I've talked to Lonnie a few times about some of those really wild looking props like the one you attached. I can't go into his shop without spending a couple hours picking his brain on these. What he's told me is that the prop like you pictured are a very big compromise for noise with power loss. In theory less noise should make more power but as I understand it these are for the DOD and defense contractors and all they really care about is the noise for drones. Some of them are really freaking cool though. 

On Sep 11, 2017, at 10:28 AM, jay@... [Q-LIST] <Q-LIST@...> wrote: