I’ll make this one short and sweet.

The real article I wrote deals with the need for slowing the events down. (no dammit, I’m not suggesting we all run Jetts), but I couldn’t get it out without offending every single NMPRA member. I had to put it away for a while.

** LET’S TALK THE SAME LANGUAGE **

Crap Trap 2 , I think, talked about testing and taking data. It would not hurt to go back and read it about once a week. It is obvious that some of you were not listening. You must take good, solid, consistent data. I have a radar gun, temperature gage, humidity gage, air density gage, and wind velocity gage. Still, things are confusing at times and you must have many data points to make sense of it all.

I suggest that we all use the same engine unload taching propeller. Jetts, Nelsons, and Edmunds. This is relatively easy to do.

Take the APC QM practice propeller, 7.4 x 8 Carbon Fiber, PN LP 07480C, and cut it off to 6.375” (6 3/8). Do not work the prop down in any way. Cut the tips off square and deburr only enough to avoid cutting yourself. Put no more than 1/16 radius on the leading and trailing edges of the tips. Unless you go hog-wild, the above is not critical, except for the length - this must be right.

What should it TACH? Ok, read the Crap Trap II. Use a test stand and a good tank. Use a good plug and a known fuel. If you use your airplane, don’t bother to read the rest.

Taching results depend upon where you are, but expect RPMs above 27000. Under certain conditions I have seen close to 28000 in Houston, but generally expect between 27000 and 27500. This includes all brands of engines. The important thing is to have your group of flyers, and as many others as you can get, to use the same prop. Do not loan your prop, except for calibration purposes, and store it in a cool, dry place.

Finally: Work safe!! Don’t stand in front of the propeller when you tach. Use a remote NV on your test stand. You can use a remote, even when you have the standard NV up front, just open the NV a few extra turns. Do not allow anyone to stand in front of your propeller (or to the side) when you run!!!! Don’t be really stupid and stick your finger in the venturi. I had a propeller blow a blade. In an instant, the engine rotated 45 deg. and broke one of the lugs. If my hand had been on the NV or in the venturi, I would be fingerless. A word to the wise......

I suggest this propeller because it is cheap, reliable, consistent, and easy to replace.

Food for thought: You can be yourself around your caller because he already knows you are an idiot.

Dub