After finishing the wing and doing a lot (!) of boolean ops for the tabs and slots I started creating the apges to be used to lasercut the 1mm parts. This included converting everything into two layers. One layer will be used for cutting, the other layer will be used for engraving.
I also had to take care of the little tabs/bridges that keep the cut parts from falling out immediately. For cutting efficiency I tried to keep these as few as possible.
As you can see for the spars I ended up dividing them into two parts and I used an A3 sheet. Note to myself: Don’t use this type of spar for a functional model!
I started with creating the base plate (well, first of all I pushed the wing construction aside):
As you can see the base plate was allready divided into sections which can be puzzled together. Each of the parts fits onto an A4 sheet.
I realized the „tab coding“ by simply giving each foot a tab of different length on one side. To show you this, I lifted the foots a bit:
From now on every rib has its unique position. I took the idea one step further. I would like to have everything stable and the hands free for mounting the spars. „To work with reasonable control“ as Leif would put it. So I added a lateral spar, some kind of comb to keep the ribs level and perpendicular.
Have a look:
These were also „tab coded“ and the long one was split into pieces that fit onto A4:
Now on to creating the rig. I was fascinated by the method which UweH uses when building his RC wings. Check it out. He is including the building board in his kits and the wing is build on this board using tabs and slots. Every tab is different so that the assembly is coded in the design. Every part only fits in one place, no instruction needed. I will try that.
To do so I added little foots to the ribs which are only attached by small tabs and will be cut off later. To be able to access these areas afterwards I had to turn everything upside down:
After finishing all the rolls and fittings I declare the wing design finished. I am now heading towards the building rig. Every plane is only as good as the rig it was built in. And I will incorporate some of the methods used in building RC planes. More on that later.
The fittings for connecting the wing support wires are drawn straight from the plan. They are drawn as simple sheets with one side creased by 90°. The mounting holes get doubled with a piece of welded material. And this is exactly how it was done. I had the markings on the spar allready inlcuded (lucky me), so positioning the parts was easy. To tell the thruth I only made one and the other three were just mirrored. The spars are exactly parallel and same size and the parts itselves are mirror symmetrical.
And the fitting in its natural habitat:
Oh yeah, here you can see a little bracket that gets attached with the same screws as the fitting. These are used to connect the fittings with a steel cable to accomodate some of the load by the support lines. Some of these run to the central wing tower and some are running backwards to the fuselage.
And finally the other other one:
Yepp, forgot to include the bracket here
The inner guide roll in its place. The rolls are the same as on the outer guide. I simply made them of stacks of 0,2mm metal discs. These discs will be soldered together. At least I will try to do it so. The guides will get screws in appropriate scale as axles. The plan says M6, this would be roughly M0,7 in my scale.
Interesting detail here: The small rectangular hole beneath the access hatch is the exit opening for the aileron control lines. These run „open air“ from here on.
As I mentioned before I tried to find readymade hardware. However when I started designing the guide rolls none of these seemed to fit very well. So I started creating these parts in a way that they can be made from etched metal. Well…these guys came out really small:
At least from my point of view. If you ask anyone from the ship-cardmodelling department they will laugh at you. They are using even smaller parts like blocks in 1:250.
The above roll in its working place:
The two guide pulleys of the aileron control lines do have two access hatches. These are simply made from three parts of spruce. The planking piece, a frame and the hatch itself. I still have to decide on a hinge to use.
Having finished the corner bracings I moved on to the planking. This was pretty straight forward. I included an offset of 0.1mm as I am planning to use 160gr/m² cardboard for this. My experience for these parts is that the neutral fibre is roughly in the middle for the larger curvatures. Thickness for this material is about 0.2mm. For the root rib I could have used an 0.2mm offset. However ther difference is marginal and the final piece will need a little bit of trimming anyway.
Designing with fully coloured cardboard in mind gives new perspectives. I don’t have to pay that much attention to details. Parts like the planking can be designed a bit larger and then trimmed afterwards. Howver I am aiming to get it perfect 🙂
I revisited the thought that I could make the controls movable. This would require a decent brand of wire. I started thumbing thru our archives at www.kartonbau.de. I knew there was something…
…and found it. There is a supplier for model ship accessories and this one carries an amazing amount of stuff for this project:
The website is … well … old fashioned but they carry machine-laid rope made from stainless steel. These ropes are made of 7×7 = 49 wires and start at an diameter of 0,27mm !!!
This is one step further into making the control surfaces movable.