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: 1467
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

With workbench nearly cleared of other projects, it’s time to start the next major build from the Laser Cut Sailplanes range - this one being a 1/3 scale version of the Jaskolka from the drawing board of Jilles Smits.
I’ve always wanted to build a Jaskolka & nearly did the 1/4 scale one from the John Watkins plan many years ago.

A couple of areas have been in hand for a few weeks in order to identify potential mods to the standard short kit - these being the nose tow release and retract.

The bespoke nose release is similar to that built for the Olympia & ASK13, but is based on a 7/16” brass tube, so I wanted to make sure that I could reliably get a tow loop into it before fixing in the 3D printed nose cone & front former.
The release mechanism comprises a 45degree front angled dowel in the brass tube plus an 1/8” brass rod cross-bar and 2mm release pin which goes through the dowel & rests on the top of the cross-bar.
I used a piece of 3/32” x 1/8” strip resting on the inside of the tube to drill very small (0.7mm or so) pilot holes across the tube at just under 5mm up from the bottom of the inside, then opened these holes up to take the cross pin.
This allowed a builders line sized loop to be slid under the cross-pin & just left enough room above it to get the release pin to go through the loop.
The other tip is to make sure the angled dowel is far enough behind the cross-pin to allow the loop to pass & angle up to the top of the tube. The drawing gives dimensions for wedge & cross-pin distances from the rear of the tube.
Tube & cross-piece
Tube & cross-piece
Tube from front
Tube from front
Tube & loop in place
Tube & loop in place
View from rear
View from rear
The plan identifies the use of a 4” Dubro wheel, but I am using a firmer FEMA wheel which is 8mm wider - hence the retract & fuselage mounting need modification.
For the retract, the mods are as simple as making the brass spacing pillars & 1/8” steel pins 8mm longer. The F9 & F13 formers are also tweaked to move the retract mounting slots out by 4mm each side & up by 2mm to prevent the retract metalwork protruding from the curved fuselage. Cliff will be cutting some modified formers to check-out these mods.
Meanwhile, the retract looks like this:
Wheel down
Wheel down
Wheel up
Wheel up
Elliot Howells
Posts: 297
Joined: 18 Mar 2015, 08:18
Location: West Wales
Contact:

Re: SZD-8 Jaskolka 1/3 Scale

Post by Elliot Howells »

ooh, 1:3 scale Jaskolka?! Yum.

Can't wait to see your build pics, Ell.

would love to see some thumbnails of the plan, what type of wingjoiner etc?
User avatar
Peter Balcombe
Posts: 1467
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

Hi Elliot,
Wing joiners are twin 15x2 steel blades mounted into a substantial laminated fuselage scissors type block.
Tailplane halves have separate servos & are mounted using a pair of 1/4” diameter round joiners.
The wings are quite busy as there is what appears to be a good Fowler flap operating mechanism, plus the normal top/bottom Schemp Hirth airbrakes

Fuselage assembly will start tomorrow with the laser cut forward fuselage parts, including the long sliding canopy cockpit surround, whilst I await the revised formers to take the wider retract assembly. Hopefully, the fuselage skeleton will go together over the next week or two once I receive my impending stripwood order.
Peter
Steve Walton
Posts: 4
Joined: 22 Sep 2021, 05:50
Location: Perth Australia

Re: SZD-8 Jaskolka 1/3 Scale

Post by Steve Walton »

Hi Peter
The retract unit looks very neat & tidy , Is it your own work

Steve
User avatar
Cliff Evans
Posts: 723
Joined: 29 Dec 2019, 15:13
Location: Bristol
Contact:

Re: SZD-8 Jaskolka 1/3 Scale

Post by Cliff Evans »

The retract unit was designed by Jilles and is on one of the plan sheets.

Screenshot (76).png
https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk
User avatar
Peter Balcombe
Posts: 1467
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

The retract parts have been a collaborative effort, with 3mm steel (rather than 4mm aluminium) side plates laser cut by Stuart Marriott & the longer FEMA wheel brass spacers turned up by Steve Vincent - many thanks lads :)
The torsion spring used to counterbalance the wheel weight is from a mole trap mechanism, but a little too strong. I may end up making a bespoke spring which relieves servo forces in both up & down directions as at present the down going load is much higher.

The wing joiner arrangement is shown below. The removeable retract goes through the section noted as to be removed later & fits between 2 keel pieces which extend from the nose to just aft of the retract area.
Wing joiner arrangement
Wing joiner arrangement
Steve Walton
Posts: 4
Joined: 22 Sep 2021, 05:50
Location: Perth Australia

Re: SZD-8 Jaskolka 1/3 Scale

Post by Steve Walton »

Thanks Cliff
Very neat design
Steve
User avatar
Peter Balcombe
Posts: 1467
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

The fuselage is now being built up on a straight/flat length of 6” x 1” planed softwood, 2.4m long to cope with the 2.2m+ length over the fuselage formers.
With the board sitting on a flat bench & a centreline marked along its length - let’s get started :)

First job was to glue the base of Former F1a to the building board in parallel with adding the 2 nose skid doublers to the centre keel. I then used the notched centre keel to position the next two ‘based’ formers (F5 & F8) on the building board.
At this point, I realised that once these extra formers were fixed to the building board, I wouldn’t be able to slide the 2 main keel pieces into position, so added small hardwood strips to the bases of F1a & F8 to enable them to be screwed back into the correct place once removed (see photo).
Forward formers secured to board
Forward formers secured to board
Once this had been done, it was a simple matter to remove the 3 formers + centre keel assembly & fit the 2 main keel (K1) pieces into place before re-fixing everything back onto the building board. Formers F2 & F3 can then be fitted & secured at the top centre with S2. F6 & F7 can also be added, plus the tow release & retract servo trays ST1 & 2.
I’ve currently left fitting the canopy frame surround & upper nose strips (S3) as these need the former slots to be angled from their 90degree laser cuts. Thus I will wait until the glue has set on the initial assembly.
Forward Assy + servo trays
Forward Assy + servo trays
Whilst waiting for the glue to set, I can glue up the main wing joiner box assembly using epoxy to provide a really rigid unit. This unit comprises 4off slotted ply pieces (each taking a 16x3mm brass tube) sandwiched between 2 ply formers & everything pegged together using 4 alignment dowels.
User avatar
Peter Balcombe
Posts: 1467
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

Fuselage build now with upper nose longeron strips, canopy front and canopy frame in place, although rearmost canopy frame joints as yet unglued to allow it to be raised slightly whilst further formers are fitted behind F8.
D2138ECC-B9D4-449A-853D-62731FC66EA0.jpeg
Note that a good way to position the bottom legs of F4 is to temporarily screw the front canopy plate (C4) onto the top of the sloping fuselage canopy frame (CF) using the pre-cut holes/pilot holes provided.
The bottom legs of F4 should rest against the front face of C4.
Last edited by Peter Balcombe on 05 Oct 2021, 12:54, edited 1 time in total.
User avatar
Peter Balcombe
Posts: 1467
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: SZD-8 Jaskolka 1/3 Scale

Post by Peter Balcombe »

My stripwood order from SLEC arrived yesterday, plus some 15x2 joiner strip/tube from Cliff - so onwards with the fuselage build :)
The joiner tubes (each 226mm long) are glued into the 4off F11 parts as these are sandwiched (2 LH next to F10, followed by 2 RH, followed by F12) between F10 & F12 & everything positioned using 4 dowels through everything.
Remember to use epoxy for these bonds as noted on the drawing.
Fit F9A to the rear of F9 and F13A to the front of F13 (retract attachment doublers) & then the formers back to F14 can be added (remembering to fit BR6 between F12 & F14 via F13 as you go).
Most of these formers need the canopy base to be raised up a little as they are inserted & dropped into their keel slots, so the rear of the canopy base can be secured once TE formers are in place.

With all the formers in place, the wing Root LE profile FR1 can be inserted, followed by the root ribs which slot over several formers. Note that the root ribs are settled in slightly different places to suit the staggered joiner positions.
Finally, F14A can be added behind F14, aligning the circular lightening holes to get the rear incidence tube slots in the correct place.

Moving rearwards, the top spine piece can be slotted into the tops of F13 & 14 & F15 to help position the rear fuselage formers in due course. Meanwhile, splice up two lengths of 3/8” x 3/16” spruce to produce the rear keel strip S6.
Centre section
Centre section
Wing joiner area
Wing joiner area
Rear incidence doubler
Rear incidence doubler
Post Reply