At many of the prop forums I've given at various fly-ins, I'm asked about the influence of Jack Norris' book on my propeller design. My friend Oscar Grassle offered 1/2 interest in his Lancair 235-320 while I was still building mine and I accepted. Because I had a passing interest in things aerodynamic, and had done a lot of reding about wings and airfoils, I felt that I could make a minor mod to the tip of his Great American prop to up its performance. Well, without changing the diameter and only a minor re-shaping of the LE and making the tip come to a sharp edge on the top of the blade, we increased speed from 215-216 mph to 218-219 mph! That 1.4% speed increase amounted to a 4.2% efficiency increase, just from this little change. Sometime after this there was a prop strike during taxi that required obtaining a new prop. Oscar called several prop makers and settled on one from whom we got a prop after telling them about our plane's performance. It was not as good, so we sent it back describing how it worked. We got it back and it still wasn't as good as what we had, so sent it back a second time. It still wasn't as good, so we gave up on that route. I had done design of electronics and physical processes, such as refraction and radar noise, and I knew that physical processes were very predictable, so I decided to write a program to design a propeller. After getting to know the program results, I designed a two-blade prop on 1998 August 11 to be able to turn up higher rpm for racing with Oscar's Lancair, as we wanted to participate in the EZ races. I gave the blade sections to Klaus of LSE, who was still making props, to make this prop for me. He tried to talk me out of it since it was unlike anything that had been made before, but I told him I needed it made in order to see what, if any, corrections needed to be made to the program if it didn't result in the predicted performance. I had predicted the performance of this prop at three different density altitudes at 100 rpm increments from 2400 to 3200. I wrote these predictions on a piece of paper and had Oscar sign it. I got the prop and flew it in January and February of 1999 and it performed exactly as predicted speed and rpm-wise.
After I completed my Lancair, I flew it with this prop initially, but my 125HP engine wouldn't turn it as fast as Oscar's 160 HP, so I designed a three-blade prop on 2002 July 25 and sent it off to Craig Catto to make for me. Again, I wrote down its predicted performance as before and had Oscar sign and date it, and it performed about 1-2 mph faster at the altitudes and rpm during testing at the end of 2002. I was getting really good cruise and climb efficiency, so I sent an e-mail to C.A.F.E to come to Santa Maria and check this thing out since they were supposedly interested in aircraft efficiency. They wrote back that they no longer did that, but they would pass this on to their prop expert. Several weeks later I got the first of many several-hour calls from Jack. He told me about Andy Bauer and him and their BGT concept, and asked me about my design concept. I told him that since Prandtl thought that the elliptical lift distribution on a wing was best, I felt that it was the best goal in my design equations. I didn't hear again from Jack until after the 2004 Reno air races when Tom Aberle's Phantom biplane, with the three-blade prop I designed for it, performed so outstandingly and garnered much publicity. From then on Jack would call or send me e-mails and mail print-outs of sections of his yet-to-be published book, whose first edition came on 2007 July. So as you can see from this tome, my original two-blade prop pre-dated any contact with Jack by over four years. I was delighted to see that Jack had included a comparative description on P. I-28 - Bk II of the BGT and elliptical designs and notes that the elliptical design, by moving the blade loading more inward, would "logically lose less off the tip, better than the B-G-T ideal" 'Nuff said!
After I completed my Lancair, I flew it with this prop initially, but my 125HP engine wouldn't turn it as fast as Oscar's 160 HP, so I designed a three-blade prop on 2002 July 25 and sent it off to Craig Catto to make for me. Again, I wrote down its predicted performance as before and had Oscar sign and date it, and it performed about 1-2 mph faster at the altitudes and rpm during testing at the end of 2002. I was getting really good cruise and climb efficiency, so I sent an e-mail to C.A.F.E to come to Santa Maria and check this thing out since they were supposedly interested in aircraft efficiency. They wrote back that they no longer did that, but they would pass this on to their prop expert. Several weeks later I got the first of many several-hour calls from Jack. He told me about Andy Bauer and him and their BGT concept, and asked me about my design concept. I told him that since Prandtl thought that the elliptical lift distribution on a wing was best, I felt that it was the best goal in my design equations. I didn't hear again from Jack until after the 2004 Reno air races when Tom Aberle's Phantom biplane, with the three-blade prop I designed for it, performed so outstandingly and garnered much publicity. From then on Jack would call or send me e-mails and mail print-outs of sections of his yet-to-be published book, whose first edition came on 2007 July. So as you can see from this tome, my original two-blade prop pre-dated any contact with Jack by over four years. I was delighted to see that Jack had included a comparative description on P. I-28 - Bk II of the BGT and elliptical designs and notes that the elliptical design, by moving the blade loading more inward, would "logically lose less off the tip, better than the B-G-T ideal" 'Nuff said!
