret probably offers about 15cm resistance Vs WW-II APC type ammo.

Allow user to modify armor levels and penetration values.

On the issue of 75mm Vs Tiger-1, the ricochet of a 75mm AP shot should be about [ from test]... 600m/s = 45o+/- 5o 800m/s = 55o +/- 5o So if the 75s are not penetrating the front hull its because the angle must be ~ 40o.... at that angle even the 100mm bow plates and driver face plates are nearly 200mm effective resistance. On the issue of Bazooka Vs Tiger-1 , the ricochet angle should be some thing like 20-30o making hits difficult . The original warhead was 2.67 inches?, and test on bazooka suggest ~ 2 cone diameter penetration depending on stand off.In addition there should be a shot to shot variation of some thing like +/- 1/2 a cone diameter. So at any kind of angle Bazooka penetration of the hull or side armor would be possible but not very likely. The front turret is out of the question cause the 200mm cast and rolled plate is uneffected by free edge effect and should offer about ~ 200mm resistance. I'll check these when I get home and edit if needed.

Davids just finished an upgrade and his site has alot of good data that I think you guys should check out. [url="http://www.wargamer.org/GvA/index.html"]http://www.wargamer.org/GvA/index.html[/url] [/HTML]

The book is titled "Applied Operations Research", by a group from 'Royal Ordnance and Royal Military College of Science'England {off course }.Heres the results of the work charts derived from WWII data on tankloses,to predict the average expected out come of a large number of fire fights.In these charts a “kill” probability is assigned baced on increacing “overmatch”.In there version “overmatch” is the term denoting how much the penetration exceeds the targets armor,in the form of a ratio.Here are the approximate survivablity ratios Vs increasing “overmatch” for an “average” tank. <font color=white> <PRE> 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9+ 3% 10% 17% 30% 40% 55% 65% 70% 73% 77% 80% </PRE> <font color= orange> In the matter of plate hardness = resistance APFSDS test suggest 0.156% per BHN difference between 275 BHN standard and the new plate , so a 220BHN plate should offer ~ 9% less resistance or the plate offers 91% resistance of RHA standard. RM Ogorkiewcz reports that API bullits [7.62-12.7] Vs 380BHN plate and 180 mild steel ... the difference in resistance is 0.8 Vs 1.0 suggesting the 200BHN points amount to 20% or 0.1% per BHN difference. Note that due to performance in the extremes these values don't apply below 180BHNor above 400BHN. As 600BHN armor offers only 1.19 compared to 1.0 for 380BHN [ about 0.6 per BHN] , while 110BHN mild steel offers only 0.66 of RHA 380 or 34% over 270 points [ 0.13 / BHN]. <font color=black> What hardness figures does the game use ? If I use RM Ogorkiewcz figures , our late war Stug III has 80mm armor problably 220BHN and thus offers conservatively 94% or 75mm resistance. So what is the penetration for the 75mm gun @ 300m 500m & 1000m range and whos figures US or Brits? [This message has been edited by Paul Lakowski (edited 08-14-2000).]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Heidman: Paul, if nothing else, the site you posted the URL to has some really interesting pictures of the battle damage. One thing that stands out is that most of those destroyed and damaged vehicles were hit multiple times. Whether this is because it often took multiple hits, or because SOP was to keep hitting them till you were sure, is unknown. Likely both. Jeff Heidman<HR></BLOCKQUOTE> Jeff; I have an 'Operational Analysis' text book that includes calculating kill ratios and 'Lanchester equation' etc etc. In there they had 'WW-II' data on kill rates related to 'overmatch' and you don't reach 80% 'kill' until you 'overmatch' the targets armor by 50-60%[off the top of my head ]

On the general subject, If you recall in Guderians 'Panzer Leader' he reports that from 43 on all Assault guns and SP guns are to be manufactured with 'mild steel'. If you check out the link below you'll see that the Jagd Panthers Glacis was only 210 BHN which is the same as the Tiger 2s and the Hetzer has 240 BHN glacis!well below the acceptable 270-280 BHN.Mild steel is upto 180 BHN [url="http://www.mobilixnet.dk/~mob75281/ga/apen/bhn/bhn.htm"]http://www.mobilixnet.dk/~mob75281/ga/apen/bhn/bhn.htm[/url] [/HTML] [This message has been edited by Paul Lakowski (edited 08-14-2000).]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Maastrictian: By my understanding, after the war it was found that the fragements generated by the penetration of the round did more damage than a charge at the base of the round. This is why modern AT ammo has no burster. <HR></BLOCKQUOTE> Chris, The report is in Jentz 'Tank Combat in N Africa'... and it refered to 'partial penetration', which means the projectile didn't penetrate plate.... your talking about penetrating hits result in 'spalling'. BTW; From what I've read, APHE was in use by Americans and Russians with the 90mm & 100mm gun tanks of the post war era through the 50s.

<BLOCKQUOTE>quote:</font><HR>Originally posted by kipanderson: Charles,hi, thanks for the info. Can not wait to have it in my hands. All the best, Kip.<HR></BLOCKQUOTE> If this is the same work then I have a copy Kip maybe we can make an exchange for the ' 50 pages ' we discussed earlier .The formula is quite complex...I hope your good at 'Logs'? BTW Robert Livingston told me the angle component of the equation is wrong and recommended another approach. Rgds Paul.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Big Time Software: "Penetration of Armour Plate" PB91127506 Enjoy! Charles<HR></BLOCKQUOTE> Are you refering to ...... Ordnance board " The PENETRATION OF ARMOUR PLATE" compiled by the Co-Ordinating Sub committee of the Armour Piercing Projectile committee.1950? [This message has been edited by Paul Lakowski (edited 08-14-2000).]

I had another look at Helge's diagram and while the thickness of this mantle might be 100mm at the edges the main part thicker > It looks like the mantle in the middle thickness right to the front turret wall. Now the gap inbetween the Mantle and the front turret is ~ 100mm leading to the assumption that this thickness is 200mm . Also the area were the front turret and mantle over lap looks like ~ 100mm mantle + 115mm turret front as its backed up by a plate. OK to summerize the Tiger -1 front turret armor in a different presentation .... <PRE> From left to right / 80mm RHA @ 65o = LOS 21cm [ 100mm Cast + 150mm turret corner |(edge)100mm Cast + 115mm turret front or 200mm Cast (middle) [ 200mm Cast [ 88mm gun] |(edge)100mm Cast + 115mm turret front or 200mm Cast (middle) [ 100mm Cast + 150mm turret corner \ 80mm RHA @ 65o = LOS 21cm </PRE> Cast manlte offers only 90% resistance , and the free edge effects the whole area . At the mantle corners both values are x 0.6 to 144mm. The gun barrel area is 200mm cast mantle x 0.9 x 0.88[free edge] = 159mm. Inbetween the mantle is 200mm cast x 0.9[cast]x 0.88 [free edge]= 158mm in the middle . The edge has [100mm Cast x 0.9 + 115mm Front ] x 0.6 x 0.97 air gap. = 119mm The side turret is 210mm or more due to the angle. so it should look like this <PRE> From left to right / 80mm RHA @ 65o = LOS 21cm = 210mm [ 100mm Cast + >150mm turret corner = >144mm |(edge)100mm Cast + 115mm turret front or 200mm Cast (middle) 119-158mm [ 200mm Cast [ 88mm gun] = 159mm |(edge)100mm Cast + 115mm turret front or 200mm Cast (middle) 119-158mm [ 100mm Cast + >150mm turret corner = >144mm \ 80mm RHA @ 65o = LOS 21cm = 210mm </PRE> So I would estimate.... 1/2 Mantle @ 159-144mm 1/3 is the side & top turret @ 170- 210mm. 1/6 is the Mantle edge @ 119mm. OK I posted this in themorning and edited it at lunch and again at supper [This message has been edited by Paul Lakowski (edited 08-10-2000).]

OK the Panther used on the test was almost definately with a face hardened glacis heres what Jentz reports. “On 30th March , the requirement for face hardening the glacis plate was deleted . Based on thebacklog of precut, Heat treated and welded compontents , completed Panthers without face hardened glacis plates would have first appeared in August 1943.” pp29 ‘Germany’s Panther Tank’Thomas Jentz. GrossDeutcschland would have recieved the first of these in Aug 1943 followed by I.Batt 2 SS Pz Rgt.Its most likely -infact almost certain -that the Panther was the face hardened version. Now looking at the figures for Face hardened penetration Vs Homogenous penetration in Ivan Hogg's THE AMERICAN ARSENAL the difference is - 0.8 inch for the 90mm AP and + 0.4 inch for the APC round .So a 122mm APC should result in atleast a 10mm increase in penetration . PS; Kipp I am serious about getting a copy what would it take to wrestle a copy from you ? I have hundreds of 'Engineering research papers' on modern terminal ballistics and armor of all types.