Paul Lakowski

<blockquote>quote:</font><hr>Originally posted by Jeff Duquette: Paul: I can't figure why you are being mysterious about the actual reference name. Is this based upon work by G. Birkoff for Aberdeen? What is the name of the reference you are relying on? You refer to a test being conducted at 6 cd stand-off against mild steel…was this production quality ammunition…or was it a precision made test charge? Was testing conducted @ 12 cd stand-off as well, or was this extrapolated?<hr></blockquote> Jeff not mysterious , just haven't had enough time to respond...These days with work and the family I have to steal time to be here! I posted the reference on the Google Sci Military thread, so I assumed that you read that. If you'd like I'll copy the article and mail it to you. The figures refer to two different papers one in 1948 and the other a couple of years ago . In the J of Applied Phys paper the warhead was a simulated warhead that was fired at varoius standoffs out to ~ 8Cd standoff , but the regression line is very flat at that point and predictions out to ~ 12Cd are still possible. [ 11-03-2001: Message edited by: Paul Lakowski ]</p>

<blockquote>quote:</font><hr>Originally posted by Jeff Duquette: Birkhoff's work with Aberdeen? The M20 super-bazooka sure was a different beast over its dad the M9.<hr></blockquote> No Jeff it was a WW-II warhead, they refer to german and american steel lined shaped charges along with a diagram of what looks like the Bazooka's M6A3 warhead in American Arsenal. Then a series of test with similar shaped steel lined shaped charges 1.63 inches in diameter where tested against a series of targets and standoff distances [ ~ 330 shots in total] .Its been shown that scaling has little impact in shaped charge penetration results so as long as the cone angle and liner material and liner thickness are the same it should generate the same penetration figures when scaled up.

Jeff the regression lines are linear until about 4-6 Cd standoff and then start to move asyemtotically to a certain value.In the 1948 paper where a scaled bazooke warhead is tested @ 6 cd the value is 2cd into mild steel and its almost linear out to 1.2 cd @ 12Cd standoff.

<blockquote>quote:</font><hr>Originally posted by Jeff Duquette: Paul: You posted this over @ Group:sci .military. If I am reading this correctly the optimum stand-off for a steel lined shaped charge vs. 180BHN plate falls-out at 2 to 3 cone diameters. Penetration at this stand-off is 3.5 times the cone diameter. Beyond three cone diameters penetration begins to drop off. Several Questions: In the case of the M1A1 or M9 “bazookery” cone diameter is slightly less than 2.36”. So optimal standoff is 4.72” to 7.08”? And Penetration at 2 to 3 cone dia stand-off is 3.5 X 2.36”? The tip of the ogive on a bazooka round sits a good 1 to 1.5 cone diameters in front of the actual charge?<hr></blockquote> As I measure it the distance from the cone to the ogive tip is 1.9 cone diameters so against mild steel that should get ~ 3.1 -3.5 cone diameters penetration. Ogorkiewzc tells us that HEAT penetration into mild steel is 67% [ 100BHN] -80% [180 BHN] of RHA [270 BHN]. So that should generate 2.3 to 2.4 cone diameters [Cd] penetration into RHA or 5.4 to 5.7 inches or 138-144mm penetration. If the standoff goes out to 12 'Cd' or more [ standoff the side skirts should offer], then the penetration should drop off to about 1.7 -1.8'Cd' into mild steel [ 100BHN] or ~ 1.1-1.3'Cd' into RHA . Thats about 2.7- 3.0 inches or 65-76mm. The 10mm mild steel plate should offer ~13mm and the back plate ~ 30mm , so the Bazooka should be able to penetrate the side hull clealy from straight on.

ASL , Troop commanders recognizing a threat and actually getting the immensely thick bureaucracy to do any thing about that threat are two entirely different things....and yes they are often a year behind the curve. When the first Russian heavies were meet many battle commanders demanded bigger guns and heavier armor for the pz and this didn't happen for about a year....and that was a high priority item. defense against ATR was a recognized threat that was never really addressed until the side skirt were proposed.Maybe it wasn't until some bright soul showed how this could be done with out totally rebuilding the tanks , that it finally was implemented As early as 1948 it was shown in ballistic research that layering plates of differing materials would boost HEAT resistance and yes their was a HEAT threat even back then. So why did it take the tank designers until the 60s and 70s to finally get around to doing something about that threat? And I don't agree , it seems that Hitler was the 'rate determining step' in allot of the tank development in Germany. Rgds Paul.

The answer to why the skirts weren't mounted until '43 is easy , they weren't need until then because the germans rolled over most of their infantry opponents until then...it took until mid to late 1942 for the russians to rebuild their infantry units and supply sufficent stocks again. Since until this point Hitler perceived most german attacks were successfull it wasn't until the Stalingrad debacle that he saw any need . You now that layered armor was shown to be particularly more effective against HEAT warheads back in 1947-48...the only reason they took so long to be developed into the standard armor for tanks was the threat didn't matured and ballon in to the RPG/ATGM threat , until the 70s.

I think I posted this before but her it is again The results are as follows Yawed impact of Steel Ogive AP shot [ 4:1 L/d ] at sub ordnance penetration velocity produced Yaw as follows from tests. Int. J . Impact Engng Vol 22- (1999) REVIEW Non Ideal Projectile Impact on Targets ,pp 100-381 [pp212]. [PRE] APC @ 800-900m/s °YAW = loss of pen.... 2° = 1% loss 4° = 2-3% loss 6° = 3-4% loss 8° = 4-6% loss 10° = 5-7% loss 20° = 10-14% loss 30° = 15-21% loss 40° = 20-28% loss 50° = 25-35% loss [/PRE] I'll have to look into this deeper later but I'm sure I remember that post impact tumble rates of 10-15 ° over 15cm travel are common with API projectiles , so over 60cm side skirts the yaw could easly be 40-60°.

Thin mild steel spaced plates and spaced mesh plates, have been repeatedly demonstrated to shatter /decap the tips of hard penetrators and induce hugh amount of yaw to the penetrator so that given sufficent space will result in the penetrator striking the main armor plate side ways or cut in half. Either way it would dramatically reduce the penetration to thin 30mm side main armor plates. The idea that these are "anti heat sheilds" in a none started because they would have increase not decreased the penetration of most HEAT warheads except maybe the bazzoka , due to the fact that most of these warheads had insufficent standoff. The bazooka wasn't even know to the Germans when the decision was taken to mount the skirting plates in early 1943. I like Jasons point about protecting the track wheel assembly, thats much more to the point.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Dan Robertson: Just incase you've never been to Panzerfaust page. Panzerfaust Most of the info you want.<HR></BLOCKQUOTE> Thanks Dan I actually lost that link when my hard drive died!

I heard that on the Achtung Pz site it was reported that the design was started in 1941 but dropped because it was not seen to be needed and then subsequently forgotten about!!!

I just tried to do a search on the German X-7 ATG missile and waited and waited and waited [ 5 minutes later] nothing. Is their something wrong with the search function or is the data base that big? Any way on to the question...wheres Markus H when you need him? I heard from another poster that the X-7 was developed early in the war [ 1941?] and could have been pressed into service but it was not viewed as needed then and forgotten about by the end of the war. Can Markus or anyone varify this ? Also while I'm at it what where the X-7 figures ? [iE weight diameter, speed range penetration etc]. Thanks.

Lorrin , on the question of Tiger-1 mantle thickness, did we ever settle on a figure? Also I have other research papers that do deal with short blunt penetrators @ varing velocities including against armor -some hardened -but nothing on face hardened armor...no one uses it any more, so not much point in testing it. I'll digg through what I have later.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Freak: I think the early ap shatter flaw in higher muzzle velocity guns was disguised by the lower muzzle velocity of the 75mm sherman. When higher muzzle velocity sherman 76 was introduced, the shatter problem was discovered when 76 sherman ap failed to penetrate 100mm thick Tiger IICRC. I am not fully sure on this, but this is what my memory recalls. Wasn't there a fix this situation of the 76mm ap shell? AFAIK, german ap ammo shell did not have this flaw. (flaw in ap shell)? Again, this is off the top of my head, and I am trying to recall rexford posts.<HR></BLOCKQUOTE> The fix to shatter problem was supposed to be softer caps put on the penetrator ...It was the blunting of the tip that change the shatter problem... In modern AP shots [ for auto cannons] they is no APCBC just AP with a windscreen with either a blunt or sharp nose under the windscreen depending on what you want to penetrate. Modern APFSDS are all blunt/ flat tips, because at that velocity all metals will shatter at the tip, even if they are 700 VHP WC or modern DU/WHA rods. The harder the penetrator the higher the thresh hold so , for the velocities they choose , the german ammo survived because it was harder.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Freak: Not sure but I don't think so. German ammo AFAIK, was made better.<HR></BLOCKQUOTE> All AP projectiles will shatter , its just a question of reaching the right [ or wrong] angle of impact and striking velocities.

[ 06-18-2001: Message edited by: Paul Lakowski ]

The area were the turret meets the turret ring is probably a weaked zone offering less resistance than the LOS thikness suggests.

I too am patiantly awaiting the book , how much for us grunts! Don't wait for the Russian AP Vs Facehardened armor stuff , just publish it and offer a volume two later with updates!

Hey Jason if you continue to write in clear short snappy paragraphs ...I may just have to read more of your posts Keep up the good work and thanks for the insight into your loading howitzers experiences. Are they as loud as they appear?

Russian penetration figures are 80% certified penetration figures...that means that 80% of the projectiles have to penetrate the plate inorder to achieve the penetration figure. In most cases other armies use 50-50 ballistic limit value.The difference could easly be 10% penetration improvement for Russian guns...when compared to others....they may also use harder plate as targets as there are still some discrepance after the above adjustments are made.

<BLOCKQUOTE>quote:</font><HR>Originally posted by M Hofbauer: Username - As regards the 251/7,5cm L/70 combo, out of the hundreds of weird vehicle/gun combinations I am sure there was also a plan to put the KwK 7,5cm L/70 onto a 251 chassis: remember the regular 7,5cm PaK 40 mount onto the 251/22, and I have documents here that there were trials involving a full-grown 8,8cm PaK 43 onto the SdKfz 251 :eek: , of course it was not feasible but they sure tried. So I think it is very reasonable to assume that inbetween these two they also tried the 7,5cm L/70.<HR></BLOCKQUOTE> I thought that Chamberlin and Dolyes book reported that the 75L70 mounted on half track was tried in 1943 and found to be a failure ...too unstable?

Yes if the propellant isn't matched to the barrel lenght it may peak to high and burst the barrel. Lewis , close examination of the projectiles shows the penetrators are not the exactly the same both L-70 & L-71 feature slightly longer sharper penetrators which boost vertical penetration in relation to there mass, and at the expence of slanted penetration.....Although that might also be a consequence of the higher striking velocities.

<BLOCKQUOTE>quote:</font><HR>Originally posted by kipanderson: Paul, hi, you said it all, we posted at the exact same time! Good to see you are still out there. All the best, Kip.<HR></BLOCKQUOTE> Hi Kip , Good to talk to you again I just came into alittle money,and awhile agoe we were discussing data on russian penetration from that 1000 page report from Bovington, do you remember? Any way I still want them and I lost your Email so drop me a line and if you can still make copies I'd like to do that and send you a check! What do ya think? psl@interchange.ubc.ca

<BLOCKQUOTE>quote:</font><HR>Originally posted by Mr. Johnson-<THC>-: So, do they fire the same round? How about the medium and long 88? Do they add more propellent?<HR></BLOCKQUOTE> The penetrators are longer and sharper while the charge is much larger...which is why they both penetrate more than the shorter versions of these guns.

according to Dunns Soviet Economy and the Red Army 1930-1945, Total track in use 1941 74,000 km track 1942 62,900 km track 1943 81,646 km track 1944 106,000 km track 1945 112,868 km track In 1941 German captured only 15% of the rolling stock but most of the locomotives escaped.About 25,000 locomotives were thought to be in use in late 1941 and 3/4 million freight cars.This explains why they were able to spirit away the industries to the east of the urals. Through out the war the stock of locomotives and freight cars remained more or less the same ...so the production and lend lease replaced most losses. It seems the locomotive factories were converted to tank production so most of the replacements came from America.But this total is only 1981 trains and 11,155 freight cars. While in 1943 Russians produced 2000 trains and 56,000 freight cars in 1943 by themselves. So in this area Lend Lease was a help but they could have managed with out it. Trucks 379,903[65% of total ] plus 35,170 cars and 35,170 motorcycles sent along with 12,755 tanks [ 11% total ]and 22,206 planes [20%] Russian total truck production was only 205,000..... so this represented only 1/3 of the total trucks sent to them [205,000/584,900] The truckage was important since wagon based covoys could only average 60km between depot [rail head] and destination [ divisional]truck based convoys could average 300kms from the rail heads. As the Russians pushed back to their boarders it became increasingly difficult to rely on trains as these had to be converted back from German to Russian gauge. In the end Lend lease didn't alter the out come of the war it shortened it for the Russians...how ever as they are inclinded to point out a "second front" would have shortened the war a whole lot faster!

<BLOCKQUOTE>quote:</font><HR>Originally posted by Johnny D.: If the skirts were designed to stop ATR's then why wasn't they deployed a lot sooner than '43, when ATR's were in use prior to the war beginning. I think it's more than irony that schurzen wasn't seen regularly on german vehicles until near when the Germans started fielding HC weapons themselves. The Germans were one of the first to discover the power of the shape charge and one of the only armies with standard protection against it.<HR></BLOCKQUOTE> There was always a battle between the branch that build the Pz and those who use them and a year was about right for the 'solution' to be implimented. Remember from the arrogant German POV the war in the east was never supposed to extend beyond 1941. When it did they institued a number of programs to 'solve' some of the technical problems ..like the Pz could resist 76mm ammo and ATR etc.