Christof Beaupoil is back

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I like his problem-solving attitude.

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That looks good Christof. Did you get the same data than Rod? He recently did a peak at 1000W, 140 RpM, 70N.m
Do you have a brushless FOC control ESC?Iā€™ I gave rod a little help on that some months ago. We use Vesc board that are really fine!

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Unfortunately Christof is not part of the forum yet. You can ask him on twitter or youtube or drag him here.

Iā€™LL mail him to invite him

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All,

Thanks for the invite and the positive feedback! Planned on joining for a while - but when I am in ā€œbuild modeā€ itā€™s hard to get me out of the workshop :slight_smile:

@Kitewinder: Yes I am using a VESC 4.12 (not the fancy V6 that Rod is using ;). I am controlling it with an Arduino and a PID library (adding this to the system was the main part of this weekends test) The controller works great thanks to Keith!

I am far away from Rodā€™s kW. Here is why: I have a 190Kv BLDC generator that is not spinning fast enough with the 1:2.5 belt drive I had at hand. Somewhere between China and Spain is a box with a 45Kv motor and a new belt drive. With that I hope to get to the 350W that the rotor is designed to get @120RPM in 10m/s wind. More than happy to reach out to you once I have put it together to get some help!

The other important upgrade were the new connectors. I can now build longer Helices way more efficiently than before. The printer is glowing - making the 200 I need:

to build a 100ft version right after the holidays.

On a side note: I have never been gone :wink: Just moving from the US to Spain with a family of 5 is not an easy project either. On the positive side now I have plenty of wind and space and do not have to worry about homeland security asking why I am flying strange objects close to Logan Airport :slight_smile:

Enjoy!
/cb

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Welcome! :blush:
Is that a Zortrax printer?

Thatā€™s a Raise3d N1 Dual - ā€œhalf price off because end of productionā€ - printer. Upgraded to a Bondtech extruder because the out of the box one suā€¦ed.

/cb

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What for the PID? The Vesc has an FOC control mode for
Position control
Speed control
Current Control
Regenerative braking

I would guess that is enough to do anything needed. On kiwee we use FOC control with position control to reel in and regenerative braking for the power curves.

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The rig looks really nice. Thanks for sharing

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And now with a bill of materials too

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But wait, there is more!

Couldnā€™t wait for the rest of Team Tueddelpower to be able to come to Spain from Germany (fā€¦g Covid) and took the all new base station out for a flight yesterday.

Good news: The system made the 100W I was hoping for and the new base could handle a lot more.

Bad news: We used a chinese controller with build in ā€œemergency breakā€ instead of the VESC. The break kicked in and overloaded the helix. Hope Keithā€™s has his new software release with torque limit ready soon :slight_smile:

Anyways:

First footage just up now

I will upload some more detailed footage and documentation over the next days.

Enjoy!
/cb

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And from the side

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Wow
The uniformity and initial torsional rigidity of that shaft under tension is amazing.

The best bit is we also got to see a fail at the end. Thanks @someAWE_cb /cb

What I like about the fixed angle video is how easy it is to pinpoint the geometry of the working system.
We can see wiggle and wobble in the system as a whole.
Not surprising given the length of unsupported shaft and the geometry ratios.

I donā€™t think this wobble is necessarily lethal to the design. Although vibration on any frequency wonā€™t help. and this wobble looks like fairly high amplitude in relation to the other major forces.

Anything which smooths out the whole system while encouraging tension inline will likely help.
I donā€™t know the exact configuration but Iā€™d suppose
Actively smoothing the tracking on the base station will likely help.
Only generating when there is enough tension will likely help

As per my comment from YouTube
I donā€™t think itā€™s a buckled rod.
looks like a mix of longitudinal tension shock (going up and down the set) combined with a transverse wave (maybe from imbalance in the TRPT or alignment from end to end)
The highest bending on the OTS often looks close to the rotor. I was expecting an end piece material fail from vibration.

Maybe an over sized generator which progressively backs off through the gust when it sees the load risingā€¦? might help?

/cb Legend!

Looks like the stabilising line on the generator frame had broken leading to the wobble.

Great video ā€¦

Do you have any rough idea the size of gusts so we might work out where the rotor was in terms of itā€™s max torque

As for where the generator torque might have been.
well thatā€™s probably even trickierā€¦ too high - at that end moment for sure

My comments suggesting an over-twist due to tension torque imbalance conflict with the /cb report of a buckle. So buckle it is.

Test flight 2020-10-15 Details of self destruction

I reckon this failure needs looking at in real slow motion (around 15 seconds in this video)
2020-10-19_08-53-16
Whichever way the fail went itā€™s the same result from roughly the same problem.