Which one you mean?
20char
“Foil Drive” Assist, the commercial but fairly prototype looking system in Australia.
I’ll give it a shot!
They failed by blade separation/shattering, presumably?
They look like they are. Does anyone have thoughts on two props rotating side by side? I saw something like that on a forum here yesterday, I could find it with some digging. But would that lower the force on each one by 50% or do the forces not increase linearly?
What do you mean? Just draw it in pencil on paper and take a picture.
Or casted in aluminium using @jeffM method, a 3D printer can print in lost wax too which gives a very nice finish.
Im thinking of two props arranged side by side like the rotors on a chinook helicopter, apologies in advance for the terrible drawing. Would it benefit in any way, or would the extra losses in drag on a second prop and from the gearbox assembly take away too much to make it worthwhile?
Plus the colossal drag if a much larger shroud was to be installed…
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There wouldn’t be much benefit unless you wanted to downsize the motors and props. I designed a similar system to utilize 2 jets off one motor but there’s no real point as its just increased drag at the end of the day…
I guessed as much. In a similar vein, what if the motor shaft protruded from both ends and a prop could be fixed to the front also?
I only have access to a 3D printer so it would be great to have blades that dont break, without getting too invested in carbon fibre molding or alu casting.
Like so:
I notice I’m going off topic. let me do some research and I’ll start a new thread if i think its plausible. Thanks!
Its already been tried on the forum and had no advantage unless you wanted to use smaller motors…
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Ah ok. Good to know. Thanks.
If it was beneficial, it would have been promoted, tested, optimized, etc. here on the forum for several years. I think the main drawbacks are as follows:
- reduction in drive efficiency by about 30% (drive efficiency is the most important parameter for all e-drives)
- significant increase in system failure rate
- higher acquisition costs
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What was the failure mode of these PLA+ folding props, a photo would be interesting to see?
I wonder if polycarbonate would make for a stronger prop, if you could get it to print with enough detail, or sand it smooth.
The flexidrive folding propellors have a bumper to soften the shock of the blades opening up.
Problems I always had with any 3D printed prop is it just vibrating itself apart. Such a pain to get it balanced. I wish someone would just make a motor with the same shaft as Lift motor or someone would make a strong folding prop for the 65161 motors. I’ve tried making my own 3D folding prop designs but they never hold up for more than a handful of sessions. I should ask a machine shop for a quote.
Which filament were you using?
PETG prusament. 100% infill for blades and 70% for hub
Which part broke whilst vibrating to bits?
It seems that PETG is strong but brittle, and may not be the best filament for the impact of a folding prop banging open.
Polycarbonate might be more shock resistant and stronger.
ASA could be more suitable for post-processing, sanding, gluing extra weight, which is difficult with pla and petg.
The lift folding prop is expensive, and not feasible for a cheap foil drive build. Balancing props looks time consuming, likely more so with a folding prop, and one that mounts to 4 bolts onto an outrunner.
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That makes a lot of sense. I think in the coming weeks I’ll still look into machining an aluminum option. It’s definitely going to be expensive but that’ll be worth it if I can finally ride swell unpowered.