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Jun 11, 2019, 08:18 PM
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old4570's Avatar
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R4 (3mm) Depron Sheet Wing


I kind if tend to start with the wing when starting a new project , that way ! If you stuff it up , then just make a new wing till you get it right . Then build the rest of the glider around the wing . ( But thats just me )

So just draw out a wing profile on your depron ( 3mm in my case ) and cut it out .
Then copy it 3 more times so that you have 4 wing panels .
Lay them out so you have a left and right wing ..

With the bottom panels :

I made a bevel on the LE so that the top panel would slope forward and glue in place sort of sloping forward
Also used some depron 3x5mm as a spar and backing for a carbon spar 3mm x 0.5mm ...
This also gives us the airfoil for the wing .

Once these are glued in place , the top panel can be glued to the bevel that was cut/sanded into the LE ( See Pictures )

I myself , put the bottom panel on the floor and lay books down onto the depron to hold them FLAT and in place as the glue dries ..
Just along the area being glued ..

When it comes to gluing the top panel to the SPAR and TE ...
I lay books over the LE and TE to hold the bottom sheet flat to the floor .
At this time I make no attempt to glue the TIPS .

Once the wing is glued and dry , then I glue the tips ..

With the wing glued :

You could sand the wing to shape , unfortunately this removes material and may create weak spots ( R3 )
This time around I used the crush method .
Using a round piece of PVC pipe , I crushed the LE and TE to shape .
I lined up the wing with the edge of a ( Table if you like ) and then used the edge of the ( Table if you like ) as a guide whilst crushing the depron to the desired shape . Actually worked out ok ..
Next time I do this , I will also bevel the TE of the bottom sheet for a much smoother transition .

With the wing formed and glued together .. I used some 10 thou laminating film to cover it .

So thats how far my R4 project has come ..
Will be a 700mm ( there abouts ) DLG with hopefully decent performance .
The R1 / R2 and R3 were very much Research Projects and the R4 is a slightly more serious attempt at a Depron DLG ( Low cost - simple - functional )
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Jun 12, 2019, 06:51 AM
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Neil Stainton's Avatar
It looks good, but I think a 6mm thick trailing edge will hurt performance. Can you taper the sheets to reduce this?

Neil
Jun 12, 2019, 10:29 AM
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old4570's Avatar
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Originally Posted by Neil Stainton
It looks good, but I think a 6mm thick trailing edge will hurt performance. Can you taper the sheets to reduce this?

Neil
LE and TE were crushed ..
I put the wing up against an edge ( Wood Board )
ANd then used PVC pipe to crush the LE and TE to as close to an ideal profile as possible .
This way I was compressing the material rather than removing material .
Once I got a decent TE and LE , I used the laminating film which should hold the wings form rather nicely and add surface tension and strength .
Posted pictures are before I did the crush forming and laminating
Jun 12, 2019, 11:08 AM
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Neil Stainton's Avatar
I don't think crushing is ideal for the trailing edge, which really needs to be either thin or with (close to) 90 degree corners, to aide clean flow separation. Crushed foam will try to recover its original shape and the result will be a convex trailing edge and a ragged flow separation.

It would be better to actually remove material from the bottom sheet so the TE is tapered, and then stick the top sheet to that.

Neil
Jun 12, 2019, 06:25 PM
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old4570's Avatar
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To each their own .
It's been a few says now and there are no signs of the LE or TE doing anything . ( Depron crushes well )
Just need to check if I have 0.5mm music wire ..
If I have some I will do the RE and boom as well the pod .
Probably - the pod will be like on my R1 and I will do the boom with 3mm square carbon tube .
Jun 13, 2019, 09:15 PM
It's time for me to fly
JimZinVT's Avatar
My first few DLGs were hot-cut XPS cores (AG04, 800-1000mm span) covered with 3 mil laminating film, no spar. With a little care they held up pretty well and flew great. With 10 mil yours should be stiff and durable. Might be a challenge to get it around the LE and tips? I've never worked with any thicker than 5 mil.


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