Author Topic: Mortar accidents (Read 4429 times)

Cannoneer · « **Reply #30 on:** September 03, 2011, 05:14:42 AM »

Response to Double D, Reply #27

Well, yes, I understand that, but those rules were enacted to prevent the cannoneers and audience from suffering serious injuries; do you think the blowback that you're talking about is capable of doing real harm?

gunsonwheels · « **Reply #31 on:** September 03, 2011, 05:54:07 AM »

Upon ignition, the gas blast, with windage, will be up the muzzle bore wall, past the projo and out the muzzle in the direction the muzzle is pointed. However... as the projo emerges out the end of the muzzle, the gases are going to blow out over an area which is bounded by the angle of the muzzle face (normally 90 degrees) on one side and the changing angle which is a tangent to the the emerging radius of the projo. Coning the muzzle face or even a short section of the muzzle face will now limit the blast angle spread to be confined between the emerging tangent and that coned angle. My backgound as an engineer and in amateur rocketry helps me to visualize the gas blast and its changing "nozzle" effects. A good rocketry handbook and the chapter(s) on designing a nozzle will aid in being able to visualize what is happening. Mine has been out of print for years or I would recommend it. If you can visualize it, it's easy to understand and agree with what Douglas is telling us. The Physics predicts it will "go down" (or up and out) the way Douglas says... as to generating a controlled test set-up and actually demonstrating those physics and gathering the data... I doubt anyone has done that because its like driving a speeding car down an alley between two concrete walls... no matter how drunk the driver, with the gas pedal mashed down the car will stay between those walls. Why pour the concrete, bugger up a car and get someone needlessly drunk to prove it?

Standing or being in the blast of a rocket or artillery piece is not wise at the least and downright dangerous at best. Additionally a foreign body from off the projo or from within the powder could be lethal. Regardless of the injury history (or lack of one) I'll continue to try and not be in blast zones...

Double D · « **Reply #32 on:** September 03, 2011, 06:23:24 AM »

Quote from: Cannoneer on September 03, 2011, 05:14:42 AM

Response to Double D, Reply #27

Well, yes, I understand that, but those rules were enacted to prevent the cannoneers and audience from suffering serious injuries; do you think the blowback that you're talking about is capable of doing real harm?

Took a week and a half for the blister on my lip to heal, 4th of July...can't image getting hit in the eye...

Cannoneer · « **Reply #33 on:** September 03, 2011, 06:25:19 AM »

Quote from: gunsonwheels on September 03, 2011, 05:54:07 AM

Standing or being in the blast of a rocket or artillery piece is not wise at the least and downright dangerous at best. Additionally a foreign body from off the projo or from within the powder could be lethal. Regardless of the injury history (or lack of one) I'll continue to try and not be in blast zones...

gow,
Is this a direct response to my post, which precedes it?

Double D · « **Reply #34 on:** September 03, 2011, 06:31:28 AM »

John,
My burnt lip from blow back form vent has another lesson in it. If you are left handed and ignite quill from the left side do not start lighting fuses in a series of guns from the left side of the line. start at teh right side. That way instead of passing behind a mortar with a lit fuse, to light the next, you are moving away for the the lit fuse to light the next.

I think George is replying to Victors post.

Cannoneer · « **Reply #35 on:** September 03, 2011, 06:52:13 AM »

Quote from: Double D on September 03, 2011, 06:23:24 AM

Quote from: Cannoneer on September 03, 2011, 05:14:42 AM
Response to Double D, Reply #27

Well, yes, I understand that, but those rules were enacted to prevent the cannoneers and audience from suffering serious injuries; do you think the blowback that you're talking about is capable of doing real harm?

Took a week and a half for the blister on my lip to heal, 4th of July...can't image getting hit in the eye...

I hope that you're wearing something over your eyes to prevent that from ever happening, because I sure do, whether firing one of my Model 700's, or when (even more of a must) fiing any of my miniature artillery pieces.
Were you standing directly behind the mortar when a live ember hit your lip?

Cannoneer · « **Reply #36 on:** September 03, 2011, 07:00:27 AM »

Douglas,
Either you're very intuitive, or I type very slowly; maybe it's a combination of both, but any way you slice it, you've already answered my question.

Now don't misunderstand my posts, I'm not putting the idea down, because I believe that almost any safety measure is good safety; but if I had a choice in the matter, I don't think that I'd opt to use a shield when firing with fuse or quill.

Double D · « **Reply #37 on:** September 03, 2011, 07:16:25 AM »

Quote from: Cannoneer on September 03, 2011, 06:52:13 AM

I hope that you're wearing something over your eyes to prevent that from ever happening, because I sure do, whether firing one of my Model 700's, or when (even more of a must) fiing any of my miniature artillery pieces.
Were you standing directly behind the mortar when a live ember hit your lip?

When I got glasses, the wife made me buy the safety lenses. She knew me well..

About the burnt lip,

Quote from: Double D on September 03, 2011, 06:31:28 AM

John,
My burnt lip from blow back form vent has another lesson in it. If you are left handed and ignite quill from the left side do not start lighting fuses in a series of guns from the left side of the line. start at teh right side. That way instead of passing behind a mortar with a lit fuse, to light the next, you are moving away for the the lit fuse to light the next.

Artilleryman · « **Reply #38 on:** September 03, 2011, 10:07:48 AM »

Quote from: Cannoneer on September 03, 2011, 03:57:07 AM

Quote from: Double D on September 01, 2011, 06:08:43 PM
As far a vent debris flying out of the mortar on firing, at the N-SSA events mortars are required to have a vent shield.

I an thinking about requiring them at future Montana shots.

I believe that these skirmish assoc. rules came into being because they use friction primers to ignite their mortar charges, and the spent tubes are blown out with considerable force. Were there any issues at the 'MT Shoot', with debris blowing back out the vents of the mortars?

Not all skirmish assoc. mortar crews use friction primers, but all are required to use a vent shield. I use vent shields that have a plywood defector. After examining the condition of the shield I am glad that I use one.

gunsonwheels · « **Reply #39 on:** September 03, 2011, 10:17:37 AM »

Cannoneer:

Quote

gow,
Is this a direct response to my post, which precedes it?

I think the answer is yes... by the time I finished typing about the gas vectoring I saw your post and added the last paragraph. I've been bit by fuse debris more since getting Ed's mortars than all previous cannon shooting... I need a few new ideas about staying safe with mortars

Cannoneer · « **Reply #40 on:** September 03, 2011, 11:57:48 AM »

"Standing or being in the blast of a rocket or artillery piece is not wise at the least and downright dangerous at best. Additionally a foreign body from off the projo or from within the powder could be lethal. Regardless of the injury history (or lack of one) I'll continue to try and not be in blast zones... "

Well George, I'm also open to (at least I hope I am) new ideas, as a matter of fact, if they're delivered in a congenial manner I can be downright appreciative; but if someone delivers them in a preachy and condescending manner, I'll freely admit to you that it rubs me the wrong way. Now I'm going to assume that you're aware that I'm an adult, so I would like to ask you a simple question: Who, in your opinion, but someone with the intellectual capacity of a young child, would not comprehend without being told, that it would be extremely dangerous to be in the near vicinity of a rocket's exhaust, or the blowback coming out the vent of a muzzleloading artillery piece?

Cannoneer · « **Reply #41 on:** September 03, 2011, 01:08:10 PM »

Quote from: Artilleryman on September 03, 2011, 10:07:48 AM

Not all skirmish assoc. mortar crews use friction primers, but all are required to use a vent shield. I use vent shields that have a plywood defector. After examining the condition of the shield I am glad that I use one.

Artilleryman,
I've personally only fired a 1-inch, GB, and beer can sized mortar, so I have no hands on experiece with the big stuff. This is only my individual viewpoint on using a shield with these smaller sized mortars: I think it would be overkill, but this opinion doesn't mean that I don't respect the choice that another cannoneer might make to use one. When I fire these mortars I make sure that there's no one close behind the mortar, and that I'm standing well off to the left side. Now if I was firing yours, or a 10-inch mortar with a fuse, quill, powder train, or friction primer then you can bet that I'd be using a shield.
What is the diameter of the vent hole on your 8-inch mortar?

Artilleryman · « **Reply #42 on:** September 03, 2011, 02:29:02 PM »

The friction primers have a .188 inch diameter, so I would say the vent is approximately .200 of an inch. I don't have any experience with anything less than a 12 pdr mortar, and my comments are only related to the larger mortars.

Double D · « **Reply #43 on:** September 03, 2011, 02:32:05 PM »

I under stand what you are saying about the small mortars. Is it overkill? Maybe. When you find blown out quill debris 10-15 feet behind the gun, then you have wonder.

Here is the mortar that got me. My Dom dictator pop can mortar.

A littel over one second clip showing the hot gases blowing out the vent.

Here is three consecutive frames to give you some idea how fast and high the gas vents. Each frame is 1/30 second apart.

Here is the same setup in a golf ball mortar.

Again three frames 1/30 second apart.

No I don't know what that little puff is before the gun fires.

Do I think these little guns need vent shields. Depends.

When South paw and I get together for informal drive golfball mortar shooting, probably not.

But a formal gathering like CBCC with 10-15 Cannoneers on the line and spectators up behind watching, probably

gunsonwheels · « **Reply #44 on:** September 03, 2011, 02:54:28 PM »

Cannoneer:

Quote

...do you think the blowback that you're talking about is capable of doing real harm?

Quote

Well, yes, I understand that, but those rules were enacted to prevent the cannoneers and audience from suffering serious injuries; do you think the blowback that you're talking about is capable of doing real harm?

Well... I read both of the above statements again and I guess I am not at all sure what you are trying to say by making them... I certainly didn't mean to be condescending or insulting in my response but I did certainly mean to be emphatic but primarily for any third party that might be following along. I think the statements could be construed as trying to justify ignoring the safe practices recommended previously in the thread. $:-\$ If I am completely off base, again I further apologize and am sincerely sorry they came across in a manner which was not intended.

George

Artilleryman · « **Reply #45 on:** September 03, 2011, 02:56:56 PM »

Nice set of pics showing what is going on at the vent. The little puff of smoke prior to the mortar "firing" is gases escaping from the vent before the projectile has time to leave the barrel. I agree that it is a good idea to have a vent shield up when there are other crews and spectators around.

I wonder if it would be worthwhile to put up some newsprint at various distances behind the vent to "pattern" the debris. Just a thought.

GGaskill · « **Reply #46 on:** September 03, 2011, 07:24:07 PM »

I have several burns on my old high power rifle shooting coat from fuse fragments ejected from a golf ball mortar. While I do not think these would be dangerous from a kinetic point of view, they were obviously hot enough to char the cloth and would be a danger to eye sight.

I have taken to placing a soda can half filled with water and with an opening cut into it in the upper half to catch the debris behind even golf ball mortars. I think some kind of barrier is a good idea.

Cat Whisperer · « **Reply #47 on:** September 04, 2011, 04:02:55 PM »

Quote from: GGaskill on September 03, 2011, 07:24:07 PM

I have several burns on my old high power rifle shooting coat from fuse fragments ejected from a golf ball mortar. While I do not think these would be dangerous from a kinetic point of view, they were obviously hot enough to char the cloth and would be a danger to eye sight.

I have taken to placing a soda can half filled with water and with an opening cut into it in the upper half to catch the debris behind even golf ball mortars. I think some kind of barrier is a good idea.

Excellent! We tend to overlook the power and hazards of fuse and muzzle blast. The force (at the muzzle is enough to snap a 1" board adjacent to the barrel! Likely close to the same force ejecting the fuse.

1Southpaw · « **Reply #48 on:** September 04, 2011, 07:13:13 PM »

@ CBCC II I recieved a nice burn on my forehead from firing off a steel ball from my Golf Ball Mortar.

Way more pressure from the vent than a golf ball.

It had enough force to bounce off my hat brim and on top of my safety glasses ,a bit caught the top of my eye . Not smart , I was using a "Quick Fuse " . It blew back before I had time to "Duck"

I'm happy to say it healed fine , but do you think it would excuse my poor spelling ?

Cannoneer · « **Reply #49 on:** September 04, 2011, 11:06:02 PM »

Well fellas, the number of hits on this thread has just risen from 666 (that's just for Tim, I didn't want him to miss it

), so I can only hope that this doesn't hint at any ominous connections to anything of an apocalyptic nature being close at hand.

Does anyone else have any views on, or personal experiences with this subject, that they'd like to relate? I count four members who've already admitted to being hit (and burned) by solid residue being ejected out the vents of their mortars upon firing them. Come on Cat fess up, by the exitement shown in your post, I bet that that you've survived a still burning fuse remnant that hit right on the ten ring of an unprotected cornea; or are you a nerd like me, that always wears eye protection when involved with things of this nature?

Cat Whisperer · « **Reply #50 on:** September 05, 2011, 03:11:08 AM »

666 eh? Not anymore. (but thanks). (Did you see the bumber sticker: "333" "half wicked" ?)

I did put the ember out. But I don't shoot much for targets with mortars.

And yes, I've been hit and nearly hit by flying fuses. You guessed my enthusiasm correctly - for a SOLUTION that catches the hot flying fragments of fuse.

In industry, one always will get better reliabilty if a machine or a computer does the repetitive task rather than the person.

flagman1776 · « **Reply #51 on:** September 05, 2011, 03:36:33 AM »

delete

Ex 49'er · « **Reply #52 on:** September 05, 2011, 07:24:38 AM »

One of the first times I was firing my Beercan mortar I smelled smoke and looked down at my chest. My shirt had caught an ember from the fuse and was burning. That shirt became my lucky mortar-shooting shirt. After that episode I made a shield from a wall mounted kerosene lamp reflector. On my gb mortar I've got a shield that folds out of the way made with 1/16" gap wire mesh. At the shoots we used to have all mortar were required to have a shield to stop burned-fuse-blowback. Seems like somebody stuck a cast-iron skillet in the ground and it did the trick. That's my 2 cents worth.

Cannoneer · « **Reply #53 on:** September 05, 2011, 08:19:50 AM »

Ex 49'er,

Well I got to tell you that that's one good looking shield; in my opinion Cat Whisperer would be making a wise choice if he took some inspiration from your design when he starts constructing the shields he's going to be making for his own mortars.

Is your shield attached near the top of the tube, and is the firing procedure to lift it, light the fuse, then set it back down over the fuse, or is it just stuck in the ground behind the vent when you fire?

gunsonwheels · « **Reply #54 on:** September 05, 2011, 08:24:11 AM »

Thanks for the multiple reminders about safety glasses... I guess I'll get out my old silhouette shooting box and dig out the side shields for attaching to my glasses when shooting.

Cannoneer · « **Reply #55 on:** September 05, 2011, 08:35:34 AM »

Your welcome George, we've got to keep those novices in mind when we're dicussing safety. Even when I'm launching ball bearings from my magnum slingshot at the butt of the pesky squirel that's chewing up the wooden bird feeder in my yard, you can be sure that I'm wearing safety glasses.

Ex 49'er · « **Reply #56 on:** September 05, 2011, 08:42:34 AM »

Quote from: Cannoneer on September 05, 2011, 08:19:50 AM

Ex 49'er,

Is your shield attached near the top of the tube, and is the firing procedure to lift it, light the fuse, then set it back down over the fuse, or is it just stuck in the ground behind the vent when you fire?

The shield is pierced through the top and bottom with a narrow slit and the shield slides down over the upright 1" wide piece of metal that sticks out above it. It rests on the bottom of the upright which is curved to go almost around the barrel of the mortar and the curved part rests on the trunnions. The whole thing rotates to the side to insert the fuze and is then rotated back to cover the vent. There is enough fuze sticking out to be lit. Hope this helps.

Cannoneer · « **Reply #57 on:** September 05, 2011, 09:11:09 AM »

Okay, thanks, I think I got it. At first sight, I thought that was a reinforce ring by the breech; so the shield is attached to the ring, and the ring rotates to the side, you insert the fuse, rotate the shield back over the vent with fuse sticking out to light, and you're ready to go. Ingenious!
What are those light colored dowels seen on the top of the bed, do they go through and into the ground to anchor it?

Ex 49'er · « **Reply #58 on:** September 05, 2011, 09:46:11 AM »

Yup, you got it. The ring lacks about 2 inches of reaching all around. The shield and the mount can be taken off and apart to wash after firing.

The dowels are actually stainless bolts that have nuts attached between the braces on the bottom of the sled and act as levelers on uneven ground. There is a level attached on the top left of the sled and I've got a bubble level that can be set wherever on the sled to level it all out.

Cat Whisperer · « **Reply #59 on:** September 05, 2011, 02:09:17 PM »

Quote from: Cannoneer on September 05, 2011, 08:19:50 AM

Ex 49'er,

Well I got to tell you that that's one good looking shield; in my opinion Cat Whisperer would be making a wise choice if he took some inspiration from your design when he starts constructing the shields he's going to be making for his own mortars.

Is your shield attached near the top of the tube, and is the firing procedure to lift it, light the fuse, then set it back down over the fuse, or is it just stuck in the ground behind the vent when you fire?