I am in the process of designing a 2.56" internal-rotor helicopter. I am planning to get some helicopter experience first with an Apogee Gyro Chaser, so by the time I build this I will not be a total helicopter noob. However, I have a few questions about the blades. First, will 1/4" balsa be strong enough for the rotors, or should I use something like basswood or even thin plywood? I am basing this off of BABAR's Whopper Flopper Chopper, https://www.rocketryforum.com/threads/build-thread-for-whopper-flopper-chopper.28887/, which was 380 grams, flew on Estes E9s, and used 1/4" balsa for the rotors. My design, with the 1/4" balsa rotors, is ~500 grams and will fly on composite E through G motors, more specifically 29/40-120 reloads. For reference, the rotors will be ~22 inches long. Second, should I go with four 2"-wide blades or three 2 5/8" blades? I calculated those sizes based on the interior circumference: 2.56*3.1416/3 = 2.681, and 2.56*3.1416/4 = 2.011. I am going to be using Gyro Chaser-style blades, with a curved leading edge and straight trailing edge. I will bend them using the Apogee method, softening them with ammonia and curving them on a mandrel, so their circumference will equal the internal circumference of the tube. Which blade count would be better? Third, does anyone know of any resources on the aerodynamics of helicopter rocket blades? I would like to understand how they work, so I can better design my own.