DG Flugzeugbau GmbH
Flight manual DG-500M
4.5.5 Cruise engine on and ultilisation of the wing fuel tanks
General
The engine of the DG-500 M is not designed for continuous cruise with
the engine.
Due to the high drag of the extended powerplant and as the propeller is
designed for optimum take off performance cruise with higher speed is
not efficient.
The optimum cruise is with the so called sawtooth technique.
After climb with Vy retract the engine and glide with airspeed according
to the Mc Cready theory, flying slowly in lift and faster in sinking air.
The medium cruise speed achieved by sawtooth technique is not much
less than for level engine on cruise, but the range will be more than
doubled.
Performance data see sect. 5.3.5.3 and 5.3.5.5.
Utilisation of the wing fuel tanks (Options)
The wing fuel tanks have no fuel level indication. Therfore it is best to empty
the fuselage tank to approx.10 l (2.6 U.S.gal.) and then to transfer the fuel from
one wingtank into the fuselage tank. Should the fuselage tank become
completely empty and the engine RPM's begin to drop, set the throttle
immediately to idle and open one wing tank valve. After about 45 sec. there
should be enough fuel in the main tank to apply full throttle again.
Another aid in determining fuel levels is the engine elapsed time indicator as
with normal flight fuel consumption of 25-29 l/h (6.6-7.7 U.S. gal.) and
knowing how much fuel was in the aircraft at take off, the amount of fuel left
can easily be calculated. The engine hour reading should therefore be noted
before take off or the daily elapsed time indicator in the DEI (see page 7.12)
should be set to zero at take off.
Issued: April 1997 App. 4.19
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