Nessalco Posted February 15, 2012 Posted February 15, 2012 As a high-power rocketeer, I got very involved with building composite structures, and have lots of materials left over - including yards of 22oz fiberglass weave. I'm considering making a bunch of 4" mortars from it. I've seen the Chinese fiberglass mortars, and plan to make mine a bit differently. There will be a wooden plug fiberglassed into place, and the muzzle reinforcement will be 12k carbon fiber. I made a couple of 3" mortars using this technique, and they've worked fine. I'll only be using these mortars in electrically fired setups. All my other mortars are HDPE, but as the size goes up, so does the weight...and I'm getting old and lazy. Has anyone else gone this route? If so, what problems did you run into? One thing that is pretty cool - unless you add dyes to the resin, fiberglass sets up mostly clear. It will be easy to see if anything is in the gun, and the visual form the lift charge is pretty cool. FWIW, I've also made comet pumps and puck rams from fiberglass/kevlar/carbon fiber with great success. Kevin PS> No, there is no real cost savings. I'm just hooked on the DIY model.
allrocketspsl Posted February 15, 2012 Posted February 15, 2012 As a high-power rocketeer, I got very involved with building composite structures, and have lots of materials left over - including yards of 22oz fiberglass weave. I'm considering making a bunch of 4" mortars from it. I've seen the Chinese fiberglass mortars, and plan to make mine a bit differently. There will be a wooden plug fiberglassed into place, and the muzzle reinforcement will be 12k carbon fiber. I made a couple of 3" mortars using this technique, and they've worked fine. I'll only be using these mortars in electrically fired setups. All my other mortars are HDPE, but as the size goes up, so does the weight...and I'm getting old and lazy. Has anyone else gone this route? If so, what problems did you run into? One thing that is pretty cool - unless you add dyes to the resin, fiberglass sets up mostly clear. It will be easy to see if anything is in the gun, and the visual form the lift charge is pretty cool. FWIW, I've also made comet pumps and puck rams from fiberglass/kevlar/carbon fiber with great success. Kevin PS> No, there is no real cost savings. I'm just hooked on the DIY model. how much would you charge to make a three inch mortar in the clear resin.Yeah I bet the effect is cool when it blows
Peret Posted February 15, 2012 Posted February 15, 2012 It won't be clear after you fire it a couple of times.
allrocketspsl Posted February 16, 2012 Posted February 16, 2012 It won't be clear after you fire it a couple of times. hum yeah your right,lol
Arthur Posted February 16, 2012 Posted February 16, 2012 With enough glass in there for strength there is little transparency to a GRP item, even less when once fired. IIRC the transparent mortars used for occasional videos are polycarbonate tube -it obviously works once, when used at a suitable safety distance, but I wouldn't want to hand fire one. IMO in a GRP tube the resin plug is a good idea as it has the same properties as the resin bound tube. With a wooden plug which can expand and contract with moisture content there could be issues with degree of fit.
Nessalco Posted February 16, 2012 Author Posted February 16, 2012 (edited) With enough glass in there for strength there is little transparency to a GRP item, even less when once fired. IIRC the transparent mortars used for occasional videos are polycarbonate tube -it obviously works once, when used at a suitable safety distance, but I wouldn't want to hand fire one. IMO in a GRP tube the resin plug is a good idea as it has the same properties as the resin bound tube. With a wooden plug which can expand and contract with moisture content there could be issues with degree of fit. True enough - I think "translucent" is a more correct descriptor. When the tubes are new you can see enough to know the tube is loaded. Even after firing a few times you can see the lift charge going off. The wooden plug is fiberglassed into place, sealed completely in resin, so I don't believe moisture absorbtion will be a problem. I'll probably try a couple with just a resin plug to see how it works for me. <hack> It would be an easier layup to skip the wood. I build the plug in 2 layers, sandwiching the ends of the fiberglass cloth between then vacuum bagging the works. This gives me a wooden base I can screw into without affecting the integrity of the mortar</hack> allrockets - a friend once told me the best way to ruin a hobby is to turn it into a business. If you like I'll take pics and do a tutorial. Kevin Edited February 16, 2012 by Nessalco
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