Paul Lakowski

I read that in testing modern APFSDS, the MV can change as much as 40m/s if the temperature is changed by as little as 5°C. THis is the reason that modern tanks have heaters in the tanks, to keep the ammo warm. But what about WW-II ammo or ATGunners...how much difference did ammo temperature make on Muzzle Velocity? Was there any thing gunners did to keep the ammo warm?

Even if Raus is lying, it would seem odd for him to resort to Soviet propaganda. So, what kind of person is he anyway? Maybe some analysis of his person and his history would help to understand why he wrote such things after the war. </font>

This tale is typical of the way some war correspondance is reported. Early in Barbarossa the soviets had little chance of victory so every desprite tale became a focal point to make up for the lack of any good news. FOr example the divisions that were allegedly held up actually were to the east of the river encircling soviet mechanized korps destroying 200 tanks for the loss of 40 of there own tanks. You see the samething happen to the germans at the end of the war. Great attention is paid to detailed accounts of individual acts of heroism and success while their own army crumbles around them.

In 1941 a squadron of T-35 was ambushed by a troop of KV tanks. THe T-35 were directed to mass fire on the KV tanks aiming for the turret rings and succeded in disabling two of these tanks before chasing the other away.

Heres a question that has vexed me for ages! What is the velocity down range [iE 500m, 1000m & 2000m] for the following weapons? German 50mm L60 & 50L42 Russian 76mm L41 gun Russian 85mm gun Russian 100mm Gun All firing AP/APC ammo?

Originally posted by Andreas: What part of the T-34s armor is 8cm thick and what other materials do they use other than steel and cast?

It should just be Spaced plate erosion by determine the t/d ; angle & effectiveness of the plate material . Then (t/d)^0.5 to determine the 'spaced plate effect' So 2cm Aluminum [0.5d] vs 3cm API becomes 2/3÷2^2=0.8 x 2= 1.6 1.6 x 0.5[te]= 0.8cm The spaced plate effect becomes 0.8/3^0.5 = 0.5cm If there is insufficent gap, multiply 'spaced plate effect'by x 0.7. If the penetrator is high strength reduce the 'spaced plate effect' by x 0.7 So if the penetrator was high strength and the gap insufficent it should be x 0.5. </font>

2cm/3cm ÷ 2^0.2 ....yes thats right.

It should just be Spaced plate erosion by determine the t/d ; angle & effectiveness of the plate material . Then (t/d)^0.5 to determine the 'spaced plate effect' So 2cm Aluminum [0.5d] vs 3cm API becomes 2/3÷2^2=0.8 x 2= 1.6 1.6 x 0.5[te]= 0.8cm The spaced plate effect becomes 0.8/3^0.5 = 0.5cm If there is insufficent gap, multiply 'spaced plate effect'by x 0.7. If the penetrator is high strength reduce the 'spaced plate effect' by x 0.7 So if the penetrator was high strength and the gap insufficent it should be x 0.5.

Hi Jeff I have this paper.... OK the skirting plate was untreated 1/4 inch plates sandwiched together [doesn't state how]. This could mean mild steel which can be 180BHN [0.8 Te] or down to ~ 100 BHN [~ 0.66]...anything lower would be soft steel. Since its not stated which steel is used this could be either or and will modify the results. More importantly is the fact that the researchers identified the 57mm ammo to do better than they thought since it had higher longditudeal properties. Now I'm not sure what they mean't by this but it sounds like high strength [as opposed to high hardness]. Its long been known that high strength penetrators do better than regular strength penetrators in both penetration and multi layered armor penetrations....and spaced armor is no different. THis is why modern APFSDS are moving back to these. In modern ballistics tests with APFSDS such a high strength penetrators demonstrate a 70% lower spaced plate effect [goes from 1.3d to 0.9d] . If we apply this to the 57mm case the situation improves dramatically. BTW the body diameters of these rounds look to be 5.75cm M70 and 5.6cm M-86. Two 1/4 inch mild steel plates and one 2 inch RHA plate workout to [cm sorry I'm sooo European ] 0.635cm x 2 plus 5.08cm. The t/d Vs M-86 works out to 0.56 & 0.91 respectively ..adding Te = 0.37 x 1.27= 0.47cm and 4.61cm. The spaced plate effect should be SQRT [0.61/5.6] = 0.33d x 0.7 = + 1.3 The angled plate looks to be 7.9cm or about 3.1 inches. This doesn't explain the parrallel plates but looks close to the opposing plates.... Looking over the parrallel plates I recall the yaw and pitch factor that altered the impact on the second plate reducing the angle by up to 7°.That never happens with APFSDS so they never added that factor....guess thats a modification that needs to be added for AP level penetrations. That should reduce the back plate contribution to 33° or 4.61cm ÷ 0.84= 5.5cm + 1.3+ 0.47cm = 7.3cm or 2.86 inches. While this may look like a problem it may not be. The M-86 is an APC. Modern research suggest that the cap will truncate the spaced plate effect....and this may be an indication of just how much.If we eliminate the spaced plate effect due to the cap, then the values become 6.6cm [2.6"] and 6cm[2.36"] respectively . It also should be noted that with spaced plate their seems to be a higher scatter on results than normal AP shots with SD being as high as 10%. I must be gettin old cause I Fu#$ something else!!! The spaced plate effect is not modified by V, just t/d...its the back plate effect to determine penetration in the first place , thats modified by V..... big sorry for that

Jason Lower hull is 80mm @ 20-30°...the resistance is ~ 7cm @ 30° and the penetration of 76mm APC is ~ 7cm @ 700-900m 1/2 hits. I'll add more later

I don't have any numbers or the game so I don't know what your refering to?

Haven't got a clue what Jasons on about so I'll just let it alone for now..... Yes usually I don't include the angle since its a property of the projectile penetration...IE if the effective resistances is 49mm @ 60°, then you have to find out at what range 37mm can penetrate 47mm @ 60°...which is none existance. So for the 75mm the range at which a 42mm can be penetrated @ 60° should be about 1/2 hits @ 1400m Yep with RHA being referenced to BHN 275 rolled plate. SHS depends on the amount,450BHn is about 1.25 while 380BHN RHA is going to be around 1.1 Yes but strickly speaking the angle should be an expression of the projectile. And yes to the 52mm FH plate....but usually at shallow angles the COS of the angle is sufficent especially when the projectile is blunt like many soviet WW-II and modern penetrators. When you get into ogive penetrators the projectile will slide and exagerate the LOS penetration through the angled armor. [ November 17, 2003, 11:30 PM: Message edited by: Paul Lakowski ]

That is correct. For example 37mm Vs 45mm SHS of T-34 glacis is [45mm/37mm/2 ^0.2]*1.2 or 49mm @ 60°...while if 75mm hits thats [45mm/75mm/2 ^0.2]*1.2 or 42mm @ 60°. # 4) I did wonder about that but the shattering was severe as I recall not minor.In anticipation of that very question I was reviewing some of the ballistics experiments. In one very involved study hard Steel short rods with sharp ogives were test fired into hugh blocks of aluminum. The actual aluminum penetration was easy until it hit the next block placed adjacent to the first. Either the penetrator veered off at 45° after crossing the boundry or it shattered! In similar modern long rod penetration studies against steel the blocks surface of both exited block and reentry blocks were severly distorted showing massive expenditure of energy. Layering in modern ballistic armor is expected to yeild anything from 10-40% improvement in the overall armor resistance. There is a direct connection some where here but I have still not been able to quatify that. #3) this is not easy to answer since the damage effect on penetrator is determined by the spaced plate ...and when breaking it down it works best if you make that simple distinction.VEry large gaps tend to increase the overall resistance of long rod penetrators or even short rods @ > 1km/s impact velocity to the tune of 10-20%...but these are over vcery large gaps of 20 diameters. I recall Zukas did a paper that for 10:1 L/d rods @ 1.5km/s the gap increased dramatically when the gap got to 3-4 diameters. On the other hand Holher and Stilp show that below 1km/s impact V, short rods penetrated more than two thinner plates easier than one thicker plate when the air gap was 20 diameters. I tend not to factor large airgaps in. #3) where large airgap becomes significant is in the area of shaped charge resistance. The formula is The erosion of the skirting plate plus the base armor [minus t/d] and the standoff effect plus 0.7d...so if the skirting plate is 1cm mild steel and the warhead is 10.5cm that adds upto 8.1cm plus the standoff effect[depends on liner material etc]. 2) because its all got to do with how much damage the skirting plate does to the impacting penetrator...remember Dr Elders paper on "spaced armor at sea", if the damage was insufficent to decap the APCBC the projectile could contiue to travel 24 diameters airgap and still penetrate with almost full effect. For example the steel mesh the germans employed is perforated plate armor and should increase the damage to the impacting projectile by 1.6 times [and double that if its a HVAP shot]...that explains why those 14.5mm HVAP shattered and did almost no damage to the Pz-III hulls....it literally shatters the penetrator! 1)If it was straight steel there would be no 1.3 modifier at the end and it would resist less. Additionally if the skirting plate was aluminum its Te is ~ 0.3 to 0.4, so you'd need three times as much thickness skirting plate.

THe basis of all modern ballistics test are semi infinite reference point...this is the only way to compare differing levels of resistance etc. The task is then to back calculate the t/d effect etc. Angled impact is controled by projectile nose design, since this controls the back plate effect. As to the airgap it doesn't take much to allow shatter to occur, remember the case of the 90mm HVAP shot hitting two plates that were treated as one in the test. Should have penetrated cleanly but ended up shattering inbetween the plates. Now that I've had a chance to review this I need to make a correction.The formula was developed from APFSDS back through APDS to AP penetration and in all my modern cals the 'te' is factored independent of t/d so thats in the wrong place in the forumla I put down. It should read... [Thickness) ÷ projectile thickness]÷ 2[semi infinite] ^0.2 * Te. So 3cm FH @ 10° t/d should become 3cm÷ 7.6cm ÷ 2^2 x 1.3[Te FH]or 0.723 x 3cm x 1.3 = 2.82cm @ 10°= 2.9cm Then 'spaced plate effect' becomes; SQRT [2.9÷7.62] = 0.61* 0.1d*V[km/s]* 0.7[poor gap]= 0.26d or 2cm additional protection. That should mean the driver plate offers 2.9[3cm FH ]+ 2cm[space] + 5.2cm =8.1=>10cm, depending on if the plate bulges or not during impact. Jeff 'Te' means 'thickness effectiveness' and the + 2cm is the reduction in penetration due to the airgap. If this air gap was 1d or more [iE 7.6cm] it should result in + 2.8 cm loss in penetration. Against higher velocity GErman 75mm guns this type of applique mounted on a KV-1 should mean higher loss due to higher velocity.However with APCBC ammo you have the possiblity that the sectioned nose will truncate the damage done to the penetrator by such spaced plate limiting the loss of penetration...that and the fact that these are longer penetrators which lead to more penetration anyways. [ November 17, 2003, 12:15 AM: Message edited by: Paul Lakowski ]