# What are those abacus-like things mounted around this US armored vehicle? **URL:** \ **Category:** Factual Questions\ **Created:** [October 6, 2021, 1:20am UTC](https://boards.straightdope.com/t/what-are-those-abacus-like-things-mounted-around-this-us-armored-vehicle/951962 "2021-10-06T01:20:24Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [October 6, 2021, 1:20am UTC](https://boards.straightdope.com/t/what-are-those-abacus-like-things-mounted-around-this-us-armored-vehicle/951962/1 "2021-10-06T01:20:24Z")
This is a pic of a U.S. armored transport vehicle [now in the possession of the Taliban](https://www.nytimes.com/2021/10/05/world/asia/us-weapons-afghanistan.html). [![](https://static01.nyt.com/images/2021/10/05/world/05afghan-weapons-004/merlin_193953183_ed762a92-24a3-455c-adf6-dde479821d66-superJumbo.jpg?quality=90&auto=webp) ](https://static01.nyt.com/images/2021/10/05/world/05afghan-weapons-004/merlin_193953183_ed762a92-24a3-455c-adf6-dde479821d66-superJumbo.jpg?quality=90&auto=webp) What is the function of the things that look like abacuses mounted around the vehicle? Do they block rocks, bombs, etc. from hitting the vehicle? That seems like overkill for an armoured vehicle. Are they there to prematurely detonate incoming shells and missiles, i.e. like a form of slat armor? Looks like they’re too flimsy for that. Am I even close? ---
**Author:** ![mikecurtis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mikecurtis/32/3284_2.png) [@mikecurtis](https://boards.straightdope.com/u/mikecurtis)\ **Post date:** [October 6, 2021, 1:22am UTC](https://boards.straightdope.com/t/what-are-those-abacus-like-things-mounted-around-this-us-armored-vehicle/951962/2 "2021-10-06T01:22:55Z")
Right on > **[Q-Net](https://en.wikipedia.org/wiki/Q-Net)** > > Pages for logged out editors learn more > > The Q-NET is an add-on armor kit developed by QinetiQ to counter the threat of rocket-propelled grenades. > The Q-Net is an armor system that stands off from the vehicle's hull and "catches" the RPG before it hits the outside of the vehicle itself, using metal nodes connecting the net to disrupt the fusing of the warhead. The Q-Net is similar to other add-on systems like slat armor cages, but with additional benefits of being cheaper and 50-60% lig... ---
**Author:** ![Hatchie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hatchie/32/3983_2.png) [@Hatchie](https://boards.straightdope.com/u/Hatchie)\ **Post date:** [October 6, 2021, 2:00am UTC](https://boards.straightdope.com/t/what-are-those-abacus-like-things-mounted-around-this-us-armored-vehicle/951962/3 "2021-10-06T02:00:27Z")
“Q-Net”? It can stop grenades, but will it Stop the Steal? Seriously though, what does “fusing of the warhead” mean? I was thinking the grenades would just bounce off it like a tennis racket. ---
**Author:** ![gdave](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gdave/32/3683_2.png) [@gdave](https://boards.straightdope.com/u/gdave)\ **Post date:** [October 6, 2021, 2:31am UTC](https://boards.straightdope.com/t/what-are-those-abacus-like-things-mounted-around-this-us-armored-vehicle/951962/4 "2021-10-06T02:31:44Z")
A thrown hand grenade might bounce off, but a thrown hand grenade isn’t a threat to an armored vehicle like that anyway. It’s designed to defeat “rocket propelled grenades” which aren’t really grenades, they’re anti-tank rockets with shaped-charge warheads. The explosive charge is literally shaped so that its force is concentrated forward into a conical section of the warehead, which is then transformed into a superplastic jet of metal, which is highly effective at penetrating armor. However, this requires pretty precise timing of the detonation. Too close to the target, and the jet doesn’t have time to form. Too far, and the jet disperses. You can’t just use a simple impact fuse. The warhead will typically have a piezoelectric nose probe which forms a circuit with a fuse assembly in the rear. When the nose probe is compressed on impact, it triggers the fuse assembly in the rear. The whole bit is very carefully calibrated to optimize the formation of the penetrating jet. The net can interfere with the fuse circuit, and cause the charge to detonate improperly, and inhibit the formation of an optimized jet. (Caveat: although I have read material on how all of this works, and have even delivered briefings on some aspects, I Am Not An Expert, and the above is about the limits of my understanding of how it all works mechanically). ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [October 6, 2021, 2:22pm UTC](https://boards.straightdope.com/t/what-are-those-abacus-like-things-mounted-around-this-us-armored-vehicle/951962/5 "2021-10-06T14:22:39Z")
**gdave** is correct. It’s all about detonating the warhead early so it won’t penetrate. A relatively simple system like that can work against RPGs but wouldn’t work against a HEAT round or antitank guided missile. For weapons like that they have reactive armor or the Israeli Trophy system that is being fielded by the US Army. Or you hope your armor is thick enough. \* - that’s an oversimplification. It’s not just about thickness. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [October 7, 2021, 1:53pm UTC](https://boards.straightdope.com/t/what-are-those-abacus-like-things-mounted-around-this-us-armored-vehicle/951962/6 "2021-10-07T13:53:47Z")
Egypt says the netting does not always work against PG-7WM RPG As the PG-7WM has a fairly sharp point containing the piezo electric trigger (“fuse” ) , that will initiate the shaped charge explosion … , only the point directly hitting the netting would trigger it early. So most likely the PG-7WM would just barge through the netting and detonate as designed. > **[ART20198222.pdf](https://www.ijsr.net/archive/v8i5/ART20198222.pdf)** Maybe the vehicle has to try to avoid being targetted on perpindicular trajectories… but also they can target the enemy back when they are on perpindicular, so they are hoping the risk is from the angles … Net also provides protection from slower moving shaped charges. Like a suicide bomber trying to lie on your tank to aim the shaped charge, or a magnetic mine limpet thing directed toward the vehicle ? There’s some extra protection from lucky long shots,or someone very close , being able to get explosive or offensive substance ( molotov, poison ) into a window or vent ?