Dr B, have you ever had to add weights to your plane?
Abso-freaking-lutely! If you’re flying your plane without checking CG, you’re rolling the dice every time you launch.
Where does the battery sit in the compartment- there is a 1/2" space between the battery and nose side or tail side of the compartment.
Take a trip to the Arts and Crafts store. If you don’t want to be seen going into the Arts and Crafts store, send your wife, but get a block of foam-rubber (two-inch thick or so). You’re going to use it to keep your battery from sliding around inside the fuselage.
Now, build a CG Machine – it’s cheap and easy. A block of wood with a couple of wooden dowels glued into it. You just have to make sure the dowels are square with the block – use a small carpenter’s square.
www.bobvila.com/images/HowTo/IHouse/WorkshopGarage/Combination-Square.jpg
Click here to see my DIY CG Machine:
i196.photobucket.com/albums/aa62/tkrahlin/RC_Plane/Motor%20Swap/Balancedwith15-grams.jpg
ORIGINAL: crakey
Question: Lately, when I have flown and got some high speed (like in a dive), the plane "grabs the air" and does a nasty climb (with no elevator input), putting massive stresses on the wing. I saw it lift off the fus. today about 2". Scary. Also, now, when I fly inverted, even with full elevator, it will NOT stay level, it "climbs" towards the ground. Are both of these related to COG?
You can’t be sure until you balance your plane. However, if it were the CG, it would be tail heavy even when upside-down and wouldn’t climb toward the ground. I’m not sure, but it could be that big prop. That’s a pretty big screw cutting through the air and maybe it’s twisting the plane. You ever get a drill bit stuck?