...
Currently waiting on aileron design and as it may end up splitting ribs into 2 pieces
Will still want to some test cutting of ribs next week
Need to ask RPC about tolerance for spar
The laser cutter has a kerf (thickness of cut) of 0.1-0.175mm
For manufacturing, start with tolerance of -0.175mm, test for fit with box tube and try again
Need to keep pitot tube design in mind
Half on the wings to avoid prop wash
Need to keep gps mounting in mind
Most likely at the tip of the wing
Author: Nathaniel Li Date:
Meeting with Joshua Perry (WatArrow) about Wing Manufacturing
Discuss manufacturing process (iron)
What are your post-comp takeaways?
3kg plane
Tail very heavy since it was fully 3d printed
What iron did you use? Was it CSA approved?
Hangar 9 sealing iron
Not CSA approved
It was pretty simple to use
What material was the heat shrink laminate?
MonoKote (same as the one we are trying)
Why are you moving away from heat shrink laminate wings?
Manufacturing is too difficult
Heat applied for monokote (300 f) will easily damage other components like foam and ABS prints
What is your new wing being made out of?
Foam
Using a carbon fibre tube (about $10 each, might be worth a try)
Author: Nathaniel Li Date:
Manufacturing Update:
All materials in now for first initial trial of 3 ribs
Waiting for new rib spacer CAD for manufacturing
8 ribs with a negative 0.175mm tolerance (for laser cutting)
Easiest way seems to overshoot the negative tolerance and sand down until we get the desired fit
DWG of ribs found in:
WARG_CAD\Fixed Wing\Fixed Wing Design\Wings\DWG
FW_WINGS_P006_RIB_UPDATED.dwg is the original file
FW_WINGS_P006_RIB_UPDATED_4INx36IN_SHEET_0.175MM_TOLERANCE.dwg is the file I created with 8 ribs and the tolerance applied → This is the file I’ll give to the RPC
Author: Nathaniel Li Date:
Initial Wing Manufacturing Trial
...
1/16” ribs are too thin → 1/8” or even 1/4” should be tried
Fragile and break easily when sanding and assembling
Ribs warp and deform from shrinkage of ultracote
Very little surface area for bonding to ultracote
-0.175mm tolerance for laser cutting can be reduced to -0.1mm and 0mm in future tests to get a more precise fit
Sanding is almost always inevitable
LE and TE covers work
Doesn’t melt even at high temp of 350F (used CF PETG but ABS should be fine)
TE cover is pretty small → make larger (further back on chord)
Easier manufacturing
Prevent top and bottom layer of ultracote from sticking together
Need to use rib spacers on spar for even spacing
Iron works well but shrinking technique can be improved
At lower temp of 242F, adhesive starts melting and is pretty easy to deal with
Risk of burning and over melting is rare; just keep the iron moving
Best to slightly tension each section as you iron it
At higher temp of 350F (shrinking temp), it can be harder to work with and requires special attention
Staying in one spot for even slightly too long will overshrink
Gets rid of almost all wrinkles
Best to slightly tension each section as you iron it
A little concaving as shrinking starts
Causes: Thin ribs, not enough tensioning
Can possibly be mitigated by tensioning more during shrinking
Need sharper knives or xacto knife to make cleaner edges/seams
Overall feedback about process:
Long and tedious process to make
May not be suitable for small control surfaces (like ailerons and stabilizers)
Any mistakes accumulate and require a full redo to correct
Design Changes
Thicker ribs definitely needed
Super simple and lightweight internal spacers (for manufacturing)
Jig for manufacturing wing?
Holding the larger full size wing can be tiring and difficult
Larger overall wing (changing height/thickness of rib)
Prevent sticking of top and bottom layer of ultracote
Fit servos and other components
Author: Nathaniel Li Date:
Overall Size Increase
...
Increased the size of ribs (and appropriate LE and TE spacers) to have a 50% larger footprint
This should help accommodate components like servos
Still retains the NACA 4412 profile