Wren 44 TurboProp Users Manual. Copyright Wren Turbines Ltd February 2008 Page 3
The new Wren 44 TurboProp
Introduction
This new development from the highly popular Wren 44 Gold thrust engine stable, has been long awaited. It
has built on the success of the Wren 54 Turboprop which has now been on sale in various forms since 2002.
The engine has been the outcome of a long R&D programme primarily concerned with maximising the
performance and minimising the aggravation of installing and operating, allowing the flier to get on with the
business of flying.
We have been careful to keep the weight of the unit down but have not compromised stiffness which has
shown itself to be a major concern for turbo-props. The engine is not modified for use in this application
apart from a small hole drilled in the case to add a lubrication port, enabling the full perfomance to be used
in driving the propeller, producing performance usually described as “
awesome”
by all those witnessing it.
The gearbox assembly is strongly built to withstand many hours of operation and is designed to be
lubricated with a small fuel take-off from the engine. All this is automatic and the user need do no more than
put fuel into the tank, charge batteries and go fly!
We have tried hard to produce a compact high power to weight engine capable of filling the gap left by the
noisy medium to large I/C engine, and the existing range of turbo-prop engines now becoming available.
Most of these are really only suited to large aircraft around 2.5 to 3m (8’ to 10’) wingspan, which has
implications for cost, transport and suitability of flying field. There are a large number of airframes already
available in the 2m (6’) size that are attractive for conversion to turbo-prop for the reasons outlined above
and are suited for the average club flier. The low installed weight around 2kg compares well with equivelent
2-cycle engines and helps to keep the wing loading sensible.
Noise is becoming a major concern and the 44 turbo-prop enjoys a remarkably low noise figure, rivalling
electric models in many cases. The noise is predominantly propeller noise and with the smooth application
of torque and total absence of power pulses enables a very low perceived noise level to be achieved.
The Wren 44 Turboprop enjoys the same highly responsive engine as the Wren 44 Gold thrust version so
the absolute minimum throttle lag can be appreciated by those keen on prop hanging and the usual
aerobatics. The small engine size enables the fuel consumption to be described as “stingy” so no need for
lugging a big fuel bottle around.
Importantly, the engine is already well established so you are not buying an unproven design. Parts and
service is readily available and the hundreds of Wren 44 Gold customers across the world will testify to the
longevity and ease of use of this world-beating engine.
Above all - Enjoy!
From all the team at Wren Turbines Ltd
February 2008
Special thanks to:
Lucien Gerard, a good friend and colleague of all at Wren
Turbines, who was the first customer to build a Wren 54
turboprop back in 2002 that still flies in an Embrear Tucano
and encouraged this development from the start.
Lucien supplied aircraft for flight testing the 1
st
and 2
nd
Wren
44 turbo-prop prototypes and undertook all the test flying. His
generous help and feedback has greatly assisted and
encouraged us to push this unique development forward into
successful production.
Thank-you.
