The tool is useful to get to a CGthat is flyable. But easier yet, You most likely have an old ACE Extra 230. Set the CGon the blade joiner and go fly. Let the airplane tell you where to adjust from there. If the airplane is built strait a neutral CG will mean little or no elevator trim will be required. Thats test one. Test two is to pull a 45 degree upline, roll inverted and see what she does hands off. My personal preference is for it to self level inverted in about 5-6 seconds.