SZD-8 Jaskolka 1/3 Scale**

[Peter Balcombe]

Longer (20mm to cut down as required) M2 screws arrived today, so I was able to fully secure the 3 flap cranks to their supports & connect the 3 flap pushrods to the track attachments in place of the 3/32” brass pins which will be fitted later.
The temporary M2 fixings give a little bit more play than should be present when the final 3/32” (2.38mm) track pins are fitted & M2 locknuts will be fitted to other attachments, but the servo appears to operate the long flap ok.
Note that the wing is inverted

[Peter Balcombe]

Rudder hinge pin guide tubes fitted today using 3/32” aluminium tube spaced 0.4mm off the 1/4” initial balsa LE to place the hinge centreline 8mm in front of the rudder post spar. As shown below, the tube sections were glued in place once aligned with a long 16swg wire through all 3 dry fitted hinge points.

Rudder hinge pin guides

The hingeless pin hinges will now be removed & the guide tube buried inside the balsa LE when the remaining thickness is added. The pin hinge centres will be rediscovered from the rear & opened up in due course.

[Mike F]

Nice work on the flap mechanism, Peter!

[Peter Balcombe]

The rudder structure now has the rest of the LE balsa fitted & cut to the correct outline prior to nose profiling.
The balsa tip has also been fitted & rough shaped. The pic below shows the long hinge pin going from top to bottom.

Rudder LE & hinge wire

The flap has been disconnected & removed from the wing by undoing a few M2 fixings & then short pieces of 3/16” spruce used as temporary spacers between the 3 sets of flap tracks to support them at the front - particularly the centre one - to keep the flap straight & resist a tendency for the TE to snap as there is not much meat to resist bending loads when the flap assembly is off the wing.
I have fitted flap & aileron LE profile templates every few ribs then infilled with balsa to give a LE profile guide on each item. Seems to be working ok & I should have a much more accurate & consistent LE on each part.
The balsa TE outer layers have been sanded back to give a tapered profile with ply core just exposed at the rear to give a uniform TE thickness prior to adding the ply capping.
The aileron LE strip is 1/2” balsa, whereas the flap LE is a bit wider, so I’m using two thicknesses of 3/8” balsa & sanding back to the templates.

Flap LE prep

Flap & both ailerons

[Peter Balcombe]

Th fin skinning has now been completed and the balsa fin top added/shaped.

Fin top added

With the extra strip of balsa added to the flap LE, this is now ready for shaping back to expose the ply templates.
Meanwhile, attention has turned back to the cockpit area.

Th front canopy hoop has been added with the top 11mm forward of vertical & balsa dummy panel former/side rails added to support the 0.4mm ply binnacle sheeting. The dummy panel former has been mounted 5mm forward of its normal position to allow for the visible panel thickness (see much earlier post for pic of panel made by Cliff Evans).
Note that the forward canopy is removeable as it slots into the fuselage former at the front & is retained using 2 screws (inserted from below) at the rear.

Front canopy binnacle prep

The sliding canopy uses 3 slotted brass section rails (available from Mick Reeves models). A rail is fitted each side of the fuselage canopy opening at the front, with a single (central) rear rail fitted in the underside of the canopy as shown below. M2 cap head screws are fitted in the sliding canopy side frames & the rear fuselage to engage in the slotted rails.

Fuselage side rails

Rear rail

Canopy frame sat in place

[Peter Balcombe]

And after a productive afternoon getting the three M2 cap screws in place, the sliding canopy now fits & slides ok.
Next up will be fitting the forward canopy binnacle sheeting, the sliding canopy hoop & headrest, prior to tackling the metalwork for the canopy latch.

Front slide retaining cap heads

Rear slide cap head in fuselage

Fully back - rear just engaged

Closed

[Peter Balcombe]

Forward canopy binnacle now in place and Cliff’s dash panel just sat in place for now (until canopy unit painted ready for glazing in due course).
Front hoop also epoxied to the front of the sliding canopy, so can now see the overall effect.

Printed dash panel

Forward canopy frame in place

Sliding canopy closed

…and open

[Peter Balcombe]

Onto the canopy latching mechanism today.
The notched brass strip is made from 1/32” brass strip (Four 2mm holes slotted to the edge).
The tiny brass crank is also fashioned from 1/32” brass strip before being fitted (soldered) with short pins.
I found an eBay outlet that made 4mm tension springs to any defined length.
The knurled knob will be secured on the outside of the canopy later. This allows the latch pin to be lifted to disengage it.
The 4 positions are: Closed, 15mm gap, 30mm gap & fully open.

Latch parts

Left side

Detent strip & latching pin

[Peter Balcombe]

Having started a spate of metal fettling, I’ve moved on to the airbrakes & cut out the 6 brass arms & soldered the pivot tubes in all items at the same time as shown on the plan to ensure all have the same centres etc.
There are 3 arms per brake, so 6 blade pivot pins & 3 box pivots are required per brake assembly.

Brake assy metal part set

Small laser cut 0.8mm ply axle washers are provided to fit on the inside of each blade, acting as pivot hole doublers.
Make sure that these washers are fitted on the correct side for each ‘handed’ brake assembly, otherwise the blade assembly will not fit in the 9.5mm wide brake assembly.
The plans call for 6mm wide blade spacers, but I’m hoping to get away with 1/4” balsa.

The RH brake blades have been glued up & dry assembled onto one of the brake box sides (front) as shown below in both closed & fully open positions.

RH brake closed check

RH brake open check

The blade pins can now be carefully epoxied into the blades, hopefully ensuring that the pins rotate freely in the blade axle tubes. Once the pins have been filed flush to the blades, the assembly can be fitted into the wing box & connected to its servo, plus the blades profiled to match the wing outer surface - which means the blade tops being distinctly angled front to rear.

[Peter Balcombe]

With blade pins safely epoxied into position & then filed flush, the brake assembly can be slotted into the box gap, the 3 main pivot pins inserted and a check made to ensure free movement (may need to tweak main pivot pin alignment to make sure the blades sit centrally fore & aft in the box aperture).
My use of a 1/4” blade spacer gave me a snug (0.8mm gap each side) fit in the box, so any distortion is more critical, but it seems to work ok with the blades centralised using 0.8mm ply strips as feeler gauges.
1/8” hardwood/ply pivot pin support doublers are fitted on the outer faces of the box at each pin position & these help to maintain any tweaked pin positions & get good free movement. It is also a good idea to take the sharp edges off of the brake box openings & blades to help guide the blades back into the box, rather than jam.

I hooked the brake up to another slim wing servo using a 2mm pushrod, extenders & M2 clevises.
Note that the photos below are all from the underside of the wing in order to see the servo connection better.

Brake inboard end

Brake outboard end

Hopefully, Cliff can add a video of the brake cycling shortly.