PROBLEMS OF MECHATRONICS. ARMAMENT, AVIATION, SAFETY ENGINEERING ISSN 2081 5891 2 (2), 2010, 17-25 Protection of Light Armours Aginst Shped Chrge Projectiles Adm WIŚNIEWSKI Militry Institute of Armment Technology, 7 Wyszyńskiego St., 05-220 Zielonk, Polnd Astrct. The herey work descries the exmples of protection of light fighting vehicles rmoured with dditionl rective rmours. The wy of protecting of light fighting vehicles with the use of composite-rective rmours ginst penetrtion with HEAT projectiles (with penetrtion ility of 300 mm RHA) nd ginst smll clire (up to 14,5 mm) rmour-piercing ullets re shown on the exmple of the BWP-1. Technicl prmeters of the CERAWA-1 rmour nd its ssemly on BWP-1 re presented. The work lso presents the results of sttic tests of severl vrints of rective-pssive pnels of light fighting vehicles ginst PG-7 projectiles perfortion t the ngle of 60 nd 72 from norml to the cssette surfce. Depending on the surfce mss of the light rective-pssive rmour pnels, different levels of dmge to the rmour witness plte were chieved. Keywords: mterils technology, explosion, explosive rective rmour, shped chrge projectile, rmour protection 1. INTRODUCTION Armours of fighting vehicles fter the II World Wr nd other wrs, especilly in the Middle Est, usully reched high degree of resistnce to perfortion of shped chrge projectiles. * Presented t 8 th Interntionl Armment Conference on Scientific Aspects of Armment nd Sfety Technology, Pułtusk, Polnd, 6-8 Octoer, 2010.
18 A. Wiśniewski It concerns first of ll: HEAT (high explosive nti-tnk) hnd grendes, tnk rounds nd guided missiles with the penetrtion ility of up to h = 1300 mm of the RHA (rolled homogeneous rmour) [1-3]. Armours of such vehicles must effectively distur the penetrtion of shped chrge projectiles nd e resistnt to the detontion of lrge quntity of high-energy explosive, contined in the shped chrge projectiles. Such quntity of explosive in guided missiles nd in shped chrge projectiles s well s thick csing of such projectiles, effectively destroy ERA rective rmours usully situted s dditionl protection [3]. Only few constructions of rective rmours, eg. ERAWA-1 nd 2, re minimlly sensitive to such destructive effect [3]. The rmours of light nd medium fighting vehicles (BWP), re not resistnt to perfortion even y typicl HEAT hnd grendes, eg. RPG-7. Nowdys such vehicles re protected with the use of other, lighter thn RHA rmours from the perfortion of RPG-7 hnd grendes with the PG-7 projectiles (the most often used in the world) with the penetrtion ility of h = 300 mm of the RHA nd ginst AP ullets of the clires d = 7,62 14,5 mm. The BWP protection from the perfortion of PG-7 projectiles is provided y different rective rmours (Fig. 1). 1 1 1 1 1 Fig. 1. Light fighting vehicles with ERA cssettes (1) protecting from PG-7 type shped chrge projectiles; Brdley with different non modulr cssettes, FV432 Mk3 BULLDOG with modulr cssettes For lrge quntity of light western LFVs nd Russin BWP-1 type LFVs mde round the world, s well s the proposls for their moderniztion y the Polish [4] industry, the necessity rose for incresing the protection level of this type of rmours. It is for this purpose tht the modulr CERAWA-1 composite- -rective rmour [5, 6] which protects ginst the perfortion of shped chrge projectiles with the penetrtion ility of h = 300 mm RHA nd ginst 14,5 mm AP ullets hs een developed. This rmour, with the mss of 920 kg nd the re of 3,5 m 2 protects front upper, ottom nd side prts of the hull nd the front nd side prt of the turret. During horizontl firing, the CERAWA-1 cssettes, inclined t some ngle,
Protection of Light Armours Aginst Shped Chrge Projectiles 19 effectively shield the whole front plte, despite the fct tht their re is much smller thn the re of this plte. This rmour, fstened on the BWP-1, ws displyed t the III Interntionl Exhiition of Defence Industry Kielce 95 in Polnd. Thnks to its full modulrity, smll thickness nd esy ssemly method, the CERAWA-1 [7] rmour cn e pplied to other fighting vehicles. 2. TESTS OF THE REACTIVE-PASSIVE ARMOUR The sttic tests which were crried out, tested the protective ility for the rective-pssive rmour pnels with ERAWA-1 rective cssettes composed from n luminium lloy, during penetrtion with shped chrge jet generted y PG-7 projectile [8]. Three different constructions of rmour pnels (Fig. 2) hve een used nd on every pnel, the tests with the use of shped chrge projectiles plced t ngles of α = 60 nd α = 72 from norml to the surfce of the externl cssette were crried out. Fig. 2. The rrngement of the PG-7 shped chrge projectile in reltion to the ERAWA-1 rective cssette The pnel of the rective-pssive rmour (Fig. 3) consisted of the ERAWA-1 cssette (1) mde of n luminium lloy which ws screwed on to the steel chnnel section (4) with the length of 500 mm y mens of nuts (7). Fig. 3. Rective-pssive pnel version 1: 1 ERAWA 1 cssette, 2 steel plte 1, 3 RHA plte 2 (witness), 4 steel chnnel section, 5 sleeve, 6 screw, 7 nut
20 A. Wiśniewski This chnnel section ws screwed with screws (6) to the steel plte 1 (2) to which the sleeves (5) with screwed holes were welded on. The chnnel section with the ERAWA-1 cssette ws plced on the steel rmour plte 2 the witness, with the thickness of 8 mm (3) without dditionl fixing. The steel plte 1 (RHA or St3) with the re of 500 500 mm ws supported in two plces on the RHA plte 2 (witness). The RHA plte 2 (witness) with the size of 600 500 8 mm ws rrnged on two chnnel sections without ny fixing. Setting of PG-7 shped chrge projectiles in reltion to ERAWA-1 rective cssettes [8] nd prmeters of ll pnels with the height of c < 160 mm were shown in Tle 1. TABLE 1. Prmeters of pnels of pssive-rective rmours No. of pnel /No. of vrint Setting ngle of PG-7 projectile in reltion the surfce of ERAWA-1 cssette, deg Mteril of plte 1 Surfce mss of pnel, m [kg/m 2 ] 1/1 72 RHA 227 2/1 60 RHA 227 3/2 72 St3 211 4/2 60 St3 211 5/3 72 RHA 221 6/3 60 RHA 221 The view of pnels of version 1 with ERAWA-1 cssettes efore nd fter the initition of the PG-7 projectile is shown in Figures 4-5. Fig. 4. Pnel 1 with the ERAWA-1 cssette efore the initition of the PG-7 projectile t n ngle of α = 72 () nd the RHA 2 plte (witness) fter the initition of the projectile () On the rmour plte 2 (witness) no trces of shped chrge jet were scertined. The PG-7 shped chrge jet ws stopped y the detontion of explosive in the ERAWA-1 cssette s well s the RHA plte 1 which ws dmged in the plce where the cssette ws fixed.
Protection of Light Armours Aginst Shped Chrge Projectiles 21 Fig. 5. Pnel 2 with the ERAWA-1 cssette efore the initition of the PG-7 projectile t n ngle of α = 60 () nd the RHA plte 2 (witness) fter the initition of the projectile () The shped chrge jet pierced the RHA plte 1 nd on the witness rmour plte trce ppered in the form of copper lyer from the shped chrge jet, ut the penetrtion of the rmour witness plte did not tke plce. In the following version 3 (Fig. 6-7) insted of the RHA plte 1 the steel St3 plte 1 with the re of 500 500 mm ws used nd the remining elements of the rmour were exctly the sme s in tests 1 nd 2. Fig. 6. Pnel 3 with the ERAWA-1 cssette efore the initition of the PG-7 projectile t n ngle of α = 72 () nd the RHA plte 2 (witness) fter the initition of the projectile () Fig. 7. Pnel 4 with the ERAWA-1 cssette efore the initition of the PG-7 projectile t n ngle of α = 60 () nd the RHA plte 2 (witness) fter the initition of the projectile ()
22 A. Wiśniewski The shped chrge jet pierced the St3 steel plte nd penetrted the rmour witness plte in the depth of DP = 4,5 mm. As result of the detontion of explosive in the shped chrge projectile nd in the rective cssette the deflection of the rmour witness plte out 8 mm lso occurred. The shped chrge jet pierced the St3 steel plte nd lso pierced through the rmour witness plte DP = 8 mm. The deflection of the upper metl sheet s result of the initition of the explosive in the shped chrge projectile nd in the rective cssette mounted to 22 mm. In the susequent version 3 of the rective-pssive rmour (Fig. 8) its construction with reltion to vrints 1 nd 2 ws chnged so tht the steel plte 1 with the re of 500 500 mm ws supported in three plces on the rmour plte 2 (witness), i.e. every 150 mm in the plces of centres of following luminium ERAWA-1 cssettes. This three-point support cused tht the construction in vrint 3 to ecme stiffer thn in vrints 1 nd 2. The distnces etween pltes 1 nd 2 in vrint 3 of the pnel were smller thn the distnces in vrints 1 nd 2. Fig. 8. Pnel of the rective-pssive rmour version 3: 1 ERAWA 1 cssette, 2 steel plte 1, 3 RHA plte 2 (witness), 4 steel chnnel section, 5 sleeve, 6 screw, 7 nut The view of pnels with ERAWA-1 cssettes in version 3 efore nd fter the initition of the PG-7 projectile is presented in Figures 9-10. Fig. 9. Pnel 5 with the ERAWA-1 cssette efore the initition of the PG-7 projectile t the ngle of α = 72 () nd the RHA plte 2 (witness) fter the initition of the projectile ()
Protection of Light Armours Aginst Shped Chrge Projectiles 23 The shped chrge jet ws stopped y the detontion of explosive in the ERAWA-1 cssette nd y the RHA plte 1, nd the deflection of the RHA plte 2 (witness) ws 11 mm. Fig. 10. Pnel 6 with the ERAWA-1 cssette efore the initition of the PG-7 projectile t n ngle of α = 60 () nd the RHA plte 2 (witness) fter the initition of the projectile () The shped chrge jet pierced the RHA plte 1, on the rmour witness plte where trce ppered in the form of copper lyer from the shped chrge jet, ut the penetrtion of the rmour plte 2 (witness) did not tke plce. The deflection of the rmour plte 2 (witness) mounted to 13 mm. The list of the results of sttic tests with the use of shped chrge PG-7 projectiles nd pnels of rective-pssive rmours is shown in Tle 2 nd in Figure 11. TABLE 2. Results of the firing t pnels of pssive-rective rmours with the use of PG-7 projectiles No. of pnel / No. of vrint / setting ngle of PG-7, α [º] Mteril of steel plte 1 / penetrtion depth of RHA plte 2 (witness), Sizes of holes in RHA plte 2 (witness), x [mm] DP [mm] inlet outlet Deflection of RHA plte 2 (witness), d [mm] 1 / 1 / 72 RHA / - - - - 2 / 1 / 60 RHA / 1 ~3 3 - - 3 / 2 / 72 St3 / 4,5 51 13-8 4 / 2 / 60 St3 / 8 34 17 10 6 27 5 / 3 / 72 RHA / - - - 11 6 / 3 / 60 RHA / 2 ~3 3-13
24 A. Wiśniewski c d Fig. 11. The depth of penetrtion of the plte 1, the RHA plte 2 (witness) nd the deflection of the RHA plte 2 (witness): in the function of mss of the rmour pnel for the ngles of α = 72 () nd α = 60 (), in function of the height of the rmour pnel for the ngles α = 72 (c) nd α = 60 (d) 3. CONCLUSIONS On the sis of tests crried out, the following conclusions cn e drwn: 1. The pnel of the rective-pssive rmour with ERAWA-1 cssettes from luminium lloy cn protect light rmoured fighting vehicles ginst the perfortion y PG-7 projectiles hitting this rmour t n ngle of 60 o α 72 o (18 o β 30 o from the surfce of the rmour). 2. After the perfortion of the rective-pssive rmour on the surfce of the hull of protected vehicle, smll crters with depth of severl millimetres nd trces of dispersed copper from the shped chrge jet of PG-7 cn occur. 3. The est protection ws provided y the rective-pssive rmour in version 1. The shped chrge jet did not pierce plte 1 with the size of 500 500 mm oth for the ngle of α = 72 s well s for α = 60. There ws lso no deflection of the steel rmour witness plte with the size of 600 500 8 mm s result of the initition of the explosive of the shped chrge jet projectile nd the ERAWA-1 cssette.
Protection of Light Armours Aginst Shped Chrge Projectiles 25 4. The protection ginst the perfortion of the shped chrge jet ws lso provided y the rective-pssive rmour in version 3. Deflections of the steel rmour witness pltes (11 mm pnel 5 nd 13 mm pnel 6) occurred for α = 60 nd α = 72 setting ngles of the shped chrge jet PG-7 projectile in reltion to the norml externl surfce of the cssette; the deflections were cused y the smller distnces etween pltes 1 nd 2 nd lso ecuse of the greter stiffness of plte 1 s result of its eing supported in three plces on the plte 2 (witness) nd s result of smller distnces etween pltes 1 nd 2 in vrint 3 of the pnel thn the distnces in vrints 1 nd 2. REFERENCES [1] Witkowski I., Light nd medium rmoured fighting vehicles (in Polish), Pulishing House WiS, Wrsw, 1993. [2] Wiśniewski A., Włodrczyk E., Zuik T., Hj W., Podgórzk P., Protection of fighting vehicles (in Polish), Prolems of Armment Technology, Militry Institute of Armment Technology, vol. 89, 2003. [3] Wiśniewski A., Armours construction, designing nd reserch (in Polish), Scientific nd Technicl Pulishing House, Wrsw, 2001. [4] Brmowicz J., Pwlk S., Wojdn J., Moderniztion of infntry fighting vehicle BWP-1 (in Polish), Prolems of Armment Technology nd Rdioloction, Militry Institute of Armment Technology, vol. 58, 1996. [5] Wiśniewski A., Brmowicz W., Wojdn J., Jskot S., Segment rmour protection, Polish Ptent No. 178940, 1995. [6] Wiśniewski A., Pssive-rective rmours, Proceedings of IVth Interntionl Armment Conference Scientific Aspects of Armment Technology. WAT, Wplewo, 9-11 Octoer 2002, pp. 820-829, 2002. [7] Foss C.F., CERAWA-1 Explosive rective rmour system. Jne s Armour nd Artillery, Jne s Informtion Group Limited. 1996. [8] Wiśniewski A., Tomszewski Ł., Pcek D., Tesing of protective ility of rective pnels, Report of the Militry Institute of Armment Technology, (unpulished), Zielonk, 2010.