Ozarks Posted October 10, 2017 Posted October 10, 2017 IIRC the effectiveness of ERA is based on the production of a transverse shearing moment against long rod penetrators thereby exploiting their small cross sections and somewhat brittle nature. What effect would ERA mounted on conventional steel armor have against a conventional, pre long rod, AP shot?
lastdingo Posted October 10, 2017 Posted October 10, 2017 I suppose it would enlarge the range of angles at which the shot bounces, and reduce the normalization effect. The metal of the ERA would also add to the armour as passive armour. In most extreme cases the spacing afforded by the ERA might trigger the delay base fuze too early, though this might be limited to ERA on track skirts.
Hakka Posted October 11, 2017 Posted October 11, 2017 IMO it would fracture the shot so that a much thinner steel plate is enough to shatter it. The metal of the ERA would also add to the armour as passive armour. That's really not how ERA works, as I understand it. First and most important thing is that the shot should already have reached the explosive layer beneath the flyer plate, so it's not a case of the shot penetrating the flyer plate from the nose like normal armor. Rather, the flyer plate begins moving while the shot is halfway through it.
lastdingo Posted October 11, 2017 Posted October 11, 2017 IMO it would fracture the shot so that a much thinner steel plate is enough to shatter it. The metal of the ERA would also add to the armour as passive armour. That's really not how ERA works, as I understand it. First and most important thing is that the shot should already have reached the explosive layer beneath the flyer plate, so it's not a case of the shot penetrating the flyer plate from the nose like normal armor. Rather, the flyer plate begins moving while the shot is halfway through it. The outer layers is a plate. This plate is matter, and it's in the trajectory of the threat ammunition. This means it's got a passive protection effect. This may be 5 mm RHAeq, it may also be 60 mm RHAeq (depends on ERA model and angle) - but there's some passive protection value to it.
bojan Posted October 12, 2017 Posted October 12, 2017 Most ERA would not be activated by AP, since it needs hit velocities of about 1100+m/s to work.
Inhapi Posted October 12, 2017 Posted October 12, 2017 Bojan: Thus that mean that a tank protected by ERA could be more efficiently attacked with plain AP in stead of APFSDS ? many greetings, Inhapi
lastdingo Posted October 12, 2017 Posted October 12, 2017 It depends on the base armour. Some WW2 guns and shots may be able to penetrate the side protection of modern MBTs, but those tanks with heavy skirts and the Russian turrets would likely resist. BTW, most ERA isn't really meant to defeat APFSDS anyway, particularly not the early thin modules.
Hakka Posted October 15, 2017 Posted October 15, 2017 IMO it would fracture the shot so that a much thinner steel plate is enough to shatter it. The metal of the ERA would also add to the armour as passive armour. That's really not how ERA works, as I understand it. First and most important thing is that the shot should already have reached the explosive layer beneath the flyer plate, so it's not a case of the shot penetrating the flyer plate from the nose like normal armor. Rather, the flyer plate begins moving while the shot is halfway through it. The outer layers is a plate. This plate is matter, and it's in the trajectory of the threat ammunition. This means it's got a passive protection effect. This may be 5 mm RHAeq, it may also be 60 mm RHAeq (depends on ERA model and angle) - but there's some passive protection value to it. Yeah, the plate itself gets penetrated at the very beginning and it has some passive protection value there, but its usually fully perforated by the time the explosive charge detonates, so its passive protection value stops there. When the plate becomes a flyer plate, the interaction between the shot and the plate can no longer be reasonably quantified in terms of RHA.
Blunt Eversmoke Posted October 16, 2017 Posted October 16, 2017 Re conventional AP against modern armor: LOSAT comes to mind.
lastdingo Posted October 16, 2017 Posted October 16, 2017 LOSAT is not "conventional AP". It's an APFSDS-like long rod propelled by a rocket.
Ozarks Posted October 20, 2017 Author Posted October 20, 2017 Most modern armors depend on exploiting the long rod projectile's vulnerability to lateral shear of flexing. APFSD rods can be as much as 20:1 length diameter ratios and as small as 20-28 mm diameter. They also tend to be made of brittle material especially susceptible to lateral forces. Neither of these weakness really applies to short L/D AP shot made of materials that are comparatively shock resistant.
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