Propulsion System - Motors, Gears, etc

and nice carbon work there :+1:

Thanks thats some great info for when I am programming my ESC acceleration curves, as well as receiver antenna locations. This info should hopefully save me from burning out a gearbox a well. I am still a long way from getting the whole setup mocked up, but this forum is a great location for people to share their learnings! Unfortunately I’m up in Canada and won’t be able to do some full testing till next spring

Thanks, I’ll be sure to post the finalfoil when it’s all complete

Has anyone been able to get over the fact that most of us are using gearboxes rated for 5000 RPM input at ~20000 RPM?

My Neugart PLE 8:1 has a nominal input rating of 5000 RPM with a max mechanical speed of 18000 RPM. I’m running it close to 22000 RPM with thermal paste and a metal heat sink to the water.

My unit has a max output Torque of 10Nm and I suspect I’m operating it closer to 25Nm at take off and 10Nm at cruise.
Good thing these are German.

The 5:1 gearbox has better Torque ratings. Looking back, I would have gone with lower voltage (or lower motor Kv if possible) with a 5:1 gearbox.

We have some nice working prototypes out there with the SSS 56104 (what I used) , but I wonder how long the gearboxes will last.

You are absolutely correct. Thinking about it all the time. We need to aim for lowest possible kv to reduce gear input speed. Gear ratio 5:1 and 4:1 have the best torque ratings in most of these single stage planetary gearboxes. Lowering voltage is another way for gearbox longevity but you will run higher amps, less efficient and more heat. So I’d like to stay at 12S. Best would be if someone develops/sells a custom low kV motor and we get rid of the gearbox.

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That’s for sure so can you ask TFL for custom KV ?

Hi @pacificmeister can I ask you how much you weight? :).
I could find that you using about 40A current on 12s. Me and my friend have 4:1 gearbox and 300kv 12s, my friend weight 100kg and his usage is about 60-70A, I weight 75kg and I have 30-40A usage…
See the telemety logs of my friend riding…This is about 25% plopeler slip at 9"pitch and 140mm dia.

Best Regards!

Yes, but it depend on the foilwing you have… If you use like regular kite foils it is in the range of 20-25kg at a speed of about 10knots…After lift of it reduces significantly
We managed reduce the lift of speed, which reduces power needed&effectivnes of prop siginificantly… However we went to an impeller solution now due several reasons…;-.)
Cheers Jay

Hey this telemetry data logger is cool. What kind do you use? would be interesting for all of us too, so we can compare values;-)

Hi Jay!

I m using frsky telemetry with taranis rc radio setup. You can see direct data from foil on rc transmitter and have also option for loging it to the sd-card , for late night analyse :smiley:

Best Regards!!

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Thanks Elevate!
Do you mind sharing your impeller size and motor you use?

Well actually its not a kind of impeller on the market so far.. it best describes as "expeller" At this stage cant tell you more:sunglasses:… But we used impeller with 80mm size and it works fine with the motors you use:wink:
effectivity is not that perfect as on a ducted prop with 130mm…But the thrust ratio at speeds >10 knots gets better…so it`s kind of finding the correct balance…
And it further all depends on what foil wing you use…so not easy only to compare the thrust of the systems at 0 knots!

We are researching this way quite a while :innocent: (If I interpreted your post correctly)
no sealing neaded…with ceramic bearings no care needed…
but not that cheap where we want it to be… so far;-)
sneak preview


Cool. 80mm if that is direct drive you must be pulling some hefty Amps…

About 80A at 10S 100kg…only for takeoff after that about 40A…If you can go to a 80mm Impeler it will drop dramatically…and your motor can handle this;-)

Nice! it all depends on the RPM you are turning that in terms of amps. I would think your running RPM at 80A is 10,000rpm ish or are you running that at 16K impeller speed?

yes the lower one;-)

Has anyone tried this engine? SSS 56114/360KV Brushless Motor 6 Poles

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I have ordered one of these. I assume the 56114 is a typo and it’s also a 56104 form factor with just different windings, but not sure. The 360kv would be a bit easier on the input RPM of the gearbox but I may need a bigger prop with my 5:1 gears which increases torque load which is also over the limits with the gearbox. It’s finding the right balance.


I am also interested in knowing this