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LRTM-100

Posted: Tue Sep 25, 2007 2:40 am
by Killjoy
LRTM-100

Long Range Tactical Mortar- 100mm


Specs:
-4" diam barrel 5.5 feet long
-4" diam chamber 5 feet long
->Over 10 feet long

-Stun gun as ignition source
-One end pluged with two 1/2" thick particle bored cut outs.
-1" inch ball valve for venting screwed and glued into plug.
-80mm fan for venting.
-Designed for use with large bottles and depleted propane canisters.
Approximate range=over 500 yards with 100g projectile.

I built this cannon using nothing but stuff I had lying around, and only because I became too fed up with trying to get my new hyrbid to work.

The Plug.
Discs came from the cardboard tube some pipe came in from mcmaster. The ball valve came from a scrapped project. Fitted in a whole and then screwed and glued in for support.
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The Fuel Meter.
Used 1 1/4" pvc pipe, screwed in the gauge and valve into the pvc, and then cut some 1/4" acrylic and expoxied it on (and screwed the propane and torch head into one side. I had to use pumbing strap to keep the acrylic from blowing off the one end as it had done during preliminary test). It is filled to 60 psi with propane.
Image

The Cannon
I used old 2x4s for the stand and bailing wire to strap the cannon down (couldn't find the plumbing strap after cleaning the garage). The barrel is connected to the chamber by sliding it on to a 3" end cap (has top cut off) that has been glued and screwed into the end of the chamber. The Barrel is then screwed onto the cap.
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The Hinge
Made using 3/4" sch 40 pvc and 1/2" rebar. Two pieces of pvc are screwed on to the stand, and one piece to the 2x4 the cannon is strapped too. The rebar is then pushed though and screws put through the ends of the pvc to keep the rebar from sliding out. The hinge is also loose, so I can adjust the horizontal direction of the cannon with out having to move the entire stand to either side.
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Th first tests were succesful but not to impressive. An empty tin can was fired and almost completly flattened, and a golf ball richotched of and hit my neighbors house (oops).
Later tests with the stand fitted resulted in an empty 1 liter bottle taking off a small tree branch and a 1/2 liter bottle filled with water taking off another larger one.
I conducted one range test, and the bottle a 1/2 litter water filled bottle (not completely full)flew well over a road, a house, and the road on the other side of the house (lost sight of it). The house marks roughly 300 yards and the road 450. Joanna's rang calculator also said the range would be about 500 yards.
Currently the camera with the videos is being used my my mom for her work, so it could be a while before I can get some videos up here.

Posted: Tue Sep 25, 2007 2:58 am
by TwitchTheAussie
I love it. Shes truly a beast. Lets call her Jennifer in memory of my ex :lol: . truly a beast. Keep up the good work man :P

Posted: Tue Sep 25, 2007 10:29 am
by dauphinoise potato
Nice beast of a cannon. She is really awesome.

Posted: Tue Sep 25, 2007 11:32 am
by Fnord
Are you expecting a war? Whats with the cut timber wall in the background?
Lemme guess, your house also has merlons on the roof and is surrounded by a moat :)
With sharks in it.


If I was one of your neighbors I'd be a little scared.
Give it some camo or black paint and it'll be perfect.

Posted: Tue Sep 25, 2007 1:19 pm
by iPaintball
Sweeeeet. I can't imagine the muzzle flash on that thing!

Posted: Tue Sep 25, 2007 1:51 pm
by Killjoy
Thanks you guys.
The cut wood fence is just something my parents put in because they wanted a natural, rustic look, but theres no moat sorry (there is a cactus wall I built a couple years ago, some vanderlizer got caught in it last year haha.).
And I've only fired during the day, but I know the muzzle flash has to extend at least 3' or so because when I fire blank shots into the tree, it will blow leaves out and set them on fire.

Posted: Sat Sep 29, 2007 6:37 pm
by DYI
For a spare parts gun, that thing is pretty good. How many ignition points did you use for that 5' long chamber though? I've been thinking of making a big combustion, but venting and ignition problems have always prevented it from happening. What kind of a sound does that thing make when it fires? I imagine that a 100mm bore launcher must be pretty loud, even at the low pressures that 1x propane combustion generates.

Also, how exactly do you add a preview picture that can be seen on the main cannon showcas forum?

Posted: Tue Oct 02, 2007 12:10 am
by Killjoy
I was planning to have two ignition points, but the only screws I could find had this coating on them that didn't conduct electricity, and I was two lazy to grind it off on the screws for the second gap, so for now it only has one spark gap about 1.5' from the end. And i thought venting and igniton problems would be a problem to, but the igniton works fine and i use justa a plain 80mm fane which is able to vent it in around 30 seconds.

And it leaves my ears ringing everytime I fire it. No where near as loud as my hybrid, but I guess it isn't exactly a fair comparison.

And underneath where you write all the stuff for your cannon, there should be a space that says thumbnail, just put the link to the picture you wnat int here. I usually resize the pictues to 55 pixels by 70 or something.

Posted: Wed Oct 03, 2007 3:07 am
by Billy Bob
Nice cannon :)
Currently the camera with the videos is being used my my mom for her work
at work ?

Posted: Wed Oct 03, 2007 9:28 am
by Killjoy
yeah, and when its being using for work she gets real pissy if other people use it, even if she isn't using at that moment.

Posted: Wed Feb 27, 2008 4:09 pm
by brogdenlaxmiddie
I like how you recycled some of the parts :D