This idea came to me for how to make an auto engine conversion work without the normal complications and expense. I'm not an engineer, I'm a new pilot who from the beginning has been fascinated with how antiquated and expensive the current options for engines are in the general aviation world. So, I started looking at auto engines and the biggest issue is that they produce their max HP and higher rpms thereby requiring a complicated/expensive PSRU. So, I started thinking about what if one made a propeller that could be fitted directly to a Honda Fit engine for example that would spin at say 5000 rpms. I realize the problem with doing this is that you would then have to make the prop length short enough that it avoided the speed of sound issue and if you made it short enough it's efficiency would be greatly reduced. And the reason for this is that the air is relatively thin and not enough of it would be going across the smaller area of prop to produce the same thrust as a bigger prop.
But what if you added elongated fins protruding from the nose of the prop. Such fins when spin with the prop and would create a vacuum that would suck air from the area outside the prop to inside and push more air across the prop itself. I don't know if I explained that very well, I will try and draw a diagram and post it here. But has this idea been discussed before? What would the limitations be of this, and would it work?