There are a lot of different factors involved in getting a plane to knife edge. I strongly suggest you get aerobatic trim charts and study them to help understand all the things involved. Basically, they tell you how to adjust your plane to get it to KE. I have had planes KE on first flight. Others, I can't get a good KE no matter what. Keep an eye on this sight, I will get some more information together for you in the next day or two. I just don't have the time now.