ASK13 1/3 Scale**

[Peter Balcombe]

A little bit more progress in that I have fitted small plates in the rear fuselage to support the rudder C/L guide tube exits.
I have also fitted a removeable shelf above the tow release servo to carry a brace of batteries in due course.
The plate sits on a pair of cross-rails & is secured by sliding into a slot at the front & a couple of easily accessible screws at the rear.

0.6m ply skins have been cut for the upper nose section & forward turtledeck section, so they should once I have added some balsa glueing doublers to the front of the canopy hoop.

[Peter Balcombe]

Jilles’ detailed aerotow release assembly now fabricated less the rear retaining pin.
Pics below show the main tube & crosspin, plus internal carrier for actuation pin.
Front view of assembled unit also shown. Tow loop is directed by angled wedge up behind crosspin where the actuation rod comes forward to go through loop, trapping it between actuation pin & cross-pin.

The release will be fitted later once I have the nose cone to hand & forward fuselage skins fitted.

[Peter Balcombe]

A start has been made on the upper fuselage skins using the recommended 0.6mm ply.
The slightly thicker ply is a fair bit tougher than the 0.4mm ply I’ve been used to, but is more picky about going around complex curvature.
As a result, I’ve had to do the upper nose section in 2 pieces & the forward part of the turtle-deck has split into 3 pieces over the wing root length. However, it looks as if I might be able to use larger pieces further aft.
I’m using the white PVA glue & hot iron technique.
The nose section has just had PVA applied to both sides of the joint, so I’m waiting for that to dry before starting the ironing bit to re-activate the glue with the ply in position.

[Peter Balcombe]

And with the first bits done, rapid progress has been made to complete the upper left side skinning up to the wing TE.
On the flat sections, I used PVA, but have clamped them together wet. (Gives the option to use iron later if needed).
Right hand side under canopy frame & around wing root to do next, then completion of the rear fuselage

[Peter Balcombe]

Upper fuselage skinning just about done - only rearmost fuselage side piece to do on RHS, plus pieces above tailskid.
With the upper skins virtually in place, the fuselage former building stand extensions can be removed.

You will see that in the end, i skinned in single former space sections on all curved areas (apart from the bit near the wing root, which I suggest others do in 2 sections)

[Peter Balcombe]

Upper fuselage skinning now complete, fin skinned and rudder C/L tubes epoxied in place, with wire outlet cleared.
Just the skin panel joints & fin LE to tidy up with a little bit of filler & that area is completely done.

Skinning the fin with the 0.4mm ply (as on the plan) was much easier than using the 0.6mm as used for the rest of the fuselage. I used one panel on each side of the fin (remembering to leave the small rear overhang for rudder hinge shroud) after putting a balsa doubler strip around the lower side of fin rib FR2 (to provide support for the front part of the skin LE as it curves in below that rib).
The fin skin could be pulled in around the faired off balsa LE infill, leaving just a small gap to fill at the LE once excess skin had been removed. I didn’t try wrapping the skin around the LE, except for the section below FR2 (which worked well).

[Bovin]

Hi Peter,

Its looking good!
About the ply, there are strange differences, I had 0.4mm ply which was quite brittle and 0.6 which was more manageble. A German member of Retroplane had just the opposite, like you. It looks like there are differences in the fabrication of ply,

Vincent

[Peter Balcombe]

Vincent,
It probably depends on the orientation of the wood grain in each of the ply layers.
Usually our ply will happily bend in one direction, but less so in the other.
On curved areas, I therefore arrange the ply to bend easily over the curved surface, but when the surface curves in both directions, you usually have to reduce the width of the strip to cope with the amount of bend available.
Wetting the ply surface & then applying with a hot iron (to re-activate the glue) after letting PVA applied to both surfaces dry, gives a degree of steam bending as the piece is fixed.

[Bovin]

Hi Peter,

Thanks for your answer, but I like to explain what happened; most 0.6 mm I could bent with boiling water to a radius of 2-3mm, I am always astonished that it works,

but I had some 0.4mm ply that cracked and delaminated when bending with boiling water. that why I mentioned it.

Vincent

[Peter Balcombe]

Hi Vincent,
That makes more sense as small differences in the ply can probably make the difference between success & failure when dealing with tight curves such as you describe.