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Scratch built Slingsby King Kite 1/4

Let us all watch your new project progress.
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Cliff Evans
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Joined: 29 Dec 2019, 15:13
Location: Bristol
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Re: Scratch built Slingsby King Kite 1/4

Post by Cliff Evans »

Lovely build!
Laser Cut sailplanes

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Bovin
Posts: 69
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

Thanks a lot Cliff!

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VinceC
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Re: Scratch built Slingsby King Kite 1/4

Post by VinceC »

Nice build

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Max Wright
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Joined: 10 Mar 2020, 19:57
Location: Clayton Bay South Australia

Re: Scratch built Slingsby King Kite 1/4

Post by Max Wright »

Very innovative. 8-)
Max

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Bovin
Posts: 69
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

I went on with the vertical tail.
The fin was already ready with one side sheeted, but fortunately I saw that both on the drawing and on the photos that the vertical tail had a much rounder nose than the profile I had chosen, afterwards that was not the right choice. I had already sheeted one side, so I ripped that off. I glued filler pieces to the ribs
IMG_2274.JPG
and sanded them, along with those of the rudder, with a long sanding batten into a more rounded profile.
With the boiling water technique I was familiar with, I bent the plywood into shape and and sheeted both the fixed part and the rudder itself
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Finished it with capstrips on the ribs and sanded the gusset plates in shape
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The vertical stabilizer was now roughly ready, and weighs 50 grams.
With the tailplanes in this stage I can start with the fuselage.

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 »

Very nice Bovin 👍

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Bovin
Posts: 69
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

After finishing the tail planes it was time to digitally draw the fuselage. I decided to having a go at it and bought Devfus, a program that is still affordable for a hobbyist.
After a lot of messing around with terms on the screen that I had never heard of, I got familiar with some things! Unfortunately, sometimes drawings were suddenly put (by magic??) in a different folder and I could no longer open them in the drawing program (Yes, laugh ...) Thats why I drew the hull about three times, practice makes perfect they say ... Gradually I found out what is possible, it is easier to make a hull straight in a drawing than to sand frames down or glue some extra material on.
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Here you see some of the drawings of the frames and
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the placement of the frames and the 3d view of the fuselage.
Schermopname (132)kl.png
I thought it would be convenient to use a central batten to align the frames. My friend Adri was kind enough to CNC the frames and he did it excellent. Just like with the Gull, I made a construction setup of a panel of chipboard to which I screwed 10 x 10mm battens at frame distances. I deliberately made a “jump” in it because I wanted to sheet parts of the hull on the construction setup. The tail at the top and the nose at the bottom.
IMG_2289kl.JPG
In this way, it stays nice and straight and the stringers can be as thin as possible, to keep the weight of the tail down. Aligning the frames took a lot of time and I would like to hurry up, but I know sadly that errors in the frame setup are difficult to correct later .
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One of the two main bulkheads is prepared so the wingjoiner can be slid through it.
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Here is the 3X3mm spruce batten which slides through the centre of the frames,. I first wanted to screw them on the jig, but clamps actually do it better.
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I first glued in both stringers left and right and then made the wide bottom (keel?) stringer, where the landing skate will be attached later.
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So nice that the frames were “aligned” ( Ican’t find the correct word for that), I didn't have to sand them much! Designing took quite a bit of effort, but this was very satisfying.
IMG_2321kl.JPG
It's starting to look like a fuselage!

Vincent

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Bovin
Posts: 69
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

Sorting out the tail.
First I had to make the tail shoe, I laminated the bottom girder and made two small frames, I had to deduct that from the photos how that was constructed, nice to find out, but sometimes it takes a while!
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I could not find any details of the fuselage to the horizontal stabilizer transition in any photo. I think the mounting method would be just like the Gull I built before. It was stuck with 4 horizontal pins that were inserted from both sides
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this gives an idea of how that was made in the real Gull.
In the model of my Gull I solved that with 2 continuous 1mm steel wire pins and that is how I want to do it for the King Kite.
The design of the fuselage at that location was not clear to me.
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First I made the frames at the stabilo position according to the drawing. Partly because I did not know the thickness of the stabilizer profile, this was not correct, so it did not work. I remade it 3 different ways before I felt that I had it right. For the fairing of the fuselage at the front of the horizontal stabiler I laminated a plate? from balsa and 0.4mm plywood on both sides, which I sanded in a in contour of the fuselage
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It turned out that there was also kind of infill in front of the vertical fin
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Unfortunately, I had made the vertical fin a bit thinner than the real one, so that now the elevator no longer fitted nicely to it, I also changed that a bit. So, after gluing the vertical fin
IMG_2332.JPG
and properly positioning the stabilo
IMG_2333.JPG
I thought that , when sheeted with ply, it will look just as the real thing.

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 »

Very nice Vincent.
I admire your persistence in getting the nice result :)

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Bovin
Posts: 69
Joined: 30 Sep 2017, 12:43
Location: Hillegom

Re: Scratch built Slingsby King Kite 1/4

Post by Bovin »

The placement of the servos was next. Before I started, I first made a tow coupling. On the Gull I had made one that worked well and took up little space inside. I soldered a piece of 6mm internal brass tube and another piece of 2mm internal brass pipe at right angles to each other with silver
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Drilled a 2mm hole through and through and made it a bit larger with a reamer,
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so that a 2mm iron round could move freely through it. Over that 2mm round I soldered a piece of brass tube, which I flattened at the end with a hammer and drilled a 1mm hole for the operating rod
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I glued the coupling in the front fuselage frame, reinforced it with some roving to take up the forces .
IMG_2364.JPG
(the 2mm drill is only temporary while the resin sets)
Now the servo’s. I wanted to have them in the front (good for the CG) and low, so I can make a scale interior , which I like to make... After some thinking I came up with a servo tray for the 3 fuselage servos
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The blue arrow points to the rudder servo that actuates the rudder with 2 pull-pull cables, the yellow arrow to the coupling release servo, the rod will go under the rudder servo arm to the coupling. At the red arrow is the elevator servo, that will actuate the elevator with a push-pull Bowden cable, fixed in the holder? (black arrow).
After figuring out the servo’s, I went on with the cockpit area of the fuselage. Cut through the two frames, adjusted the sloping frame and glued it in.
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Then I sheeted the inside with 0.6mm plywood. The front of the fuselage is now quite stable.
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Its my intention to sheet the top end of the fuselage while its still secured at the building rig to keep it in shape while putting the ply on.

Vincent

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