I have the same question...the book says 1/78 to 2/78...but from where...upside down....right side up...next to fuse...at tips. This is all I lack to fly her and I have had no luck. Both of mine were flown prior to me buying them....the owners never CG ed them, and they have no clue about the subject. If you get the skinny please pas it to me at [email protected]