The Gu-365 is back

A couple of weeks ago I got my hands on a GU-365 3-axis flybarless stabilizer. I been wanting to build a tricopter for quite a while but the cost have kept me from taking the plunge, but now that I’ve got a 3-axis stabilizer that might work, the cost would drop enough for me to justify buying the rest of the parts.

But I didn’t want to chance that the GU-365 might work so I asked a friend in Denmark that have loads of tricopters to try it out for me.
Unfortunately the results of the testing were not what I had hoped.

– “It was out of control like nothing else I’ve ever flown, and it was FAST, I gave up counting the rolls as I gave everything I had in pilot skills to get it down in one piece…”

This means no tricopter for David, at least not for now…
Hmmm, might put it on a plane…

Click on the “Read More” to get read the entire flight testing and watch a video of the tricopter in action
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This is all the reports from Sebastian;

– “As I left for the workshop I emptied my mailbox and viola! A GU365, a loan from Dadde, our friend from Sweden.

I mounted it on my most beat up tricopter (also the best I have) and after 10 mins. of dialing (it has ALOT of switches and pots) it’s in the air.

I’m not sure about it’s usability as a tricopter stabilizer though, it feels like it has built in negative expo and so far I havent figured out a way to really tweak it, but then again, I’ve only had it in the air (low 2.1 m. ceiling basement workshop) for a few minutes.

I’ll keep working on it, and I’ll take it outside for a spin when I find the time.”
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– “It feels like if the gyro damping itself, but not the travel has negative expo, more sensetive around midstick, pretty weird to fly with, but I’m slowly getting there, some more tweaking and this might turn out to be good after all.

The tail is very snappy and best in rate mode, HH is rock solid but makes it bounce back once if the stick is released quickly, this drops the tail on the tri a little and affects the stability.

The gyros feel very strange, very different to anything else I’ve tried, it feels like HH mode but it isn’t, it flies very similar to the Alien air Jumpjet, sort of self correcting but not entirely

I really need to get it outside, somehow it feels like it’s urging to flip and roll

Thanks for the link, I’ll check it out right away.

And I promise to bring the cam to the shop tomorrow

Stay tuned.”
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– “I tweaked it a little more today and has found what I belive to be the best settings achievable.

It’s still very hard to control inside, it feels as if it has badly calibrated accelerometers onboard, it tries to self level but the unit has too much drift for it to work properly, and one click of trim is too much, it just shifts drift direction
Maybe it’s better outside, I expect it’ll self level and drift back and forth in 2-5m. circles.
I’ll experiment some more with foam dampening on the unit as the drift might be from vibration.

I’m sure it’ll be super fun outside in fast circuits, but it won’t be any good for AP, it simply too sensetive around midstick.

Here’s the complete setup.

Tricopter:

!!!REMOVE PROPS!!!

Left motor ESC – Aileron

Right motor ESC -Pitch

Center motor ESC – Elevator

Yaw servo – Rudder

Transmitter:

Spektrum DX7, these settings will work with most radios.

Heli

120 deg. swash

All channels 100% travel exept GEAR ( yaw gyro) 85% up (rate mode)

All channels – Normal, except RUDD – rev (depends on your yaw mech and choice of servo)

Swash:

Aile 50%
Elev 50%
Pitch 100%

Expo:

Ail +30%
Elev +30%
Rudd +20%

GU-365:

Connect all wires to RX as described in the manual.

Reverse Aileron (switch nr. 5 OFF)

Reverse elevator (switch nr. 7 OFF)

Yaw direction depends on your yaw mech. and servo

The rest of the switches – ON

Calibrate unit as described in the manual WHITOUT PROPS!!!

Start with 50% (horizontal nick in pot) gain on Aile and Elev and work your way up slowly, no need to re-initialize the GU between adjustments, just dial and go.

Test

Mount props

Go to your favorite flying field and impress everyone looking
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– “Well, I took it to the park yesterday, preflight check, power on, take off, slight wind, everything OK.

Hovered in front of me for a while, the took it to about six meters, slowly circling above me, the wind caused a little drifting and I applied three-four clicks of throttle, which combined with a little cyclic input is apparently the secret command code for autonomous flip-roll mode followed by immediate self destruct attempt.

It was out of control like nothing else I’ve ever flown, and it was FAST, I gave up counting the rolls as I gave everything I had in pilot skills to get it down in one piece, sucess, not even a broken prop.

Pack up the tri, back to the workshop, dismount the GU, packed and ready to ship back and never ever consider using a GU-365 with a tricopter again.

David, I hope you have a heli for this, otherwise it’s Ebay time.

Thank you for trusting me with your stuff, and I’m sorry that it didn’t work out the way we wanted it to.

It was a fun experiment though, and I finally got the answer I had searched for during a year or so.

Over and out.

-Sebastian

http://www.youtube.com/watch?feature=player_embedded&v=nEIKfM8oQLE

Thanks for testing it for me Sebastian! I’m glad it didn’t destroy your tricopter.

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