Rotax 618, 618 Rotax engine  fuel burn.

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Fuel burn of the 618 Rotax engine.

While surfing the web I came across this article about the fuel burn on the 618 Rotax engine. DL

Michael Coates wrote:

 There has been a lot of discussion on several newsgroups recently
 about high fuel consumption in Rotax engines, well i recently fitted
 and tested a new LCD Instrument Panel called the Skydat GX1.

 The Skydat has a built-in, calibrated Fuel Flow meter and i have
 recorded the following consumption rates which make for interesting
 evaluation. The figures come from a Rotax 618 with 60 hours on the
 clock, fitted to an X-Air running a three blade  prop through a
 3:1 gearbox, altitude 1000 ft ASL temp 24 degrees C.

              3500        3.6 l/hr
              4000        4.7 l/hr
              4500        6.6 l/hr
              4800        7.2 l/hr
              5000        9.1 l/hr
              5200        11.0 l/hr
              5400        15.2 l/hr
              5600        18.4 l/hr
              5800        22.4 l/hr
              6000        24.7 l/hr
              Full Throttle 6250        23.5 l/hr

When fitted to the X-Air around 3750 is the minimum rpm where i can  maintain level flight (about 32 knots). I normally fly at 5300 (13.5  l/hr) for 60-65 knots, what is interesting is how much the consumption  increases say at 5800 rpm (70-75 knots) at 22.4 l/hr; almost double  the consumption for 10 knots extra speed. I have learnt from this  exercise that 5200 rpm will give me over 5 hours endurance at 50  knots; that's 250 miles where at 5600 rpm using 18.4 l/hr i can only  get about 200 miles, interesting figures...... any comments ? 

Regards Michael Coates  X-Air Australia.

I guess it would be neat to add the MPH for each of the fuel rates, multiply and get the distance flown per fuel unit relative to each RPM.
BTW, I too have a 618 on my GT 500 and can attest that the fuel burn is 3.25 GPH at 5400 RPM which is 85 MPH. 

This is about what a friend gets with his 912 on a similar plane, but somewhat slower airspeed due to the extra weight perhaps.


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