had a pretty close call yesterday morning. went to the field around 9:30 with my "clean" p-51 pts, did my pre-flight checks and (despite the wind , which was pretty gusty) took off. climb out, turn into the standard pattern, then the plane seemed to twitch after I leveled the wings form the turn. at this point, I assume it's a radio hit, so I decide to try and land and do another range check. I do land succesfully, but miss the runway and touch down in the grass and after a short roll nose over, killing the engine. the plane is acting "funny" the whole time.

while carrying the aircraft back to the starting stand, i can feel weight shifting inside the fuse. after closer inspection, I discover the battery free-roaming under the fuel tank. there is some foam around it, so I'm not sure if it just came unwrapped or what. I stuffed some more foam in there and shook it a couple of times to make sure it was snug. I re-checked the CG and it seems ok. At this point, I decide to pack up and go home because the wind continued to pick up.

do you guys think the free roaming battery is what was causing the plane to act and feel funny in flight?