It can finally be made public.

I bought the first prop designed by John McGinnis (Synergy aircraft). It is being made by a new New Zealand company that can be found at: www.kiwipropellers.com
It is designed for my RV-7A.

When I have flown the prop I will do my usual, honest, objective write-up.

The prop is on its way back to Kiwi-land (New Zealand) for a couple of reasons:

1. It will probably be changed so that it can be installed on my RV without a new extension. It's an issue of part of the blades being aft of the base of the hub in the current version.

2. John, the Mitchells and I all agreed on a good ground-testing plan which will precede putting it on my airplane.

The prop was a big hit at AirVenture and many people expressed interest in having one designed for their airplanes - some of which are not RV's.

Here are some things that I learned about it:

  • constant Reynolds number
  • 25 custom NLF airfoils blended, all by Synergy designer John McGinnis
  • some L/D ratios on some of the airfoils that are so high I won't say them out loud, here.
  • lift distribution more parabolic than elliptical
  • makes good use of the "q" near the hub
  • twist is less than "normal" because the necessary advance ratio is accomplished with airfoil design.
  • The airfoils adapt in thickness, camber, and design Mach number as they move outward. Keeping the Reynolds number constant prevents unnoticed lift/drag changes as those factors are varied in pursuit of the desired lift distribution.
  • all composite construction - no wood
  • I have not seen it yet but there will be a custom spinner with it

One more thing: a few people tried to compare it to a Paul Lipps prop. I mean no disrespect to the late Mr. Lipps, but, no, that's not even close.

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