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]

Originally Posted by copeab

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.

[leonpoi]

Originally Posted by Fusilier

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.

Paul, Law?

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

[pmulcahy11b]

Originally Posted by bigehauser

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.

[Fusilier]

Originally Posted by leonpoi

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.

[kato13]

Originally Posted by copeab

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.