Thank you! It is a great frame, and one of my favourite machines.

So dry it weighs 235g, and with an 850mAh 4S pack it is 333g - sadly nowhere near the 250g 'limit'.

I made my own in TinkerCAD, but I have dropped the STL here if you are ingterested: https://drive.google.com/file/d/1EZ4MemwLzXFIr-lX_w5w8m9MQmhGShMJ/view?usp=sharing

thank you for getting back to me and sharing those! I think this is going to be my next build, are you liking it since posting this? my planned build is a little different but similar

My pleasure! So I have managed to get this machine flying really quite well now, but it was a bear to tune; loads of mid-throttle shakes that defied all tuning out. But finally, once I upped the ESCs to 48kHz, and got RPM filtering on there, I managed to tame it. And now it's an absolute favourite.

I am flying more 3" machines these days, less and less local opportunities for the big rigs, and the Gecko always goes out with me; it's fast, agile, not as alarming to the passing civilians as the big machines, and still records HD. Ideal. Build one, or similar, they're great! :-)

See? https://www.instagram.com/p/CFqcbn1Ht6G/

wow man, great footage, flying, and location! That thing looks sweet! I can't wait to build one and will definitely save this comment and do the same things. thanks again!

I am indeed, and yes, without that filtering it would be way worse I am sure. But that's not the real problem. I know what's happening but I don't know what's causing it or how to stop it. When my throttle gets above 1500, the yaw D-value starts to show big oscillations, that feeds into the P, and the resultant yaw oscillations cause the machine to shimmy - you can see it in the video and it shows up in the yaw gyro trace. As soon as the throttle drops below 1500, it's smooth sailing once more.

At least I think it's working that way around. Maybe the gyro just goes bonkers abvove that throttle because of frame harmonics, but I doubt it as this has happened to two of my small, powerful 3" machines with the iFlight Twin-G FC, but different frames. It could be P spiking that the D is fighting? I really don't confess to understand this stuff in detail. But it feels like software, because it's just the yaw-D, yaw-P, and yaw-gyro traces that show osciallation, if it were excessive motor noise or other vibration, I would expect to see something in the other axes, but the Pitch and Roll traces all remain nice and clean. But what to do? More TPA perhaps?

So maybe I'll take the plunge and give 4.2 a go. I've never felt that 4.1.x was great for 3" machines, but perhaps I have just been unlucky? If you get 4.2 onto your Gecko, please let me know how it goes!

I put 4.2 on three machines yesterday.  They all fly superb on defaults.   The Gecko is definitely next.   I dont have blackbox logging on mine, so I cant tell if it does the same as yours on the traces, but it sounds similar.   I know that 2.5" - 3" seems to be the most difficult for me to get smooth and my Gecko is the worst.  I will keep you updated.

Brilliant! Yes, please let me know how it goes with your Gecko. Fingers crossed that 4.2 is the cure for 3" ills...!

Hi , still having throttle issues ? try changing the motor frequency in bl32 if you can.
Cheers

Yeah, it's so strange, this machine is doing pretty much the same thing as the 3" DJI-F5; that high throttle shimmy-thing on the yaw axis. So currently the PWM Frequency is 24kHz; what would you suggest? This is something I have never done. Instruct me, oh guru! :-)

In bl heli 32 the esc operaiting speed , for want of a better name, can be altered.
Increasing it on micros can X2 the flight time. changing it on bigger craft can stop or reduce bad vid, and sometimes the motor esc frequency combo can cause issues, a problem that shows only above 50% t has to have a mechanical and electrical problem , a resonance between the magnetic hysteresis of the windings the magnets and the operaiting frequency of the esc..
Please let me know if it helps
Cheers

Interesting! Alrighty, I will give this a go as I'm certainly seeing this above 50% throttle. Also, I have learned an excellent new word today; "hysteresis" - thank you. Yeah, totally makes sense, I can see how fiddling with the fequency could affect issues of that nature. Definitely something I will try. I'll let you know what happens!

So I tried a more basic route to start, I upgraded to 4.1.6 (I was trying to go back to 3.5.7 just to see, but that... didn't work out so well). Same initial tune and suddenly the yaw oscillations at 1500 have moved up to 1800+ throttle and are way better, which I can live with for sure. Interesting. I guess something or other was refines in 4.1.6 which has helped. But still, I'll keep the PWM frequency in my back pocket as I still have more tuning to do!

I installed 4.2.0 on mine today. Huge improvement. Default pids and cut / pasted the CLI from the HD quick settings from the Tuning Notes (https://github.com/betaflight/betaflight/wiki/4.2-Tuning-Notes). I also adjusted the notch filter settings as recommended for rpm filtering. This is the best my Gecko has ever flown. I ran without a ND filter and pretty low jello. I was even running some pretty beat up props. More testing tomorrow, but this was very exciting for me.

Excellent news. Alrighty, that's where I go next. Thanks for the update!

I may also try emuflight.  The new release is getting great reviews for cinewhoops and micros.   Seems like the Gecko is pretty finicky, maybe it is more like a micro for tuning than a 5"?

I know this is pretty much ancient history now, but I thought I'd give you an update on the Gecko's yaw shimmy issue - I managed to solve it entirely, and the solution might be of interest to you. I put BF4.2 on it, and it flew nicely at lower speeds, but still shook at high throttle. The solution was to change the ESC PWM frequency in BLHeli_32 Configurator, upping it from 24kHz to 48kHz. Suddenly the high-throttle shakes were gone. The machine is slightly lower power now, but it's flying very smoothly. And now I can start actually tuning 4.2...

cool

Yes! I was about to tell you that I had indeed, at long last, done this. :-) Thank you good sir, you were absolutely right! Sorted me out a treat. Should have done it straight away. I've done the same thing to two other rattly 3" machines and all of them are flying a lot better. Many thanks for that advice!

Nice. Glad you got it worked out.

Hi guys im running a similar setup as this build. ive got beta 4.2, rpm filtering and changed esc,s to 48khz. Any other settings I can change to get it flying smooth and locked in? any advice is appreciated
Cheers

Hard to help without knowing more .but
1, move the filter sliders as far right as poss without frying the motors.

1. turn off D min
2. In the pids tab , follow the help prompts on the sliders, the trick here is to move one at a time in the direction that improves things , untill things go bad then back off.
3. In the reciever tab check for jitter in the chanels window and add some dead time .
   Finaly even if your chanels are clean adding a small amount of dead time , I find synks up the visual input from the goggles with the feedback from your fingers. What i mean is in my case my visual feedback is quicker than the feelings i get from the sticks. so its hard to not overshoot because the quad seems to move before my fingers tell me ive moved the sticks. in effect the dead time allows the eyes to see and the fingers to feel like one.
   Finally . Lower your rates.
   Be careful go slowly MAKE NOTES
   Cheers

Thanks for your reply, I will give these a go. Ive built several quads but never really got the hang of tuning seems like there is alot of trial and error to get things sweet .

FYI my build is
Frame: Armattan Gecko 3"
FC: Talon F7 V2
ECS: Spedix GS25a 4in1
Motors: Tmotor F20ii 3750kv
Cam: Caddx Vista
RX: Crossfire nano
Props: Tmotor 3140

My rates are around
roll/pitch 900
yaw 700

Tune is pretty much just betaflight 4.2 stock settings. Beside what you guys have mentioned in the earlier comments. It flies pretty sweet but I guess where it could be bette is I get a fair bit of propwash after say a powerloop and you punch out of it. if that makes sense? could my idle valve be to low?

Thanks

Idle too low , try jacking it up a couple of % , but without actually looking at blackbox ( which i never use) nailing the perfect tune is hard without a ton of experience.
Also dropping in out of a loop is the worst for p wash, in that case i fly arround it, just keep on the throttle a bit and try to slide through the dirty air not just drop in to it.
Keep tweaking

I installed the latest Emuflight on my problematic Gecko last weekend. If flew well on BF 4.2 but i couldn't tune it enough to get any better . (no blackbox logging makes it more difficult). The 3" cinewhoop preset on Emuflight works just as good and possibly better. I have only flown a couple of packs but the motors are staying cool and I dont get much for vibrations. Havent tried any tuning beyond the preset. Emuflight seems to be easier to setup than BF 4.2. -- no VTX tables and rpm filtering. I really like the idea of presets for different size / style rigs. Also the stick feel PIDs are amazing. I do save and backup my 4.2 settings so I can flash back if needed. Might be worth a try on yours?