O3 Fuel Burn vs Speed Calculations

[Jeff_S]

I had a nice, fairly calm day yesterday so I set out to do some "test piloting" in my O3, to see the difference between different RPM and fuel-flow settings on speed and fuel burn. My goal was to come up with some rules of thumb for cruise settings.  At the three selected altitudes, 7500, 8500 and 9500, I show MP at WOT and the rest of the data came from the readouts on the G1000. Fuel rate was set at 20° ROP and 20° LOP.

 

What this tells me is that in general, if I'm flying into the wind I'm going to go at 2500 RPM LOP to pick up a few minutes of time at minimal fuel cost. Flying with the wind, 2400 RPM and LOP for best efficiency. I tried to compare these numbers to the POH performance charts but it's really tough, since I left it at WOT and used only the Lean method for fuel flows.

 

Your mileage may vary, of course, but here's the data if you're interested.

 

 

GPH Calculations.pdf

[Robert C.]

Jeff,

That looks pretty much identical to my experience. The 9500ft LOP numbers in particular match mine closely.

Robert

[Cruiser]

was there a reason you didn't test 2300 RPM? 

At 7000 to 9000 feet I typically run 2300 and get 169/170 KTAS

[Jeff_S]

Hi Tom,

 

I didn't test 2300 because I just didn't think about it. For the fuel burn difference I suspect I would not use that setting just to maintain a bit more forward speed, but  I could give it a try.  But I typically reserve 2300 for the approach setting either to fly the final legs of an instrument approach or to help slow down for a visual. I've found 2300 and 15" with gear out and approach flaps to put me right on the 100 KIAS number down the approach path.

[Robert C.]

was there a reason you didn't test 2300 RPM? 

At 7000 to 9000 feet I typically run 2300 and get 169/170 KTAS

 

Life's too short to fly slow !!