Was able to finally get my Saturn to the flying field today. 37 degrees, 5 MPH wind down the runway and sunny. It was nice.

As I mentioned earlier, the only thing I changed on my setup was replacing my carb with Jim Oliver's. Everything else was exactly the same. Fired the OPS up and adjusted the highspeed needle. Well, to my surprise, the engine ran exactly as it did with my carb on it. Full throttle was uneven and as soon as my son held the nose straight up the engine went lean and died if held up long enough.

The next thing I did was open the low needle up 1/4 turn. Seemed like it helped but engine still went to lean. Opened the low needle another 1/4 turn and it helped a little more but still going lean. Wasn't even good enough to try flying.

Out of discus, I tacked the engine. It was turning 12900 rpm. I had a 11 x 7 1/2 Zinger prop on the OPS. I decided to try one of my Handcrafted Props by Max Dailey that I use to fly the Saturn with back in the 70's. It is a sweep tipped blade, thin, 11 x 7 1/2-7 pitch. WHAT A DIFFERENCE. Without changing the needles the OPS turned this prop 13900 rpm. My son held the Saturn's nose straight up and the engine did not go lean.

I had said I would never fly any of my Max Dailey props because they are not replaceable and collectables as far as I'm concerned. Well, when I heard the engine running perfectly, I could not resist flying it. I could tell on takeoff that this prop was going to make a big difference in the flight performance. Once I got altitude and trimmed a little I tried a few loops and top hats. The engine was a shade rich but not bad. The engine pulled through the loops and top hats with no problem. I then did a couple straight uplines for a considerable distance. It leaned just a fraction but was what I consider normal without a pump.

I remember someone telling me the 11 x 7 1/2 was to big for the OPS Redhead, but I didn't believe him. I think that he is right now. What I think is happening is the bigger prop is lowering the rpm enough that the tuned pipe is to short for the slower rpm when the plane goes vertical and it comes off the pipe or causes the engine to go lean.

My next thing to try is an APC 11 x 7 prop. It appears to be about the same or less blade area as the Handcrafted prop. This is the prop that most of the CPA flyers in this area are using. Although it weighs 1.4 oz as compared to the Handcrafted prop at .5 oz.

After trying the APC prop I am then going to try my carb instead of Jim's. Mine has an in flight adjustable needle which will let me fine tune the card without landing.

I can't believe that I have messed with the OPS for so long without trying a different prop. I sure hope that the wrong prop is all that was causing my problems.

I'll let everyone know how it goes the next time out.

Ralph White