I have the BTE Delta Vortex with retracts, powered with a YS 61R. The tank is on the CG to allow for installation of the nose wheel retract. Balance it as called for on the plans(21" to 22" from the trailing edge) without fuel and the retracts up. Mine is balanced at the more reaward limit because when the nose gear is down it shifts the balance point foward. How much it shifts is dependent on the size and weight of the nose wheel.