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Easier mould-making for a ultralight Low Aspect Ratio

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nestofdragons

Well-Known Member
Supporting Member
Joined
Jun 8, 2016
Messages
875
Location
Near Antwerp, Belgium
Just trying to find a way to make a wing in composites for a motorized, ultralight low aspect ratio.
My goal of this discussion here: finding a way to make the composite wing with as easy to make moulds. I had very bad experiences with endless sanding of moulds that start with hotwired or CNC routered foam.

Lets start with why i choose to make the wing with three panels at each side. Easy to explain. The round wing would demand that technique of CNC routering and placing gelcoats and so and i really really would like to avoid that way. It is not easy to do for everybody and it demands tiiiiiiiiiimeeeee. And if you look at the wing. It nearly has the same shape as the three panelwing.
You can see my Low Aspect Ratio ideas here. Low aspect ratio sport plane ideas
The more lineair editions can be seen at Low aspect ratio sport plane ideas
That project is still being developped.

Now lets make a mould for that kind of wing.

I would make wooden jigs combined with alu plates or some other plate material. Three sections need to be made and assemble them afterwards. Here you see how the three parts would look together. Sorry, i drew a single panel where the jigs are placed together to be quicker.
SPAR01.jpg
SPAR02.jpg
Each section can get its mould panel easily. Just slide in a plate of alu or copper. Push it onto the cut out shape. If you want you can use silicone to keep it a bit in place while you draw a line at the part which sticks out. So, no need to draw a complex unfold template. Just lay down. Fix it a bit (but keep it removable). Draw the line so you can later cut of the part that sticks out. Remove plate, cut of part you don't need. Glue the plate back onto its place. This time it needs to stay there.

Do that three times. And place the sections together. There might be need for some filler and some sanding at the joints, but ... i guess it is a doable task to just sand those joints.
You now have this.
SPAR03.jpg
SPAR04.jpg

Ok, you can now start doing your composite skin. I would prefer some carbon, thin foam and another carbon layer. You might go at the same time for your carbon for the spar caps.
SPAR05.jpg
You can install D-tube rib noses now.
SPAR08.jpg
The ribs don(t all have the be full ribs. Halfway you can place a trapezium foam part over which you place some composite to create a tough fake rib. Just like my team did in the DragonWing. It really is easy to do. You make one foam part and you can use it for all fake ribs.
110688-f1190ae824bedac1759343159db7fd34.jpg

Now i need your opinion. How would i easily make a spar vertical so the spar doesn't buckle. Just insert a thick foam plate which has carbon layer at both sides? Or do i place L-angles just next to the spar caps inside edge so i can glue a thinner foam with carbon layers onto it onto that L-profiles? I could repeat the same L-profile and plate technique to close the D-tube. If any fear of these verticals buckling one might add some trapezium reinforcements like mentioned above onto the vertical thinner foams at the "inside of the spar". You can do that after you glued the first vertical. For the closing vertical, you need to do that in advance before glueing the vertical to the L-profiles.
 

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