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Re: 1/4 Scale Charlesworth ASK13

Posted: 10 Oct 2019, 11:15
by Peter Balcombe
So...., with a set of laser cut parts as shown below, let the build of the 2nd wing commence.
The first job was to cut & splice the tapered spars as for the first wing, but this time the rear spar web can be assembled & glued to the spar ready to accept the ribs.

Then it is a simple matter to slot the ribs onto the spar/rear web over the plan, the lower building tabs giving the washout angle along the length of the wing. The False LE is also added to correctly align each rib as you go.
(I initially used a couple of 1/4" blocks to support the lower spar at root & mid span until enough ribs were in place to take over the job)
The 2 servo trays are also fitted between the appropriate ribs as these are slotted into place. Thin wing type servos can easily be fitted into the plates from the bottom.

Finally, the root rib is attached to the spar (with the dihedral angle defined by the end of the root web) & the separate root piece of false LE inserted.
Th pic below the initial assembled structure with the top spar sat in place to check fit.

Re: 1/4 Scale Charlesworth ASK13

Posted: 11 Oct 2019, 19:02
by Greg Smith
I am amazed at your productivity, Peter: congratulations! I am still off and on with the second wing of the Olympia, but events here in the US are consuming an addictive attention, to say nothing of events there, too. Best, Greg.

Re: 1/4 Scale Charlesworth ASK13

Posted: 11 Oct 2019, 20:02
by Peter Balcombe
Many thanks Greg.
I have to keep moving as I still have another 3 projects waiting in line :o

Re: 1/4 Scale Charlesworth ASK13

Posted: 11 Oct 2019, 23:40
by Cliff Evans
And the rest!!

Re: 1/4 Scale Charlesworth ASK13

Posted: 12 Oct 2019, 11:35
by Peter Balcombe
The ply TE strip can be held in place beneath the ribs & quickly attached using cyano.
Then the balsa infill can be glued into place (use of spruce strip underneath to ensure straightness is recommended). I used a 25mm wide strip of 1/16" balsa followed by a further 1/4" wide strip at the front. (the infill is sanded to profile before the top TE ply strip is put on later).
The main joiner tube is epoxied into the rib slots & then blocked in using 1/8" ply as for the first wing before the top spar is added.

Once the top spar is in place, inverting the structure allows the ply front spar webs to be put on (I needed to run a thin file down the rib slots to slightly enlarge them as the main spar had encroached a little).
Then, the webs pieces can be carefully slid into place. I applied cyano to attach the web faces to the spars once they were fully in place, but slower acting glue could be applied before final insertion once you are sure that they are going to slide fully into place.

With the rear incidence tube slid into place through the laser cut holes, this can be epoxied at each rib. (I double checked that the rear tube was parallel to, & at same angle as the main joiner by temporarily inserting blade/rod).
Once the rear incidence tube is fixed, it can be blocked into each rib & other lower sub-spars fitted.

The pics below show the progress and also show the aileron servo cable, & root rib servo connector, access holes as manually added on the first wing.

Re: 1/4 Scale Charlesworth ASK13

Posted: 16 Oct 2019, 12:50
by Peter Balcombe
With the 2nd wing quickly built to about the same stage as the first, I decided to get to grips with the wing root TE fairing.
The drawing has note which says that a 2.4mm balsa sheet fillet is inserted between the 0.4mm ply TE strips, but then talks about tapering from 4.5mm to zero over the span of the fillet! The shaped fairing is then skinned with 0.4mm ply.
Looking at a photo of the full size, what I think the drawing note means, is to insert a fillet core between the 0.4mm strips, then 4.8mm balsa is put each side to block out roughly to the the root rib thickness, tapering the blocks to nothing over their span.

I have decided to use a 0.8mm ply core to give a better defined edge, with 1/4" balsa blocks as shown in the pics prior to shaping.

Re: 1/4 Scale Charlesworth ASK13

Posted: 17 Oct 2019, 14:35
by Peter Balcombe
Now that the 1st wing root TE has been strengthened, the outstanding job of making holes in the root end ribs for the rear incidence tube can go ahead, using the other wing to ensure good alignment (2nd wing had laser cut holes for the tube).
Finally, the part built wings can be put together.

Re: 1/4 Scale Charlesworth ASK13

Posted: 17 Oct 2019, 17:14
by RobbieB
Started a K13 - ended up a Horten!

Re: 1/4 Scale Charlesworth ASK13

Posted: 20 Oct 2019, 14:23
by Peter Balcombe
Don't worry Robbie. The wings will soon be attached to a fuselage :)

Meanwhile, the airbrake slots have been released in the wing ready to accept the brake boxes & the brake components prepared.
(The blades & box sides come as laser cut items)
In order to ensure all parts have the same centres, the brake arms are assembled as a set, checking that the three pivot centrelines match up.

Re: 1/4 Scale Charlesworth ASK13

Posted: 22 Oct 2019, 13:04
by Peter Balcombe
Just to put your mind to rest Robbie, Ive got the fuselage prepared to accept both wings as below - although still tailless :)

With the dihedral now in the wing joiner tubes, the fuselage joiner/incidence pins are both simple straight-though affairs (yet to be encased in ply doublers).
The wings will be retained by a single band/spring.
MPX connectors will be fitted into the fuselage wing roots just behind the main joiner - with 'floating' connectors in the wings.