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.