A few things to consider. First of all reinforcing the wing with cf above plastic from underside. Make sure it hits corner of servo for longest possible. Also 8X9 on a what? 2s pack? That prop sounds a bit too large and too much pitch. Even an 8x8 might be a bit much. Hard to tell without having info on how many cells. Anyways here is the picture of the bottom of the Stryker during surgery. The front line with foam is another design flaw. It's fiberglass that has not been scuffed. Eventually will give and separate at middle.