So, while we are waiting for our approval to go past 19500' we found other stuff to test....
Anyway, at present I am turning a P-Prop 70' x 80", which is all very nice, but how do you actually know when you have the perfect prop?
Well, you could have several made up, or you could borrow, which is what I did.
Jannie Versfeld (he's the one with the Cozy w O-540) is turning a Catto 66" x 88" and I always wondered how course I could go ... wonder no more, he lent me his spare prop!
So I decided on a minimum static (2000rpm) and if that was attained (or very close), we'd do a trial run, with a predermined go/abort point (500m at BaraG on 31, 13 was not to be used for this type test!)
Today I fitted this black monster to my Cozy and tried it out - Wowie!
Static turned out at 1950 (close enough!) and after some soulsearching I decided that I'd take it to the runway to see how quickly she'll unwind.
At the 500m marker we were already airborne and accellerating, not quite as chipper as I had gotten used to with the other prop, but this promised to be a quick run. At the end of the runway we were turning 2100 rpm with a positive climb out at 90 KIAS.
Goodie, I let it climb from 5300 to 6500 and kept a racetrack pattern to the drome. by the first downwind we were indicating 150 KIAs , the rpm looked like they were increasing steadily, and on the pass over the runway it was doing 165 KIAS with the RPM at 2400 and still increasing. On the second downwind the gauge started giving trouble and since the motor was turning smoothly, I figured that it is the pick-up point or the gauge, so I called it a day ... things only get worse and this was as good as it was going to get.
Thus I killed the power and tried to get it to slow down for a landing ... no way could I get it to less than 120 KIAS, so yet another flight with the by now customary go-around. Second attempt was perfect with the figures nailed at 90 Downwind, 90 base, turn final, cut to 80, pull brake, slow down some more and 70 over the numbers, touch down at 60 KIAS.
Turns out the wiring had come adrift at the pick-up point to the motor.
All and all an exciting episode.
Tomorrow we'll try again, this time with the RPM gauge working
Conditions ... 20C, no wind to speak of, 1028 Hpa. Runway 31 in use.
1/2 tanks, me alone @ 206 lb and ballast in the nose.
It appears that this prop may be a little coarse and my next one may be 70" x 84" which will allow me to take off on gross at this field (FASY)
Just thought I'd share my fun!