CineStar 6 WKM build
- Thread starter RTRyder
- Start date
I found a similar problem with big props and big distance between motors with the DJI. I now have smaller, 11x5 carbon props. and 700mm between motors also tiger motors and ESC. It is interesting that DJI chose 450 mm between motors for their own version. I have seen better stability in high wind for smaller craft.
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BorisS
Drone Enthusiast
Hi rwilabee,
four sources for carbon props.
http://aerobot.com.au/shop/all-products/36-aerobot-12x38-carbon-fiber-propeller-set.html, I think ken is using these
http://www.lcc-shop.de/index.htm go to propeller
https://www.mikrocontroller.com/ind...id=614&zenid=b68947d00d99cfa25d84986c7591c416 these are my favorite.
http://mikrokopter.altigator.com/xo...5-p-268.html?zenid=0ifbi542qe1p78m6c4sppshbv7 XAOR, never tried them the price hurts if they suck.
but there are a couple chinese products coming which i will check out.
Boris
four sources for carbon props.
http://aerobot.com.au/shop/all-products/36-aerobot-12x38-carbon-fiber-propeller-set.html, I think ken is using these
http://www.lcc-shop.de/index.htm go to propeller
https://www.mikrocontroller.com/ind...id=614&zenid=b68947d00d99cfa25d84986c7591c416 these are my favorite.
http://mikrokopter.altigator.com/xo...5-p-268.html?zenid=0ifbi542qe1p78m6c4sppshbv7 XAOR, never tried them the price hurts if they suck.
but there are a couple chinese products coming which i will check out.
Boris
Thanks Boris....
Is it better to have a stiffer prop like carbon fiber or a more flexable prop like APC I'm only running 10 x 4.7
Is it better to have a stiffer prop like carbon fiber or a more flexable prop like APC I'm only running 10 x 4.7
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Those are the Aerobot C/F props I have, I would not recommend them. They are advertised as balanced tip to tip and are anything but, in the first set I received one of six was semi close to balanced, the rest were way off. I requested and RMA for a new set and the second set I received were no better than the first and this time all six were out of balance. For the $ spent they're simply not worth it, there are better quality C/F props available now but I don't see the advantage over standard props other than significantly lightening the wallet and the bling factor. I'll just say it was an expensive experiment that didn't work out in this case.
With the WKM I've found it likes stiffer props like Graupner and Xoar, it has a tendency to wobble with more flexible props like APC especially on large multis and if the props are larger than they need to be. On my Y6 I could not get a smooth flight with APC 11 x 4.7 or 12 x 3.8 regardless of what I did with the gain settings. Changing over to Graupner 11 x 5 made a world of difference and I was finally able to find settings for a nice smooth flight. I also tried some Xoar 12 x 5 and had good results with them as well but it seemed a tiny bit better with the Graupner so I stayed with those.
The CS is significantly different than my Y6, while I expect the gain settings needed for smooth flight will be similar I think the C/F or Xoar props will be the ones that produce the best flight. If Graupner made Eprops in sizes larger than 11 inch I'd certainly be using them but unfortunately that isn't an option, at least not yet. Depending on the final RTF weight it's not beyond possibility that the CS would fly well on the Graupner 11 x 5 with small cameras, only flight testing can determine what works and what doesn't and I'm very close to doing that. Possibly later today, more probably sometime tomorrow, the CS6 will lift off for the first time and then the fun begins!
Ken
With the WKM I've found it likes stiffer props like Graupner and Xoar, it has a tendency to wobble with more flexible props like APC especially on large multis and if the props are larger than they need to be. On my Y6 I could not get a smooth flight with APC 11 x 4.7 or 12 x 3.8 regardless of what I did with the gain settings. Changing over to Graupner 11 x 5 made a world of difference and I was finally able to find settings for a nice smooth flight. I also tried some Xoar 12 x 5 and had good results with them as well but it seemed a tiny bit better with the Graupner so I stayed with those.
The CS is significantly different than my Y6, while I expect the gain settings needed for smooth flight will be similar I think the C/F or Xoar props will be the ones that produce the best flight. If Graupner made Eprops in sizes larger than 11 inch I'd certainly be using them but unfortunately that isn't an option, at least not yet. Depending on the final RTF weight it's not beyond possibility that the CS would fly well on the Graupner 11 x 5 with small cameras, only flight testing can determine what works and what doesn't and I'm very close to doing that. Possibly later today, more probably sometime tomorrow, the CS6 will lift off for the first time and then the fun begins!
Ken
Never, for that I'll use an MK with waypoints setup. Did I mention the buckets might be a bit far apart...
Ken
GGoodrum
Member
I'm really looking forward to seeing the results of your prop tests on the CS6 (my frameset arrives today... ). I have a theory that the reason some have had problems with wobbling on larger WK-M setups is because many are using larger diameter props, which are going to spin slower for a given amount of lift, and will have a greater amount of inertia that will resist speed changes. This might be the underlying cause of the wobbling effect. Anyway, like I said, I'm keenly interested to see your results. I'm still researching motors and ESCs, and I still need to order a second WK-M setup, so mine won't be flying for awhile yet.
-- Gary
). I have a theory that the reason some have had problems with wobbling on larger WK-M setups is because many are using larger diameter props, which are going to spin slower for a given amount of lift, and will have a greater amount of inertia that will resist speed changes. This might be the underlying cause of the wobbling effect. Anyway, like I said, I'm keenly interested to see your results. I'm still researching motors and ESCs, and I still need to order a second WK-M setup, so mine won't be flying for awhile yet. -- Gary
DucktileMedia
Drone Enthusiast
I am also curious what the actual reason for this is. it seems that on other FC's that dont require frame measurements to be input, the controller doesnt "know" what it is flying, it just tries to keep things level. The prop thoery makes sense to me, but the frame size does not. What would happen if you input a slightly smaller frame dimension than actual? Would that compensate for lag in some weird way? Curious why the Xaircraft and MK and a few others dont need these dimensions yet the WKM does.
I'm really looking forward to seeing the results of your prop tests on the CS6 (my frameset arrives today...
-- Gary
Well, it has finally flown, not a lot yet but I've had it in the backyard and in the air. First try was with the APC 12 x 3.8 plastic props and as I expected it wanted to float and wobble, part of that probably due to the CG being up above the IMU on the CS6 with nothing hanging below the bottom centerplate except the landing legs. Changed the CG measurements and it got a bit better but a bounce on landing combined with a gust of wind pushed it over sideways and the end result was a pair of broken props thanks to the 3 second delay in motor spin down in ATTI mode
At least I got to try them out first, no spares on hand so I won't be testing with those again for a while. Next I tried the Xoar 12 x 5 and this time it was a lot more stable. Tried a couple minor tweaks to the settings to see the response, these will probably work well with some added weight, right now a 12 x 5 prop is too much lift.
Next I swapped to the Graupner 11 x 5 and got the best results so far, no surprise there, not quite as steady as the Y6 on the same settings but again the CS with just a bare frame, electronics, and 1 battery weighs much less than the Y6 did. I wish Graupner would make these props in larger sizes, I think they'd be perfect for this frame but the 11 inchers won't be nearly enough lift with any substantial weight attached.
As a final quick test just as it was starting to rain I tried the carbon fiber 12 x 3.8 and found they work exactly the same as the APC which makes sense as they were patterned after the APCs. Again once I have more weight on the frame these may work better when they have some loading on them and I have a chance to work with the settings more. I'm done for the day now, it's pouring rain outside and I have to get ready to go out for a couple hours. Later I'll work on getting the AV130 hung underneath and get the CG measurements closer than what I've got now.
The fun is just beginning!
Ken
GGoodrum
Member
This is not an input anywhere in the Assistant software that I'm aware of, for entering the size of the model. There is a screen for inputting the distances the IMU is mounted offset from the central CG point, but that really has nothing to do with the size of the model.
-- Gary
GGoodrum
Member
I would think the MC would make up for the lack of lift by spinning them faster, so maybe they are at some sort of limit. Maybe running on 5s would give it a bit more"room"?
You are right, the fun is just beginning.
I wish I could send our weather your direction, so you could get some more flight time in. Just another "boring" 75 degree, clear and sunny day here. :tennis:-- Gary
I would think the MC would make up for the lack of lift by spinning them faster, so maybe they are at some sort of limit. Maybe running on 5s would give it a bit more"room"?
You are right, the fun is just beginning.
-- Gary
It will spin them faster but do you want the motors spinning props at 70% of max rpm just to stay in the air? Doesn't leave much headroom for corrections and you can only increase the voltage/rpms so much before something has to give, I'd rather it not be a prop or ESC.
The key to getting the WKM to fly well is to balance the gain settings against the prop/motor combo and most importantly the RTF weight. It appears the firmware has some sort of sliding scale that it uses to gauge how fast to spin the motors against how much weight is present, a large craft with a lot of lift and not enough weight is going to drive it crazy and produce wobbles. I'm willing to bet the people complaining the most about wobbles on big multis with WKM would see a huge improvement by either adding weight or going down a size or two on the props. I think I'll be seeing that effect on the CS6 in the next few days and I've got a couple ideas running around in my brain about the whole tuning process with the WKM, stay tuned...
Ken
Gunter
Draganflyer X4
Ken, I'm running a big hexa (910mm mtm) weighing in at 3.5kg AUW. The props are 13x4. She flies pretty well, but still a little bit jittery, specially in wind. Do you think it's worth dropping down to 11 or 12" props? I could maybe buy some cheapies just to see the difference...
Cheers,
Gunter.
DucktileMedia
Drone Enthusiast
Ah, good to know. not having one, yet, I wasn't sure. I just heard from someone else you needed to enter a bunch of dimensions.
Droider
Drone Enthusiast
Ken / Gunter you seen these.. VERY similar to Graupners in shape but they do the bigger sizes.. they are also very strong
Dave
http://www.electricwingman.com/apc/thin-electric.aspx
Dave
http://www.electricwingman.com/apc/thin-electric.aspx
It seems to work like this. A small 450 size frame lifting say a 550D plus mount and telemetry plus a couple of batteries could weigh for example 4 Kilos. A large frame lifting the same is going to be a bit more say 4.2. The larger frame was created to swing a larger prop. So along comes a gust of wind and our 450 size model that is being supported by a smaller dia. thrust column of air at a high velocity, is slightly less effected by this side draft than the larger model that is blowing a lager dia. column at lower speed. So the larger model is displace more than the small one. Then the large model has to correct that disturbance with a greater speed change to the motors. As it is further from the center it needs more rpm to effect the lift change, but as the prop. is heavier. it has more delay in correcting the disturbance than the smaller one and it also has more inertia to stop when it gets there. As the motors are at the extremities of the frame they exert a lot of inertia. They therefore need to be as light as possible. This tells me that I should be working on smaller frame sizes with short can size motors that are spinning very light small dia. props. to get even faster response rates. My large models perform quite well but only in calm conditions. Sure a lot can be done to even things out with the PID tuning but the larger model does have some flaws in it's design concept. I think DJI saw that from the outset.
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DucktileMedia
Drone Enthusiast
So is it safe to say then that the smallest frame you can put your desired props on is ideal? My hex is about 825mm. But i could easily take away 150mm off that and have my props work. it looks great bringing out a beast and it is nice to see farther away but it is a pain packing it in the back of my car.