After months of tinkering, soldering, and plenty of trial-and-error, I finally finished my own DIY foil assist and got it out on the water this week. I’d built a Gen1 style FD before, and was contemplating an integrated board build. Midway, I changed my mind after I saw the first pics of the Duotone assist (and also seeing SkyRama’s vids).
Having the weight on the hips is a no brainer. You barely feel the weight at all and your board is light, and there’s no drag! Thought I’d share a few highlights for anyone going down the same rabbit hole. Special thanks to @nekitesurfing for passing on his knowledge.
Setup:
Motor: Saite 6384 (140 KV)
ESC: Flycolor X-Cross HV3 160A
Battery: Two 6S3P packs in series (12S total) built from Molicel P45B 21700 cells
Wiring: 0.2 mm copper busbars + QS8-S anti-spark connectors
Prop: FD 3 Blade Prop
Control: Maytech V3 remote
Box: Alu box and custom 3D printed components
Harness: RideEngine
Performance:
Pulls cleanly to take-off
Alu box acts as a mega heat sink
Runs strong until ~20-25 % battery
I’m getting roughly 1h30 min of mixed riding
No shoulder/ back/ hip fatigue wearing the box on the hips, unlike a backpack. It’s amazing!
Learned the hard way that half-plugged QS8s = smoke
Here’s some pics I clicked during the build. changed the name from Firefoil to Firefly midway too.
Thanks! Just printed some TPU inserts and glued them into the harness with Stormsure. Then used some Velcro to fasten it to clips I designed and printed for the box. These clips go into the rails of the box. My leash is just a length of Dyneema with a short bungee paracord. That hoops onto a buckle on the harness.
Nice build!
How is the motor controller connector working? Can it disconnect when crashing or by accident? Would it damage the controller when disconnected under water?
What cable are you using?
Made a custom connector, vacuum fit with 3 O-rings. Needs to be pushed in just right for it to make a strong vacuum which holds it in place. Strong enough to need some solid force to pull apart. Detaches under really strong load (like a massive crash). Works great so far.
ÖLFLEX® CLASSIC 400 P; 3G2.5mm2; unshielded; 300V,500V; Cu
No, no potting the electronics. It has some plastidip applied around the edges, to prevent any water drops from sliding in when I open the case the case. The batteries are enclosed in PLA printed cases, with some sikaflex around the leads but are not extremely water tight. The case is solidly watertight though. I use some battery grease on the seals. I should make the electronics and battery watertight, but I don’t really think it is needed - more of a peace of mind thing.
Planning on getting the same battery (12S3P from Molicel P45B 21700 cells) to build a belt assist (wanna overkill a bit so i can easily efoil back to the peak without frying anything).
Was gonna go with Flycolor 160A but read that it could be problematic under high voltage. Since then I don’t know wether to get it and try for myself or go with a Flipsky FSESC 75100… It seems i’m just underneath the weight that could be problematic with Flycolor 160A but if its still working good for you i’m willing to try as it doesnt require programming
I am going with the same case - wondering if you got the 130-65-250mm or 180x70x150mm and if you are happy with your choice?
Since im going for the same build would you mind sharing the STL files for the MT60 green sleeve, the TPU inserts & box rail inserts as well as the red casing for ESC? (Basically all of your 3D printed parts :D) Would be a huge help!
I also have a few questions:
For cooling:
-Do you place the “firefly” logo side of the red casing against a thermal pad? How do you make it hold against it ?
-Do you also recommend to place a thermal pad under the battery since the box is aluminium ?
-Is your Matek BEC12S-PRO hidden under the Firefoil logo of the red chassis?
-You use BMS only on charge for the battery ?
-The 3D Printed Hex-Mesh Cage is also acting as antenna housing ? or is it to protect power cable ? Can you please share more details on why you made this system with the cable going out of the cage then to the other side through another protection?
Thanks a lot and thanks to everyone on this forum for sharing their builds and ideas !
*For reference: I’m 78kgs, I have different boards from 44L to 100L and plan on reducing size as much as i can.
I will ride some medium / high aspect 800 / 1000cm front wing
Setup:
Performance:
