Howard Handelman
08-03-2012, 04:50 PM
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 (http://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.
KITPLANES Newsline (http://kitplanes2.com/blog/page/2/)
http://kitplanes2.com/blog/wp-content/uploads/2012/07/P1010880-300x225.jpg
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 (http://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.
KITPLANES Newsline (http://kitplanes2.com/blog/page/2/)
http://kitplanes2.com/blog/wp-content/uploads/2012/07/P1010880-300x225.jpg