Weight is the cube of the scale. A 1/6 scale object with the same density would weigh 1/216th the weight of the full scale. In the case of a plane weighing 13,500 lbs, the 1/6 scale version would weigh 62.5 lbs. A 1/6 scale P-47 would have a wingspan of 81.5", a wing area of 600 sq in, and a wingloading of 240 oz/sqft. For a 1/6 scale plane to fly, you need to be closer to 60z/sqft, so consessions need to be made with the materials used to build the model.
Another problem is that the engines we use are lower torque, higher RPM than full size engines. As a result, we need to turn smaller blades in order to achieve reasonable performance. Our engines are not capable of turning scale props. If you try, the performance would not be enough to get airborne, if you could even get the engine to run. The only way to get close to a scale prop would be to gear down the speed of the prop with either a geared engine such as the RCV SP series, or with a gearbox like the Byron. Electric motors may also aproach the torque needed to turn a scale prop. In order to get reasonable performance, you would still need to turn at higher RPMs and fly at higher than scale speed.

Scott