Efficient propeller / amphibious quadcopter build

Step-by-step building instruction book available at The book covers how to build and balance your own CW-CCW propellers suitable for slow flying aircrafts and multirotors in practically any size. High efficiency and DIY have been central objectives in the development work carried out. Quadcopter facts: 15x15 mm aluminum tubing and coroplast fairings Take-Off-Weight: 4150g, It is a 1:4 scale model, could be built lighter if your goal is making a R/C quad. Hover time: 25min