Yes, I believe I followed everything correctly. (What is wing washin?) I also played around with circle size a bit to see if that was causing the problem and it appears that it's not. Normally I would make the circle size with diameter the width of a basketball court. When we played around with CG, we tried a different variety between small adjustments and fairly large adjustments. After playing around with CG I bit I am generally able to make the plane fly level, but again it just doesn't climb and whenever I try to change something to increase the climb, the plane just stalls out. One key observation that makes my bi plane different from the monoplane is that my bi plane has less weight at the nose since with two wings it is heavier so I had to get rid of some of the clay to keep the plane around 8g.Xiangyu,
Congrats on building the biplane. Did you have the following all exactly per plan: CG, wing incidence and wing washin? Did you install the carbon diagonal struts connecting the wing LE and TE to the wing posts exactly per the plan? If not, what does each of these specs measure and what is your diagonal strut arrangement? What is your circle size? When you changed the CG during testing, how much did you move it between each test flight (this is the key question).
Thanks for you help!