John's New Model
Late 2017, Colin and I were talking about
what would be a good aircraft for me to make the next step as a newbie
to the slope soaring fraternity. I had already cut my teeth on a Weasel
(foamie wing) and was tempted into purchasing one of Colinís second-hand
machines (The Solange). Having seen Colinís Midge perform I thought
something like this would be interesting as my next model. Colin stated
that the Midge design had itís roots in an old slope soarer called the
Gnott that first appeared as a free plan in a 1990 Radio Control Models
Having expressed an interest, the next time we met Colin had a set of
veneered foam wings with servo hatches, vac formed coverings, the
original plan and build article. Well that was it, a swift exchange of
monies and I was the proud owner of this starter for ten.
Post acquiring the wing panels I had a number of decisions to make.
Wing location. Colin assured me that the wings could be seated
low, mid or high to suit my preference and/or built as a single panel or
in 2 halves. Any of these arrangements would work provided the
aerodynamic relationship between wing and tailplane is maintained. I
elected to follow the original plan and went for the mid wing plug-in
Servo location. Colinís wing panels
were already prepped for a two servo arrangement so this was a given.
However; going for plug-in wings meant a decision had to made regarding
the elevator servo location. I decided to mount the servo inverted with
an access panel in the lower fuselage skin held in place by countersunk
Ballast tube. The plan does not
show a ballast tube; however, I decided to fit one across the C of G
position which again meant a slight design change and a second access
The build of the fuselage went together as per the instructions
provided; however, some build mods that I adopted were;
Formers 2 and 3, I had issues with the strength of the
recommended balsa items so I replaced these with light ply of the same
The wing tubes that support the
wing connecting piano wires I decided to ensure that the front tube was
securely bonded to former 2 to add structural strength.
Cut holes in the fuselage sides for
the aileron servo wires and to accept the wing retaining system. (See
The wing build
This was straight forward as most of the
work was already done. Some points of note;
The wings are thin so the size of servo you use is critical. I
originally tried to fit some micro Hitec servos which were too thick. So
a quick call to Colin and I settled on Savox 0255.
The alignment of the wing incidence is
tricky with plug-in panels so take your time and use an incidence meter.
Wing incidence is about +1.5O
In order to obtain the correct dihedral I
cut slots in the wing panels to accept the retaining tubes. The tubes
were made into a sandwich with the upper and lower balsa infill. This
tube sandwich was positioned on the connecting piano wires and the wing
was then slide over the assembly. The wing dihedral was set and the wing
position marked on the tube assembly. The wings were removed and epoxy
applied to the slot and sandwich and then reassembled. The wings were
held in position until dry.
Cutting the ailerons out after covering is
beneficial and I used a finishing technique suggested by Colin which was
to use micro balloons and epoxy to finish off the forward face of the
aileron and the rear face of the wing. This was a new technique to me
however, the finish did provide a close gap between aileron and wing.
In order to keep the wings on the mounting
piano wires I decided to use a hook and band arrangement. I shaped a
hook out of piano wire which was then bonded into the wing root. The
wings are then held together using rubber bands (in my case cuts of tyre
inner tube seem to do the trick). To pull the rubber bands through the
fuselage you will need to fashion a small tool out of scrap piano wire
to hook the band and pull through the fuselage and hook onto the other
The Tail Feathers
posed a new challenge for me, I had never
built an all moving tailplane. Some build notes from my experience.
The plan shows two vertical supports to
build the fin around. Take care in getting these perfectly vertical to
the fuselage and square to the wings.
I elected to put a horizontal support beam
at the bottom of the fin which is mounted on the upper surface of the
fuselage. This provided some additional rigidity at the base of the fin.
In order to get the tailplane at 90O to
the fin I used the following technique. Cut out both sides of the fin
and then laminate the bearing surface with thin ply to suit. I then dry
assembled to the fin supports to obtain the correct dimension for the
bearing tube. I cut the brass tube to length and trimmed One of the fin
sides was securely pinned to the build board and the brass tube
accurately epoxied into the pre drilled hole using a set square to
ensure the tube is perfectly vertical in all directions. This was left
to dry and then this side of the fin was glued to the fin support
structure. The other side was aligned and glued to the fin supports
ensuring that the brass tube is epoxied into the second side.
To ensure slop free support and rotation
of the tailplane, strive to obtain the closest fit between support
bearing and piano wire. I had many attempts before I achieved a fit I
was happy with.
To ensure smooth operation of the
tailplane and longevity of the bell crank. I bushed all three holes in
the bell crank with the appropriate sized brass tubes.
Finishing of the structure was done by using fibreglass matting and
acrylic resin. Although this process went well it proved to be too
absorbent as a base for priming and painting. The amount of paint used
added more weight to my finished model than I would have liked.
Fitting the battery, receiver and switch into the nose cavity is tight
so prior planning is a must, particularly as there may be a requirement
to add weight to the nose.
I now await a good day to take the GNOTT onto the slope and get some air
under its wingsÖÖ..that will be another story.