Going Full Kiss - Martian 220mm Build Log

[Snarls]

If you are willing to spend a couple bucks extra and wait for shipping from Europe, I think you can buy one preflashed with the correct firmware for KISS. https://www.flyduino.net/en_US/shop...er-open-log-micro-data-logger-2787?category=1

I think you will still have to solder the wires necessary to connect it to your FC though.

 

[Snarls]

Finally got a log recorded on this quad. Here are the results after running the log through Plasmatree PID analyzer.

One thing I notice is just how bad the lower rate pitch and yaw step responses look. I wonder if that is from not being so aggressive in the flight this log is from. I did 10 rolls, flips, and yaw spins this flight. Usually I just fly a pack like normal, with all sorts of speeds, tricks, and mixing of the sticks.

The filter transmission on the right of the noise plots is also very concerning. That should look more like the raw gyro noise, with most noise near 0 hz, and the rest quickly tapering to 0. Instead, you can see in all the noise plots that the noise is pretty constant, and higher than desirable, everywhere. I know this build, and KISS in general, has D gain oscillation problems, so I wonder if that is feeding back into the system. The D gain oscillations are very obvious in flight when I cut the throttle.

I am going to replace the soft mounts for my FC with the original hard nylon standoffs, as Psyborg suggested. That seems counter-intuitive to the noise I am seeing on these plots, but I'll give it a shot. I am also going to put on some Emax Avan Flow props and see what happens.

 

[PsyBorg]

Keep in mind the frame you are using is not as stiff as the original Alien frame. Your noise issues could somply be the cheaper carbon and you may never find the golden tune.

I bought a knock off frame when I started my Taz project and that thing rings like a wind chime when you flick it with a finger nail.

The vibrations were so bad I could not get it to hover to even begin tuning on stock pids.

 

[Liam B]

+1 with PsyBorg. I switched to the alien after this frame was giving me trouble and, poof, vibrations gone!

 

[Snarls]

So... you're telling me to put down this seemingly good frame, and go treat myself to something fancy?? Well, only if you say so, definitely did not have the temptation beforehand.

 

[Snarls]

Here are results after hard mounting the FC, putting on Emax Avan Flow props, and doing a quick tune. The noise is still very high compared to betaflight, but the quad flies really nicely now. I'm not experiencing nearly the amount of bounce backs after flips that I had before. I also upped the P and I gains, and now the quad feels real sharp.

Only complaints I have are that inverted yaw spins still freak out when I end them, and the quad doesn't seem to hold position very well when I roll while pointed down. For instance I like to punch out, point the quad towards the ground, and then roll. I should finish the roll still looking at the ground, but I am finding myself looking at the tree tops. I'm not sure that is the tune, KISS, or maybe the difference in camera angle between this quad the Rooster I normally freestyle on. Anyway, this quad is now intended for race practice, so moves like that I should not be super critical about.

I also have looked at the black box log to see what's going on when I do inverted yaw spins. You can see my take on the matter in the picture below. I think the quad is trying it's best to recover from spinning on yaw and roll, but the motors are maxing out. The FC can't quite get the quad where it wants to with maxed out motors, so the little spasm it does is the result. That's my take anyway. I could always try flashing Betaflight on the KISS FC and see if it can do inverted yaw spins. Then I can say if it is hardware or software for sure.

 

[Snarls]

Apparently, to activate the adaptive filter on KISS, you need to run a looptime of 1 kHz. It's unfortunate they don't tell you this when you enable the filter in the GUI, because I was flying with 4 kHz looptime thinking the adaptive filter was on. I stepped down to 1 kHz and the quad was flying even better! Take a look at the new Plasmatree plots.

You can see that the noise transmission from the filters is down by a factor of 4. Overall noise is down on all axes, and with D term. No longer do I hear the distinctive D term grinding noise when I arm the quad.

The step responses don't look too good, but the flying is better than ever. Maybe if I tune it up a little more I can get even more performance.

Here is some DVR to show how it's flying.

 

[PsyBorg]

Drop down to typical 5040 tri blades or 5046 dal cyclones if you are gonna free style.

Them Avans need BIG motors to turn them properly. That is why you are dogged down coming out of maneuvers. Not enough torque to get them blades back up to speed. Tri blades will have more bite as well for more smooth flips n rolls.

 

[Snarls]

I will try that, especially since I have loads of 5040 triblades and cyclones left over. I am worried I will be back to a quad with untuneable bounce backs though. The Emax Avan Flow props are only 4.3 pitch after all. They have a constant pitch throughout the span though, unlike most other props. Another option to get some BIG motors. I am still flying these original emax redbottom motors. The 6" with litespec emax motors definitely has more low throttle punch, but I always perceived that to be a 6" and newer motor thing.

 

[PsyBorg]

Go with the cyclones they are stiffer and give the same smooth response across the throttle range.

I can run full throttle, do a 180 and punch back into fill throttle on both the alien and Taz with no shakes or bounce.

Once you get the cyclones on take a good think on when you are dropping throttle and when you are getting back into it.

Not flying into your own propwash is hard to learn but if you think about it more then likely HOW you are flying is part of the problem and its not all tune.

If you do a hard straight line, drop throttle, THEN turn letting airmode do the work in the turn and once you are 180 and back on the throttle you should be in clean air.