Got in flights 18-22 on my Xtreme today. Startng to get into "Propeller problems" due to noise issues. A Mejzlik 28-10 is turning 6900+ on the ground, and just makes a ton of noise in the air. Menz-s 28-10 is right at 6100-6150 and will start barking at 3/4 throttle, or at the slightest provocation after a downline.

WHAT to do??

I have a 29-10 Mejzlik that I intended to eventually try on the engine, after it was fully broken in, but with the 28-10 Mej zooming like crazy, and the Menz dragging the motor down more than I like during break-in, I decided to experiment with the 29-10.

If you have seen the 3W CF "3D" prop, which is 31.5 x 14x8 pitch and has a very square tip, you would think it would be very noisy. As a matter of fact, it's quieter, at the same rpm, than a Menz of the same size. That is is how I modified the tips of the 29-10. The prop was really about 28.75" in length, so I shortened it to 28" exactly, and added the "squared off" tip that has a rounded front corner and pointy rear corner on the tip, then rebalanced the prop. The blades chord is about 10% wider that the chord on a 28-10, and noticeably wider toward the tip of the blades, giving me a "wide blade" prop with a squarish tip. . VERY "Full Scale" looking prop.

How did it perform? 6300-6350 hot, after landing, no loss of pull, much smoother in the pattern, and MUCH quieter. The wider blade is DEFINITELY helpful in keeping the noise down, while suffering no loss of performance.

The current setup for the Xtreme is the stock CH ignition, 3.5" headers feeding into "70cc" PEFA Canisters. There is NO tuning from the exhaust, since the primary tube length is about 3-3.5" too short to help in the 6000-6500 rpm range. It does quiet the engine a bit, though, and with the 28-10 Mej spinning 6900 or so during an IMAC style dB test, it passed with a 94-95 dB readng at 25 feet over grass. The engine idles as low as 1100 without a whimper, and 950 can be had if you are careful getting the motor down that far.

Prop slippage is NOT a problem. I've used the two Mejzliks, and the Menz, and none of them have moved a degree once the nut is tightened. There is no sign of overheating or running problems, and the motor just keeps on running. I'm getting 17-18 minutes per flight from a 32 ounces tank, with about 8 ounces left in the tank after landing. With 20 flights so far, and about 4-5 hours on the engine, it's starting to break in a bit, but I figure it's going to be another 5-10 gallons and 8-10 hours of flying time before the engine will have reached it's performance potential.

I'm looking for a solid 6400+ with the Menz 28-10, and about 6600 with the modified Mejzlik 29-10, after the engine gets fully broken in. It's also just a tad on the rich side,during break-in, so I'll be able to play with mixture soon as well. Of course, the 28-10 Mejzlik would be seeing the high side of 7000 by that time, and that's just TOO much.

I can hardly wait till I get an airframe that will hold proper headers and canisters, so I can "tune" the exhaust for the 170 degree exhaust ports and pick up some more power.. .

Let's see. . 6700+ with a 28-10 Menz-s, and about the same with a REAL 29-10 Mejzlik . .that hurts just to imagine. I wonder if there is a 30-10 in the future for this engine.