Mortar Shell Function

[M16Rifle]

Does anyone know how a mortar shell is propelled ? I know that there is a
fuse at the bottom where a pin strikes it and ignites the propellant charge ,but
where do the gases escape from ? I think from the holes on the side but i am not so sure.I couldn't find on the internet a good cutaway image and some information about it.I also couldnt find any information about the propellant charge , maybe it is blackpowder :D
I would be very thankful someone has some good information about the mortar shell or some cutaway pics.

Thanks

[tomu]

You posted in the pyrotechnic section but I guess you mean military mortar rounds.

Usually the gas escapes from holes drilled in the hollow mortar shaft which holds the ignition cartridge and sometimes also the propellant charge. The propellant charge is a nitrocellulose based propellant and not black powder.

The propellant charge can also be placed around the outside of the mortar shaft in collar like pouches it will be ignited by the hot gases which escape the holes in the mortar shaft.

Have a look at the pictures where you can clearly see the holes in the shaft. Do a google search and you will find a lot more pictures.

http://en.wikipedia.org/wiki/Mortar_(weapon)

http://history.amedd.army.mil/booksdocs/wwii/woundblstcs/chapter1figure25.jpg

[M16Rifle]

here i made an image using mspaint how i imagine it functions.
Please correct me if this is wrong.

thanks

[tomu]

Well. thats how it works. Obviously the pressure acts to all sides not just above and at the sides of the launching tube. Also the clearance between the mortar round and the launch tube is quite small.

Among other things you will find a cutaway drawing of an US 60 mm mortar round at this site:

http://www.inetres.com/gp/military/infantry/mortar/60mm.html

and at this side you get some pics of iranian mortar rounds where you can clearly see the propellant charge collars fastend around the mortar shaft:

http://www.slugsite.com/archives/325

You can get plenty of information by just doing a google search about mortar shell or mortar round.

[M16Rifle]

Wouldn't blackpowder do approx. the same job ? (like the rpg booster)

Another small question: When the booster of a rpg shell is ignited(blackpowder) does the gas pressure break the bottom of the shell where the primer is used to be ,or do the gases just escape through the small hole of the primer ? i've heard that blackpowder needs small nozzles.

Thanks

[Cordtex]

RPG B-7 boosters contain some black powder charge in a textile wrap inside the fin assembly of the booster section, this is the primer for the booster's cordite propelling charge. Coming to the mortar function, in short, the tube and the shell work just like a piston and a cylinder in an internal combustion engine. Fairly simply to understand I guess. The mortar round may contain black powder as primer as well. In the attached images you can see the primer, there goes the black powder inside the brass tube.

[Barnacles]

I could swear I saw a mortar awhile ago propelled by a shotgun cartridge , most likely without a projectile in the cartridge. Maybe this was a makeshift propellant.

It was in an Iraqi insurgent video, I saw a guy stick a shotgun shell ino the back hole that you see in the pictures above.

[Cordtex]

Some mortar rounds come with separate propelling cartridges. So before firing, the cartridge is inserted in its place. It looks like a shotgun shell but it isn't really a shotgun shell :)

[M16Rifle]

Barnacles i think this is what you mean:

http://www.inert-ord.net/usa03a/usa5/6081/6872.jpg

[Microtek]

An 81 mm mortar grenade (of the type I used in the army; WWII style) is only propelled ca 600 m with just the center charge (the one that looks like a shotgun shell) additional charges are fitted between the fins. The number of additional charges determine the "range band" that you can fire in.

[M16Rifle]

hi all,

in the last 3 days we had again some really aggressive fightings around here ,
today i saw that one building was hit 4 times with rpg's.Near our house a shell exploded in the air and i found the sutainer motor part :D

the smell of the inner part is horrible , what type of propellant is used in the sustainer motor ?

[Cordtex]

EDIT: M16Rifle, shouldn't you follow your last post in your RPG-7 related thread?

IIRC it must be a cordite which contains some carbon and potassium chlorate. You may also check the washer like piece with holes, inside the tube. I guess it holds the tubular propellant grains away from the nozzles.