A good many designers have tried just using the full scale plane's airfoil on a serious scale model, and the results are generally pretty bad. Going to even 50% scale changes the way the wing interacts with the air so much that it will make the original design's airfoil completely wrong. Generally, models need thicker airfoils and rounder leading edges to retain the same flying characteristics. In addition, they need bigger tails and a much higher power to weight ratio because of aerodynamic efficiency losses. What works in full scale does not work in models.