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
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
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.