Electrical system fully hooked up e2e, tested, and confirmed working, so that’s fantastic!
The epoxy and fiberglass progress is slow going, but I’ve made significant progress, I didn’t take a photo but the fiberglass on the top of the board is done, just working on getting the recess for the lid fully fiber glassed and flat for a good seal. Should be done with that today and start painting here next weekend.
Any recent update on your build?
Hey everyone, sorry for the delay in update, I’ve only really been building it on weekends and late nights, so it’s taken me a while. But I’ve finished now and I’ve been able to get it up on foil on my knees.
Took me a while to get to this point. Started on my knees until I got comfortable with the throttle, then by the end of the session I was able to stand up and get a few short flights in. Couldn’t hold it yet but it flew, and I’ll take that.
First two sessions the board just would not get up. Power was capping around 1500W and 25A battery current no matter what I did.
Spent a while chasing the wrong stuff. Checked the JK BMS, set to 120A discharge with zero overcurrent events in the whole log history. Checked Battery Current Max in the VESC, set to 80A and I was only pulling 22A. Neither was the problem.
Got VESC Tool connected over Bluetooth and watched RT data while pulling full throttle. Motor current was pegged at 79A against an 80A Motor Current Max.
That was it. I’d been watching battery amps going “well that’s nowhere near the limit” when the motor limit was the thing choking it. Battery current is roughly motor current times duty, so 79A at 38% duty gives you about 25A battery and 1271W. Motor was torque starved and couldn’t spin the prop up.
Raised it in stages and logged each one:
80A motor: 22A battery, 1271W 120A motor: 41A battery, ~2300W 150A motor: 79A battery, 4169W measured 180A motor (where it is now): should be around 5.3kW
Worth knowing the 75200 Pro V2 has Bluetooth built in, I was about to buy an NRF module before I found out. Being able to read live data on my phone at the lake would have saved me two trips.
14S9P, 126 BAK N21700CG-50, 45Ah, 2331Wh, all welded stacked nickel with no copper jumpers.
2mV cell spread at rest, 6mV under load. At 78.8A draw the pack only sagged from 56.8V to 52.8V. Peak FET temp over a 66 minute logged session was 47.4C and it actually dropped back to 37-38C after the hard pulls. Cutoff starts at 80C so way more headroom than I expected on passive cooling.
Cavity flooded over about 1 hours out.
The gasket itself seems ok, I pulled the lid off and pushed the hull under and nothing came in through the mast penetration or the wire holes. What I found is water coming through the fiberglass cut edges at the cavity ledge and wicking through the XPS foam. Found it by pouring water on isolated sections of the ledge until I saw where it came through.
Sealed those with thickened epoxy, then more of them, then eventually thickened epoxy over the whole cavity interior plus 4200 in the hinge screw holes, which nobody had sealed and they go straight through the ledge into the cavity. Finished it off with a Flex Seal paint coat over the whole inside of the cavity as a last layer.
That got it from a lot of water down to a slow accumulation, but it still filled up over a long session. Might still be getting some past the gasket too, hard to say.
I think the nosedives are a big part of it, every time you go over the front you’re driving water at the deck under a lot more pressure than any static test I did in the garage.
Good news is both enclosures did their job perfectly. The ESC box and the battery box stayed completely dry through the entire flood, not a drop in either one, and everything inside kept working flawlessly the whole session. The printed enclosures with the aluminum lids and the CESFONJER IP68 glands have been the one part of this build that just worked from day one. That layered approach is the only reason I still have electronics.
Lesson for anyone else building, seal every laminate cut edge with neat epoxy. Costs basically nothing and would have saved me a lot of hassle. Also make sure to never wrap fiberglass over sharp edges, that is pain. Also if i were to do this again, def vacuum bag
Board is drying out, then I need a proper fix for the ledge rather than another coat of something.
Setup for anyone curious:
Board: 1600x600x153 XPS core, hand laid glass, 96.6L Motor: Flipsky 65161 120KV ESC: Flipsky 75200 Pro V2 Remote: VX3 Pro on UART Foil: Gong Allvator V2, 85cm alu mast, X-Over V2 XL 1650cm2 Prop: printed PETG 160mm, running uncoated for now, Flite prop is next Battery: 14S9P, 45Ah, 2331Wh, JK BMS
Thanks to everyone whose threads I read about a hundred times getting here. jkoljo for the motor mount, sat_be, DutchFoiler, nicolasLGM, Gustav for the board layout.
Congrats on your first flight!!
This is awesome Derek, grats on getting on foil!
Do you have any more insight into the prop you are using? 3D printed at ‘medium’ pitch? Do you know the pitch by in or mm?
Thanks
Thanks : )
It’s the printed one from MakerWorld, 160mm 1.1 pitch 3 blade:
https://makerworld.com/en/models/433274
Printed in PETG, 0.4mm nozzle, 0.12mm layers, 100% infill. It’s designed for the 65161 so it drops right onto the threaded shaft with the drive pin, no adapter needed.
I’m running it raw at the moment, no epoxy coat or sanding, just as a test article since I’ve got spares printed. Know that’s leaving performance on the table but wanted to get on the water first.
Flite prop reamed out to 12mm is the plan once I’ve got the leak sorted, DutchFoiler and Foilguy both pointed me that way. There’s a drill guide for it here if anyone else is going that route:
https://www.printables.com/model/583026-flite-prop-drill-guide
