I'm working on my Bull Puppy and it has G10 fins and a plastic boat tail. How would you lay down the fillets for it. More specific would you mask the fillet so it follows the contours of boat tail on the fin or would you go straight across or am I asking a stupid questions. :confused2: Since the boat tail flows down ward would you position it so it stays level to make the fillet uniform?
Not a stupid question, I had the same thought when I did my Bull Pup. I followed the contour of the boat tail using the following method and materials.
Materials: (you can use any epoxy, I just prefer this mix for this type of rocket and fillet)
Red Baron 30 min flex cure epoxy, I used this because these fins have a relatively long semi-span and can flex quite a bit
Micro Balloons, I added some micro-balloons to lighten the epoxy and it also makes it easier to sand. The trade off is strength, however I did both internal fillets and 2 part foam so I was not as concerned with the strength but more so the look, finish and aerodynamic qualities.
Masking tape, hobby knife and metal edge ruler or equivalent
Mixing:
I mixed the parts about 3/3/3 based on volume.
Technique:
To mark out the fillets I used my GLR Mariah method, wooden dowel carbon paper, trace the dowel edge along the carbon paper against the body and fin. This leaves a black mark that I then masked off. Once I masked off the area and mixed the epoxy I used a 2-3" wide strip of wax paper (important that it has no creases) to lay down onto of the full length of the fillet and a bit beyond each end. Once the fillet is poured I find the best way to ensure the fillet is all the way down to the masked off area is to push the down down evenly until you can see the fin through the wax paper. On a flat fin this is much easier, on the contoured fin it is harder because it may wrinkle and transfer that wrinkle. if so no sweat you will just have to sand down one size. Once cured remove wax paper and cut away excess following masking.
This should result in a nice smooth, light, relatively flexible fillet that requires less sanding.
I can post some close up pics of my fin and (mock) canard fillets tomorrow so you can see the result to get a better idea if this is what you want to do.
