Clair Pecinovsky in Cresco, Iowa
“I bought my 1986 Tierra single place ultralight 25 yrs. ago. The Tierra had 150 hours and was built at the factory in Clear Lake, Iowa about 80 miles west of where I live. It was powered by a Rotax 447 engine through a 2.58:1 A-Box PSRU, turning a 59 inch, 4-blade Ultra-Prop, with 13-degree pitch blocks; all standard equipment from the factory. I flew a little over 100 hours a year.
Later, I replaced the 2.58:1 gears with the 3:1 gears. Found that 17-degree pitch was about right for the 4-blade Ultra-prop. With this 3:1 gearbox, I tried four different propellers from my club friend’s larger engines (503 & 532 Rotax). All were noisier, not as smooth, and none performed as well as the 59 inch 4-blade Ultra-prop I had except for a Brolga prop. My club friend Kevin had been using it on his 2-place Tierra powered by a 532 Rotax and standard 2.58:1 PSRU. The Brolga was a 3-blade propeller sold by Competition Aircraft, the same company that makes the Ultra-Prop. I found that propeller was not available anymore.
Kept flying through the years with the same engine and Ultra-Prop propeller, and then last autumn I noticed Competition Aircraft had a 66-inch Ultra-Prop II. Talked to Bob Davis, the company’s owner, and I bought the 3-blade Ultra-Prop II. I remember my delight on that first flight with the new propeller… how smooth it was and much more noticeable thrust. Oh, how I liked that propeller! :) (Except for the noise at the 4,400 to 4,800 RPM that I liked flying it at.)
Thinking about that while flying, I figured it was caused by the close 2 to 3-inch distance the blades operated at the trailing edge of the wing. I purchased a 3-inch prop extension and to my delight, that took care of that noise. The 10-degree pitch for the 66 inch, 3-blade Ultra-Prop II was just right for my old Rotax 447 engine and 3:1 PSRU. Hanging up my old prop on the wall, I notice that it doesn’t seem to show any wear after the 2,100 hours I used it.
I now have flown 30 hours with the Ultra-Prop II and I have the feeling that I’m flying a new airplane. I remember how nice my first landing turned out using my new propeller… and then the 2nd and 3rd and… hhhmmm.. why did it seem easier to land?! After more hours of flying and landings, I discovered it was because the new propeller is still producing some thrust even at lower, idle RPM and doesn’t have the drag to cause the plane to lose momentum as quickly, and thus can settle in more gently, so to speak.
One other nice thing about both Ultra-Props is their light weight, which makes quick maneuvers easy without the resistance of the gyroscopic action of the heavier props I tried.