Cutler Posted July 9, 2006 Posted July 9, 2006 I am trying to set up a demonstration of a mortar bombardment in miniature. My goal is to launch a shell to distances between 100 and 300 yards and have a small report approximately 15 feet above the surface. My gun is a 1-3/4" cast iron mortar that is capable of handling much higher pressure than I will be working with. In my first attempt, i had problems getting any kind of distance with a 1-5/8 plastic shell due to it's lack of mass and thus momentum. I needed ballast, but something that did not provide a shrapnel hazzard. I will launch into a safe area, but I do not want bits of shrapnel flying at high velocity, so I tried modeling clay. I used a piece of 1/4" jap time fuse glued in the fuse end of the shell with 1" in and 1" out to allow field adjustment of timing. I then packed the modeling clay into the fuse half taking care to leave the fuse end expose. I added my report to the other half and super glued the two together. During launch tests, I found the fuse needed a prime to ignite reliably...I split the end of the fuse and added a pinch of my lift charge and closed it back up..reliable ignition. Flight was acceptable, but I could still use a bit more ballast. About 1/4 of the shells actually ignited the report. When they did, all worked well and I was able to adjust fairly accuratle how far and how high they reported. The fuse ignited as seen by a trail of sparks, but the fuse failed to ignite the charge. What did I do wrong?
PyroJoe Posted July 9, 2006 Posted July 9, 2006 For the best reliablity when using time fuse, cross match both ends of the fuse. Cross match the lift charge side, and the inside as well. It will insure that everything will ignite and make the timing even more precise.
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