I admit it, I am a novice. But I am experienced in building many mechanical and electrical things throughout my years. So, I decided to build the FliteTest Corsair. Build seemed to go fine. But I am experiencing a serious problem on take-off. On my first take-off attempt, the plane got three feet off the ground, and then suddenly cut hard to the left, back rolled, and crashed. I repaired the Corsair and after some counsel from an experienced pilot, lessoned the lead loading in the nose (I am using a 3-cell, the build video suggested lead may be needed to balance the plane). It seemed to balance well. Second take-off, made it to seven feet when the same radical left arc and back roll occurred resulting in a devastating crash. I had left all controls at normal position with a slight rear stabilizer up position for take-off. This behavior does not seem like common left-torque pulling because the behavior is so sudden and radical. Take-off was perfectly straight until it wasn't. Any helpful counsel???