DIY Foil Assist Gen 3 thoughts for optimization

Can’t trust rc motor specs, normally a fantasy number the seller just makes up.

A proportional comparison shows that a 56100 sized outrunner can be estimated to have equal max torque to a 6384 if the airgap flux is the same. In reality it’s unlikely to reach same flux density, with smaller diameter the area for steel in the stator teeth and room for copper between the teeth gets smaller. Efficiency will be also be lower at max torque.

What happens at smaller diameters is also that (for same power) the efficiency is shifted towards higher rpm so the smaller motors can have good power and efficiency but are not the best for direct drive where torque needs to be higher.

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A question to those of you who’s been here and built for years now. Is it pure wisdom and testing that established 63mm as the diy defacto choice?

Wisdom is a strong word😀
I’ve tried smaller motors without success, they burnt without reaching foiling speed even though i tried a few props. Torque and power just wasn’t enough.

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Trial and error into a pre-existing range of motor diameters : 50 56 58 63 70 80mm

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so what’s the closest motor for Foil Drive Gen 2, from Ali or michobby.com etc?

The EXACT genuine Foil Drive motor is Saite 6374, you can buy it waterproofed from Saite. No magic with Foil Drive Gen2 components. Flipsky 6374 or 6384 140kv motor is easier to source.

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That motor requires waterproofing, for example saite 6374 from Saite?

I checked few guides here, any advice on the best way to waterproof? Also I assume need to replace bearing to ceramic ones?

Ceramic bearings will fail very quickly, especially on 12s.

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one more question, I’ve done some search and I see no one actually (or didn’t find yet) tried to make battery/electronic case at the mast base (similar to FDGen2), I would expect to find CNC files and STL to reproduce that, but everyone seems to be just throwing in the box on top of the foil… so no one done design for bat/electronics for mast base?

Hello, I have made a similar attempt for a friend (a box with everything between the mast and the board). He is currently putting it together. There battery is 14s3p, 50S Samsung.
I’m currently making a bigger one for myself, with a 14s5p battery.
I’m still in the fusion 360 stage, but I can send a picture if you’re interested.
When and if it works out, I’ll post info on the forum.

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yes, would be great if you can share pics at the least, STLs would be great

Gonna go with a flipsky 6374 140kv my word due to easier sourcing. Hoping to use it with a small 6s battery setup (through a cross 160a) so I’d imagine the extra kv might be helpful. Any thoughts of the 6384 over the 6374 for assist use (not full time efoiling)?

Are you lightweight or will use big board ? FYI most people have success with a minimum of 10s2p…
Flipsky 6374 - people had success with it at all conditions, look at the Flipsky waterproof threads - there are at least two.
I have one, but didn’t test it yet

by the way, what is the possible configuration of FDGen2 slim battery

  • Nominal Voltage: 39.6 V
  • Max Voltage: 46.2 V
  • Rated Capacity: 4.2 Ah
  • Rated Capacity: 166.32 Wh
  • Battery Weight: 1kg (2.2lbs)
  • Certifications: UN, CE, IP68

likely 9s2p so they probably have two blocks of 9cells in one row, as battery is quite thin?

That would probably be 46.2V/4.2V=11S (since 4.2V is the usual max for li-ion cells). And 4.2Ah hints that they probably use the molicel P42 cells. Didn’t realize they would have 1P packs though

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Like I said, it’s still a work in progress.
Nothing is 100% ready nor tested.
That’s why I refrain from uploading files to the forum.
As I said, the smaller version is partially assembled and I can show and share what I thought and did.
The second one is still just a drawing and I am constantly changing something. Not ready to share.
But ok, in a few days I will open a new topic to share my ideas and possibly progress.

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ok , as I am starting design I have few questions regarding packaging of whole thing under mast base, that is bat 11s (or what not see above, slim setup), ECS, BMS, wireless module, cable connectors. May be even hand drawings, photos - how you plan to package all this?

Sadly not lightweight. But the aim is solely as an assist for light wind winging. Which will be on at least a +30L high volume board. Either a 6’2” mid size or longer downwind board. Which is why I’m hoping to get away with a bare minimum lie capacity 6s setup. I’ll ride the efoil I built if I’m proper efoiling.

Is the foil drive gen 2 motor the same as the flipsky 6384?

It’s 10mm shorter than Flipsky 6384 because they us 6374.

Lighter but a bit less powerful