Eyeballing Prop Blades for Performance. 

Builders,
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Pictured below are two carbon fiber, ground adjustable prop blades from two known and respected US manufacturers, who have been on business 30 years (L), and 80 years (R) respectively. Let me share with you what you can tell by eyeball about the performance of each of these different blades.

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Above, A Warp Drive blade with nickel leading edges on the left. There are more than 150 of these flying on Corvair powered planes. I have been a WD dealer for more than 20 years, and you can look at pictures of my Pietenpol from that far back and see a 66″ two blade on it. The prop on the right is a Sensenich Saber blade, in the correct airfoil and pitch distribution to be a fair comparison to the WD prop. It has not flown on a Corvair, it was directly provided by the factory as a test article, the blades still have the node marks from their in house vibration survey. I have been a Sensenich dealer for almost 15 years.

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Here is what you can tell about their performance comparison by Eyeball : Nothing. The only valid commentary that will come, will be from impartial testing, period. Plenty of people will offer some comment on nearly any prop, but will they buy you a new one if it doesn’t work? I haven’t seen that yet. Ask any group of people at an airport or an EAA meeting about a kind of prop, and wait for the first guy to answer, then ask the four questions his expert opinion neglected to include: Have you ever flown that type of prop on the engine I asked about ?  Are you a dealer for that brand so you would have full access to their support staff? Have you ever had any formal training on propulsion, A&P work or worked in a prop repair station? Has anyone ever paid you a dime for you opinions on props, or is your advice worth exactly what you charge for it, nothing?

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Without even asking, you can pretty much guess the answer to the questions.  On the other hand, even though I had Dr. Ernest Jones as a mentor in propulsion at ERAU, am a 25 year A&P, have been a prop dealer for decades, Have worked in a certified prop repair station, and was paid about $80K a year by a global prop manufacturer, my experience tells me that you can’t tell anything valid by eyeball, only real testing counts. Show the picture above to the guy at your EAA meeting who dispenses advice on every subject that comes up, and ask him which blade will perform better. Regard it as a study of aberrant humans, not valid performance advice.

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-ww.

About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at www.FlyCorvair.com and in more than 50 magazine articles.

8 Responses to Eyeballing Prop Blades for Performance. 

  1. Robin Oldfield says:

    I’m sure we’ll all figure this out since you wrote the Sensenich has the markings but the Warp drive is on the LEFT and not as you wrote on the RIGHT

  2. Bruce Culver says:

    Not enough coffee…..

  3. Dennis McGuire says:

    I assume you thought about testing the
    two propellers with the same or as nearly the same weather conditions.

  4. Dan Branstrom says:

    I’ll volunteer my opinion on the props. It’s worth what you’re paying for it: nothing.

  5. Jeff Moores says:

    Love the Warp Drive. I have flown them off water and snow for over 20 years. When on rough water on a windy day it is amazing how much water can go through that prop without damage thanks to the nickle LE.

    William, when I first started with the Corvair you convinced me after some discussion to shorten my 70″ Warp to 68 or even 66″. Contrary to all I have learned about floatplanes needing a longer prop I cut my prop. I remember on that first takeoff with the shortened prop on my 2.7 L thinking dammit William is right again !!!

    Thank you for that,

    Jeff

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