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Re: Slingsby T.50 Skylark 4

Posted: 16 Dec 2018, 21:22
by Peter Balcombe
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 :?:

Re: Slingsby T.50 Skylark 4

Posted: 16 Dec 2018, 21:38
by B Sharp
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.

Re: Slingsby T.50 Skylark 4

Posted: 16 Dec 2018, 23:18
by Jolly Roger
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...

Re: Slingsby T.50 Skylark 4

Posted: 17 Dec 2018, 11:15
by John Vella
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.

Re: Slingsby T.50 Skylark 4

Posted: 18 Dec 2018, 16:39
by B Sharp
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.

Re: Slingsby T.50 Skylark 4

Posted: 18 Dec 2018, 17:22
by John Vella
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.

Re: Slingsby T.50 Skylark 4

Posted: 18 Dec 2018, 19:04
by B Sharp
That's the problem John, there is still very little torsional rigidity as it can still be twisted through almost 90 degrees.
Brian. :evil:

Re: Slingsby T.50 Skylark 4

Posted: 18 Dec 2018, 22:17
by RobbieB
Brian, are the leading edges faced or is that the bench I can see through the LE of the front one?

Re: Slingsby T.50 Skylark 4

Posted: 18 Dec 2018, 23:16
by B Sharp
Robbie, the braced aileron is faced with 1/32 ply. The one furthest away is yet to be completed, I.e no leading edge facing.
Brian. :cry:

Re: Slingsby T.50 Skylark 4

Posted: 19 Dec 2018, 12:22
by John Vella
Brian, maybe the construction of my long MU13 aileron might help. The aileron is 3ft 7in long and 2 in plus wide. The facing is from 1.5mm Balsa on 5mm sq spruce. The front box is top and bottom 0.4 mm ply. The TE is balsa /0.8mm ply/balsa sandwich. The cap strips are 0.4mm ply. The structure is torsionaly stiff and weighs 3 ozs. Regards John.