Sport Pilot Talk

jake · Joined: 25 Oct 2009 Posts: 80 Location: minnesota

My P2008 took about 5250 RPM to get 120kts before the hot weather. Now it seems to take 56-5700 to get the same cruise speed. I can now also hit redline fairly easily in level flight.

I am wondering if this is normal or is something else going on?

Jake

roger lee · Posted: Sat Aug 20, 2011 10:17 pm Post subject: RPM vs OAT

You should set your grond adjustable prop on your Rotax to achieve 5500-5575 rpm WOT flat and level at your normal cruise altitude. 5200-5300 WOT is overloading your engine and causes higher engine temps and excessive wear and stress on metal parts. RPM change will depend on when you set your prop pitch. But generally in the summer with less dense air it will tend to be slightly higher and when it turns cold and the air is more dense it should be a tad less rpm. The change though is usually only about 60-80 rpm. The yellow area of the rpm range for Rotax starts at 5500 and red line is 5800. You can run 5500 all day technically. Most tend to cruise around 5000-5300. I tend to be 5100-5200 for cruise, but my WOT is 5560. You can only run over 5500 up to 5800 for 5 minutes.

What is you WOT flat and level at your normal cruise altitude will help?