On the swallow the correct cg is 165-175mm not the 115 mm that the instructions specified. The two i built took no weight with a ys 91 and a 110. to get it to balance at 115mm it would have taken 12 ounces of lead. I used a hayes 16 oz. slimline tank to mount it closer to the cg. Hopefully you did'nt use the supplied hinges. if you did i would say to just cut them out no. The wheel pants will last about 8 flights on a grass field.

Dennis