Installation service by Step-Four Tips from the experts

Rubrik
The “Fairey Rotodyne” is ready for its maiden flight.
An extraordinary scale model is created with
the “Basic 540”
Phillipp Gardemin from Baden-Württember,
Germany,
reports about building
this helicopter model with
the aid of a Step-Four Basic
540. With a rotor diameter
of almost three metres,
this is a mighty big chopper.
I dreamt for years about building a “Fairey
Rotodyne” scale model. I flew this extraordinary
helicopter in the late 50s, in England
– but unfortunately this project didn’t
get past the prototype status. This helicopter
was extraordinary due to the fact that
the almost 30 m main rotor was tip-driven.
The tips were powered by a mixture
of fuel and compressed air bled from two
wing-mounted turboprops.
The model was constructed at a scale of
1:10. In order to be able to bypass the mechanical
complexity of the tip drive, the
plan was to operate the model as an autogyro
aircraft. This means that the rotor
is driven by the airflow, thus, allowing the
model to take off. The first drawings were
created on the CAD. The dimensions were
then taken over from a plastic model by the
Airfix company.
Realisation with Step-Four
The fulfilment of the dream, however,
could only take form with the acquisition
of the “Basic 540” milling machine.
The general layout drawings in the CAD
gradually became a tangible plan. Thus,
the individual parts separately drawn, exported
to the milling software, and then
be directly milled. Only poplar plywood in
thicknesses of four and three millimetres
was used. The sheeting was made from
1,5 mm balsa.
Ten month construction period
During a construction period of over ten
months, the milling machine became a
best friend. Even the smallest of parts
were drawn, exported to the milling software,
and subsequently milled. The large
cockpit, for instance, was quasi drawn
from nothing in the CAD, the parts exported
and milled. After a total construction
period of twelve months, the model
stood on the meadow, ready for flight.
Two Hyperion external rotors with 4 blade
airscrews from Varioprop and a 6s LiPo
6500 mAh served for propulsion. The rotor
blades – consisting of a Styrofoam cores
with carbon reinforced plastic spars and
plywood sheeting – rotated in a four-blade
rotor hub from Varioprop and a self-built
swivel mechanism. The entire model now
weighed 10.5 kg.
Test flights
The “Fairey Rotodyne” was unfortunately
unable to perform its maiden flight, which
was due to the fact that the self-built autogyro
mechanism wasn’t powerful enough
for the enormous rotor diameter of almost
three metres. The model is currently undergoing
modifications, whereby mechanical
details are being improved upon, as
well as the mechanic of the swivelling vertical
tail fins. New test flights are planned
for spring 2010. The “Basic 540” will certainly
provide me with many more good
services until then.
Philipp Gardemin
10 STEP-FOUR | March 2010