KISS quad rebuild

Finally done with the 3rd total rebuild of my KISS quad.

The first build I wasn't satisfied with the placement of the battery on the bottom of the quad, it made landing difficult and caused the props to damage quickly each landing the quad tipped over. The voltage beeper I had installed was oversensitive, such low capacity it beeped almost every time I throttled up. The Emax RB 2600kv motors I had bought were much too powerfull and drained the battery superquick. But the worst part is I had the nasty 'midrange throttle oscillations' that are famous in the KISS world.

Second build I made the KISS stuff into my old 180 sized frame with 4 inch props. At first with the 2600kv RB motors, but after having the same oscillations-problem, I temporarily replaced them with old and worn motors. They were better, but still caused some oscillations, probably because the motors bearings are worn, making the motors a bit wobbly.

For the third build I bought a new frame and went for 5 inch props again, also bought some new motors. Only need to upgrade the FC and ESCs with latest firmware, and mount the gopro a bit better. Before flying the gopro, I must buy some protection for the frontglass. If I still experience midrange throttle oscillations on this new build I'm going to flash Betaflight on the KISS FC.

Looks a nice tidy build m8.
Are those the emax RS 2600kv (red bottom) bottom motors you mention ? I have some
of the newer "S" version ones that are supposed to be a bit more efficient but not tested
yet obviously as still not finished my build,although I am on with it .

Is there a fix for this kiss fc problem yet ?

muckyman wrote:

Looks a nice tidy build m8.
Are those the emax RS 2600kv (red bottom) bottom motors you mention ? I have some
of the newer "S" version ones that are supposed to be a bit more efficient but not tested
yet obviously as still not finished my build,although I am on with it .

Is there a fix for this kiss fc problem yet ?

Thanks

And yes, was talking about those Emax's. Apparently they are too powerful for the KISS setup. Recently read somewhere in the youtubecomments that the KISS oscillations are partly caused by motors drawing too much amps, also the accelerometer on some KISS FC releases is supersensitive.

Not sure about an easy fix, there are a lot of solutions and tips to get rid of it. Last attempt will be upgrading firmware on FC and ESCs to latest version. If that doesn't work I'm going to try Betaflight.

Must say that I'm amazed how fast this KISS gear has been downgraded from 'high end' to average. Most new flightcontrollers are just as good or better.

btw had the ISOsetting of my phonecamera accidentaly set on max, so that explains the extreme graininess in the pics.

Nice n sexy looking little build there buddy.
Like the protection on the ESC wires with cut props, may have to either wire mine underneath or do something similar.

I can offer some ideas on your oscillations based on not having 1 single air mile under my belt yet though, so what I ask or suggest might be blatantly obvious to you...

I know you changed the motors, but have you checked they're within vibrations limits in the G-tester in Cleanflight/Betaflight and balanced them with tape? It's slightly possible both sets of motors might have 1 or 2 that are out of balance, I did this when I first built my quad.

Obvious thing to also check is, if you see the vibration on FPV, check the camera on tight and lens isn't loose or something, also the FC is mounted solidly...

...but as you say it's most probably the widely reported common problem with Kiss FCs, of which I know nothing about...

Do you have Blackbox, can you check PIDs performance on graphs maybe, see if they are struggling?
Can you try Autotune to re-balance the PID settings automatically maybe?

Next step might be a new FC I guess, that'll at least eliminate the possibility that's causing it.

PapaLazarou wrote:

Nice n sexy looking little build there buddy.

 

Quote :

Like the protection on the ESC wires with cut props, may have to either wire mine underneath or do something similar.

I can offer some ideas on your oscillations based on not having 1 single air mile under my belt yet though, so what I ask or suggest might be blatantly obvious to you...

Tips are always welcome  

Quote :

I know you changed the motors, but have you checked they're within vibrations limits in the G-tester in Cleanflight/Betaflight and balanced them with tape? It's slightly possible both sets of motors might have 1 or 2 that are out of balance, I did this when I first built my quad.

Didn't know about G-tester, so obviously have never tried it. But this is KISS's firmware, not sure if it's compatible. Have never tested the motors for balance actually, only thing I look for which also affects balance, is if the bearings are still good. When they get worn the motorbell becomes loose and the quad gets wobbly.

Quote :

Obvious thing to also check is, if you see the vibration on FPV, check the camera on tight and lens isn't loose or something, also the FC is mounted solidly...

I could hear the motors stuttering, so the quad was shaking, meaning it wasn't the camera. I managed to tune it out a little bit by changing the PIDs, but not completely. The FC was mounted well, but it could be excessive vibration through the frame, so maybe softmounting the FC is an option. Have not tried yet.

Quote :

...but as you say it's most probably the widely reported common problem with Kiss FCs, of which I know nothing about...

Do you have Blackbox, can you check PIDs performance on graphs maybe, see if they are struggling?
Can you try Autotune to re-balance the PID settings automatically maybe?

Next step might be a new FC I guess, that'll at least eliminate the possibility that's causing it.

I tried looking at the Blackbox, but I'm not good enough to analyse the graphs in such a way to know what PID to change. Unfortunately no autotune in the KISS firmware.

There are still a few things I can try, not giving up yet. But at some point I have to consider getting other FC and ESCs.

CANNER wrote:

Didn't know about G-tester, so obviously have never tried it. But this is KISS's firmware, not sure if it's compatible. Have never tested the motors for balance actually, only thing I look for which also affects balance, is if the bearings are still good. When they get worn the motorbell becomes loose and the quad gets wobbly.

I'd say it's pretty important to balance motors, especially if you have vibration, there is another very easy way to do this with a phone app that measures vibration and some small bits of insulation tape. I know it's probably not this, but it's worth doing at some point.

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I could hear the motors stuttering, so the quad was shaking, meaning it wasn't the camera. I managed to tune it out a little bit by changing the PIDs, but not completely. The FC was mounted well, but it could be excessive vibration through the frame, so maybe softmounting the FC is an option. Have not tried yet.

Indeed definitely soft mount your FC, mine isn't yet, but I've just been reading about this recently and it's well worth doing as soft mounting can remove, specifically, mid throttle oscialltions! Some Gyros are over sensitive and this tames them a little. Removing any high frequency oscillations from the motors means the PID loop isn't doing overtime trying to compensate for something that doesn't need compensating for, modern Gyros can pick this up. Joshua Bardwell (or The Bard as I like to refer to him as) on Youtube has a great video on this very thing.
If you have to replace anything though I'd go FC replacement first because it might just be THAT well known issue, if not, then you have a much newer up to date FC. Noise from the motors is sometimes ok too as I've seen and read as I'm sure you know.
First thought I would defo do soft mount, as it's cheapest and a likely culprit...
Good luck.

If I can't fix it maybe I just buy a newer version KISS FC, they are not that expensive. I also have KISS ESCs don't know if they work with another brand FC.

Have put these in my shoppingcart, will be ordered asap. : https://www.banggood.com/4-PCS-Realacc-M376-Flight-Controller-Fixed-Screws-for-FPV-Racer-p-1135527.html?rmmds=home-mid-recommendations

 

If the motors are really out of balance, you can often send them back to the store if new, or simply order and replace the axis or bearings. If the imbalance is so little that it can be reduced with a piece of tape, the flightcontroller can normally correct it quite well. Not sure how long a piece of tape will hold on moist days, maybe half a battery?

CANNER wrote:

Have put these in my shoppingcart, will be ordered asap. : https://www.banggood.com/4-PCS-Realacc-M376-Flight-Controller-Fixed-Screws-for-FPV-Racer-p-1135527.html?rmmds=home-mid-recommendations

Those are the very ones I would have suggested, perfect, let us know how you get on, I'm going to order those very ones from a UK site on Monday...

Quote :

If the motors are really out of balance, you can often send them back to the store if new, or simply order and replace the axis or bearings. If the imbalance is so little that it can be reduced with a piece of tape, the Flight Controller can normally correct it quite well. Not sure how long a piece of tape will hold on moist days, maybe half a battery?

All motors are balanced at the factory, but not always perfectly, and not always to the precision sometimes required on Quads. It's very common to use small pieces of tape, motors spinning as fast as these do only need a tiny bit of weight on one side to make them vibrate wildly, or in the case re-balance them. A small chip after a crash or slight imperceptible dent can have a drastic effect on balance and even sound like the motors had it, when in fact a small piece of tape costing nothing may fix. Try it, it's easy, you might be surprised and it costs nothing, if the tape comes off, stick some more on.  

Jay I managed to flash all the latest firmware on the FC and ESCs.
Took me over an hour to get the pc to recognize the FC's USB port properly, before that it would not connect.
Still need to softmount the FC though, but that can be done later.

This means the quad is now ready for testflights.

CANNER wrote:

This means the quad is now ready for testflights.

Excellent dude, keep us updated....


Just re-done mine with anti-vibro mounts yesterday, it's amazing how 4 simple little things means an almost complete strip down just to make everything fit again, including de- and re-soldering a few things, then having to re-calibrate the ESCs too as one wasn't throttling up with the others... 1/2 step back, 1 step closer...

Good luck...

PapaLazarou wrote:

CANNER wrote:

This means the quad is now ready for testflights.

Excellent dude, keep us updated....

Will be trying tomorrow if the weather allows it.

Quote :

Just re-done mine with anti-vibro mounts yesterday, it's amazing how 4 simple little things means an almost complete strip down just to make everything fit again, including de- and re-soldering a few things, then having to re-calibrate the ESCs too as one wasn't throttling up with the others... 1/2 step back, 1 step closer...

Good luck...

That's why I now keep the wires a little bit longer then needed, I also had to desolder half the quad once to replace something small. Could have been done in 5 minutes, but took half a day because I made all the wires short as possible.

Just back from the first testflights. Despite expectations the quad flies great. Had not yet installed anti vibration standoffs, so I thought it would shake at least around midthrottle, but almost no vibrations. Only when the wind picked up, it started getting a bit shaky. Haven't even changed default PID's yet.

The cut props I taped on the ESC's for protection, also helped stiffen the legs a little, which then cause lesser vibrations.

I had recorded the flights, but accidentaly chosen a weak channel, so lot of interference on the recordings. Can't check for video signal strength with my cheap gear, so selecting a good channel is a bit of a gamble.

Must say now I practiced about a year with cheap and old CC3D FC's, I really notice the KISS FC flies much better. Much more freedom when it comes to movements. The CC3D can get choked up on difficult moves, while the KISS just keeps flying smoothly.

CANNER wrote:

...the quad flies great.

Actually that's a bit of an understatement. It flies fantastic more like it. Best quad I've build so far.

Still need to do some small improvements like add vibration dampers, a LC-filter for the fpv camera, and fix the gopro mount to the quad.

CANNER wrote:

CANNER wrote:

...the quad flies great.

Actually that's a bit of an understatement. It flies fantastic more like it. Best quad I've build so far.

Still need to do some small improvements like add vibration dampers, a LC-filter for the fpv camera, and fix the gopro mount to the quad.

Awesome mate, sounds like you've cracked it, and not a single fist was used...  

Good to hear your little annoying problems are getting fixed m8.

The great thing about building your own quad (anything actually) is the
ability to tinker and modify a set up things exactly the way YOU want
them to be.

Here's a video showing how well it flies. :



The shitty videoquality and interference don't really do the awesomeness of the quad justice, but it's all I got at the moment.

CANNER wrote:

Here's a video showing how well it flies. :

Ace mate, looks proper locked in now dude, nippy little fellas those aren't they...




Are you getting a HD recording setup at all, or not too bothered about it?

PapaLazarou wrote:

CANNER wrote:

Here's a video showing how well it flies. :

Ace mate, looks proper locked in now dude, nippy little fellas those aren't they...




Are you getting a HD recording setup at all, or not too bothered about it?

I have a Gopro Session4, which I bought specially for on the quad. But I haven't bought a screenprotector for the frontglass yet, not going to fly without. Besides the risk of crashing, simply landing a bit rough can make the quad flip, eat dirt, and damage the cameraglass. It only takes a small stone or branche to make an ugly scratch on the gopro.

CANNER wrote:

I have a Gopro Session4, which I bought specially for on the quad...

I don't blame you for wanting to protect that mate, very nice camera.

After messing about with more throttle oscillations, sometimes none, sometimes really bad, changing with each batterychange or after switching to different props, I had added vibrationdampers to the FC. After that I did notice the vibrations almost gone, but not totally. Then I decided to flash Betaflight to the KissFC, and all oscillations disappeared. Now finally it flies like supposed to. Did notice the KissFC is much more reliant on airmode then the F4 Flame. Did not have airmode on during this test and as soon as I throttle down too much, the quad wants to tumble. Also needs a bit more pid tuning, these are stock Betaflight settings. But only need to tune so it handles better, instead of tuning to make it flyable.

Oh yes and 7 minutes airtime, though I did not fly very hard, batterysize was 1500mah/50c.