Hello everybody.i downloaded a file from rc powers (f18 v2) & I built it with foam board from Walmart, with a super mega jet from Grayson hobby. Is the foam board with the paper cover on both sides. the one kids use for school projects. is a1/4 of an inch thick. For glue I used hot glue. Everything I did, I followed the instructions. When I tried to fly this thing it drops like a brick. Oh this is my second one the first one I painted so I thought that I spray to much paint & it was to heavy. The second one i didn't paint & it still to heavy. I'm thinking the foam board that I got is not good for this type of project. My question is. What will be a cheaper alternative to depron foam that I could get locally in my area? I new doing scratch builds & I would appreciate the help. Thanks in advance.