I ran a Saito 100 and also had used an OS 91 on my US 60. I placed the battery perhaps half way between the trailing edge of the wing and the tail. I put the plane on balance and then slid the battery pack till I hit the balance point. Then I made a compartment on the bottom with hatch. This plane will fly great with either size engine. Also, the slow speed abilities are outstanding. it will slow down till it looks like it will fall out of the air!

Bruce