# A military question. What can go wrong firing mortars? **URL:** \ **Category:** Factual Questions\ **Created:** [May 4, 2017, 5:13pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863 "2017-05-04T17:13:14Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [May 5, 2017, 6:27pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/21 "2017-05-05T18:27:08Z")
My Dad was on an 81mm mortar team in WWII. The baseplate (to keep the tube from burying itself in the ground) alone weighed 90 pounds. Although one soldier carried only the baseplate, you still want the whole package to weigh as little as possible. One accident he witnessed: when dropping rounds into the tube, you are supposed to hold them in such a way that your hand is never in front of the tube – the round is, but your fingers will pass just down the outside of the tube as you release. One time a very tired young man, feeding rounds into the tube with the urgency of someone under attack by Nazis, let his hand cover the opening of the tube for a moment after release. No explosion, possibly because of the safety measures described above. But the round (and fins), traveling at high velocity, did remove his fingers. ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [May 5, 2017, 6:30pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/22 "2017-05-05T18:30:14Z")
> [@MichaelEmouse](#): > > What’s the CEP on average infantry-carried mortars? Per General Dynamics, the latest generation of (US) 81mm mortars have a CEP of under five meters at ranges from 980 to 4000 meters. Some other (possibly less-biased) sources claim 10 meters. 60mm mortars claim around a 10 meter CEP - Not sure why the diminished terminal accuracy claim, unless it’s simply practical field reporting. As a datum, 120mm mortars also claim a sub-5 meter CEP, though that’s definately stretching the definition of ‘man portable.’ > [@](#): > > Even if simplicity is what they’re optimized for, have there been recent advances which add worthwhile complexity? Anything beyond the usual GPS/laser guidance? Improved sights and fusing systems are always in development. Laser-guided projectiles are an option, but there are experiemental extended range programs, including things like [ACERM](http://www.dtic.mil/ndia/2014/armaments/Wed16557Steelman.pdf) (PDF), which inlcudes wings and guidance packages, and intend to reduce CEP to under one meter. Haven’t actually heard of anything like this from my buds in green in the field, though. ---
**Author:** ![MichaelEmouse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/michaelemouse/32/101_2.png) [@MichaelEmouse](https://boards.straightdope.com/u/MichaelEmouse)\ **Post date:** [May 5, 2017, 7:28pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/23 "2017-05-05T19:28:17Z")
> [@Tranquilis](#): > > Per General Dynamics, the latest generation of (US) 81mm mortars have a CEP of under five meters at ranges from 980 to 4000 meters. Some other (possibly less-biased) sources claim 10 meters. > > 60mm mortars claim around a 10 meter CEP - Not sure why the diminished terminal accuracy claim, unless it’s simply practical field reporting. > > As a datum, 120mm mortars also claim a sub-5 meter CEP, though that’s definately stretching the definition of ‘man portable.’ > Improved sights and fusing systems are always in development. Laser-guided projectiles are an option, but there are experiemental extended range programs, including things like [ACERM](http://www.dtic.mil/ndia/2014/armaments/Wed16557Steelman.pdf) (PDF), which inlcudes wings and guidance packages, and intend to reduce CEP to under one meter. Haven’t actually heard of anything like this from my buds in green in the field, though. The ACERM looks like a mini-small diameter bomb. If that 10m CEP50 is accurate, it seems the main weak points are detecting the enemy and getting the right targeting data. Laser designators seem to do a good job of getting precise targeting data. What other ways are currently or will soon be used to detect and get targeting data? ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [May 5, 2017, 7:29pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/24 "2017-05-05T19:29:30Z")
> [@MichaelEmouse](#): > > If that 10m CEP50 is accurate, it seems the main weak points are detecting the enemy and getting the right targeting data. Laser designators seem to do a good job of getting precise targeting data. What other ways are currently or will soon be used to detect and get targeting data? Light drones are quite popular. 🙂 Some of the newer ones can even designate. _Edit_: BTW, and FYI - I’m getting most of my information from the husband of my wife’s best friend, whom is a Marine Artilleryman. ---
**Author:** ![Dissonance](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dissonance](https://boards.straightdope.com/u/Dissonance)\ **Post date:** [May 5, 2017, 8:31pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/25 "2017-05-05T20:31:07Z")
> [@MichaelEmouse](#): > > If that 10m CEP50 is accurate, it seems the main weak points are detecting the enemy and getting the right targeting data. Laser designators seem to do a good job of getting precise targeting data. What other ways are currently or will soon be used to detect and get targeting data? The joint Finnish/Swedish [AMOS](https://en.wikipedia.org/wiki/AMOS) (Advanced Mortar System) is a twin 120mm mortar that: > [@](#): > > When fitted to a vehicle, both GPS- and inertia positioning are used. The electronic fire-control system utilises digital maps. The twin barrelled AMOS is able to keep up rate of fire of 12 rounds per minute. Using its computer-controlled MRSI feature (multiple rounds simultaneous impact) it is possible to set up a burst of up to 16 rounds that hit the target simultaneously.[2] The first rounds are fired at higher angles with more propellant so that the rounds fly in a high arc. The next rounds are shot later with a slightly smaller angle and less propellant so that they fly a lower arc to the same target. This can be done seven times in a row, always adjusting the angle and power. The adjustment between shots is done by a computer. The strike of one AMOS unit roughly equals one strike of an artillery battery. It, or any other 120mm mortar, can fire the Swedish [Strix](https://en.wikipedia.org/wiki/Strix_mortar_round) anti-tank mortar round that uses imaging infrared to self guide itself. > [@](#): > > STRIX is fired like a conventional mortar round. The round contains an infrared imaging sensor that it uses to guide itself onto any tank or armoured fighting vehicle in the vicinity where it lands. The seeker is designed to ignore targets that are already burning. > > Launched from any 120 mm mortar, Strix has a normal range of up to 4.5 km. With the addition of a special sustainer motor, however, range can be increased to 7.5 km. > > The Strix mortar round uses twelve midsection lateral thruster rockets to provide terminal course corrections.[1] > > The tail unit is loaded first with the necessary propelling charges (up to eight increments), then the sustainer motor (if required) and finally, the programmed projectile. A hand-held programming unit is connected to the projectile by cable prior to loading to feed in flight time before seeker activation, and with allowances for terminal phase ballistic conditions. [Previous page](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863.md?page=1)