# Fencelike structures on patrol vehicles in Afganistan **URL:** \ **Category:** Factual Questions\ **Created:** [March 28, 2014, 12:07pm UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756 "2014-03-28T12:07:05Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Deflagration](https://avatars.discourse-cdn.com/v4/letter/d/3ab097/32.png) [@Deflagration](https://boards.straightdope.com/u/Deflagration)\ **Post date:** [March 28, 2014, 12:07pm UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/1 "2014-03-28T12:07:05Z")
For example on this [Mastiff](http://www.army.mod.uk/equipment/23248.aspx) At first I thought it was some kind on armour but I can’t see them stopping anything. What are they and how do they work? ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [March 28, 2014, 12:15pm UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/2 "2014-03-28T12:15:02Z")
> **[Slat armor](https://en.m.wikipedia.org/wiki/Slat_armor)** > > Slat armor (or slat armour in British English), also known as bar armor, cage armor, and standoff armor, is a type of vehicle armor designed to protect against high-explosive anti-tank (HEAT) attacks, as used by anti-tank guided missiles (ATGMs) and rocket-propelled grenades (RPGs). > Slat armor takes the form of a rigid slatted metal grid fitted around key sections of the vehicle, which disrupts the shaped charge of the warhead by either crushing it, preventing optimal detonation from occurrin... ---
**Author:** ![Deflagration](https://avatars.discourse-cdn.com/v4/letter/d/3ab097/32.png) [@Deflagration](https://boards.straightdope.com/u/Deflagration)\ **Post date:** [March 28, 2014, 12:25pm UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/3 "2014-03-28T12:25:51Z")
Thank you. ---
**Author:** ![Chihuahua](https://avatars.discourse-cdn.com/v4/letter/c/dec6dc/32.png) [@Chihuahua](https://boards.straightdope.com/u/Chihuahua)\ **Post date:** [March 28, 2014, 12:28pm UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/4 "2014-03-28T12:28:05Z")
The most common antitank weapon is the Soviet-style RPG. The warhead is a piezoelectric fuse in front of a shaped charge. If the warhead gets stuck between the slats and the fuse doesn’t crush, there will be no kaboom. The shaped charge itself is a copper cone (or something) that implodes to form a stream of liquid metal. This liquid metal is what actually penetrates the vehicle. If the warhead goes kaboom prematurely (from striking a slat) it will result in less-than-optimal penetration. ---
**Author:** ![the\_diego](https://avatars.discourse-cdn.com/v4/letter/t/7bcc69/32.png) [@the\_diego](https://boards.straightdope.com/u/the_diego)\ **Post date:** [March 29, 2014, 11:27pm UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/5 "2014-03-29T23:27:46Z")
As I understand it, a well-designed shaped charge can cut thought steel even if it detonates several inches (or feet) away from the steel. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [March 29, 2014, 11:37pm UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/6 "2014-03-29T23:37:34Z")
The solution isn’t a perfect one, but the average muj isn’t going to have an ideal set-up when he launches that RPG. Anything that can disrupt the stream from the hit is good. If you can get it to detonate away from the skin, all the better. Slat armor is a compromise between protection and weight. Otherwise an RPG will turn a Hummer into scrap metal. With the armor the troops have a bit of a chance. ---
**Author:** ![FoieGrasIsEvil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foiegrasisevil/32/16638_2.png) [@FoieGrasIsEvil](https://boards.straightdope.com/u/FoieGrasIsEvil)\ **Post date:** [March 30, 2014, 12:50am UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/7 "2014-03-30T00:50:11Z")
> [@Chihuahua](#): > > The most common antitank weapon is the Soviet-style RPG. The warhead is a piezoelectric fuse in front of a shaped charge. If the warhead gets stuck between the slats and the fuse doesn’t crush, there will be no kaboom. \*\*The shaped charge itself is a copper cone (or something) that implodes to form a stream of liquid metal. This liquid metal is what actually penetrates the vehicle. \*\* If the warhead goes kaboom prematurely (from striking a slat) it will result in less-than-optimal penetration. Is that accurate? Reading from this article would seem to indicate that a “slug” or “carrot” solid projectile is what eventually penetrates the armor and causes the spalling, killing the inhabitants inside. > **[Shaped charge](https://en.wikipedia.org/wiki/Shaped_charge)** > > A shaped charge is an explosive charge shaped to focus the effect of the explosive's energy. Different types of shaped charges are used for various purposes such as cutting and forming metal, initiating nuclear weapons, penetrating armor, or perforating wells in the oil and gas industry. > A typical modern shaped charge, with a metal liner on the charge cavity, can penetrate armor steel to a depth of seven or more times the diameter of the charge (charge diameters, CD), though depths of 10 CD and ... ---
**Author:** ![Habeed](https://avatars.discourse-cdn.com/v4/letter/h/a587f6/32.png) [@Habeed](https://boards.straightdope.com/u/Habeed)\ **Post date:** [March 30, 2014, 1:15am UTC](https://boards.straightdope.com/t/fencelike-structures-on-patrol-vehicles-in-afganistan/684756/8 "2014-03-30T01:15:36Z")
The cheap RPGs used in Iraq/Afganistant apparently are not “ideal” shaped charges. Probably, if they are not against a solid surface when the charges detonate, then most of the energy is dissipated to the sides. An RPG warhead does not have a heavy metal casing like used here : [Explosively formed penetrator - Wikipedia](http://en.wikipedia.org/wiki/Explosively_formed_penetrator) . I think the RPG has to slam into the armor plate and the surface of the armor itself acts to help contain the blast. But yeah, they make various anti-tank missile systems such as the Javelin that would presumably make scrap metal of any U.S. vehicle in use.