FastEddieB Posted January 12, 2012 Report Share Posted January 12, 2012 I think I brought this up once before, but I want to re-solicit some opinion... I posted about my Warp Drive prop blades going back to the factory re: loose leading edge strip. I should get them back tomorrow. As background, my Sky Arrow prop has never been adjusted in the time I've owned it (since new). I checked it once, and the pitch was exactly what the AMM called for - about 13.5º, IIRC. My performance has always been OK, but on takeoff I only see around 5,000 rpm, but this again is what the book calls for. Initial climb is just under 5,000 rpm, and here is a full power climb through 10,000': (check out the groundspeed on the Garmin!) Here's full power cruise at 13,500': Having last owned a plane with a constant speed prop, I can't help but think of the wasted performance. That is, our engines (ROTAX 912ULS2 in my case) are rated for 100hp, but that's at 5,800 rpm. IOW, if our engines never see 5,800 rpm, we virtually never see 100 hp, hence the waste. I'm toying with the idea of setting a little less pitch when reinstalling the blades. I'm Experimental, so its OK to "experiment". I know that less pitch will result in better performance in the climb - I'm wondering what effect it will have on cruise. My analogy is that many cars and bikes will go faster in something other than top gear - lower gears let the car/bike rev higher and hence go faster. I'm sure this is something you guys have experimented with. 1) How did a bit less prop pitch affect climb vs. cruise? ...and... 2) Did you find that full power cruise was hurt or helped? ...and... 3) Do I remember correctly that 1º of prop pitch change equals roughly 200 rpm? If that's the case that's probably where I'll start. PS - I'd love to go to a constant speed prop, but even as an Experimental I believe the regs prohibit that to stay in the Light Sport category. Link to comment Share on other sites More sharing options...
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