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Scratch built Slingsby King Kite 1/4

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Bovin
Posts: 90
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

The assembly of the left wing went without a hitch and I could fit both wings on the fuselage. Then I discovered a huge mistake!!! In a kind of having a blind spot I had made the dihedral in the wing equal to the dihedral of the wing connector; ERROR, that had to be half of that , oops. :shock: :shock:
After some bad moments, I thought better now, than much later in construction. So I cut out the curvature in the top spar
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and with my powerfile I beveled both sides 1 in 10
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I changed the angle in the build board (extensively checked now!) and glued two 1X10mm battens under the topspar to get a stable situation .
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I fitted pieces of 2x10 mm spruce and glued it between the spar with 24h epoxy with wood dust as filler.
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.
At least now The King Kite looks in proportion, just a few pictures in the garden.
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IMG_2571.JPG (30.92 KiB) Viewed 277 times
Vincent

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Bovin
Posts: 90
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

Now that the basic structure of the wings was ready, it was time for the ailerons and flaps. First the ailerons.
I found differences between the ribs in the drawing and the photos..
vleugel KK.jpg
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In the drawing, the aileron even seems to consist of two parts, of which nothing can be found in the photo. I therefore decided not to divide the aileron in two parts. Another problem was that the aileron was “enclosed” on both sides. I therefore chose the same hinges as the horizontal stabilizer. The aileron remains removable. With the help of a curved strips you can unlock all hinges at the same time, place the aileron, and then remove the strips.
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After cutting off the aileron from the wing, I realized how long and narrow it was, 115cm long and 4.5cm wide. .
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The profile choice did not help either, unfortunately. The aileron was therefore only 6-7mm thick. I also became convinced that I had to control the aileron in two places and luckily was able to find place for an extra servo in the wing.
The balsa ribs in the aileron were very thin and fragile. So I replaced the balsa ribs with 2mm solid spruce, took out one, replaced it with spruce, went on to the next, so that I kept the dimensions.
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I wanted to make a plywood D section for the nose of the aileron. With boiling water I bent U profiles of 0.6 plywood around a 6mm tube and let them dry. I slid the aileron skeleton into this profile and clamped it to a plate with a batten. I had covered both the batten and the board with tape, in order not to get adhesion with glue. I also built in some twisting. I set the plank upright and dripped thin cyano between the rib skeleton and the plywood U profile.
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Now I had a much firmer unit. I further built up the rear frame with 0.6mm plywood and sawed, cut and sanded the U profile and the TE into shape.
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Then I added capstrips and the aileron was finished roughly, still needed some sanding.
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Vincent
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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Scratch built Slingsby King Kite 1/4

Post by Peter Balcombe »

Vincent,
The 3 view drawing in your latest post looks the same as the one on page 66 of the Martin Simons book Slingsby Sailplanes.
The photo on page 70 of the same book shows a King Kite being moved at the Wasser-kuppe in 1937. This photo clearly shows 2 upper surface aileron control horns.
It may be that the long, narrow ailerons needed to be split into 2 pieces to avoid warping over their length, much as you thought necessary.
Peter

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Bovin
Posts: 90
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

Peter,

This photo is a part of the one in Mark Simons book, you guessed that right. I know the other photo
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and it has indeed two rudderhorns.
On the drawing (and my model) you can see two places where the aileron it strenghtened for the rudderhorns and even the pulleys for the aileron actuation are in the drawing.
I guessed the designers thought it was neccesary to split the aileron, but at the same time quite some big gliders (20m span) used ailerons in one piece.
I tried on my model to move the aileron while I bent the wing at the same time, and worked OK. I presume that the aileron is horizontally not that stiff, so it won't "straighten"the wing when flexed.

Vincent

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Bovin
Posts: 90
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

9-4-21
After I built the second aileron, I went on with the flaps. These are much shorter (56cm) than the ailerons and completely sheeted. They are even thinner than the ailerons, less than 6mm thick. So I liked to sheet them in one go. I took a strip of 9cm wide, 0.6mm plywood, and bended it around a 6mm round rod, whilst pouring over with boiling water, see also this video (sorry, Dutch subtitled). Then I clamped and let it dry
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Also on the photo is the backbone consisting from the ribs, main spar, back frame with balsa filler strips. It is a very weak skeleton. By fitting this skeleton into the folded plywood, I could mark, cut and sand the plywood.
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Covered the structure with PVA
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clamp it and with a 10X10mm batten en strips of 4mm ply with big clamps.
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After the glue had dried I could fold the plywood “open”, and I drilled 1mm from the inside pilot holes so that I could make the openings at the hinges and rudderhorn later
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I smeared the top of the ribs with glue and clamp the whole thing together, just like before.
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With a Dremel I made the openings for the hinges and after some adjustments it fitted neatly into the wing.
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Vincent

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VinceC
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Re: Scratch built Slingsby King Kite 1/4

Post by VinceC »

very interesting work and thanks for the video on how you bent the plywood

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