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?

Any major componet free to flop around especially fore and aft certainly will give a pilot fits.

John

Well, it may not have been the cause, but it sure didin't help things any. Besides the shifting of the CG, there was a good possibility that it would "pull the plug" at some point and the CG would have been a mute poit.

Go get a flat swim noodle and cut it to fit to lock down the battery and any thing else that may want to roam around in the cabin when inflight. Wrappedd foam and rubber bands will come loose and the soft grey foam will soak up fuel like a sponge if your tank develops a problem. Having just bought a couple of experienced planes that had things wrapped in the grey foam, I'll tell you that the foam breaks down and leaves a gooey mess at some point, fuel or no fuel. Get some of th closed cell foam, the swim noodles are one source, the white packing material is another, not the styrofoam, but the rubbery white foam. It is very light and has enough stiffness to be able to lock in place under stringers and such to hold things in place. The fuel will not atack it, and even if you dump a full tank of fuel in, the foam will not gain more than a gram or two in wieight and that is only what is wetting the outside of the foam.

Don

Most definitely


I had a 4*-60 that required that i mount the battery under the fuel tank compartment. During a somewhat aerobatic flight i noticed it "acting up"....it kept ballooning up and was pitch sensitive, and i had an usually hard time landing it. So i decided to call it quits for that airplane and took it apart and i noticed the battery pack was tangled in the pull pull wires, thank God for the safety clip, otherwise it sure would have disconnected and made matters worse

Just another thought on common things that will change the CG in flight and is very common is using those stick on weights Usually used up front and if external they just fall off and used internally around the tank or inside cowling they will not hold and will fail unless glued with some other form of glue besides the double face tape.

John

If your CG is shifting around your going from very sensitive in pitch (CG aft) to tame in pitch (CG fwd).....not to mention lateral balance....