I’m considering making longer arms for a Holybro X500 V2 frame. It’s uses 16mm carbon fiber tube arms, and has 2mm thick top and bottom plates.
I’d like to extend the arms 10mm to support 17" props.
Are there some rules of thumb to keep in mind regarding arm length for a given tube size?
Thanks you for any and all comments.
I’ve got a QuadX8 (octaquad) here with 16mm CF tube arms that are about 330mm long.
Currently there are 2 x 13inch props on each arm with plenty of room to spare.
This leaves 100mm between the prop tip and the centre plate.
The motors are mounted within the length of the arm, the motor mounts don’t protrude out past the end of the arm.
There’s about 50 mm of arm within the centre plate for the clamps.
This leaves 240mm exposed arm between the centre plate and motor mount.
I think they would easily take 16inch props regarding clearances, 17inch props would be “doable” but you might start having more prop wash problems and vibrations.
I’m not sure about the maximum payload, I would say they could handle 2 kilograms per arm total take off weight (ie: 4 arms x 2kg = 8kg total take off weight) . We have used this same frame type in quad format (not octaquad) to lift up to 5kg payload - in addition to the copter weight (so probably total 8kg as I estimated before)
For the Holybro X500 V2 you would almost definitely want to replace the plastic arm and motor mounts with aluminium.
