knowledge. I've no knowlege in mechanical engineering(except courses in classical mechanics and mathematical elasticity) but u can tell he made at least 2 mistakes;He didnt use a(or 2) motorcycle engine and made it a biplane.Look at it, the wingloading is too high.Number of Chinese attempting to build homemade planes is still small and there's no readily available infos or similar aspirants within easily commutable distance

http://en.people.cn/n/2015/1123/c90000-8980479.html