Yes, a radially different concept for Prop design.  I remember when the bi-plane picked up something like a 20 MPH increase in speed with Lipps prop - it had us all drooling to think that perhaps we could gain a 10 MPH increase with our RV aircraft.  Unfortunately, in the one example I am somewhat familiar with when put on an Rv-6 the outcome was somewhat disappointing - I think it was a gain of only about 1-2 MPH.

Now in all fairness, Paul's admits his design approach is dependent on somewhat untradiational accuracy in engine HP and drag of the platform information - which may have been lacking in this first attempt.  However, since there has not been a flood of aircraft with the Lipps prop, I'm inclined to believe that it has not yet reach the promise that first seemed likely.

While folks can point to the 20 mph increase in the bi plane's performance, I can't help but wonder if perhaps the original prop on the bi plane may have been a poor choice whereupon replacing it with the Lipps (better matched) make the performance gain seem all related to the Lipps prop rather than replacing what may have been a poor original choice - but, just spectulation on my part.

I really wanted to see the Lipps prop deliver all it initially seemed to promise, but I can't find any data yet to support its initial promise - at least on the type platforms and speeds we normally fly.  It’s the first really different approach to prop design I've seen since - well, since the Wright brothers {:>)

If anybody has a source for information that indicates my impression is incorrect regarding its performance on Rv type aircraft (or similar), I would like to receive it.

Thanks

Ed