The myth about aluminum sheeting/skin causing problems has been around for a long time and as far as my experience it is just that, a myth. At least as far as 2.4. I built a ginat scale model, sheeted it with .0010 aluminum roof flashing and had no radio issues in the numerous flights we made. I used 2 Futaba 2.4 recievers, one in the wing with antennas extending outside of the wing skin and one receiver in the fuselage near the top with the antennas inside the canopy. Prior to flying the aircraft we did range testing at various distances and aircraft to transmitter orientations and experienced no problems. I also have a friend that has built several all aluminum aircraft and has not experienced any radio issues in the years he has been flying model aircraft with this type of construction.