I could see amazon using slightly modified rotors. why would it cost that much more. Don't know about ducted rotors. The fenestron is ducted with "variable a

I could see amazon using slightly modified rotors. why would it cost that much more. Don't know about ducted rotors. The fenestron is ducted with "variable angular spacing"[1]/"modulated blade spacing" like more stealthy helicopters[2] I kind of doubt amazon helicopters would get up to the "thumps" from passenger helicopter main rotors. But I could see bigger rotors turning slower, or maybe more rotors, each turning slower. Sort of like replacing fast but noisy 80mm case fans in your computer with slower and quieter 140mm or 200mm case fans. I think the PR of quieter drones would be good, not that costly. You can see other companies like waymo getting a lot of bad PR with noise (remember the honking problems?) [1] https://en.wikipedia.org/wiki/Fenestron https://en.wikipedia.org/wiki/Fenestron "Fenestrons have between seven and eighteen blades; these may have variable angular spacing so that the noise is distributed over different frequencies." [2] https://en.wikipedia.org/wiki/Helicopter_noise_reduction#Methods_of_noise_reduction https://en.wikipedia.org/wiki/Helicopter_noise_reduction#Met...