traplet.gif (5084 bytes)

Back to Flair Models Ltd
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.
Structure.gif (67434 bytes)
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.

Wheel.jpg (4593 bytes)
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.

Carbon_rod.jpg (4639 bytes)
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.

Hinge.jpg (4909 bytes)
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.

Batteries.gif (18366 bytes)
"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.

Model_finished.jpg (10792 bytes)

Looks like the real thing: Rainer's "K8" in the "classic" German finish.

Rudder_servo.gif (14133 bytes)

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.

Seat.gif (12049 bytes)

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.

T_skid.jpg (4993 bytes)
The airbrakes are quite effective.

Tail_skid.jpg (3571 bytes)
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.

Instruments.jpg (8190 bytes)
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 ...

Main_skid.jpg (5115 bytes)
The landing skid with additional protection made from aluminium.

Tail_fixing.jpg (6416 bytes)
The tail plane is bolted to the tail boom.

In_flight_1.jpg (5983 bytes)   In_flight_2.jpg (5504 bytes)
Rainer's "K8" during her maiden flight.

Full_size.jpg (6462 bytes)
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!

Elevator_Joiner.gif (5004 bytes)
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.

Wing_Structure.gif (4071 bytes)Fuselage_Structure.gif (6905 bytes)

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.

In_flight_3.jpg (6684 bytes)  In_flight_4.jpg (6763 bytes)
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.