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Polish Explosive reactive armor:
ERAWA-1 and ERAWA-2
·Origins of the ERAWA armor
·ERAWA -1 – the build and effectiveness
·ERAWA -2 – the build and effectiveness
·ERAWA armor on PT-91 and PT-91MZ
·ERAWA-2 unique features, and compare whit other ERA armors.
Origins of the ERAWA armor
The ERAWA armor is connected whit person of the Prof. Ph.D.
D.Sc. Adam WISNIEWSKI from Military Institute of Armament Technology (WITU) in
The origins of the ERAWA are hidden in half of the 1980s when polish Military
Institute of Armament Technology had started (in person Prof. Ph.D Wisniewski) development process about new armor for deep
modernization of the T-72M1. In fact WITU work had started about whole family
of the armor whit two „tank” part: ceramic CAWA armor for main tank armor and explosive ERAWA armor as external layer.
Rumors about eastern (
New armor ERAWA-1 was available in 1993 whit
first PT-91 prototype.
ERAWA -1 – the build and efectivnes
Basic parameters of the ERAWA-1 cassette:
(Photo description:
Left: ERAWA-1 TX cassette
Right: ERAWA-1 patent draw: 1-casette; 2-HE (trotyl or
trotyl-heksogen); 3- external HHS (HB500) plate ~6mm thick; 5,6 – screws;
7 - brackets for ERAWA-1 cassette in
distance 30-50mm form armor )
I. Parameters:
1. Size of the ERAWA-1
cassette - 150x150x26 mm
2. Mass of the ERAWA-1
cassette -
ERAWA-1 is build form RHA cassette whit HE insert (TNT or TNT-hexogen) cover by circa 6mm HHS
plate whit 500HB hardness. Whole cassette is mounted by two screws to the brackets. This build, seems to be primitive,
but thanks to strong explosive and very good quality HHS plates provides very
good capability of the protection:
Capability of the Protection is based on formula:
CP - capability of protection In result ERAWA-1 (single layered) have sucht efectivnes valued in CP
factor:
against hand held AT weapons sucht
Komar (The Mosqito), PG-7 and PG-9 whit (circa 300-330mm RHA penetration):
CP = 92%
against 9M113 warhed (circa 460mm
RHA penetration):
CP = 83%
against 125mm BK-14M round (circa
450mm RHA penetration):
CP = 94%
ERAWA-1 casettes are
insensitive to react:
·during impact of
·AP small calibre
amunition
·fragments from
exploding projectiles
·during burning of
by: petrol, napalm, thermite
Seafty tests ERAWA-1
photos:
ERAWA -2 – the build and effectives
ERAWA-2 (two layered) was answer for modern
thread: AT weapons whit precursor (PG-7VR, MBT LAW, Panzerfaust-3T etc), EFP
projectiles formed from 100mm cone diameter, partially APFSDS penetrators, and
challenge to reduce RCS tank signature. ERAWA-2 and ERAWA-1 cassettes are fully
swichable.
Basic parameters of the ERAWA-2 cassette:
Photo description:
Left: ERAWA-2 TX02 cassette
Right: ERAWA-2 patent draw: 1-casette; 2 double HE layer (trotyl or
trotyl-heksogen); 3- thin HHS plate separation two HE layers;
4- thin metal lid ; 5 – ceramics layer; 6 – thin HHS plate; 7-
rivet/screw; 8 - brackets for ERAWA-2 casette in distance 30-50mm form
armor; 9 – screw between cassette and brackets, 10 – mounted nut. )
Parameters:
1. Size of the ERAWA-2 cassette - 150x150x46 mm
2. Mass of the ERAWA-2 cassette -
Internal build of the ERAWA-2 cassette is
much more sophisticated then ERAWA-1 and it's very different then other known
ERA cassettes.
Basic build is similar to the ERAWA-1 – metal
cassette attached by mounted screws to
brackets in distance 30-50mm from armor surface. But internal ERAWA-2 build is
different. First they are two HE layers inside cassette separated by thin
(circa 2-3mm) HHS plate whit hardness above 500HB. Probably both HE layers have
slightly different HE material whit different reaction time and other
parameters. Second – external ERAWA-2 plate is not thick HHS plate but
multilayered layout made by: thin metal lid then circa 4-5mm thick ceramic
layer and second thin (circa 2-3mm) HHS plate whit hardness above
500HB.
Such, unusual, layout make ERAWA-2 different
then other known ERA. And give surprisingly good capabilities of the protection:
·Agiainst single SC (HEAT) warheads like 9M113 (Konkurs) or 9M111M (Fagot) or BK-14M
CP = 95%
·Against single EFP formed form 100mm cone diameter and penetration circa 85mm RHA
CP= 94%
During test ERAWA-2 proof abiities to protect in PT-91 hull top and turret
top against EFP formed from 50-155mm cone diameter (so up to 120mm RHA
penetration) and to protect hull sides against EFP formed form 200mm cone (so
up to 150mm RHA penetration).
·Against APFSDS rounds 3BM15 (125mm)
and DM-33A1 (120mm)
CP in first case (3BM15) was equal to 57%
CP in second
case (DM33A1) was not given, but ERAWA-2 placed on PT-91 hull model (so T-72M1)
was enought to stop APFSDS whit guaranted 470mm RHA
penetration, from 600m distance:
In this case DM-33 penetartor was heavy damage during ERAWA-2 penetration,
then perforate first plate and rebound from deeper (glas textolite) layers
without reach second RHA plate (backplate)
PT-91 hull is consist by: (for 90 degree)
So layout for 68 degree is: ~120mm ERAWA-2 cassette +
160mm RHA + 280mm STEF + 146mm RHA
Guaranteed DM-33A1 penetration is 470mm RHA on 2000m.
DM-33A1 after passing ERAWA-2 perforate first
RHA plate and circa half STEF layer then rebound.
In theory ERAWA-2 give CP=42% in this case (using formula: CP=(H-Hw)/H)
but in author opinion such test is not relevant cause rather rebound mechanism
then only ERAWA-2 working. Some sources (Kajetanowicz
J., POLIGON 2/2013, „Czolg podstawowy PT-91 Twardy” page 7.) give ERWA-2 abilities to reduce
APFSDS penetration up to 30-40%. What is consist whit above example. For
the other hand - both used on test
APFSDS rounds are not modern. 3BM15 is complete obsolete and antic and
DM-33A1 is not really young (DOI 1987). Probably ERAWA-2 test against much modern rounds (DM53, M829A2, KEW-A2, OLF-F1, M332) will
give much worse results. Anyway - ERAWA-2 ERA incares a lot protection of the
PT-91 tank against non monoblock penetrator, so: 3BM15, 3BM22, 3BM26, 3BM42 and
even help against first generation longer monoblock penetrator (DM33). So for typical angle +/- 30. degree from longitude tank axis and against APFSDS from half of the 1980s
decade ERAWA-2 have capability of the protection – circa CP= 50-60% for
penetrator whit tungsten or steel slug inside and achieve unknown
(30%?) but rather significant protection against
slightly younger APFSDS whit monoblock penetrator (DM33A1).
·Against SC warhead (HEAT) whit precursor.
Proliferation of the AT hand held weapons
whit precursor able to destroy ERA cassette starts to be serious problem for
armor developers in 1990s decade. Most of the precursors are working not as typical SC warhead able to perforate armor and are not working in idea
„fast ERA detonation” before main warhead SC jet hit target. In modern hand
held AT weapons (PG-7VR, MBT-LAW, PzF-3T and IT600, probably in RPG-29)
precursor is working in different way. As Panzerfaust-3IT developers wrote: „The
dual warhead has a small first charge and a main shaped charge. The first
charge penetrates the reactive add-on armor on the combat vehicle without
initiating the charge inside itto ensure it does not compromise or
pre-vent the armor-piercing action of the main shaped charge.” Such
mechanism was describe in some ballistic symposium
thesis too:
ERAWA-2 was tested against several tandem warhead (main warhead + precursor) AT weapons, but probably
the most difficult test was against Pzf-3T and PzF-3IT600:
Pzf-3IT600 main warhead (110mm diameter) is able to perforate 900mm RHA
plate, and PzF-3T warhead is able to perforate 800mm RHA plate.
Both of them where tested against ERAWA-2 cassettes placed on angle 30 and
15 degree (so 75 and 60 degree form the surface):
The result was more then good:
ERAWA-2 against PzF-3T placed at 30 degree (60) achieve CP = 50% what
including sophisticated precursor in Pzf-3T and powerful 110mm warhead (800mm
RHA penetration) was greater success.
·Reduce tank RCS signature.
ERAWA-2 casettes are covered by 4mm special
absorber layer (1K2KS and 1KF2KS absorber) whit mass 6kg/m2 and able to protect
against radar working in band X and Ku whit f=8-16GHz. On typical PT-91 such
absorber cover circa 20m2 and achive reduce detecting
range at 50 to 60% for typical conditions.
ERAWA armor on PT-91 and PT-91MZ
There was three generation of ERAWA armor on
PT-91 tank.
First generation consisted 394 ERAWA-1 cassette. On hull front was placed 118 cassettes and on
turret 108 cassettes.
On each hull side was placed 84
cassettes. Such cover weight circa 1144kg.
ERAWA-1 cassettes are mounted by screws and
nuts to individual metal brackets on armor
surface:
Photo:
First generation ERAWA mount on early PT-91 tank
prototype:
Second generation ERAWA armor on serial PT-91
tank consist 296 ERAWA casettes:
·204 x ERAWA-1
·92 x ERAWA-2
With total weight 2014kg and mounted by
screws to the special metal bar- brackets:
Photo:
second generation ERAWA mount on serial PT-91 tank :
Third generation ERAWA armor on PT-91 tank
consist 259 cassettes:
·164 ERAWA-1
·92 ERAWA-2
Weight 907kg. The main change is
modular designed to achieve faster replace damage cassettes on
battelfield. On hull are placed 79 segments, on turret 90 segments and on
each hull side 45 segments. This generation layout is used on PT-91M „Pendekar”
(or „Malaj”) for
Photo:
Third generation ERAWA mount on serial PT-91M „Pendekar” tank :
It is importand to notice that typical ERAWA
can't be use on light platforms like IFV or APCs. ERAWA armor will not be use
on Polish Leopard-2A4 and 2A 5 tanks for law resons – agreement whit KMW and
German Republic excludes non authorisated and non tested solution in
Leopard-2 modernisation program. Cost of sucht certification
and legalization problems propably will be to big to put ERAWA
armor on polish Leopard-2.
ERAWA-2 unique features, and compare whit
other ERA armors.
Polish ERAWA armor have some special features
whit make ERAWA-1 and 2 very interesting example of different principles during
ERA development process.
First – ERAWA cassette have small dimensions.
While in other countries ERA cassettes are rather big, ERAWA developers had
tried to make ERAWA cassettes as small as it possible, whit under cassette
montage system. This solution give possibility to
mounted ERA cassettes without heavy metal frame known from other ERA or without
space between ERA cassettes. In some ERA gaps between cassettes are almost 50mm
wide. ERAWA ERA haven't such problems, so it can
better cove the tank. Any flat surface cover by ERAWA is protected in 95% of it's area.
Photo:
Lack of any gaps between
ERA cassettes on PT-91A hull and present sucht gaps on T-72B hull.
Photo: Compare turret cover by ERA:
Second special features of
the ERAWA is its high effectiveness even on great
angle. While most developers are trying to slopped ERA cassettes at 60 degree
(30) form 0 to achieve some needed effectives level ERAWA-1 and ERAWA-2 can be slopped at smaller angle whit the same
effectiveness.
Typical ERAWA-2 CP value (capability of the
protection) against single SC warhead is CP = 95% at 60. Degree ERA slopped
angle. But even for extremely difficult for ERA cassettes angle 70-90.
ERAWA-2 is effective in impressive CP=67-80%
Photo:
ERAWA-1 and ERAWA-2
effectiveness at difficult angle grater then 60.
Third special feature of the ERAWA armor is
confirmed abilities to significant reduce (CP=50% for 60. slopped angle) modern
AT hand held SC (HEAT) warhead whit precursor. So Pzf-3T, PzF-3IT600, PG-7VR,
RPG-29, MBT-LAW, etc
Some ERA manufacturer claimed that they ERA
have counter double warhead abilities (Relikt, Knive -Duplet, ARAT-2, ERAWA-2,
etc) But till now only in Poland (and Ukraine) are known and have confirm in
open public sources evidences that ERA armor can withstand such thread.
Despite that ERAWA-2 ERA can stop most EFP warhead what is rather unique feature
too, and it's cover by microwave absorber to reduce
tank RCS.
The last, maybe not unique, but really good
ERAWA armor feature is it's insensitive for AP small caliber ammunition,
fragments from exploding projectiles, and burning of by: petrol, napalm,
termite., insensitive for 10m height drop, and chain reaction after ERA
cassette explosion. What more – ERAWA have confirm abilities to work in -50 to
+
In compare to exist now ERA ( BRENUS, Blazer, ARAT-1, ARAT-2, Kontakt-1, Kontakt-5,
Relikt, Knive /Duplet,) etc. ERAWA have the
smallest cassettes and it can cover the biggest tank area (except Ukrainian
Knive ERA in Oplot-M modules). ERAWA-2 abilities to stop single HEAT warhead is
rather no different then other ERA, this what is special in ERAWA is it's ability to work even on greater angle (90-70.) whit
significant effectiveness (CP=67-80%) and abilities to stopped even big EFP
warhead. Unknown is effectiveness of the ERAWA-2 againt big tandem ATGM warhed
like in Kornet, Ataka, etc. Probably ERA will not achieve such good results in
this scenario. But for the other hand – ERAWA-2 have confirm (not only in
marketing ads) abilities to deal whit modern hand held SC (HEAT) warheds whit
precursor. Reduce at 50% penetration for such warhead like PzF-3T (for 60 angle) and abilities to similar reduction in other modern AT
weapons (like RPG-29) should be notice as extremely good.
This what modern ERA (Relikt, Knive, etc)
have definitely better then ERAWA-2 is ability to stop APFSDS penetrator.
Probably ERAWA can deal with only 1980s penetrators (3BM26, 3BM42, 3BM32,
DM33A1 etc) whit fluent effectiveness between 30-56% and in case modern
monoblock 1980s penetrator rather based on rebound mehanism (like in DM-33A1
case) then destroying penetrator. So effectiveness against modern APFSDS (even
1990s) is rather highly questionable. Good ERAWA feature is covered ERA
cassette by microwave absorber to reduce RCS.
In summary: ERAWA-1 and ERAWA-2 are good
example completely different way making ERA to achieve quite good results. Of
course ERAWA seems not to be so good as the most modern IBD, FCCT Microtek, NII
Stali solutions, but it's not bad anyway. For
polish point of view ERAWA armor was necessary and relatively cheap way to
increase a lot PT-91 (so originally T-72M1) armor protection.
Future of the ERAWA armor in
Lighter platforms don't need such heavy ERA
as ERAWA-1/2 and in polish Military Institute of
Armament Technology was developed whole family armors for lighter then tanks
platforms like:
- CERAWA-1 composite-reactive armor
- lightweight special bar armor (the cage)
- ceramic armor
CAWA-4 and CAWA-3
- main multilayer
passive armor CAWA-2 and CAWA-1NA armor
In other institutes in
for Rosomak (AMV) APC.
In fact ERAWA successor can be used only in
future IFV.
Bibliography:
1. Wisniewski A., Pancerze, budowa,
projektowanie i badnie, Warszawa 2001
2. Wisniewski A. „Protection of Light
Armors Against Shaped Charge Projectiles”
3. Wisniewski A. „Computer analysis of
explosive sensitivity to projectile impact”
4. Kajetanowicz J., Czolg podstawowy PT-91
„Twardy”, POLIGON 3/1013
5. Opis patentowy Nr 156463 „Segmentowy
pancerz aktywny”, WUP 03/92
6. Opis patentowy Nr 168122 „Czolg z
pancerzem reaktywnym”, WUP 01/96
7. Opis patentowy Nr 174119 „Segmentowy
pancerz reatywny”, WUP 06/98
8. Koning P. J, Mostret F. J, „The
Designand performance of non-initiating shaped charges whit granular jest
against ERA”, 20th international symposium on ballistic Orlando
2002.
9. Podgórzak P., Wisniewski A., „RESEARCH
RESULTS ON PRECURSOR OF THE TANDEM SHAPED CHARGE PROJECTILE MODEL”, WITU
2005.
10. Dynamit Noble Defense, „Urban Warfare
2.0 How asymmetric threats dominate conflicts”, 2010.
11. Szudrowicz M. „ANALYSIS OF BAR AND NET
SCREENS STRUCTURE PROTECTING VEHICLES AGAINST ANTI-TANK GRENADES FIRED FROM
RPG-
12. Magier M., WSTEPNA ANALIZA ZJAWISKA
RYKOSZETOWANIA WYDLUZONYCH PENETRATORÓW POCISKÓW KINETYCZNYCH, WITU 2010
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