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Slingby Kirby Kite 1:3 Jilles

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Jilles
Posts: 230
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