Cotton cord vintage race tires

Side detours, but coming back to working on the cotton cord tires, I'm discovering that my assumptions bring an interesting conclusion: the pair of sidewalls are heavier than the tread due to narrow tread and tall sidewalls! Not true for nylon cord tires of similar size. Has minor implications for wheel inertia.

The battle for getting the correct shape into the spreadsheet continues. Looking into using Blender to create the coordinates and exporting as CSV.
 
Progress on the shape! This is a pinched 650-16 tire on a 16x5 rim, 71 nodes.

TGM cotton pic.PNG


Using a cross section image of a cotton cord tire as a background in Blender aligned to rim, section width, and tread width dimensions, I followed the inner and outer edges of half the tire with Bezier curves. Convert the Bezier curves to mesh, then manually reduce the number of vertices to a reasonable number (even number at this step). Loop Tools, "space" distributes the vertices evenly. Apply a mirror modifier (total nodes become an the required odd number due to the midpoint) and now you have the complete tire shape, so export each object to a CSV file so you can paste the numbers into the TGM spreadsheet.

The CSV export I used has some quirks. For some reason, it was important not to use any transformations in Blender or you'd just get weird numbers. And the order of nodes for the mirrored half of each line needed to be reversed.

Now to figure out the rest of the TGM spreadsheet... plies and cord material seem obvious, but there's other stuff that isn't.
 
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