Wren 44 TurboProp Users Manual. Copyright Wren Turbines Ltd February 2008 Page 20
Installation
DO’s:
Ensure adequate supply of cold air to the engine intake behind the firewall. This must be an
independent supply and isolated from the area in front of the firewall which can get warm in
operation. It is good practice to fit a fine wire mesh at the entrance of this area to prevent buildup
of grass etc from clogging the engine intake. An ideal material for this is the fine high quality
stainless mesh available from Wren Turbines at modest cost.
Ensure adequate ventilation of the stagnant area in front of the firewall to prevent build-up of heat
around the exhaust sections from distorting the fuselage or cowling or affecting the paint finish of
same.
Ensure the area of the firewall is properly sealed using a sealer approved for use with turbine
fuels and oils.
Engine should be mounted using the six bolt radial-mounting. No other means of mounting the
engine is allowed.
Ensure the engine is firmly secured to the firewall using six M3 bolts, and captive nuts to prevent
pulling through.
Any up/down or side thrust should ideally be added to the firewall and not simply a couple of
washers under the engine mounting which can cause distortion of the mount and potential
alignment issues within the engine.
Ensure at least 6mm (1/4”) of clearance around the exhaust from any part of the cowl. The
exhausts get hot in use and may distort or discolour the finish if clearance is too small.
The glow plug and lubrication feed pipe must be positioned upwards – see the cutout template at
back of manual. This is to ensure correct operation of the engine internal lubrication system
during start-up. Inverted flight manoeuvres do not affect the lube system during normal running.
The fuel pump should be mounted at least 100mm away from the intake of the engine. The pump
can emit electrical pulses that cause the speed sensor to transmit incorrect rpm information to the
ECU.
The fuel pump should be mounted with the spindle in the vertical position with the motor
uppermost and the black cap downwards. In the event of any fuel seeping from the pump this will
not pass through the electric motor. Note the pump is supplied fitted with built in suppression to
reduce radio frequency noise.
The centre of the fuel tank should be mounted laterally as near to the centre of gravity (CofG) of
the model as possible. This will minimise the CofG shift as the fuel is used during flight.
If breaking a quick release “Festo” connection, always trim the last 6mm (1/4”) from the end of the
tube to expose a fresh area for the connector to seal onto. To release a “Festo” type connection,
push the blue ring inwards with one hand and gently pull the tube out with the other hand, whilst
holding the collar in its retracted position.
The air ducting to the inlet of the engine must have a minimum area of 2500sq mm, (4sq” )
equivalent to at least 50mm (2”) square.
If an extension to the exhaust ducting is required, it should be approved by Wren Turbines Ltd.
