Armor Technology

[Paul Lakowski]

Against the 115mm & 125mm 10:1 L/d steel APFSDS matters change even more,the

 

The effectiveness of an spaced armor plate is dependant on the amount of damage is done to the projectile by the spaced plate prior to it impacting the main armor. If the effectivness is simply to 'decap'& 'yaw' the projectile then an effective increase of 10-20% is possible where decapping occurs and average yaw rates of 5-7° on AP/APC type projectiles are experienced. Studies I've seen in the Int.J.Impact Engng with small bullet /thin plate experiments , show that yaw angles are variable from shot to shot in some cases the swing is as much as 10-15° and near vertical impact angles, which probably explains the range of results. If the projectile is also shattered , the armor effectiveness could be boosted by 50% and even as high as 70-80% if the shattering of the projectile is substantial [as in the case of 90mm aluminum sheathed tungsten carbide HVAP ].

 

Long rod [10:1 L/d ] penetration of thin plates [1:1 t/d] @ sharp angles [60-70°] @ 1.5km/s suggest the mass loss alone on a spaced armor plate should be >4 projectile diameters @ 65-70° Vs t/d 1:1 and ~ 3.3-3.8d Vs t/d 0.7. At 0-30° impact angle thats ~ 2d @ [@ ~ 4km/s impact its 4-5 d loss @ 0-30° & ~ 3.5d loss @ 65°]. The yaw on such an impact [10:1 L/d @ 1.5km/s]should be ~ 5°,which should reduce the penetration by ~ 0.7d for a 10:1 L/d WHA penetrator and 4d Vs 20:1 L/d WHA penetrator.[int J Impact Engng Vol-12,pp281-292; Vol 14, pp 561-571; Vol-22, pp 71-91 & vol-10, 81-92].

 

But the above model applies to DU & WHA heavy metal rods impacting a hard steel spaced plate , while the BM-6 & 9 are hard steel so the damage to the penetrator is going to be much more !I will add another projectile diameter of loss to reflect this.

 

Thus impacting the LEO-1A3 spaced plate @ 1.5km/s , a 42mm diameter 10:1 penetrator should lose ~ 5 diameters penetration or reduced to ~50% penetration. The BM-6 @ 1.6km/s should do 23cm LOS [@ 60°] which translates into ~11.5cm LOS penetration Vs the LEO-1A3 spaced plate armor.The 125mm 41mm diameter BM-9 should do 29cm LOS penetration @ 1000m range and angle translating into ~14.5cm against the LEO-1A3.

 

The base calculation for both should change due to the more favorable t/d ratio .Compared to RHA , this effective armor should be 4.5cm VHS [ 1.34 (te)x 0.7(t/d)]+ 1.5cm SHS [ 1.25(te) x 0.5(t/d)] + 1.5cm RHA [ 0.5(t/d)] = 4.2+ 0.94 + 0.75 = 5.9cm @ 65° = 13.9cm. Sounds like the LEO-1A3 front turret armor is still effective in resisting BM-6 @ 1000m range .

 

This also doesn’t include the layered base armor. In tests with the 90mm HVAP against RHA plates stacked together, @ 10 inches [ 2 plates welded at the edges ] , the shot penetrated the first plate and failed on the second when it should have penetrated 10inches easly, suggesting an additional loss due to layered target.[A Hurlich ‘Spaced Armor’,pp3-4] Against 30:1 L/d penetrators @ 1.5kms , against targets with solid RHA & thin hard plates stacked together@ 60-70°,resulted in a the same penetration , when it should have been less due to t/d of the thinner plates[90%].[ pp 246-247 of Vol22 Int.J.Impact Engng], this a 10% reduction not included in the above figures. However the above assement doesn’t include lateral confinment of the target which becomes important for APFSDS impact velocities and should mean the target offers 95% resistance due to proximity to gun embrasure. Thus the modified resistance should be around 13.9cm x 1.1 x 0.95= 14.5cm just eoungh to limit 125mm BM 9 to 50% penetration chance at 1000m range.The 115mm BM-21 and 125mm BM-15 should both do ~ 31-32cm LOS [@ 60°] at 3km range, so should have no problem penetrating LEO-1A3 front turret armor at that range.

 

 

[Edited by Paul Lakowski (15 Dec 2001).]

[Paul Lakowski]

If any of you have read Dr Elders paper on spaced armor on Battleships and the testing of spaced armors through WW-II, you'll know that this is a very difficult armor to quantify.The up shot of his findings seem to show that against APC type BB shells the best ratio of spaced plate to attacking projectile was a angle of impact of 0° and a t/d of ~ 0.17.This effectively 'decaped' the cap of the Armor piercing capped shell . Since these caps are their to prevent shattering of the AP shot , its likely that 'decapping' will lead to shattering of the projectile nose.The net effect was a net 20% increase in the effectiveness of the armor ...or a corresponding reduction in armor mass needed. Thicker plates at sharper angles will achieve the same or better results...but for obvious reasons are impractical in designing the armor for WW-II battleships.

 

These more oblique cases are however of interest to AFV design and are informative. When the spaced plate was inclined the T/d was 0.3 to decap the projectile and when this reached 0.5 t/d the projectile was 'decaped' and 'shattered', so it couldn't penetrate the main armor belt.This effect on projectiles was tested on 37mm M51B2 APC & M-62 76mm APC shells and found to be consistant at impact angles of 20°-50°. When the impact angle reached 60° all that was needed to effect shattering and decapping of the projectile was a spaced plate with a 0.3 t/d.

 

An interesting finding was [ARD Terminal Ballistic Report No. 7/44] that the lower the impact velocity the thicker the spaced plate needed to be to achieve the decaping , and the harder the plate the easier it is to decap.

 

@ 480m/s the spaced plate had to be 0.35 @ 30° to decap

@ 600m/s the spaced plate had to be 0.3 @ 30° to decap

@ 760m/s the spaced plate had to be 0.25 @ 30° to decap

 

Another interesting finding of the battleship spaced armor studies , was that a similar mass spaced armor arrangement filled with concrete achieved the same results but with a thinner array.The array was 0.3 d spaced plate + 1.1d concrete + 1 d FH armor = 0.4d spaced plate + 2.5d airgap+ 1.17d FH armor.Applying this to say a 100mm APC shot , it says that 40cm spaced armor arrangement with 15.7cm steel should offer the same resistance as 24cm steel concrete steel armor.Both of which should offer the equivellent to 17-21cm RHAe against 100mm APC @ 0°, and extrapolating further if this armor was @ 60° , it should be 12cm thick with 3cm steel outer plate + 4cm concrete + 5cm steel .This should shatter , yaw and decap the projectile resulting in about 1.5 -1.7 times the effective resistance or ~ 26-32cm RHAe.The same effectiveness should be achieved by 4cm spaced plate + 12cm airgap and 5cm FH armor plate set back at 60°.

 

Now the LEO-1A3 tank turret is reported to feature a spaced armor arrangement 54cm thick thats said to be 17cm thick @ 65° while its predicessor , the LEO-1A2 featured 8cm cast armor at the greater angle.This suggests a 17cm spaced array with ~7.5cm steel. The side turret armor is reported to be 1.3cm VHS outer plate [very hard steel-515BHN] followed by an air gap 6cm plus a main armor thats 3 plates welded together ~ 3.5cm thick [550-415-250 BHN].Following this pattern , the front armor of the LEO-1A3 turret , proportionally should be , 2.5cm outer VHS spaced plate + 10cm aigap , followed by 5cm thick VHS-SHS-RHA armor .Now this arrangement is not quite the same as mentioned, the spaced plate is too narrow [ 0.25/ 0.3] but since its VHS, this can be ignored. Thus to a first approximation it should shatter and yaw 100mm APC enough to result in a 1.5-1.7 times the effective resistance.

 

Compared to RHA , this effective armor should be 4.5cm VHS [ 1.34 (te) x 0.5(t/d)]+ 1.5cm SHS [ 1.25(te) x 0.5(t/d)] + 1.5cm RHA [ 0.5(t/d)] = 3+ 0.94 + 0.75= 4.7cm @ 65° x 1.7= 18.9cm RHAe. More than enough armor to stop the 100mm APC shot, which can only do ~17cm at these angles at muzzle, the side turret should do ~6cm more than enough to stop 30mm API.

 

Against the 100mm APDS matters change alittle. The effect is enhanced because the T/d is more favorable to the armor and the projectile is more brittle WC, thus the effective increase should be atleast 1.7-1.8 times . Inaddition the calculations are again more favorable to the armor due to the t/d.Compared to RHA , this effective armor should be 4.5cm VHS [ 1.34 (te)x 0.6(t/d)]+ 1.5cm SHS [ 1.25(te) x 0.5(t/d)] + 1.5cm RHA [ 0.5(t/d)] = 3.6+ 0.94 + 0.75 = 5.3cm @ 65° x 1.7-1.8= 21-23cm RHAe. The 100mm APDS should do

Muzzle 29cm @ 0° & 22cm LOS [@ 60°]

1000m 26cm @ 0° & 20cm LOS [@ 60°]

2000m 24 cm @ 0° & 18cm LOS [@ 60°].

 

This suggest the armor is more than enough armor to stop the 100mm APDS at any range. The side turret armor should do ~6-7cm enough to stop the 30mm APDS.

 

[Edited by Paul Lakowski (15 Dec 2001).]

 

[Edited by Paul Lakowski (17 Dec 2001).]

[C.G.Erickson]

Originally posted by Paul Lakowski:

New question, Can any one supply the volume under armor for the following tanks total and or Turrets as well?

 

T-55 or T-54

T-62

Centurion

T-34/85

T-10

IS-3

IS-2

Kind of hard to measure in a curved surface....Give me some guidelines and next time Im down at Littlefields I can measure the T-54, T-55, T-62, I-S3, Centurian, T-34/85....

[armylion]

Paul,

 

I was digging through some of my stuff, and found a chart with some info you may find of use. It is from Rolf Himes "Main Battle Tanks: Developments in Design since 1945". On page 97 there is a chart of the armored volumes for various US and Soviet tanks (the book is from 1987).

 

First number is total "armored volume" (which I take to mean volume under armor)

Second is volume of fighting compartment

Third is volume of engine compartment

All values in cubic meters

 

US

M47: 15.00, 9.06, 5.94

M48: 17.70, 10.48, 7.22

M60: 17.70, 10.48, 7.22

M60A1: 18.41, 11.17, 7.24

M60A2: 16.85, 9.62, 7.23

XM803: 17.84, 10.04, 7.80

M1: 17.56, 10.90, 6.66

 

Soviet

T-54/55: 11.30, 8.05, 3.25

T-62: 12.50, 9.23, 3.27

T-64: 11.50, 8.37, 3.13

T-72: 12.60, 8.35, 4.25

 

 

I have also seen some volume figures in my Russian materials, but that is going to take a while to go through. Hope this helps.

 

Merry Christmas,

 

Gavin

 

[Edited by armylion (21 Dec 2001).]

[Paul Lakowski]

Thanks CG and Gavin,and a merry christmass to you both

 

 

The info I have on the M-1 is that the original model is 21m^3, while the M-1A1 design on is 23m^3 internal volume. I got 19.4 m^3 for the LEO-2A1 and 17.1m^3 for the Chieftain. The Russian tank book [universla battle tanks] reports LEO-1A5 as having a turret volume of 4.2m^3 , while the LEO-2is 4.5m^5. This doesn't sound right to me and I assume their mean the LEO-1A3/4 turret.

 

 

Does Hilmes report the volume figures for the LEO-1 variants.

 

 

BTW interesting to note that SOviet tanks have a ratio of engine to fighting compartment of < 1.5 , while American tanks are ~ 1.7:1.

[Paul Lakowski]

Heres some other volumes I've found, the first are from Steve Zaloga when he was still visiting this site and the second are from Hilmes.The internal volume data for the newer types in cubic meters

(Hull + turret) are:

T-80U= 9.2+1.93

T-72B= 9.186+1.846

T-64BV= 8.7+1.7

M1A1= 17+4

M60A3=13+5

Cheers! Steve

(mass/volume) density"

T-90 46.5 -11.04 4.21

T-80U 46 - 11.13 4.13

T-64B 42.4 -10.4 4.07

M1A2 63.1- 21 3.0

M60A3 51 -18 2.83

Leo2A4 55.2 -19.4 2.84

Leo1A5 42.5 -18.2 2.33

Chieftain 55 -17,1 3.21

Amx30B2 37 -12.8 2.89

[Paul Lakowski]

Light weight armor is being developed that can proof most AFVs against 7.62mm & 12.7mm AP shots that hardly adds much to the vehicles mass. The armor against 7.62mm would be 1/6 inch steel mass while armor mass needed to proof against 12.7mm is ~ ¼ inch steel mass. In the Int.J.Impact Engng Vol-19,pp 361-379 thin plates of aluminum and ABS sheets are sandwiched between ultra thin sheets of aluminm arranged perpedicular to the outer sandwich plates in a honey comb and wave pattern ‘flexcore’. This sandwich arrangement is shown to boost resistance 15-70% over the sum of resistance the individual elements show.

outer sheets

12.7mm vs 2x 1.5mm ABS 2x 0.8mm AL 2x 1.6mm AL

Flat 20m/s 50m/s 60 m/s

Conical 20m/s 50m/s 50m/s

 

6.35mm Vs 2x 1.5mm ABS 2x 0.8mm AL 2x 1.6mm AL

Flat 45m/s 60m/s 130 m/s

Conical 50m/s 65m/s 140m/s

 

 

While the insert 16mm insert offered

 

12.7mm Flexcore Honeycomb

Flat 15-20m/s 20- 30m/s

Conical 10-20m/s 30-40m/s

6.35mm Vs Flexcore Honeycomb

Flat 30m/s 20-30m/s

Conical 10-15m/s 10-15m/s

 

 

Thus the sum of the parts and the actual ballistic limit with the noted increase in effectiveness is below.

12.7mm conical AP shot vs 2 x 1.6mm AL & 16mm flexcore = 70-80m/s , when BL is 90m/s = + 20-30% density = 0.49g/cc

12.7mm conical AP shot vs 2 x 0.8mm AL & 16mm flexcore = 70-80m/s , when BL is 50m/s = - 30-40% density = 0.39g/cc

12.7mm conical AP shot vs 2 x 1.5mm ABS & 16mm flexcore = 35-40m/s , when BL is 39-41m/s = same density = 0.2g/cc

 

 

The sum of the parts and the actual ballistic limit with the noted increase in effectiveness is below.

12.7mm flat AP shot vs 2 x 1.6mm AL & 16mm flexcore = 75-80m/s , when BL is 119m/s = + 50-60% density = 0.49g/cc

12.7mm flat AP shot vs 2 x 0.8mm AL & 16mm flexcore = 65-70m/s , when BL is 62m/s = - 05-10% density = 0.39g/cc

12.7mm flat AP shot vs 2 x 1.5mm ABS & 16mm flexcore = 35-40m/s , when BL is 40m/s = same ; density = 0.2g/cc

A similar mass 3.8mm thick steel target should offer a BL of ~ 170m/s to a 12.7mm flat steel shot.

 

 

Thus the sum of the parts and the actual ballistic limit with the noted increase in effectiveness is below.

6.35mm conical AP shot vs 2 x 1.6mm AL & 16mm flexcore = 140-145m/s , when BL is 195m/s = + 35-40% density = 0.49g/cc

6.35mm conical AP shot vs 2 x 0.8mm AL & 16mm flexcore = 75-80m/s , when BL is 114m/s = + 40-50% density = 0.39g/cc

6.35mm conical AP shot vs 2 x 1.5mm ABS & 16mm flexcore = 60-65m/s , when BL is 67m/s = same density = 0.2g/cc

 

 

6.35mm flat AP shot vs 2 x 1.6mm AL & 16mm flexcore = 160m/s , when BL is 180m/s = + 12% density = 0.49g/cc

6.35mm flat AP shot vs 2 x 0.8mm AL & 16mm flexcore = 80m/s , when BL is 110m/s = + 37% density = 0.39g/cc

6.35mm flat AP shot vs 2 x 1.5mm ABS & 16mm flexcore = 75m/s , when BL is 68m/s = - 10% density = 0.2g/cc

 

So inorder to stop a 12.7mm Sharp AP at point blank range you would require > 11 times the 0.49 density thick array ~ 5.5g/cc or 21cm thick array or a 7mm steel mass. A similar penetration against RHA should result in armor of ~ 35mm , which gives the armor a mass efficiency of ~5 . [Te of 0.17]

 

To stop a 12.7mm flat head Shot , would require almost 9 times the thickness or 16cm thick array with a steel mass of 4.3g/cc or ~5mm steel mass.

 

So in order to stop a 6.35mm Sharp AP at point blank range you would require > 5 times the 0.49 density thick array ~ 2.6g/cc or 10cm thick array or a 3mm steel mass. A similar penetration against RHA should result in armor of ~15- 16mm , which gives the armor a mass efficiency of >5. [Te of ~ 0.16]

 

To stop a 6.35mm flat head Shot , would require almost 6 times the thickness or 11cm thick array with a steel mass of 2.8g/cc or ~4mm steel mass.

 

 

It seems the bigger the diameter of the shot the more efficient the armor becomes and it seems that from studies of the damage around the impact point the array displaces the impact energy along the flexcore members. Truth is this should also be a fairly mass effective armor against continuous jet shaped charges.In studies of shaped charge penetration of low density materials a density should result in the 21cm array offering ~13cm HEAT , while 16cm array should offer ~10cm HEAT resistance and a 10cm array should offer ~5cm HEAT protection against semi particulated jet.

 

 

 

[Edited by Paul Lakowski (14 Jan 2002).]

[gewing]

I think I need to take some engineering classes...

 

sounds really interesting in terms of mass, but boy, talk about bulky.

 

Still, I wonder how it would scale up when combined with other thngs for heavier vehicles, protection?

[Paul Lakowski]

Originally posted by gewing:

I think I need to take some engineering classes...

 

sounds really interesting in terms of mass, but boy, talk about bulky.

 

Still, I wonder how it would scale up when combined with other thngs for heavier vehicles, protection?

 

 

Definately , this is not heavy tank type armor ,It definately could have application to cheap effective naval armor if included in the construction phase of any ship design.The total mass increase in ship design could be considerable if you try to armor every where equally[just as in tank design]. But if you limit this , protection against SSMs impact and blast becomes afordable [upto a point] for a limited weight cost [several thousand tons for a large cruiser armored equally every where].

 

However the front glacis of the M-1 tanks features a 5cm thick glacis thats sloped @ 82°, which is ~ 36cm LOS RHA thickness. T/d will reduce this relative to the attacking projectile diameter , while the plate is probably harder than straight 275BHN steel.

 

But over about 90% of the effective glacis profile, this armor is backed up by other armor behind. The bulk of this is a massive fuel cell on either side of the drivers compartment. This fuel cell is about 1 meter effective LOS and is thought to employ some kind of honeycomb armor which the fuel is suspended in. The combination could offer considerable protection and be upgradable to better forms of insert effectiveness.

[Paul Lakowski]

If a steel spaced plate is 0.2 t/d [5/8 inch = 2 inch] of a steel attacking AP type projectile, then this will decap the APC/APCBC projectile. This will end up offering 1.2 times the LOS resistance for the spaced plate arrangement, thus a 5/8 inch spaced plate and a 1.87 inch LOS thickness of plate should offer 2.25 inches of RHA resistance. If the threat is a WC core APDS/HVAP with a steel sheath this should offer ~ 1.5 times the LOS resistance while aluminum sheathed WC cores appear to result in 1.7-1.8 times the LOS resistance.

 

2 inch Steel APC = 1.2 x 1.87 inches or ~ 2.25 inches armor. [+ 0.2d] 1 x t/d .

2 inch Steel-WC HVAP/APDS = 1.5 x 1.87 = 2.8 inches armor. [ + 0.5d] 2 x t/d .

2 inch Aluminum-WC HVAP/APDS = 1.7-1.8 x 1.87 = 3.2- 3.4 inches armor. [+ 0.66-0.76 d] 3.3-4 x t/d.

 

 

1 inch Steel APC Vs t/d 0.625d [x 1] + 1.87 inches x 1.33 ~ 2.5 inches armor.[ + 0.6d = 1 x t/d]

1 inch Steel-WC HVAP/APDS Vs t/d 0.625 [2 x ] = 1.66 x 1.87 inches or ~ 3.1 inches armor.[+ 1.23d = 2 x t/d]

1 inch Aluminum-WC HVAP/APDS Vs t/d 0.625 [4 x] 2.35 x 1.87 inches or ~ 4.4 inches armor.[+ 2.0d = ~ 3.3 x t/d]

 

The above is interesting because the sharp tip of a ogive penetrator only appears to add 0.5d to the projectile L/d, so clearly the damage to the penetrator goes far beyond the disintegration of the tip.

 

 

Looking at modern APFSDS work , the spaced plate will offer a certain amount of rod shortning since its reported that at least one rod diameter is lost due to exiting the rear of each spaced plate. "When the target 'fails', that is there is perforation,the projectile no longer encounters and further resistance but projectile erosion continues some microseconds because of the large residual stresses in the plastic zone". [2001 Int Symp on Ballistic- TB-16].

 

In a test shot 16.5mm diameter 30:1 L/d WHA where fired at 1.8kms per second @ a spaced plate series of 6 x 19mm [340 BHN] RHA spaced plates infront of a witness plate. When the penetrator struck this arrangement it penetrated ~ 444mm of spaced plate and back up armor set back at an angle of 65°.

 

Had the penetrator struck a straight single block of 340 BHN RHA @ the same angle this should have generated a LOS penetration of ~ 533mm . Thus the difference [444-533 = 99mm/6= 16.5mm per plate], was an additional +1d [rod diameter] resistance for each spaced plate in the armor array.

[John_Ford]

Paul, here's one for you. It is the 76 MM sabot for the M32 gun of the M41 light tank.

 

Armor penetration

 

Nato Triple Heavy at 57*

Penetrator Weight 1.68 KG (3.70 LB)

Penetrator L/D 15-1

Chamber Pressure 438MPa (63,500 psi)

Muzzle Velocity 1433 M/Sec (4700 Ft/sec)

 

 

Sorry I don't have a projo diameter, look up http://www.aaicorp.com/defense/em/76mm.htm

[Dan Robertson]

Originally posted by John_Ford:

Paul, here's one for you.  It is the 76 MM sabot for the M32 gun of the M41 light tank.

 

Armor penetration Nato Triple Heavy at 57*

Penetrator Weight 1.68 KG (3.70 LB)

Penetrator L/D 15-1

Chamber Pressure  438MPa  (63,500 psi)

Muzzle Velocity 1433 M/Sec (4700 Ft/sec)

 

Put through my spread sheet we get

 

Length 30cm

Diameter 2cm

 

Performance verse monolithic vertical RHA (with an estimated velocity drop of 80ms/1000m, because we have a chunky light round)

 

0m = 33cm

1000m = 29cm

2000m = 26cm

3000m = 23cm

 

+/1 10%cm

 

the volume efficiency of this weapon system is 0.26 which is the same as

[gewing]

Sounds like a modern 16-90mm should be able to shred anything but an MBT, though that was kind of a given. Maybe not an Achzarit, but...

 

How are the HE rounds for those calibers, anyone know?

[Paul Lakowski]

Originally posted by John_Ford:

Paul, here's one for you.  It is the 76 MM sabot for the M32 gun of the M41 light tank.

 

      Armor penetration

 

                  Nato Triple Heavy at 57*

                  Penetrator Weight 1.68 KG (3.70 LB)

                  Penetrator L/D 15-1

                  Chamber Pressure  438MPa  (63,500 psi)

                  Muzzle Velocity 1433 M/Sec (4700 Ft/sec)

 

 

Sorry I don't have a projo diameter, look up http://www.aaicorp.com/defense/em/76mm.htm

 

 

OK thanks for the links John I'll take a crack at it...combined with what I have from JANES.....

 

American 76mm M-32 gun with M464 APFSDS round ; This is 1.63 kg tungsten alloy penetrator with a MV of 1400m/s with a Vdrop probably similar to M-500 round of 76m/s/km with an L/d of 15:1 and a diameter of 20.6mm or 309mm length . Such a rod would be 103cc volume or 1.80 kg @ 17.5 g/cc density, but if the nose and tail had a ‘truncated form’ the volume could be reduced to the 93-95cc volume that a 1.66kg , close to the 1.63 suggest weight . Using Andersons the values are – 0.74 [ L/d effect] , x 1.16 [scaling] and plus 1. 2 d semi infinite conversion @ 0° and 2.4 d @ 60°….that’s + 24mm & + 48mm and the 60° penetration is a line of sight penetration. Going on these imputes the penetration should be …

 

Muzzle [ 1400 m/s] = 0.84 x 31cm = 28 cm ± 4cm @ 0° & 31cm ± 4cm @ 60°

1000m [ 1324 m/s] = 0.745 x 31cm = 25cm ± 4cm @ 0° & 28cm ± 4cm @ 60°

2000m [ 1248 m/s] = 0.65 x 31cm = 23cm ± 3cm @ 0° & 25cm ± 4cm @ 60°

3000m [ 1172 m/s] = 0.56 x 31cm = 20cm ± 3cm @ 0° & 22cm ± 3cm @ 60°

So the T-62/55 tanks and the lighter armor of most early model T-64/80 Russian tanks, can be dealt with @ 1-2km unless covered by ERA elmemets.

 

Not sure why the website has different name than JANES but they got the ammo figures wrong

 

Projectile weight.....................52 Kg (5.54 lb)

 

52kg????, even if its 5.2kg , that should be ~ 11.44 lb.

 

But NATO Triple heavy plate @ 57° is a different target, usually its @ 65°.

 

NATO Triple heavy targets Vs 21mm diameter APFSDS should be

x 10mm [ @ 412-438 kp/mm² ]+330 air +25mm [@ 100-122 kp/mm² ] +330 air +80mm, [@ 308-353 kp/mm² ] .

 

Thats 1cm SHS [ 1.2Te x 0.6 (t/d)] + 2.5cm Mild steel [0.8 Te x 0.88 (t/d)] + 8cm Heavy RHA [1.1 Te x 0.95 (t/d)] ...0.72+1.76 +8.36 = 10.84 @ 57°[/0.5446]= 19.9cm plus spaced plate effect. This should be an average of 1 rod diameter per spaced plate or + 41mm [ ~ 24cm]....

 

But with such a health air gap between plates the yaw of the attacking rod should be a factor. What little data I have suggests the yaw will be about ~ 1/COS² of the impact angle [57° ~ 0.5446 or 1/0.5446² = 3.4 times] .Since the average impact yaw 0.5 to 2° , this suggests 2-7° Yaw through the spaced plates. Given a 15:1 L/d thats a 'critical yaw' of ~2.3 or 1-3 times the Critical yaw, for a loss of 3-20% or additional 0.5-3 rod diameters. [int.J.Impact Engng Vol-12 pp 281-292]

 

 

Thats about 24.5-30cm approximate resistance for the NATO triple heavy plate @ 57° or an average of 27± 3cm RHAe against that projectile.

[John_Ford]

Paul, What is a Nato Heavy Triple Target supposed to represent?

[Allan W]

Originally posted by John_Ford:

  Paul, What is a Nato Heavy Triple Target supposed to represent? 

 

I believe that it is supposed to simulate penetration through side skirts, suspension and hull.

[Paul Lakowski]

In another paper on various energetic armors [TB61 Combination of inert and energetic materials in reactive armor against shaped charge jets . Holzwarth & Weimann] , they test fired 73mm jets into various energetic armors mounted ahead of a 230BHN semi infinite target and the following figures where generated.All arrays were 2mm steel 10mm interlayer 2mm steel and the angle of array was 60°, thus the array LOS was 28mm.

 

Preference DOP = 365mm thus difference /28mm = array RHAe

S-rubber-S = 280mm = 3 x LOS thickness

S-GAP-S = 280mm = 3 x LOS thickness

S-Gap+R-S = 250mm = 4.1 x LOS thickness

S-Gap-exp-S = 190-120mm = 6.2- 8.8 x LOS thickness

 

S=Steel

GAP=polymer

Gap+R= GAP + CaCO3 or GZT

Gap+exp = GAP + explosive

 

Now it was shown that the GAP material is forced to undergo a additional chemical reaction when a small layer [1mm] of explosive is involved resulting in P of 150-170mm or a thickness effectivness of 6.6 to 7.7. This is much more than the GAP with the CaCO3 , which generates some gas bubbles in the array, which under the pressure of impact enhance the distruption of the jet.

 

I can only conclude that the Mexas must have found a way of doing this same kind of thing without the thin explosive layer!

 

Its becoming apparent that in addition to the bulging of the plates ,the expanding gases in the ERA sandwich maybe interfering with the jet as well.

[Andrew Jaremkow]

Despite the impressive reduction in penetration provided by the most energetic armour, the residual penetration is still enough to penetrate the underlying hull armour any of the APC/IFVs out there. So RPGs will be able to penetrate MEXAS type targets with 73mm warheads (a mere 365 mm basic penetration in this case, right?), let alone the many generations of improved grenade that followed.

 

Damage will be mitigated, compared to the unprotected vehicle, but it will happen nonetheless, and it doesn't take very much residual RHA piercing power to kill a soldier, or detonate stowed ammunition in the path of the jet.

 

Definitely looking forward to those papers!

[Paul Lakowski]

Originally posted by Andrew Jaremkow:

Despite the impressive reduction in penetration provided by the most energetic armour, the residual penetration is still enough to penetrate the underlying hull armour any of the APC/IFVs out there. So RPGs will be able to penetrate MEXAS type targets with 73mm warheads (a mere 365 mm basic penetration in this case, right?), let alone the many generations of improved grenade that followed.

 

Damage will be mitigated, compared to the unprotected vehicle, but it will happen nonetheless, and it doesn't take very much residual RHA piercing power to kill a soldier, or detonate stowed ammunition in the path of the jet.

 

Definitely looking forward to those papers!

 

I agree with you premise how ever the way I understand it the current armor is probably resistant to most RPG-7V strikes...thats to say if Herr Diesenroth figure are to be taken at face value , the 20mm Mexas applique @ 10-20o is as effective as ERA @ 60o. In the other paper the 14mm ERA @ 60o offered > 11 times the LOS resistance so this suggest MExas @ 10-20o offers at least the same.

 

Thats LOS 21-22mm x 11.25 = 24-25cm...add the base armor [~ 15mm RHAe] = ~ 26cm RHAe. From the other paper on liners a simple thin PE liner should reduce kill % 10%, while other papers in that symposium suggest better materials will do better [ ~ 20%?] thats an additional 4-7cm possible resistance. This brings the potential side hull resistance up to 30-33cm from straight on ....from 30o off angle [ more likely case] thats 35-38cm effective RHAe.

 

OK I realize this is mostly calculation, but if this is totally correct it means a 16,000-17,000kg AFV can have the allround protection of a 55 ton Chieftain [ with all those lovely storage boxes and skirting plates]....any way you cut it thats a considerable increase!

 

 

BTW I on the ISB-2001, I emailed the Yahoos group yesterday but the UBC net is all F%#k up and it doesn't seem to have gotten through.

 

Basically I found I can zip the entire thing down to 24Mb so the whole package is doable in say 3x 8Mb or 4 x 6Mb packages!

 

If I wasn't experiancing these difficulties, I'd have mailed the first package last night!

[Andrew Jaremkow]

Paul Lakowski wrote: "BTW I on the ISB-2001, I emailed the Yahoos group yesterday but the UBC net is all F%#k up and it doesn't seem to have gotten through."

 

It's not just you. I'm having problems with e-mail on my end too. Stuff people sent me yesterday is still dribbling in today. Stuff I mailed to the group this morning hasn't arrived there yet.

 

"From the other paper on liners a simple thin PE liner should reduce kill % 10%, while other papers in that symposium suggest better materials will do better [ ~ 20%?] thats an additional 4-7cm possible resistance. "

 

This mixes two different statistics. Kill probability and armour protection are different things entirely. While spall liners will limit the internal effects of a penetration, they do very little to actually prevent the penetration. So while a vehicle with thin armour and a good liner may suffer the same internal effects as a vehicle with thicker armour and no liner, from a specific penetrating warhead, the two do not have the same level of protection. The vehicle with the thicker armour can still stop threats that the thinly armoured vehicle cannot.

 

In general, then, a spall liner should not be added into the vehicle's armour equivalent, which determines whether or not penetration occurs. It should be treated as a seperate component to regulate how much damage happens given a penetration.

[John_Ford]

Paul, Danno, Thanks for the reply. I'm going to call the company and see how it jibes with their results.

[Paul Lakowski]

http://www.translate.ru/rus/url/tr an_url.php?direction=re&template=General&autotranslate=true&url=url=http://armor.kiev.ua/ptur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html://http://www.translate.ru/rus/url/tr ...ur/dz/grid.html

 

OK guys I need help with the translation ....any one can help?

 

heres the original in Russian if that helps

http://armor.kiev.ua/ptur/dz/grid.html

 

 

 

 

[Edited by Paul Lakowski (23 Apr 2002).]

[Tyler Durden]

Sure...how'd you want to handle the translation?

 

Btw: What exactly is being translated?

 

[Edited by Tyler Durden (26 Apr 2002).]

[Paul Lakowski]

Originally posted by Tyler Durden:

Sure...how'd you want to handle the translation?

 

Btw: What exactly is being translated?

 

[Edited by Tyler Durden (26 Apr 2002).]

 

Hi Tyler, on the bottom link there is a rough translation but select words are not translated and the meaning is lost at times because of this...even a translation of those words would help!

 

Thanks Paul.

[Tyler Durden]

ïðòèâîòàíêîâûõ –Anti Tank.

 

ïðîòèâîêóìóëÿòèâíîé-Is anti-cumulative, i.e Anti-HEAT. Note, anti-cumulative complex means a entire anti-HEAT get up for the T-55, rather than a complex anti-HEAT get up.

 

ìîäèôèêàöè -(just above the BMP-3 picture) Modification of.

 

Øâåäñêèé-Swedish.

 

íàâåøàíû-Hanged, i.e (Merkava) hanged from circuits with steel spheres on the ends fastens. Chains with steel balls at the end.

 

Hmmmmmm...cut and paste problems. I'll sort this out in a bit.

 

 

 

[Edited by Tyler Durden (28 Apr 2002).]