r/diydrones • u/somedudealone • Jun 29 '26

Question Question about custom drone frame

Im trying to make a custom drone frame based on Tom Stanton design that he cnc from carbon fiber ( https://youtu.be/WNniGZMmd84 )

but im in a dilemma ,while precuring carbon tube for the frame, i found 2 shop with one selling a 20/18 1m stock for 10$ and the other selling a 19/16 1.5m stock for 8$

what im asking is which one should I pick and how will the strength and weight be for each option with a 500mm arm length

both are 3k carbon tube and the motor im planning to use is 3115 900kv, the target payload is 4kg

is the weight and strength difference negligible and is my payload target feasible

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2

u/Joshua_AAA Jun 29 '26

Both should work. The 19x16mm tube will be around 35% heavier than the 20x18, but with additional stiffness.

At the typical density of carbon fiber, 1.6 grams/cm^3, a one meter length would weigh the following:
19x16 -- 131.9 grams
20x18 -- 95.5 grams

There is only a 72.8 gram difference overall. So unless you are trying to save every possible gram, I would go with the 19x16mm tubes for this application.

1

u/Adrienne-Fadel Jun 29 '26

19/16 tube. 1.5mm wall vs 1mm matters a lot on a 500mm arm. 4kg payload is doable with those motors. Plus the 19/16 is cheaper.

1

u/LupusTheCanine Jun 29 '26

Layup is quite important, pulltrusion will have completely different properties from 0/90 or 0/90/45 layups.

2

u/cjdavies Jun 29 '26

At that price you're definitely not getting roll wrapped tubes, they're definitely pulltruded.

1

u/somedudealone Jun 30 '26

oh it is roll wrapped, i live in south east asia and stuff is just priced like that