Wren 44 Gold Helicopter Owners Manual
Page 3
The Wren 44 Helicopter Turbine
Introduction
This development from the highly popular Wren 44 Gold
thrust engine, has been on sale since 2005. It was built
on the success of the Wren 44 Turboprop and uses the
same engine and 2
nd
stage components. The Wren Heli
engine was 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 turbines. The gas turbine is
not modified for use in this application apart from a small
lubrication port fitted to the case, enabling the full
throughput to be used in driving the helicopter rotors,
producing performance usually described as “
awesome”
by all those witnessing it and meaning it is never needed
to use maximum power, thus ensuring long life and ease of operation.
The gearbox assembly is strongly built to withstand many hours of operation and is designed
for lubrication with a fuel take-off from the engine. All this is automatic and the user need
only put fuel (clean!) into the tank, charge battery and go fly!
We have tried hard to produce a compact high power to weight engine capable of filling the
gap currently occupied by the noisy and smoky 90’size heli I/C engines and yet keep the
package bulk and weight down to allow simple conversion without throwing all the standard
parts away. There are a large number of airframes already available in the 15cc (0.90”) size
that are attractive for conversion to turbine for the reasons outlined above and are suited for
the average club flier to expert flier alike. The low installed weight around 1.4kg compares
well with equivalent 2-cycle engines plus tuned pipe and helps to keep the rotor loading
sensible.
A major plus factor for this engine is the mountings and output shaft dimensions are exactly
mirroring the standard OS91H helicopter engine, therefore any airframe, clutch and fan,
designed for this i/c engine will fit onto the 44 Heli engine.
The main areas for modification will be the fan shroud and main frames.
Remember - fit the black washer supplied onto the shaft before the clutch, to avoid
bearing damage
