Slingsby T.50 Skylark 4

Let us all watch your new project progress.
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chris williams
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Location: Blandford Dorset

Re: Slingsby T.50 Skylark 4

Post by chris williams » 15 Dec 2018, 19:57

Pin the aileron to the board, Brian, and add diagonals...works every time

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B Sharp
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Location: Perthshire

Re: Slingsby T.50 Skylark 4

Post by B Sharp » 16 Dec 2018, 20:37

Unfortunately Chris I have already added the top and bottom capping strips so diagonals would be a bit of a problem. The structure is so long, narrow and fragile that I have no confidence that it will not twist in the air.
Brian. :(

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Peter Balcombe
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Location: Clevedon, North Somerset, U.K.

Re: Slingsby T.50 Skylark 4

Post by Peter Balcombe » 16 Dec 2018, 21:22

Brian,
If you cannot get straight bits of diagonal in place under the cap strips, what about using two thicknesses of thin ply,
You can flex them to get them in, then glue both together once in position to make a more rigid brace.
Just a thought :?:

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B Sharp
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Location: Perthshire

Re: Slingsby T.50 Skylark 4

Post by B Sharp » 16 Dec 2018, 21:38

I still think I am going with my original idea of a solid aileron. However, I was considering adding 1/32 balsa leading edge, trailing edge and cap strips on the upper surface so that they will show through the covering film and give the impression of the original ribbed structure. I did this once before and it looked quite convincing. By the way, at the moment I can hold one end of the aileron and rotate the other end through nearly 90 degrees. Bendy or what!
:? :( :? Brian.

Jolly Roger
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Location: Sutton Bank, North Yorkshire

Re: Slingsby T.50 Skylark 4

Post by Jolly Roger » 16 Dec 2018, 23:18

Are you covering with Solartex? That should improve torsional strength significantly. You could give it a go and peel off if it's still twisty.

Just a thought...

John Vella
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Re: Slingsby T.50 Skylark 4

Post by John Vella » 17 Dec 2018, 11:15

Brian, if that was my build I would cut out carefully the bottom cap strips with a Swan Morton blade. Then I would fit my diagonal bracing and reglue the cap strips. A relatively easy job and structurally much better than from solid. Regards John.

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B Sharp
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Location: Perthshire

Re: Slingsby T.50 Skylark 4

Post by B Sharp » 18 Dec 2018, 16:39

Having taken heed of all your comments I have committed surgery on one of the ailerons and fitted it out with diagonal ribs as suggested. The aileron panel is now slightly stiffer but not what I would call adequate. It is still as bendy as a “long bendy thing”. I am waiting for a timber delivery from Balsa Cabin and when it arrives I will form a solid aileron and compare the stiffness of the two before proceeding further. (Question: can you get Viagra for balsa structures?) :? :? :? :? :?
I have spent the afternoon rubbing down the epoxy/glass surface of the fuselage with 240 grit wet and dry. This is not one of my favourite jobs!!! The fuselage is now relatively smooth and ready for a coat of filler before finish sanding. However I now have a sore shoulder and no fingerprints. :x
Brian.
Attachments
SL4_52.jpg
Bendy and very bendy!
SL4_53.jpg

John Vella
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Re: Slingsby T.50 Skylark 4

Post by John Vella » 18 Dec 2018, 17:22

Brian that looks fine. Surely bendy is alright with Torsional Rigidity. I seem to remember the full size was not very aerobatic. What do you want to do with your Skylark ? Regards John.

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B Sharp
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Location: Perthshire

Re: Slingsby T.50 Skylark 4

Post by B Sharp » 18 Dec 2018, 19:04

That's the problem John, there is still very little torsional rigidity as it can still be twisted through almost 90 degrees.
Brian. :evil:

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RobbieB
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Re: Slingsby T.50 Skylark 4

Post by RobbieB » 18 Dec 2018, 22:17

Brian, are the leading edges faced or is that the bench I can see through the LE of the front one?

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