Path: spln!rex!extra.newsguy.com!lotsanews.com!news-out.cwix.com!newsfeed.cwix.com!nntp.abs.net!news-out.visi.com!hermes.visi.com!gemini.tycho.net.POSTED!not-for-mail Approved: sci-military-moderated@retro.com Return-Path: news@google.com Delivery-Date: Fri Mar 29 17:38:21 2002 Delivery-Date: Fri, 29 Mar 2002 17:38:21 -0800 for <sci-military-moderated@retro.com>; Fri, 29 Mar 2002 17:38:20 -0800 (PST) id QQmiiv11259 for <sci-military-moderated@moderators.isc.org>; Sat, 30 Mar 2002 01:19:59 GMT for <sci-military-moderated@moderators.isc.org>; Fri, 29 Mar 2002 17:19:55 -0800 for <sci-military-moderated@moderators.isc.org>; Fri, 29 Mar 2002 17:19:53 -0800 for sci-military-moderated@moderators.isc.org; Fri, 29 Mar 2002 17:19:53 -0800 To: sci-military-moderated@moderators.isc.org From: psl@interchange.ubc.ca (Paul Lakowski) Newsgroups: sci.military.moderated Subject: Re: RHA penetration of 25mm M919 from M242 Bushmaster? Date: 29 Mar 2002 17:19:53 -0800 Organization: http://groups.google.com/ Message-ID: <de5bf54f.0203291719.4789cd16@posting.google.com> References: <a7vvq90l9o@enews1.newsguy.com> X-NNTP-Posting-Host: 207.23.94.141 Content-type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Complaints-To: groups-abuse@google.com X-NNTP-Posting-Date: 30 Mar 2002 01:19:53 GMT Content-Length: 3026 Lines: 61 NNTP-Posting-Host: c912ee48.newsreader.tycho.net X-Trace: 1017451638 gemini.tycho.net 79553 205.179.181.194 X-Complaints-To: abuse@tycho.net Xref: spln sci.military.moderated:43820 TTK Ciar <ttk@NOSPAM_remove_all_after_org.ciar.org.aol.com> wrote in message news:<a7vvq90l9o@enews1.newsguy.com>... > Hello, > I was wondering if anyone knew what the penetration capability was, > in RHA equivalence, of the 25mm M919 APFSDS when fired from the M242 > Bushmaster chain gun.American 25mm M919 DU APDSFS-T. THese are estiamtes based on formula from my files JANE's AFV Retrofit systems 94-95 reports the projectile mass at 132g and the muzzle velocity at 1385m/s . JANES Ammunition Handbook 2000-2001 adds: Penetrator mass 96g DU with MV@1420m/s , with a time of flight to 2000m at 1.56s remaining velocity 1149m/s .The muzzle velocity was initially 1420m/s, then lowered (different prop) to 1385m/s due to barrel wear issues. Its believe they are introducing new (German?) propellant to bring it back up to 1420m/s. PRIMEX makes a similar round with a tungsten carbide penetrator, listed weight as 138g, MV 1420m/s. velocity drop listed as 130mps/km. The cutaway pic when measured resulted in a penetrator diameter in the 7-8mm range & approx 100mm long [L/d 13:1]. The volume should be 3.85cc and the penetrator mass about 71gm suggesting the fins and cap are only about 25gm. The penetrator nose is frustum shaped with a small spike for attaching the windscreen and the semi infinite conversion should be +1d@ 0° & +2d @ 60° or + 0.7cm /+ 1.5cm due to the frustum nose shape The Andersons inputs should be 1.044V[km/s] &#8211; 0.71 [L/d] x 1.01[scaling] x 1.24 [subscale DU] and the 60° penetration is a line of sight penetration. Muzzle 1385m/s = 0.91 x 10cm + 0.7/1.5cm = 9.8cm ± 1.5cm @ 0° & 10.5cm ± 1.6cm @ 60° 1000m 1255m/s = 0.71 x 10cm + 0.7/1.5cm = 7.8cm± 1.3cm @ 0° & 8.6cm±1.3cm @ 60° 2000m 1125m/s = 0.58 x 10cm + 0.7/1.5cm = 6.5cm± 1cm @ 0° & 7.3cm±1cm @ 60° 3000m 995m/s = 0.41x 10cm + 0.7/1.5cm = 4.8cm± 1cm @ 0° & 5.6cm±1cm @ 60° Zaloga reports 75mm @ 0° at 1000m, while the above estimate is 78mm @ 0° at 1000m , suggesting the above estimates are close . Also, PRIMEX makes a similar round with a tungsten penetrator and a projectile mass of 138g, MV 1420m/s and the velocity drop listed as 130mps/km.The volume should work out to 71/17.4 [X27X] = 4cc and given a 7mm rod diameter I get approximately 105 x 7mm rod or 15:1 L/d .I assume the rest is the same . The penetrator nose is frustum shaped with a small spike for attaching the windscreen and the semi infinite conversion should be +1d@ 0° & +2d @ 60° or + 0.7cm /+ 1.5cm . The Andersons inputs should be 1.044V &#8211; 0.738 [L/d] + 0.05 [ X27X alloy] x 1.01[scaling] and the 60° penetration is a line of sight penetration. Muzzle 1420m/s = 0.80 x 10.5cm + 0.7/1.5cm = 9.1cm ± 2cm @ 0° & 9.9cm ± 2cm @ 60° 1000m 1290m/s = 0.665 x 10.5cm + 0.7/1.5cm = 7.7cm± 2cm @ 0° & 8.5cm±2cm @ 60° 2000m 1160m/s = 0.53 x 10.5cm + 0.7/1.5cm = 6.2cm± 1cm @ 0° & 7cm±1cm @ 60° 3000m 1030m/s = 0.39 x 10.5cm + 0.7/1.5cm = 4.8cm± 1cm @ 0° & 5.6cm±1cm @ 60° Should offer the same performance as DU M919 APFSDS-T round.