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Slingby Kirby Kite 1:3 Jilles

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Jilles
Posts: 237
Joined: 22 Mar 2015, 10:27
Location: Australia
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Slingby Kirby Kite 1:3 Jilles

Post by Jilles »

Hi All. slowly the build on my scale 1:3 Kirby Kite has started. In this design the wing to fuselage and wing struts connections are close to scale
Each wing has three pins to the fuselage top with the wing struts keeping the wing at the correct angle. The means there are a lot of metal parts involved . The majority is 0.8mm (0.032") brass sheet. That requires a lot of cutting and drilling. To save time and increase the accuracy by a lot I investigated if I could have them Water Jet cut. Wate rJet cutting has the advantage over laser cutting that there is no heat involved that would deform the parts in the process. I found a local outlet that was prepared to do this relative small job. The cutting fee was AUS$88.00 roughly GBP45.00 in todays rates. I had to supply the material. 3 brass sheets of 10"x4"x.032" were required from K&S. The parts need to be nested with a greater distance between them than with laser cutting so a bit more waste. In my case they could only cut minimal 3mm holes. Most holes are 2.5mm and they were only pierced in the center at 1.2mm diameter. In my view this investment is worth the effort. It saves time and you get more accurate parts as well.
This does not mean you cannot make them by hand as long as you have the time and tools. The parts are left with little bridges in the nesting, see picture BRASS1. A couple of larger parts fell out anyway.
I made a start with preparing the parts for later fitting in the model.
First I drilled the pierced holes to 2.5mm. I used a piece of timber and in my drill press drilled holes to suit the various tubes sizes that need to go through these brass items.
Similar items were stacked together with the matching tube as guide
drilled the first 2.5mm hole and fitted a M2.5mm bolt, then drilled all the other 2.5mm holes
All done in the drill press so they are all plumb. see picture BRASS2.
The bottom bracket in the fuse for the wing strut connection has a doubler and tube ( say Boss) soldered to it.
Again a piece of timber was used to have two brackets lined up and the tubes square and parallel.
I used hard solder (No resin) and flux. With a little gas burner it was all heated up and soldered. see BRASS3
Separated the parts and trimmed the tubes to length. Smooth on one side, 1mm high the other side. parts cleaned of residue flux with water and a steel brush. then drilled the outer 2.5mm holes through the bracket and doubler plate. Piece of cake so to speak, see BRASS4
The little gas burner I got from my local hardware store for $8.00. It can be refilled but that cost probably more than buying a new one
There is more soldering work to do on other brass parts that will be performed in the same way.
Picture kb13 shows the original fuselage bracket to take the wing strutsat the bottom. Left and right are separate items. I decided for structural reasons to make them in one piece but kept the original shape were they are visible.
A model friend of mine Brian Ford invested in a large Laser cutter. and he is prepared to cut all the laser parts for me. This is for Brian a first to cut a large kit so a learning curve for him and I will not pushing him. Next post will be when the laser parts are in house.
Attachments
BRASS1.jpg
BRASS2.jpg
BRASS3.jpg
BRASS4.jpg
BRASS5.jpg
kb13.jpg

Jilles
Posts: 237
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: Slingby Kirby Kite 1:3 Jilles

Post by Jilles »

This build is not going fast. There is a short supply of spar and stringer sections and shops will not restock until April or so. I have them now made for me and have them I hope in 2 weeks. NC cut parts are also on the waiting list
In the mean time I worked on items I could proceed on, The Skid assembly is one of them
Made a template with the correct curve . 4 layers of 1.5mm ply strips were glued together on this curved template. The sides then trimmed to the final shape. Not sure if the original had them but I decided to fit metal wear strips to the underside of the skid. Gliders in the 1950 with a timber skid had these strips and with the not so smooth field I normally fly from in mind they would not be an overkill.
It required 6x1mm aluminum strips. I could only get 25x1mm so I made a make shift router with my Dremel and cut them with a cutting wheel
Just a small cut every time. It took around 20 strokes over the strip length to cut through and went through 3 disks per strip in the process.
There are no doubt better tools to do this but I used what I have at hand and it worked. Plenty of time anyway
The strip are test fitted with small nails at the moment but I try to get small screws for final fitting
The receiver bracket for the main rubber block was hand made and fitted in place. it will be painted later. The rubber block is in my case a 3D printed parts from high strength ABS. and painted black, nobody will know it is not rubber. You can 3D print with a rubber type of material but it will not have much strength. It will take all the landing forces so it need to be strong, not to mention the occasional harder than normal landing we all have and side loads in cross wind
When not building in the workshop I am working on a design for a rather large scale glider for a local customer. more on this in the near future
Attachments
skid1.jpg
skid2.jpg
skid3.jpg
skid4.jpg
skid5.jpg
skid6.jpg
skid7.jpg
skid8.jpg

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Cliff Evans
Posts: 482
Joined: 29 Dec 2019, 15:13
Location: Bristol
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Re: Slingby Kirby Kite 1:3 Jilles

Post by Cliff Evans »

The good thing about printing with TPU Rubber filament is that you can adjust the print fill and make the mount as herd or soft as you wish. About 75% infill makes the mount hard enough for an affective rubber mount. I use a filament called "nijaflex" for this type of job.

TPU Rubber tail skid mount for ASK-13
TPU Rubber tail skid mount for ASK-13
https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk

Jilles
Posts: 237
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: Slingby Kirby Kite 1:3 Jilles

Post by Jilles »

received the NC laser parts last weekend, so no excuses and start building. We are in a mini lock down so not much else to do
Started on the tail bits. rudder and Horz. stab.
Attachments
parts pack
parts pack
rudder
rudder
rudder
rudder
stab
stab
stab
stab

Dopieman1
Posts: 45
Joined: 09 Mar 2018, 09:42
Location: Den Bosch

Re: Slingby Kirby Kite 1:3 Jilles

Post by Dopieman1 »

Beautiful glider to model!
Its on my todo-list as well.
Follow with great interest!

Jilles
Posts: 237
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: Slingby Kirby Kite 1:3 Jilles

Post by Jilles »

Rudder completed, all up 105 gr. Planking of the horz.stab. in progress. All0.4mm plywood. the LE is a wrap around bit. made a cardboard template, this saves plywood in the end.
Fuselage formers were set in place. Most of my design have building stands/tabs on the formers. With these tabs there is no need for a jig.
Only the occasional bracing until the stringers and and some planking has been added.
The wing is connected to the fuse with three pine like the original. jig pins were used to make sure the three pin align and also the spacing was checked. With NC laser cut parts this is more just a check than the need to get it in the right place. the parts fall in place at the correct location or distances anyway.
Attachments
rudder complete
rudder complete
cardboard template
cardboard template
LE CUT TO SHAPE
LE CUT TO SHAPE
FITTING LE
FITTING LE
INITIAL SET UP FORMERS
INITIAL SET UP FORMERS
METAL PARTS BOLTES AND EPOXIED
METAL PARTS BOLTES AND EPOXIED
CENTER SECTION AREA SET UP
CENTER SECTION AREA SET UP
SPACER CHECK JUST IN CASE
SPACER CHECK JUST IN CASE

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