Sunday, August 24, 2014

August 23rd

After wasting the morning playing Warcraft, I went over to the airfield and repitched the prop on the Flightstar.  I've never seen more than 6100rpm, and the 503 doesn't produce its maximum power until 6500rpm.  The Powerfin prop blades are measured using a 1/4" rod in a hole, then using a feeler gauge to check the pitch, rather than a pitch protractor (which I don't have).  I removed 1mm of pitch (it was basically as far forward as it should go.  When I went out for a test flight, it climbed at around 6300rpm, which I'm happy with.  The interesting thing is that now I cruise around at around 5000rpm, rather than 4800rpm, but that puts the engine a bit further into the power band, meaning it's a bit peppier.  I doubt it'll change the fuel consumption by much, as the Rotax manual claims the best economy is around 5200-5500rpm.  The main thing is that the CHTs are now down to ~400F on takeoff, and the EGTs are above 1000F (it's a bit of a balancing act).  I'm considering that pretty close to perfect, so it's done :o)

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