Another Cinestar 8 and WKM

[Vortex Aerial]

Been monitoring this forum for about 2.5 months now and have recently been involved in an ongoing struggle to get our 14.5LBS CS8 to fly somewhat smoothly in anything above dead calm air. Even our stock Gaui 300X is more wind tolerant.
Has anyone been able to demystify this system installed on such a large machine at this weight or close to it ?

 

[Michael64]

I have a 10 pound Y-6 its fine in up to 8-12 mph of wind holds its own real well. What motors and props or you using.

Michael64

 

[Stevey]

I have a Cinestar 8 which I collected ready built from Geoff at Quadcopters UK yesterday & we tested it in winds gusting up to 25mph & it held position at about 4feet off the deck & amazingly steady.

 

[Vortex Aerial]

Well that's good news.
Can you give any detail as to things like prop diameter/pitch, aircraft total flying weight, or gain values ect?

 

[UAVproducts]

Chris,

The XYZ numbers are crucial. Most importantly the Z. Its a lot harder to figure it out on the Multi's then the Helis.

What is your Z number set to?

Pic of your setup?

 

[Vortex Aerial]

Hi Robert !
Thanks for getting involved

IMU Z#: -4

GPS Z#: - 17

Have also ran these as "+" values with no change.

Believe "above CG and/or behind CG is negative number" and "below CG and/or ahead of CG is a positive number" is this correct ?

 

[Stevey]

The props are 13x6.5P I haven't hooked it up to the computer yet because it has the latest firmware & my CX4 is on the older firmware & I don't want to upgrade it yet because it's flying really well. When I have hooked it up to a different laptop I will post the settings, I did have a quick look when it was hooked up to Geoffs computer buy I cant remember what they were but I remember thinking they weren't very high & that was with a Cinestar Camera mount & two 80000 batteries fitted.
Steve

 

[Vortex Aerial]

Thanks for that Stevey. Am using the same size props and cam mount. Sounds like the flying weights are real close on both machines. Could you perhaps post a pic of the components installation if you get time ? Thanks again for your help.

 

[quadcopters]

Hi Vortex , the gains were about 280 280 200 200 and 65 65 for Attitude and it held rock solid. And it was very similar in weight to yours by the sounds of it .
I did however find it behaved better when it had weight on it ,
Have you got the gps dead center ? because I would have thought the gps would be mounted behind the IMU , but that wont make massive difference .
The GPS Z value looks about right to me , Also have you got ESC'S programmed for Medium or High timing ?
Some prefer high timing but i have always found medium to work just fine but LOW timing they are nowhere near as good.

Hope this is of some help to you.

Geoff

 

[Vortex Aerial]

Thanks for responding Geoff.
Using medium timing on the HW Platinum ESCs.
Will give those values a go and report back.
Want the WKM to work on this rig more than anything as weve flown it on smaller rigs and its just fantastic !

 

[UAVproducts]

Hi Robert !
Thanks for getting involved

IMU Z#: -4

GPS Z#: - 17

Have also ran these as "+" values with no change.

Believe "above CG and/or behind CG is negative number" and "below CG and/or ahead of CG is a positive number" is this correct ?

How did you figure out the point to measure from?

Remember with our helis we hung the heli from the tail and then hung a plum line. The point the plum line crossed the main shaft was the origin point (or true CG point). We then measured from the origin point to the IMU and GPS.

The whole XYZ is for an algorithm. The offsett numbers is to tell where the IMU is located from the origin point. In a "perfect world" the IMU would be mounted there and no offsett numbers needed, they would all be zero.

Note: I'm still trying to figure the best method to find the origin point on Multis. A lot of different frame layouts so there is no perfect way. Maybe the WKM and Naza don't need to be as exact as they do for Helis. However, my theory and logic tells me it does on larger Multis.

Hope that makes sense.

 

[Tabb Firchau]

I have spent quite a bit of time with WKM on all kinds of platforms and so far I cannot get adequate stability with professional payloads(big cameras) running 14inch(ish) props. Henning just stopped by on his way to Maui and brought his CineStar with WKM. The stability was OK in manual mode but really bad and wobbly in Atti and GPS. He was getting some really nice footage but only in manual mode which I am not sure most people are comfortable running.

The WKM is working nice on smaller stuff but so far not up to MK performance on the big stuff for me. I realize I could go down in prop size and perhaps get adequate performance but I am not willing to deal with the lower flight times and reduced efficiency.

I am hopeful that someone will figure out a combo that works for CineStar with WKM.

Tabb

 

[Siteline]

That's to bad Tabb I was hoping you would find the pro combo! There is no mention of power surges did they go away for you?

 

[Vortex Aerial]

Hey Tabb !

Wow, Henning is getting around isnt he !
Mine flys great in manual as well.....but who wants to fly in manual ??
I can see coming down in prop size (does it really make a difference?) until it gets to 7 minutes "total" flight times. But after that its really not going to work in a real world, non hobby, scenario.

Robert; to find vertical CG ( " Y" ) i just balance the aircraft on my fingers with the booms perpendicular to the ground. At 10mm of resolution it should be accurate enough for the algorithm id guess.

 

[RTRyder]

Hi Vortex , the gains were about 280 280 200 200 and 65 65 for Attitude and it held rock solid. And it was very similar in weight to yours by the sounds of it .
I did however find it behaved better when it had weight on it ,
Have you got the gps dead center ? because I would have thought the gps would be mounted behind the IMU , but that wont make massive difference .
The GPS Z value looks about right to me , Also have you got ESC'S programmed for Medium or High timing ?
Some prefer high timing but i have always found medium to work just fine but LOW timing they are nowhere near as good.

Hope this is of some help to you.

Geoff

Interesting observation from my recent swap to Maytech ESCs on my CS6. The Maytech are TX programmable for either 8 or 16 kHz switching rate, I set mine to 16 mainly because it eliminates the high pitched whine caused by the 8 kHz rate. With the Maytechs and their current settings I found I was able to reduce the basic pitch and roll gains from the 320% range where they needed to be on the old ESCs down to the 230% range with no visible change in stability but a definite increase in GPS position hold accuracy due to lower gain settings! So now I find settings of 230, 230, 300, 200 and ATTI TX adjustable from a low of 40% to a max of 110% to be the best setup for all around use, still flys smoother on 11 x 5 Graupners than it does on the 12 x 6 APC thin electrics but I think a little more weight would cure that.

I'm not sure exactly what it is about the Maytechs that allowed the reduction of the gain settings but nothing else in the setup has changed other than the ESCs and it most definitely would not fly well with the gains this low prior to the swap. An assumption that seems reasonable is the Maytech firmware is more multirotor friendly than the Hobbywing/DYS/Turnigy types I had used before. The only other physical change that was made was swapping to a different style of power distribution board that eliminated a fair amount of the ESC power wires that were concentrated in the center of the frame below the IMU. Since the changes the GPS gets full satellite lock in under a minute consistantly, before it varied from around 1 1/2 minutes to well over 2. I believe that eliminating the large clump of power wires and associated RFI has only done good things for the GPS.

Did some test flights today in 12 mph winds and it flew quite nicely and did an outstanding job of holding steady in GPS mode even with the wind. Now that we've got snow on the ground I'm going to try and get out for a good video recording session at the first opportunity. Won't be tomorrow and maybe not at all this weekend, forecast is for another 3 to 8 inches of the white stuff during the day tomorrow.

Ken

 

[RTRyder]

I have spent quite a bit of time with WKM on all kinds of platforms and so far I cannot get adequate stability with professional payloads(big cameras) running 14inch(ish) props. Henning just stopped by on his way to Maui and brought his CineStar with WKM. The stability was OK in manual mode but really bad and wobbly in Atti and GPS. He was getting some really nice footage but only in manual mode which I am not sure most people are comfortable running.

The WKM is working nice on smaller stuff but so far not up to MK performance on the big stuff for me. I realize I could go down in prop size and perhaps get adequate performance but I am not willing to deal with the lower flight times and reduced efficiency.

I am hopeful that someone will figure out a combo that works for CineStar with WKM.

Tabb

I'm getting close to 10 minutes flight time on mine using 11 x 5 props but I'm not carrying nearly the load that you do. I'm searching for that magic combo of settings that will give the needed stability in all conditions regardless of load but I'm at the point of believeing its going to take some firmware changes from DJI before that can happen. I've pretty much pushed it to the limit of what's possible and it's still not good enough in anything but dead calm air. For casual use I can get some impressive results but it just isn't going to get the money shot 100% of the time.

Ken

 

[Siteline]

Most of us have been having much better luck with the Graupner 11X5 props. It made quite a difference in terms of dialing in smooth flight for me. But at this point i've only been playing with a relatively light payload in the GH2. We are getting flight times of about 7 mins on the nose with one 4s 6600 MaH lipo. I certainly would like to find a solution for longer flight times when adding our 5D. I have a few 5s 8000 MaH lipos on the way, but? It's just shown so much promise I hope there is a solution.

 

[RTRyder]

Most of us have been having much better luck with the Graupner 11X5 props. It made quite a difference in terms of dialing in smooth flight for me. But at this point i've only been playing with a relatively light payload in the GH2. We are getting flight times of about 7 mins on the nose with one 4s 6600 MaH lipo. I certainly would like to find a solution for longer flight times when adding our 5D. I have a few 5s 8000 MaH lipos on the way, but? It's just shown so much promise I hope there is a solution.

I'm using the 4S 8000 packs, it does help. I was thinking of using a pair of them but that's an awful lot of weight up high on the frame vs what I carry underneath.

One of the big problems and what Robert from DJI noted, it's extremely difficult to pin down the CoG as the WKM wants it measured. Correct tuning of the gains, right sized props for takeoff weight, the amount of wind, all variables that need to be taken into account, the one thing that is fixed but just as important is the CoG. I can tell when its close now, very low amounts of wobble when in the ground effect during takeoff and landing, I just need to figure out a good way to accurately measure where on the Z axis it really is.

Anyone found a good way to do this yet?

Ken

 

[Siteline]

Awesome information as always RT! Finding the right Z input is a mystery to me. I've been testing to get the gps working well with the information you've provided concerning the ATTi gains needing to be higher to maintain an accurate fix. I was really wondering if I've got to get the Z axis right before attempting work on the gains. right now the craft could be flying nicely but if I flick on GPS, it holds for 20sec and then begins to toilet bowl? But I think at this point, I'm just guessing at the Z numbers? There certainly seems to be a trade off, smooth flight in Atti, or, GPS, but not both?

 

[RTRyder]

Awesome information as always RT! Finding the right Z input is a mystery to me. I've been testing to get the gps working well with the information you've provided concerning the ATTi gains needing to be higher to maintain an accurate fix. I was really wondering if I've got to get the Z axis right before attempting work on the gains. right now the craft could be flying nicely but if I flick on GPS, it holds for 20sec and then begins to toilet bowl? But I think at this point, I'm just guessing at the Z numbers? There certainly seems to be a trade off, smooth flight in Atti, or, GPS, but not both?

From observation the basic gain settings have much to do with how well, or not, GPS hold works. With high basic gains and the lower ATTI gains the large frames need, GPS seems to easily go into TB mode. Being able to lower the basic gains helps a lot, but two things I've found that seem to make the most difference, get the IMU measurements as close as possible, and get rid of as much RFI as possible. That would include things like twisting the motor wires for the length of the run between motor and ESC and eliminating as much non shielded and straight run wires as possible. Also, and I know some people doing builds right now won't want to hear this but, get the power distribution board out of the center of the frame and out from underneath the IMU. The IMU gives off enough RFI as-is, it doesn't need any help in creating more and having the main power distribution directly below in the center of things seems to do exactly that. On both the CS6 and my Droidworx AD6 I've gone to the same power disti setup and elimated a lot of excess wiring, both have seen corresponding improvements in GPS performance. Coincidence? Maybe, but I'd be more willing to believe in a reduction of interference so the GPS can do what its supposed to.

Ken