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An Airliner emerge …

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McDonnell Douglas MD-11

Two decades is a long service period for a model. At some point, you will have to force yourself to make a decision, say goodbye and reissue the model. I’m talking about my dear old MD-11 in KLM colours, which started its career with three little 15 ccm motors and was my first turbine model. It found a new owner, who refurbished it lovingly and elaborately. What can and want you to improve when starting a new?

I didn’t think there was a reason for changing anything about the aerodynamic structure or the drive concept, designed for one single turbine in the vertical stabiliser. The base for my Airliner models are part kits, containing nose and tail section with vertical stabiliser and engine nacelles, produced in GRP construction from negative moulds. So here I found a potential for improvement. The MD-11 has been developed from the shorter DC-10, and so I used the negative moulds for my old model, that I initially built for the DC-10. But, taking a closer look shows the differences between both versions.

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The MD-11 has an elongated tail cone and the rear engine air channel in the vertical stabiliser has distinctive thickenings in the front and rear part. And so a new construction of the moulds was planned.

Also, the nose section didn’t please me anymore. The nose with its characteristic cockpit windows is an elementary part of the Airliner’s original looks. So a flawed nose destroys the visual effect of an otherwise well-designed model. Now, the old fuselage nose was not that bad, it just wasn’t really scale. Consequently, the nose was built in a new shape. And with all the new forms, the construction of a new MD-11 could be carried out without problems.

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Both frames stabilise the tail.

At first, it was about ordering some new construction parts, which I wasn’t inclined to build myself or I simply couldn’t, due to my lack of expertise and tools. The first category includes the styrofoam cores for the mid part fuselage, wing and elevator. I could use my old cutting bow, but a better quality would be obtained making use of the CNC-milling services of Manfred Köster. The landing gear and the engine are beyond my capabilities, so this assignment went to Hawe Modellbau, where I ordered an IQ Hammer 160+, just right for an Airliner above the 25 kg limit.

Rear fuselage
I started with installing the joining tubes for the elevator. I glued a 14 mm carbon tube and 3 mm steel wire into the rear fuselage, according to the V-shape with 10 degrees on each side. When installing the turbine, please note, the thrust axis has to have a preferably large angulation. If you install the turbine horizontally, there will be a strong top-heavy moment, which in the original is balanced via the thrust of both turbines pushing the nose upwards, in the model, on the other hand, the wing-pods stay empty.

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DThe GRP components of the MD-11, consisting of nose, tail, vertical stabiliser and engine nacelles. Fuselage and wings will be constructed in styro/balsa.

The air inlet of the engine nacelle should receive a prototypical appearance. This is done by creating a GRP component, inserting and glueing it into the nacelle opening. Then, the intake lip can be sanded to round it up. The rudder is a conventional balsa frame construction. The protruding joining tube intakes of the elevators were boxed, so the pushed-in styrofoam cores could be precisely adjusted and glued with the connector intakes.

After removing the protruding parts, the tail unit halves were ready to be planked with 1 mm balsa. For reinforcement, some glass fabric was inserted between styrofoam and balsa, to prevent the occurrence of predetermined breaking points. The mounting of the nose edge, wing tips, root ribs went along fast. After sanding, the elevators could be removed and fillets elaborated. The shell construction of the rear fuselage was therefore finished and put aside to save space. After all, the elevator has 1,14 m wingspan.

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The joining tubes for the elevator consist of a carbon tube and steel wire. They have been glued in a bent shape, in order to predefine the V-shape of the tail unit.

The wing
Manfred delivers the wing halves in three parts which have to be glued together. Especially at the inner wing, a significant distortion is visible. The root profile has a distinct positive angulation. In the area of the engine nacelle, the angulation has gone back to zero, further out it’s going towards the negatives. The profile choice is strongly inspired by the original, which results in great flight characteristics. Now, diverse strands for the four servos per each wing half, and the lighting, were routed in the wing tips, the landing gear carrier inserted, and the connector of the later detachable outer wings could not be left out. In order to restore a smooth profile outline, some filler and careful sanding was needed. Again, while planking with 1 mm balsa, some reinforcement with glas or carbon fibre was made. Until the hardening of the epoxy resin, the wings had to be pressed into their negative moulds. Nose edge and wing tip were quickly applied, more time-consuming was the sanding of both wing halves. After all, there were around 1,4 qm to be processed. The next step was the removing of the inner and outer ailerons. While doing this, the landing gear carriers could be already exposed for the landing gears to be inserted. Great importance was attached to the profiling of the inner and outer landing flaps, as they were meant to be used as Fowler flaps. The parting of the wing, which was unavoidable due to  …

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