Hi all. Since the post on "Streamlining " seems to also be diverging into prop design, selection, and theory, I thought a new post might be in order.
I am looking for opinions, advice and feed back from people more intelligent than me (which should be around 90-95% of you reading this post!) I want to know what is out there and what might be best bet for low noise and decent efficiency and able to handle a wide range of operational requirements on the same flight.
The last 100 years props for lower speed applications have been two blade, fixed pitch, relatively low rpm. The last 20 years alternatives have been starting to make in roads, such as three and more blades, impellers, pusher configurations, composite construction, ground adjustable, flight adjustable, P-tips, Q-tips, etc. What is the state of the propeller marketplace?
For my particular motorglider application, I would like to use around a 75HPengine. I want light weight, and would like to avoid using any type of speed-reduction unit (but might consider arguments in favor of speed reduction). I would like to feather the prop to minimize drag during soaring conditions, flat pitch for takeoff, and higher pitch for efficient cruising.
What choices and/or compromises should I consider?
BTW, I am also watching the "Streamling" post, so look that over and comment on that also. I am appreciating the exchange of ideas on these items!