Mine was heavy too...Not wasted weight though, it is very strong.
It's not the design as much as it's bad wood. I have never had a kit with wood that heavy...I think they gave me oak instead of balsa. If you see how many pins I bent...
I spent about $20 replacing all the sticks and replacing and buying some of the sheeting they decided I didn't need. I will complain about the price and value of this kit until I die, regardless of how well it flies...
