RCU does give real experience and i am very greatful for what i have learned on here , one of wich is 138mm or even 135mm is not 25% the wing cord closest to the fuse , I had one or two people on here tell me that they balanced the 50 size zero at 110 mm with a successful flight , don't know how ? but this also proved to be way way off , so on here or anywere else you have to take all information into account