The only thing i would suggest so a very good way of attaching the wheels (they appear to be lite flights) to the servo's. Idealy a completely custom hub would be best but failing that a good solid connection (i.e. more than just a blob of gloue) between the servo horn and the hub of the lite flight.
my DT teacher says to use some little screws he claims to have. I need to cut the wheels in half, because they're too wide, so that will give a nice surface to have glue as well.