Alittle out of my realm of knowledge but I will state an observation that I have made of certified engines.
They rarely if ever get anywhere close to their redline on a static engine runup. I would not be too quick to condemn the setup until you did at least a high speed taxi run to see what the prop unloads to. This will be more of a true indication of what it is doing. I am running a 52 X 48 Culver prop and don't see more than 2600 - 2800rpms static. Yet this is the same setup that Dave Selby I believe had on his flying KR2 and did not report any complaints. Our engine is an 1835cc with big jugs so it works out to 1915cc I think. Remember that there needs to be a compromise between static rpm and unloading rpm. Too much static gives a great climb rate and short takeoff, but hurts cruise speed. Too much pitch will or length and pitch will hurt the applied torque, and prevent the engine from being able to deliver maximum torque to the prop. Shorter props do better at higher rpms. Longer props get the tip speed too high, and start to require too much torque to turn the mass instead of make thrust. I read where it was compared to gears in the transmission: too little prop would be like trying to drive everywhere in 1st or 2nd gear, too much prop would be like trying to run around all the time in 4th gear or overdrive. One makes for great takeoff, but slow top speeds, the other makes for very bad takeoffs, and great top speed if you can ever get there. Example: Mooney 20J 200 hp constant speed prop, climbed with near max weight at about 500-750 fpm, but when level at cruise eventually wound up to an indicated 150knots, and at 8000 ft TAS of 162knots. Just some thoughts while waiting for the FAA to get back out to sign off N96TA.... Colin & Bev Rainey KR2(td) N96TA Sanford, FL crain...@cfl.rr.com http://kr-builder.org/Colin/index.html
