in fact wooden spars on top and bottom of the aerofoil in the wing gives great strength.  You may cover it with normal brown paper or news paper or 132 column computer paper or even photocopying paper for higher strength.  Do not forget to wet the paper before sticking it with a thinned fevicol.  OR use normal transparent or brown masking tape (packing tape) to cover the model for strength.  I use a balsa leading edge, trailing edge and thin balsa spars on the maximum camber of the aerofoil.  Then I cover it with masking tape and in the end.... cover it full with vinyl sheet.  See a 52" span is not small and it needs to be given the required strength.

If your plane weight is under 500 gram, you can use this motor  http://hobbyking.com/hobbyking/store/__8621__2210N_1000Kv_Brushless_Motor.html
with 9X4.5 prop
ESC 20A
2200mah 2S battery.