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Home Page Flair Products are grateful
to Traplet Publications Ltd for their permission to reproduce this report originally
published in Quiet Flight International - February/March 2000. The review was conducted by
Rainer Eckert, our thanks to him for a fine model and a well balanced review.
You can see more information about QFI, Radio Control Model World and the numerous other
modelling magazines at Traplet's website www.traplet.com
A wooden dream: The
"K8" finally ready to cover.
The servo to operate the aerotow release hook
Flair are known world-wide
for their range of models, all built the traditional way with lots of wooden parts. In
1997 the "K8" was presented as a new kit within their range of "Quarter
Scale Classics". The moment I saw a picture of the model, I knew I had to have it.
But I was quite amazed when the postman arrived with a rather small and heavy cardboard
box. It was hard to believe that its contents, if put together the right way, could become
a model with almost 4 metres of wingspan? They do - no worry! I have never seen such a
packed box; sheets of die-cut plywood sticks of balsa, accessories, etc. - there was not a
cubic inch of air left inside.
Except
for the fibreglass nose cone, the plastic cockpit canopy and the airbrakes, all the rest
of Flair's "K8" is built from wooden parts. To help woodworms like me to find
the way out of the dark cellar with a model ready to fly as soon as possible there are a
brilliant set of instructions plus an exact CAD plan for the wings (scale 1:1). The
instructions are fun to read: on 16 large sheets each building stage is shown in detail by
excellent 3D-CAD drawings and lots of text - written with a real sense of humour.
Don't
hurry - take your time.
A close side view of the fibreglass nose cone and the landing skid with rubber suspension.
Before you even think of putting parts together - there are more than 600 of them
- you better go through the instructions several times and start numbering the die-cut
parts as well as sorting all the different sizes of balsa and hardwood sticks. This piece
of advice is more of important the smaller your workshop is. Mine is just 6 square metres
...
The building
material is of good quality, especially if you take a close look at the die-cut plywood
parts - they almost jump off the panels and are cut precisely. Most of the necessary
hardware is included: 2 releasable hooks for aerotow and winch tow, flat strip/brass tube
wing joiner, cockpit canopy, wheel and CNC machined airbrakes, which are made from Tufnol
and represent a little kit of their own.
Once you have
got familiar with the building style of this kit you just have to follow through the text
and diagrams on the sixteen sheets and start building. Before I focus on the assembly
process I should mention at the outset that this kit is meant more for advanced and
experienced builders. Though the skill level required is only medium, there are some
stages where you need to have some ideas of your own and staying power.
A carbon fibre tube serves as a
pushrod.
A woodworm's diary
Don't be afraid: I am not going to
write down a biography about the more than 400 hours that I have spent in my workshop. I
am just going to highlight some of the details during the building process. The whole
story starts with the right wing half, which is built upside down. A simple crutch made
from balsa stringers and packing pieces help to support the trailing edge at the correct
incidence angle. Balsa sheeted "D''-boxes and two strong spars webbed with balsa
sheets take care of bending and torsional strength. The wing halves are joined by means of
flat steel strips and steel rods inserted into brass tubes. A strong hardwood drag spar
glued diagonally in between the first 4 ribs reinforces this section. All ribs are made
from liteply- a sandwich material with thin plywood and balsa layers - and have additional
apertures for further weight reduction. The airbrakes are inserted right behind the main
spars. They extract - just like the original ones - on top and bottom sides of the wings.
When fully retracted they are safely locked by the extra travel of the sliders. Each
airbrake is operated by a standard servo.
The building
of the wings is quite some work and takes a lot of time, but will not trouble the
experienced modeller. However I have to report some problems concerning the material used
for the trailing edges. They are formed by gluing strips of balsa stock onto top and
bottom sides of the ribs' rear ends (see picture). The balsa supplied with the kit was far
too soft resulting in some really wavy trailing edges. My solution was to cut 5 mm off the
trailing edges and replace it with 5 x 3 mm straight (!) strips of hardwood.
Self made threaded axles to
join tailplane and elevator, and fin and rudder.
After the
wings were ready for covering - I was really happy to get these large parts out of my
narrow workshop - the tail was up next. The tailplane and fin are sheeted
completely with balsa whereas the elevator halves and rudder are built with ribs and have
to be covered. They are joined by metal hinge plates and split pins. The split pins are
somewhat tricky to mount and cause a lot of play. This is why I chose to employ self-made
threaded 2 mm steel axles and nuts resulting in safe and solid joints (see picture). The
completed tailplane assembly is bolted to the tail boom by two M5 nylon screws. Thus the
tailplane can be removed for transportation and allow an individual adjustment of the
incidence angle.
"Nickel-cadmium
instead of lead": Two 1500mAh battery packs fit into the nose cone.
The best part
of the whole building process is the fuselage. It is constructed on a building board,
upside down with all components self jigging. All you need to do is to align the
components along a straight line on the board. The fuselage on the original "K8"
has three main longerons made from steel tube, with the model wooden dowels are used
instead. To obtain the characteristic oval shape of the "K8" extra stringers are
employed. The model construction represents the full size in a very realistic way, yet it
is strong and light. As said in the beginning, the nose is a fibreglass part - just as
with the real "K8" - and it fits to the fuselage's front end without any
problem. The landing skid is fastened to the fuselage by two bolts and has a rubber bump
stop. With most of the full size planes it was fabric covered - so I decided to do it the
same way with my model. Finally, I have to state that I really loved to build this
masterpiece of a fuselage and I would like to congratulate the Flair team for their great
engineering work.
Looks like
the real thing: Rainer's "K8" in the "classic" German finish.
The rudder
servo is linked to steel cables.
RC-installation
Although the fuselage leaves plenty of
space it is recommended to plan and to start the radio installation early. On the lest
model two strong ball bearing servos were employed to actuate the elevator and rudder.
They were screwed onto two hardwood bearers which were fastened on different levels
underneath the section were the wing halves are bolted to the fuselage. Rudder actuation
is achieved by means of steel cables; the elevator is operated by means of a 6 mm carbon-
fibre tube. According to the instructions a 12 by 12 mm balsa pushrod should be used for
this task, however this part is too thick - even when tapered - to go through the narrow
apertures inside the tail boom's rear part. One thing I have to criticise is concerning the
elevator joiner. The quality of the lever soldered to the joiner is very poor; i. e. it
comes off if stressed just a little bit. Also, the lever is 10 mm too short to be joined
with the elevator pushrod. As this element represents one of the most critical parts of
the model - imagine a quarter scale glider with lost elevator control - I decided to build
one of my own. My joiner has a longer lever and additional struts to reinforce the bent
legs - both were hard-soldered (see drawing). Hopefully, somebody at Flair will take care
of this problem.
The Mc20 - receiver is
hidden underneath a scratch-built pilot's seat.
First balance
tests of the model in the stage of "ready to be covered" revealed the necessity
of about 850 g of ballast. According to the principle "nickel- cadmium instead of
lead" I managed to install two large 1500 mAh battery packs into the nose cone (see
picture). Assisted by another 450 g of lead they keep the balance point exactly where it
has to be. Directly behind those battery packs I mounted a micro servo to operate the
aerotow release hook. The second release hook for winch tow is placed 90 mm in front of
the wing's leading edge to the left side of the fuselage main spar. However, I did not
install any means to operate this second release hook as my model is intended mainly for
slope soaring. Connection between the servo cables coming out the wing halves and the Rx
is achieved by two 9-pin Sub-D connectors, which were placed on a plywood board next to
the wing seat. A self-made pilot seat hides the Mc20 receiver plus all the cables. Thus
the cockpit looked neat and tidy motivating me to add a bit more realism to the cabin.
This gets us to the next chapter, dealing with the ...
.. Finish!
A semi-scale model like Flair's
"K8" deserves a perfect outfit, no doubt about that! However, the colour scheme
suggested by Flair - dark green and white - was not my cup of tea. I chose a
"classic" German Colouring in white and red. Adhesive decals and a set of
pictures of a full size "K8" - provided by MKO, Flair's German distributor
- helped me to get an optimum finish, luckily I found a white lacquer spray that matches
perfectly with the white Solartex covering. Thus, I only needed to spray the nose cone and
the canopy frame saving both weight and working time. The red lines on the fuselage as
well as the red spots on nose, rudder and wing tips were spray-painted as well.
The airbrakes are quite effective.
The tailskid is true to scale, however it takes some work to build it.
Next up was an instrument panel, which was
designed according to pictures I took from the cabin of a full size "K8". The
instrument dummies were built from a J-Tec (USA) kit and cemented to a thin black plywood
panel. All the other wooden parts inside the cabin were painted in white. Finally a wooden
control stick and of course "Adrian" - a latex pilot puppet offered by Flair -
make the cockpit of my "K8" look like the real thing. The last thing was to
paint the covering of the landing skid in black and to protect it against abrasive wear by
means of a strip of aluminium that was bolted to the skid.
Adds a touch of realism:
Rainer's self made instrument panel.
High in the sky at last ...
After more than I year of building
time my "K8" was allowed to come out of the dark cellar into the bright day
light. Due to former contributions to QFI some of you still may know that I live in
Kirchheim - yes, Graupner is located there, too - where we have one of the most beautiful
landscapes in Germany for slope soaring. Around the Teck - a mountain next to Kirchheim -
there are 5 different slopes to choose from. No matter from which direction the wind is
blowing, there is at least one suitable slope to go soaring. So it was clear that my
"K8" had to do her maiden flight on the Teck. As with all my 'other models I
asked my good old friend Emil Diez - to be the one to pilot the "K8" on her
first trip into the skies. Emil is now almost 76 years of age, but he is still goin
strong. He has flown full-size gliders and has been into RC-modelling for nearly 30 years.
Due to his great experience he is a well respected RC-pilot on the Teck. Some say, Emil is
able to smell thermals ...
The landing skid with additional
protection made from aluminium.
The tail plane is bolted to the tail
boom.
 
Rainer's "K8" during her
maiden flight.
The full size "K8" which
donated the colour scheme.
So, with Emil at the controls and
great expectations I took a run for some yards and threw my "K8" down into the
wide valley. A slight westerly wind was blowing and soon the model gained enough altitude
to risk an excursion away from the slope in order to look for some thermals. Emil - like
always - did a great job and after a couple of minutes my "K8" was high up in
the sky. The shiny white wings were glancing in the sun and it was hard to tell if it just
was a model or a full-size plane. A beautiful sight to look at!
With this reinforced joiner there is no
risk of losing elevator control during flight
Just like the real glider Flair's
"K8" is very easy to control and has superb handling. In light thermal
conditions the "K8" has some advantages if compared with modern fibreglass
models - every little bit of lift can be used to gain altitude. It is a pleasure to fly
the model in tight circles aided by a little rudder coupling. The stall is gentle without
severe wing drop and recovery from spins mostly occurs quickly when the pilot releases the
control sticks for a couple of seconds. With some down elevator the model penetrates the
air quite fast; this helps to get from one thermal to another with minimum loss of
altitude. Faster penetration can be achieved by adding some extra ballast (up to 1800 g).
The airbrakes work efficiently - when fully deployed the "K8" comes down in a
steep gliding angle but is fully controllable. Thus, landing approaches are very easy to
control. When touching the ground the landing skid takes most of the bumps and the
"K8" slides for 5 to 8 metres on the meadow before she comes to final stop and
one of her wing tips softly touches ground - just like the full size plane.
 
Construction
of the wing's trailing edge. The wing halves are built upside down.
With excellent 3D-drawings like these, building the fuselage is pure fun.
 
The final landing approach, as always
Emil Diez did a great job and brought her down safely.
Conclusion
This kit offers good value at a reasonable price. Almost all the accessory parts are included and - some experience assumed
- no modeller will have any trouble with that kit. The excellent set of instructions help
to make a nice quarter-scale masterpiece, which can be regarded as a serious alternative
to the more modern glass ships. The weak points mentioned above surely should be mended by
Flair, but they are - if compared to the other, positive facts of the kit - of minor
importance. So I would like to recommend Flair's "K8" to every modeller looking
for both building satisfaction and a large beautiful glider with excellent flight
characteristics.
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