I am planning to buy a DJI F550 frame for my ardupilot, my home made frame is not as perfect and strong as I would like it to be and figured it will be easier just to buy a proper frame.  I was hoping if someone that already have a F550 can tell me how large the space between the top plate and the bottom plate is (Height x Width x Length), I was wondering if I can mount the APM1 board between the…