Don't forget to check your spam folder if you don't get an activation email after joining!!

SZD-8 Jaskolka 1/3 Scale**

Let us all watch your new project progress.
User avatar
Peter Balcombe
Posts: 1496
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

A little more progress in the last day as the main joiner tubes have been completely blocked in to fill all voids between the brass tubes and the main spars, making this area a completely solid lump.
The RH wing tubes fit up against the spar web at the rear, so 1/2” x 1/4” strip has been used edgewise to block in above & below, with 2 layers of 3mm ply in front.
W9 & W12 are provided as front spar webs at each end of the joiner area.

I may also fit additional front webs between W9 & W12 as on the Left wing, the staggered joiners are towards the front of the spar. Thus the 2 x 3mm ply infill will be at the back, so a front web will finish things off.
(An ex Stress Engineer fried has since advised it prudent to fit the proposed extra webs, plus additional front webs in the next 3 or 4 bays outboard of R6 in order to provide a more gradual stress relief taper.)

Main joiner boxing
Main joiner boxing

Meanwhile, attention is turning to fitting the TE and the flap tracks.
User avatar
Peter Balcombe
Posts: 1496
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

Moving on to the wing trailing edge, I have now assembled the 3 tracks from the supplied parts, 3D printed from Carbon loaded filament.
I’ve initially assembled the tracks with just the rear brass cross-pin, plus M2 bolts instead of brass pins in the forward (sliding) fixings. My reasoning is that the bolts will allow easier disconnection/re-connection of the flap assembly until after the flap LE & wing shroud have been fashioned & all has been shown to work correctly.

Flap tracks closed
Flap tracks closed
Flap tracks extended
Flap tracks extended

The 3 working flap tracks can then be epoxied into the wing structure, the fixed part notching into a front vertical plate & the rear wedged between the rear top & bottom spars.
At this point, it becomes clear if the rear of the ribs are in the correct position or not - the movable part of the flap tracks are notched to sit in the notched flap LE webs. If the ribs re not quite aligned correctly then they won’t line up with the web notches and/or the intended gaps between the fixed TE & flap/aileron TE will be wrong!!
(So it is strongly suggested that the flap & aileron LE webs are used to correctly locate the rear of each rib BEFORE the ribs are fixed to the rear spars. You can see in the photos below where some of the LE webs have been cut and extended by a couple of mm to get the control surface ends in the correct place).

Inner flap track
Inner flap track
Centre flap track
Centre flap track
Outer flap track
Outer flap track

I am deviating from the plan (3mm ply TE core) to use a 1/16” Balsa/1/16” Ply/1/16” Balsa TE sandwich which allows me to profile the TE down to the 1.6mm ply core rather than sand ply. The sandwich is kept straight by clamping the outer layers to a sturdy spruce strip whilst the glue between balsa & ply dries.
The photos show only the upper balsa TE strip fitted to the aileron so far.

Flap/root TE core
Flap/root TE core
Aileron TE core/top strip
Aileron TE core/top strip
Mike F
Posts: 96
Joined: 18 Mar 2015, 14:08
Location: Gloucestershire

Re: SZD-8 Jaskolka 1/3 Scale

Post by Mike F »

Hi Peter

Thank you for sharing your detailed build progress on the Jaskolka. Jilles solution to the flap mechanism looks well engineered and I am also trying to adapt it to suit the John Watkins 1/4 scale version.

I now have the modified parts to suit the 1/4 scale model and your build log will be of major assistance in getting a functioning flap installation.

Thanks for sharing your build details.

Mike
User avatar
Peter Balcombe
Posts: 1496
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

Once the rib sections in flap LE/shroud gap (except for the few ribs which end with a full shroud profile) have been removed, we get the following gap forward of the flap LE web & the flap can be slid back on its 3 tracks.

Separated flap
Separated flap
Full movement check
Full movement check

Next up will be cutting out the aileron & installing the flap actuation mechanism.
Dopieman1
Posts: 53
Joined: 09 Mar 2018, 09:42
Location: Den Bosch

Re: SZD-8 Jaskolka 1/3 Scale

Post by Dopieman1 »

Thanks for posting the construction of this rather complex wing! I am following with great interest!!!
Jilles
Posts: 262
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: SZD-8 Jaskolka 1/3 Scale

Post by Jilles »

When the design of this model was started the request was to have scale like working Fowler flaps.
Some info was available about the distance travelled and rotation of the full scale flaps. The model flaps do move now to scale as dictated by the full scale data.
A test jig was made to see if it all worked and that did not have any problems
it is a complicated setup and I would not recommend this on smaller scale model with identical Fowler flaps
Even with this large scale 1:3 model you need all the space the get it moving and make sure all push rods and servo can work without interference
Not easy to build but these type of models do need more expereinced builders anyway
I am in regular contact with Peter during this build and I am sure Peter will make it work satis factory
Cheers
Jilles
User avatar
Peter Balcombe
Posts: 1496
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

The majority of the flap actuation mechanism has now been assembled, albeit using metric sized links instead of 2-56 threaded parts a shown on the plan.
The long 1/4“ dowel pushrods were also changed to 6x3mm carbon rods, with short M2 threaded rods epoxied into the ends to mate with M2 ball-link ends. The three pushrods going to the flap tracks were upped to M3 & the M2 ball-link ends drilled 2.4mm & then tapped M3. The M2 ball-link at the flap track ends were drilled out to 2.4mm to accept the 3/32” track pins which will be fitted instead of the current M2 bolts at the end.

The cranks are shown on the plan & could possibly be made from servo arms, but Cliff kindly printed some equivalents to that shown on the plan using carbon loaded filament.

The 3 flap track links & associated crank connections to the interconnecting pushrod are shown below.

Outer end
Outer end



Inner end
Inner end

I have also drawn up (& got Cliff to cut) some 1/16” ply templates for the flap & aileron LE/shrouds.
The plan is to use these to aid profiling of solid balsa LEs & act as a seat for 0.4mm ply shrouds.
Attachments
LE/shroud templates
LE/shroud templates
Centre/servo connection
Centre/servo connection
Last edited by Peter Balcombe on 16 Nov 2021, 22:19, edited 1 time in total.
User avatar
Peter Balcombe
Posts: 1496
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

Whilst waiting for some longer M2 machine screws to arrive, I’ve assembled the tailplane & rudder structures.
The tailplane halves include elevator servo mounts and also accept joiner tubes to give the tailplane its distinctive dihedral.

Tailplane halves on joiner bars
Tailplane halves on joiner bars

Whilst the plan shows that the rudder ribs are mounted at 88.9 degrees to the rudder post, this is easy to sort once the 2 TE pieces have been joined & then glued to the rudder post spar (the ribs then fit into notches at each end).
I’ve fitted a 1/4” balsa strip to the front of the rudder post spar in preparation for fitting a 3/32” Al. guide tube for a long hinge pin passing through all three 3/16” pin hinges, thereby allowing the large rudder to be easily removed.

Rudder framework
Rudder framework

Although the plan says that the balsa rudder base should be 12mm thick, this I only for the first 70mm. I have therefore fitted a 1/4” doubler, plus an extra 1/4” for 70mm adjacent to the rudder post spar.
User avatar
Peter Balcombe
Posts: 1496
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

The tailplane is attached using two 1/4” Al. joiner rods, with the rear one secured to each tailplane half by an M3 machine screw inserted from the bottom into the outer end of the joiner.
I’ve just drilled & tapped the rear bar to take the screws & checked all fits nicely - adding the unfinished rudder for effect.

Tail feathers coming along
Tail feathers coming along
User avatar
Cliff Evans
Posts: 754
Joined: 29 Dec 2019, 15:13
Location: Bristol
Contact:

Re: SZD-8 Jaskolka 1/3 Scale

Post by Cliff Evans »

Peter has only gone and got them working!

https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk
Post Reply