How a mortar works?

[leonpoi]

Just out of interest, does anyone here know how a mortar works? Is the round self contained, or do you have to have some kind of power charge (I'm talking 60mm, 81mm that type of thing)? If so, is it possible to use smaller charges for shorter distances, or do you just use real high trajectories for that?
Thanks in advance

[Fusilier]

AFAIK, all light and medium mortars are self-contained -- there is no separate charge.

Self contained, but there's more to it.

The internal charge is usually insufficient to provide enough power to propel the bomb any real distance. This is usually for all size mortars. Charges, which are often just semi-circle, plastic, ring shaped charges filled with propellant are added (or removed). An 81mm might have up to four. They are connected around the skinny part of the bomb near the bottom by the fins.

So in some situations not only do you need to figure out bearing and elevation, but also what charge setting to use.

[kato13]

AFAIK, all light and medium mortars are self-contained -- there is no separate charge.

I think most mortars can have their self contained propellant range increased via increment charges.

[leonpoi]

Self contained, but there's more to it.

The internal charge is usually insufficient to provide enough power to propel the bomb any real distance. This is usually for all size mortars. Charges, which are often just semi-circle, plastic, ring shaped charges filled with propellant are added (or removed). An 81mm might have up to four. They are connected around the skinny part of the bomb near the bottom by the fins.

So in some situations not only do you need to figure out bearing and elevation, but also what charge setting to use.

ok, thanks for that info. Do you know if these charges take much time to attach?

I've found this on wiki, but it took me a while to find because I didn't know what I was looking for:
The charges on the 80mm rounds govern how far that particular round with travel. Each round that the M252 mortar fires has four semi-circle shaped charges that can be easily attached, or stripped by hand. While the rounds can fire without the aid of additional charges, to reach farther targets more charges must be applied.

[bigehauser]

Paul, Law?

Any insight, albeit your skill sets aren't specific to High Angle Hell?

[Fusilier]

ok, thanks for that info. Do you know if these charges take much time to attach?

No time. By the time the No.1 has laid the bearing and elevation, the No.3 will have the ammo ready (this includes setting the right charges as the Mortar Fire Controller indicated).

The charges come pre-connected, but taking them off or putting them back on, only requires a flick of a finger so yeah, no time. They are only loosely wrapped around - not tight or anything.

[pmulcahy11b]

Paul, Law?

Any insight, albeit your skill sets aren't specific to High Angle Hell?

Actually my first MOS was 11C (mortar gunner), but what the other minds on this board have said are right. I can add that the 4.2" mortar uses "cheese charges" -- these are about the size a color of a slice of cheese you might put on your bread, but made of nitroglycerin and beeswax. They have a hole in the middle to wrap around the tail of the charge. 4.2" mortar rounds don't have fins (the barrel is rifled), so there is a simple retaining ring to keep the charges in place. The rounds come with enough charges to propel the round to its maximum range, so the one of the ammo bearers (there are two on a 4.2" crew) "cuts charges" -- he tears off or detaches (they come in 5-"slice" increments as well as some single slices and one 10-pack) the parts of the charge not needed. A good charge cutter will be 2-3 rounds ahead of the round being fired. If you need to drop close, you can fire the mortar on charge 0 -- no propelling charges.

Then comes the best part of 4.2" mortar gunnery -- destroying the unused charges when you're done. You dig a bit pit, throw the charges in, then throw a burning book of matches or a stick on fire into it and run. Big fireworks display, and it sounds like a jet engine for a few seconds.

Older 81mm rounds have bagged charges -- 7 for an 81mm. The 60mm are similar, but only have three charges. You just unhook what's necessary.

[Adm.Lee]

Only thing I can add is some pedantry-- a mortar shoots "bombs," not "shells," according to many sources.

[rcaf_777]

I am qualifed on the 60mm mortar and have always wonder how far the basic round no extra charges would travel

[natehale1971]

I was wondering something.

Should Mortars always be used in pairs, or is a single mortar just as effective in a pinch? Anti-Armor weapons like the SMAWS, Carl Gustav or PzF-3 seem to be good when used as single weapon team (Gunner, Asst. Gunner & Ammo bearer), but I was wondering about Mortars. Can a group that has a single mortar team work just as effectively? Or a single gunner with two assistants be able to operate two mortars?

[jester]

We operated guns with 2 man mortar crews. Gunner and A-Gunner with them prepping ammo before hand and the lone ammo man in the section and the corpsman and radioman and section leader lending a hand.

[Eddie]

I was wondering something.

Should Mortars always be used in pairs, or is a single mortar just as effective in a pinch? Anti-Armor weapons like the SMAWS, Carl Gustav or PzF-3 seem to be good when used as single weapon team (Gunner, Asst. Gunner & Ammo bearer), but I was wondering about Mortars. Can a group that has a single mortar team work just as effectively? Or a single gunner with two assistants be able to operate two mortars?

Mortars (and artillery) are not necessarily best employed by firing the entire gun line, be it 2 guns or 20. It depends on the type of mission they're performing.

That said, you'll most likely not get the most bang for your buck when you go to FFE (Fire for Effect) if you're only using one tube.

((While I'm not an 11C, I am an Infantry Company Commander, graduate of the Infantry Mortar Leader's Course and own the Battalion's Mortar Platoon.))

[pmulcahy11b]

Only thing I can add is some pedantry-- a mortar shoots "bombs," not "shells," according to many sources.

That sort of depends on where you're from -- Americans and South Koreans call them shells, for example, while Brits and Germans call them bombs.

[Fusilier]

Should Mortars always be used in pairs, or is a single mortar just as effective in a pinch? Can a group that has a single mortar team work just as effectively? Or a single gunner with two assistants be able to operate two mortars?

Not every army is the same of course, but I can say...

Part of keeping them in groups (of say 4 tubes) is due to the area effect of the bombardment (like Eddie said) with having a suitable FFE factor. However, another part is due to the limited number of personnel in your mortar platoon and the limitations of the crew...

Beyond 60mm, larger mortars are usually behind the FEBA so that they are indirect only. That means you need a MFC (mortar fire controller) to coordinate with fire controllers (spotters), and work out the calculations. There are only so many of these guys, so splitting up all you mortars up means you would have some tubes sitting idle (as in there isn't one MFC per tube). So one MFC can only do so much at a time.

So if a battalion has an eight 81mm mortar platoon, they are likely split into two 4-tube groups. Each group would have a one MFC team.

A single mortar is usually not able to preform indirect fire missions independently of a MFC. They have enough to do as it is without worrying about communicating with spotters and plotting. The MFC also will limit the number of rounds per fire mission, so you don't have gunners blowing off more than they should (or not enough).

I know I am not explaining this very well, its been a looong day here at work. But to summarize - they are grouped for the effects of firepower and due to how many MFCs you have.

For the question of 3 guys dividing their time on two mortars? If they are mortar trained, then yeah, but their effectiveness would be obviously reduced. It would probably be best to just add a 4th guy and split 2 men each (instead of 3).

[pmulcahy11b]

I am qualifed on the 60mm mortar and have always wonder how far the basic round no extra charges would travel

Well...this is more geared towards the older mortars I'm familiar with, but the book minimum ranges for M-19 60mm mortar using the small M-2 baseplate is 40 meters. For the M-29 81mm mortar, the book minimum range 100 meters. For the M-30 4.2" mortar, it's 770 meters.

That said, if your gunner know a few tricks, like propping up the legs of an 81mm mortar or hand-holding a 60mm mortar without the bipod, you can literally drop the round right on top of your self, or very close to yourself. Those minimum ranges are for safety. A 4.2" mortar, on the other hand, has a definite elevation maximum; on charge 0 at max elevation (which is NOT recommended) you can expect that heavy round to travel no more than about 50 meters. For the 81mm on max elevation on charge 0, you can just about quarter the minimum range above (and the old M-29 can superelevate; don't know about the newer ones). For the 60mm, if you are using it handheld, you can almost use it as a grenade launcher; some countries make a HEAT round for their 60mm because of that. If you are using the bipod, you can expect about 20 meters on charge 0.

60mm mortars are the most difficult to quantify, since they can be used as indirect fire weapons and to an extent direct fire weapons, when they are handheld.

[chico20854]

60mm mortars are the most difficult to quantify, since they can be used as indirect fire weapons and to an extent direct fire weapons, when they are handheld.

They are also mounted as a direct-fire weapons on some AFVs, such as the French AML-60 armored car. The 81mm mortar was also pintle-mounted on US Navy riverine craft such as the Swift Boat (http://forum.juhlin.com/showthread.php?t=911) for direct fire.

[cavtroop]

Here is a pic (stolen from the Post-apoc picture thread here on the forums), showing the charges on the bottom of a mortar:

http://forum.juhlin.com/attachment.php?attachmentid=728&d=1248909257

[leonpoi]

Here is a pic (stolen from the Post-apoc picture thread here on the forums), showing the charges on the bottom of a mortar:

http://forum.juhlin.com/attachment.php?attachmentid=728&d=1248909257

ahh, nice. thanks very much

[jester]

Okay, I have qualed with the 60mm and 81mm and spent a few years on a 60mm gunteam.

81s

They have the following components;

Guntube
Bipod
Baseplate the round type
Sight


Other equipment;
Aimming stakes <the red and white candy cane metal stake that comes in three sections and slides together>
Aimming stake lights, three of them, 2 red I think the third is orange, this clip to the aimming stake so you can sight in and aim at night.

Bore sight; this slips over the muzzle and you can level the gun using the bubbles and fire this way.

Further, a compass placed on the dozetail slot of the bipod can be used instead of a gunsight to sight in a gun.

Sectional cleaning pole with worm <corkscrew looking thing>

Plotting board, a square board with grids, a rotating arm in the center of the board. So it looks like a large piece of graph paper with a protractor arm that roates 360 so you can plot your rounds.

A data book as well as the knowledge of the gun crew who know what charges and elevation and deflection to use, and of course calculations are done by the FDC, the FDC at Bn level for 81mms and above has a larger dedicated FDC crew.

And the mortarmen also can be issued a funky vest that looks like a grenadiers vest that has pockets to hold mortar rounds on the front, it held I think about half a dozen rounds. I only saw them twice once in Infantry School and once in the armory on a working party. And in some movie about Korea where some Americans and Greeks are lost behind enemy lines, they encounter some British Troops in a Sherman Tank and they see an American mortar team of two running across a field and one of them had a vest as I am describing.

And of course binoculars are also available.

And the only spare part issues to mortarcrew, a FIRING PIN <for the 81mm>


At the 60mm level,

Same equipment as above,

They will also have a small rectangular baseplate
They do not have the spare firing pin!

The following is the EXACT SAME as the 81mm;

Aimming Sight
Aimming Stakes and Lamps
Round Baseplate
Plotting Board

The 60mm can be trigger fired, and it can be fired via a trigger, or the firing pin can be locked and it can be drop fired, the 81mm can only be drop fired.


A Fire Direction Center, at this level I have seen consist of the section leader who was also helping on a gun with the platoons Corpsman running the radio. These were called fire missions so the Corpsman who we brought up to speed took the info, plotted the info, the Section Leader would check and verify, issue the order, the guns would be dialed, the teams would prep the ammo and then the guns would be "up" and ready to fire.

In our section we had 3 60mms, seldom did we have more than 2 guns ready with just three man crews with the section leader and the Corpsman running the radio and FDC.

In our unit, most mortarmen were well skilled as FO's since they had to know the assorted calls for fire to be able to plot in the FDC. Simply put, when the guys calling for fire called whatever the fire mission, you had to know and put that data into firing data for the guns. And this also required excellent map and compass and distance determination skills.

Also, the whole aiming and leveling of mortars is similiar to other artillery the sight was the same! Thus, in theory, myself as a mortarman, I would be able to dial in the data on a 60mm mortar and the same method dail in the data on a 155 or 105, the problem of course is familiarization with the weapons system, the assorted adjustment knobs to bring the muzzle around.

I personaly find the rules very lacking for mortars in the game. As I recall we had three main drills;

Setting the gun up from each man carrying a seperate component. This was sometimes a exercise in commical acrobatics! We would move like sliding into place but slamming our component where it needed to go, as well as doing tumbles and rolls and leaps to get in place and out of the way. And when the Gunner called, "OFF MY GUN!" It was all on him to dial it in.

We had it down to under 20 seconds!

And then we had large deflection and small deflection changes.

Large we had a time limit of about 30 seconds, we had it do to under 20!

Small deflection changes we had i think 19, we had it down to under 10!

And then use, 60mms can fire direct fire!

You can boresight them, and we could even fire them without sights! Just use a rough guestimate of distance and direction, the 60mm had a cool range band level thingy on the gun so it determine the distance by the degree you lowered or raised the muzzle.

And also, you can put more than the max charge on a mortar. It is done OFTEN! I think the max charge was charge 5, the max we did was charge 8! It increased the range by about 40 or 50%.

Here is another thing to consider.

We had used rounds from the late 40s these were old and had less range, I had my "lil green book" stolen with all the nomenclature so I can't tell you, it had the types, years they were used, colors, ranges, weights, danger range and all that other good stuff.

But the Korean War and WWII stuff was old with less range, the Vietnam stuff into the 80s was the normal stuff we used, then we got some new stuff! AWESOME!!!!!!

And with stocks in Europe, I think we would have especialy with the many build ups that we had durring Korea, durring the assorted times of buildups in the 50s, 60s and 70s I would imagine LOTS of ammunition from those times would be the most common rather than top of the line modern ammo, at the very least, it would be equal, with shipping shiploads of ammo over, but then alot of that ammo would have been taken from assorted ammo dumps in the US that had been stockpiled over decades as well.

[leonpoi]

Thanks for the info, but now I have another question: the tw2 book describes the wojo combo mortar as having wooden sabots to use 60mm mortar bombs - would these sabots shoot out of the barrel when fired and be lost down range or at least damaged?

[Legbreaker]

Almost certainly. The sabot is designed to wrap around the round and are fired out of the barrel. After firing, they fall away from the round and, if they weren't damaged in the intial firing, chances are they'll be in less than perfect condition after hitting the ground.

[jester]

I would also add that the sabots would for the mortar reduce its range and accuracy.

And yes, they would be burnt and cracked in the initial firing, and as was stated them falling from so far, or hitting the ground at any speed they would be cracked, chipped, dented and in pretty sad shape.

[Targan]

I would also add that the sabots would for the mortar reduce its range and accuracy.

And yes, they would be burnt and cracked in the initial firing, and as was stated them falling from so far, or hitting the ground at any speed they would be cracked, chipped, dented and in pretty sad shape.
I reckon a viable alternative to wood for the sabots would be something along the lines of paper mache. Much easier and quicker to produce and much lighter (always a good feature in a sabot). Expanding foam or carved styrofoam would be even better but not necessarilly as easy to find the raw materials.

[Eddie]

I reckon a viable alternative to wood for the sabots would be something along the lines of paper mache. Much easier and quicker to produce and much lighter (always a good feature in a sabot). Expanding foam or carved styrofoam would be even better but not necessarilly as easy to find the raw materials.

You also have to think about the residue it would leave on the inside of the tube and all of the cleaning that would be necessary to get it off. Probably not the best thing for the mortar tube itself.

[Targan]

You also have to think about the residue it would leave on the inside of the tube and all of the cleaning that would be necessary to get it off. Probably not the best thing for the mortar tube itself.
True but wooden sabots would have their own problems. Pine would be easy to work with but contains alot of resin so it would present cleaning issues too. And many lighter woods expand greatly and/or warp when exposed to moisture so they would have to be carved smaller than the bore diameter to avoid nasty firing accidents. Harder woods would be less prone to warping and would probably be reusable as sabots but would be harder to source and machine. I guess you would lathe a length of wood to the required diamter, bore a hole down the middle, saw it into disks then cut each disk in half.

[Eddie]

True but wooden sabots would have their own problems. Pine would be easy to work with but contains alot of resin so it would present cleaning issues too. And many lighter woods expand greatly and/or warp when exposed to moisture so they would have to be carved smaller than the bore diameter to avoid nasty firing accidents. Harder woods would be less prone to warping and would probably be reusable as sabots but would be harder to source and machine. I guess you would lathe a length of wood to the required diamter, bore a hole down the middle, saw it into disks then cut each disk in half.

Don't misunderstand. I'm not a proponent of either. I'd rather fire 81mm rounds from it.

That said, the problems from wood would be a lot more easily mitigated with more options than paper mache or styrofoam, because no matter what type of paper you use, it's still mache. The same with styrofoam.

[jester]

The styrafoam would melt, and cover the barrel with melted goey plastic that would harden and made the gun unusable, or worse, cause a hangfire <BAD MOJO!> styrafoam also can burn, imagine fire touching those charge bags? Another case for BAD MOJO!

Paper Mache, it would be blown to pieces, or burn up and you would not get the tightness in the bore, which would cause the round to wobble as it left the bore which would result in a "IRRADIC ROUND!" this is another case for BAD MOJO! When you have such casses the whole crew shouts, screams, waves their arms and does a monty python reinactement of "RUN AWAY! RUN AWAY!" because that round is going someone other than where you intended it to go, and it is going to go much shorter too.

Granted, an 81mm round down the pipe of an 82mm no biggie but when its a 60mm down an 82, and its sabot was bad well that as I put it in my Spanish class, "muy malo....muy muy malo."

[Targan]

Okay, so foam and paper mache would be bad. Surely there would be a better way than a wooden sabot. A slide-in metal tube insert of the correct bore diameter?

[Caradhras]

As a complete armchair military man... 0 actual service..

Can anyone tell me how a single person could man an 81mm - would it just take 3x as long? Rules have fire rate of 1 per round.

Also, the smaller 60mm, would that be easier and therefore not x3 or ?

It's just I have a player in my campaign that loves to get a mortar set up and fire it solo and I dont know how difficult this would be.

[Fusilier]

Can anyone tell me how a single person could man an 81mm - would it just take 3x as long? Rules have fire rate of 1 per round.

Also, the smaller 60mm, would that be easier and therefore not x3 or ?

As long as the ammo is already prepped for the required fire mission and plotted I would say x2 as a GM. He could load/fire on his own and periodically check for/make minor adjustments to the leveling bubbles (as they get knocked off with repeated shots).

The 60 should be the same, unless fired direct. Then it can just be using the tube (no bipod), and can be (and is) handled by one man. Especially so if he sets it to lever action and not drop fire.

[pmulcahy11b]

I reckon a viable alternative to wood for the sabots would be something along the lines of paper mache. Much easier and quicker to produce and much lighter (always a good feature in a sabot). Expanding foam or carved styrofoam would be even better but not necessarilly as easy to find the raw materials.

I would think discarded styrofoam or styrofoam from wrecked stuff would be blowing around all over the T2K world. You can find it all over even now.

[cavtroop]

I would think discarded styrofoam or styrofoam from wrecked stuff would be blowing around all over the T2K world. You can find it all over even now.

I'd imagine that a styrofoam sabot will result in a POOF of white flakes out the end of the tube, and a clunking sound as the round slides back to the bottom :)

Wouldn't you need something more substantial? Maybe styrofoam, with a metal plate around the bottom so the charges don't disintegrate the sabot?

Edit: Duh, this was already covered, and I missed the posts :) DOH

[leonpoi]

As a complete armchair military man... 0 actual service..

Can anyone tell me how a single person could man an 81mm - would it just take 3x as long? Rules have fire rate of 1 per round.

Also, the smaller 60mm, would that be easier and therefore not x3 or ?

It's just I have a player in my campaign that loves to get a mortar set up and fire it solo and I dont know how difficult this would be.
According to tw2.2 rules a 81mm mortar has a crew of 3 for ROF 1 per round (I think that it would be technically 1 per action but I'm not letting high init characters shoot large guns faster). Also, somewhere in the combat section is states that crewed weapons add 1 action (or maybe it's round, can't remember) to reload time for each crew member lost.
i.e.
Crew 3 = Reload 0
Crew 2 = Reload 1
Crew 1 = Reload 2, so 1 round fired every 3 rounds instead of 1, but I'd agree with the comments that if the rounds were all preped and ready to go, maybe this could be 1 round every 2.
As an aside, and in general for any gun, I also put in place extra ready actions if the ammo isn't handy, for e.g. magazines in backpacks and mg belts which are not laid out or in a box ready to use. In general I let reloading a "box" fed weapon as 1 action as per the rules, but I make reloading and returning the spent magazine to webbing or a pocket as 1 reload + 1 ready action (just so that players can lose mags when on the run etc).

A 60mm mortar has crew 3 and ROF 1 in v2.2. In v1 it has ROF 2, so I've let 60mm mortars fire 2 shots per round indirect if crewed by 4.

Thanks for the discussion on sabots; I found a website that talks about firing 60mm bombs from a 81mm USA mortar using wooden sabots. It mentioned that they can be re-used about 10 times, if found. The round comes bundled in the wood case, so all the rounds are pre prepared.

[pmulcahy11b]

According to tw2.2 rules a 81mm mortar has a crew of 3 for ROF 1 per round (I think that it would be technically 1 per action but I'm not letting high init characters shoot large guns faster). Also, somewhere in the combat section is states that crewed weapons add 1 action (or maybe it's round, can't remember) to reload time for each crew member lost.
i.e.
Crew 3 = Reload 0
Crew 2 = Reload 1
Crew 1 = Reload 2, so 1 round fired every 3 rounds instead of 1, but I'd agree with the comments that if the rounds were all preped and ready to go, maybe this could be 1 round every 2.
As an aside, and in general for any gun, I also put in place extra ready actions if the ammo isn't handy, for e.g. magazines in backpacks and mg belts which are not laid out or in a box ready to use. In general I let reloading a "box" fed weapon as 1 action as per the rules, but I make reloading and returning the spent magazine to webbing or a pocket as 1 reload + 1 ready action (just so that players can lose mags when on the run etc).

A 60mm mortar has crew 3 and ROF 1 in v2.2. In v1 it has ROF 2, so I've let 60mm mortars fire 2 shots per round indirect if crewed by 4.

Thanks for the discussion on sabots; I found a website that talks about firing 60mm bombs from a 81mm USA mortar using wooden sabots. It mentioned that they can be re-used about 10 times, if found. The round comes bundled in the wood case, so all the rounds are pre prepared.

I would add that one man crewing an 81mm mortar would count as hard work for that period. And tell your player to have fun setting up the aiming posts...he'll have a hell of a time trying it, and without properly-set aiming posts (or a Mortar Fire Computer with a GPS unit), I'd multiply deviation by 5, above any normal amount of deviation.

[Targan]

I wonder how the Vasilek auto mortar works? Gravity fed ammunition feed, spring-fed or some kind of mechanical feed? Does some sort of autoloader arrangement fit charges to the rounds before firing, are the charges pre-set or do Vasilek rounds only have one charge setting? Questions, questions...

[pmulcahy11b]

I wonder how the Vasilek auto mortar works? Gravity fed ammunition feed, spring-fed or some kind of mechanical feed? Does some sort of autoloader arrangement fit charges to the rounds before firing, are the charges pre-set or do Vasilek rounds only have one charge setting? Questions, questions...

I don't know how the charges are set, but it's fed from a magazine (basically, spring-loaded) from the right side.

[Legbreaker]

http://forum.valka.cz/viewtopic.php/title/SOV-2B9-Vasiljok-82mm-automaticky-minomet/t/27217
That might help (if you can speak the language).
The first picture, while unclear, appears to show charges around the tail as is found with conventional mortars.

[jester]

The Vasilek looks like it takes normal charges from the powder bags near the fins. They just precharge em before loading them into the magazine.

We also did it with the 60mm when we drop fired it. I forget it has beleive it or not been 20 years and a couple days so I am allowed ;)

But the idea of the 60mm drop firing is, for tactical line of sight firing.

The small baseplate is carried locked, and when needed the gunner slams the gun down, uses the elevation guide and drops rounds down the tube firing using the trigger. The charges on the rounds are not adjusted!

As for hard work manning an 81mm.

Only if it is humbed. Otherwise once the gun is set up you just have to make sure the gun is adjusted back to zero which is usualy a small adjustment <the manual give us like 20 seconds, most do it in about 9 to 12> Again, ammo prep can be done before the fire mission, most fire missions even a fire for effect is usualy about 3 rounds per tube.

And one man can move a 81mm by himself, although, he would not be very fast. A 60mm our displacement method was grabe the whole system and run away a few 100m, the original shoot and scoot.

[Legbreaker]

The answer seems to be fairly obvious to me, but on behalf of all those with no experience, I ask the following of our mortar and indirect fire trained members.

How accurate would an indirect weapon be if fired from a moving platform such as a slow moving vehicle or boat without the benefit of various high tech guidance systems?

[pmulcahy11b]

The answer seems to be fairly obvious to me, but on behalf of all those with no experience, I ask the following of our mortar and indirect fire trained members.

How accurate would an indirect weapon be if fired from a moving platform such as a slow moving vehicle or boat without the benefit of various high tech guidance systems?

They do make mortars for that sort of application -- they are generally breech-loaded mortars that can be fired in direct and indirect fire modes, and often called gun/mortars. But while they can be fired with good accuracy in direct fire, indirect fire is inherently less accurate; I can't imagine getting any sort of accuracy trying to conduct indirect fire while moving. Not even the most modern SP howitzers are capable of that trick -- they may fire from a quick halt, but not while moving.

That said, light mortars were used from boats in Vietnam. It would depend on the speed, but I'd multiply the deviation somewhere from x2 to x10. Most of those boats still made a quick stop on a beach or riverbank to fire the mortar.

Hmmm...the mortar's moving and the target may or may not be moving. It sounds like a recipe for making your spotter insane.

[jester]

The mortar and set up you have I am familiar with ;)

At a slow speed, in theory I think I could do it!

If its used in the direct role, piece of cake!

In the indirect fire role, sight it in, and if the movement is not so fast and you take into account the movement, and more or less lead the target you could be on target, remember a mortar is an area weapon, and if the rounds land close to the target it counts just like horseshoes and handgrenades. A moving platform would possibly act as a traverse fire mission, where the rounds land more or less in the line of travel, going down river, keeping in mind that a minor distance on the sight will be a greater distance down range, so, firing at a rapid but steady and unhuried pace could give a similiar effect as a traverse mission. Again, this is theory and oh to be on a gunline again to test it, as it does sound interesting.

[pmulcahy11b]

At a slow speed, in theory I think I could do it!

If its used in the direct role, piece of cake!


If the mortar gunner can actually see his target, he could also do a direct lay -- that would be much easier than standard indirect fire. (In direct lay, you are sort of using your mortar sight to aim at the target; direct lay is tricky, takes a good gunner, and you are still going to have deviation, but it's not as much deviation as standard indirect fire and the gunner can function as his own spotter. The downside is that if you can see your target, the enemy can probably see you...)

[jester]

If the mortar gunner can actually see his target, he could also do a direct lay -- that would be much easier than standard indirect fire. (In direct lay, you are sort of using your mortar sight to aim at the target; direct lay is tricky, takes a good gunner, and you are still going to have deviation, but it's not as much deviation as standard indirect fire and the gunner can function as his own spotter. The downside is that if you can see your target, the enemy can probably see you...)

Thats it! Direct lay! I was thinking boresighting, direct lay, thats the term I was trying to come up with the last several days. And that is how I would do it. Like I said, in theory it could work and the results would be like a traverse fire mission along the route of travel of the vehicle.

Of course the issue I would worry about is stability especialy after the first round throwing off the gun with the rocking, this could make following round go wild, as well as strong waves, sharp turns and evasive manuvers, again, these could toss the rounds to go way off!

However, the precident does exist of firing mortars and artillery from boats, this was done durring the British attack on Ft. McHenry which inspired Francis Scott Key to pen "The Star Spangled Banner." As were mortar barges and rocket ships common, and in the amphibious landings in Europe and the Pacific many vessels had 105 and 75mm howitzers firing on them or mortars and of course rockets. The Rangers attacking Pt Du Hoc fired mortars from their craft to launch the ropes and ladders which they scaled the heights with. And I seem to recall some units in the Delta of Vietnam had 105s on LSTs or barges firing, so it is entirely possible.

Again, having been a mortar magot once upon a time, the idea is something I would love to test.

[Fusilier]

I would say impossible (for indirect). You almost never drive in a straight line, and once you've turned just a little, that's it. It its a few kilometers away, the bomb's deviation is magnified sooo much, they're be no point in even trying.

If it were possible, it would definitely be the norm.

[Legbreaker]

Assume the mortar is located on a boat and travelling through this sort of environment in predawn without sonar equipment to prevent grounding.
The boat would need to make sudden turns and stops without more than a few seconds warning.
The mortar crew also cannot see the target area although do have a general idea of it's location (as they should anyway).
Only a handful of rounds are available but an FO is on hand with an unobstructed view of the target area.

Given those details, how likely is it for even one round to strike the target zone?

http://mw2.google.com/mw-panoramio/photos/medium/892293.jpg

[jester]

Like I said, all the guncrew needs is distance and direction, then it is up to their data, they can dial in the gun and make sure it is dialed or sighted right. After that it is up to the winds, the gunsite being half a mil off or even a quarter or even the recoil of the gun as it fires as well as the round how well it leaves the barrel, how heavy, how well balanced how old, the charges did they burn right those are all some of the factors that can cause the unknown to happen.

But, they can do everything on their end, get it sighted in and the direction and make sure the data is right on their end. I am figuring they will aim for point X and firing from a moving target going at about 6 knotts they may hit target X plus 30m in the direction they are traveling, they may be a little closer, it depends on how fast their guncrew is. And then the rocking of the vessel from recoil may cause a checkerboard pattern of impacts, firing on the uproll the roads go inland and on the down they land closer, which may be cool since you could cover the target area nicely depending on the size of the round.

As for being common, they do the math for modern naval gunnery so it can be done, it just takes a good amount of math.

Remember, a mortar is not a point target weapon, can you hit the target directly SURE! I have done it many many times back in the day. But it is an area target weapon so if the round lands within the casualty radius area then it is considered a hit.