ORIGINAL: BobH
What happens is that the wings tend to separate at the trailing edge causing a gap. This is caused by the flying wires pulling the wings forward. You can elimenate it somewhat by putting a lot of tension on the landing wires. But it's not the best solution.
Same thing happened with my Snipe (which also used the metal rods) and if I would to build it again, I'd include some sort of bracket so that the riggings didn't have to do double duty.