CS8 Wookong and Plettenberg motors and battery data, and build information

remyd

Member
Hi,
I am one of the people who thought long and hard and then decided it was worth the investment to pay the high price for the Plettenberg motors. After they arrived i saw a number of posts where there had been some extreme failures leading to Octocopter crashes. Fortunately for me the people that got caught and the following discussion provided enough information for me to be fairly cautious about my build. In conjunction i have done a bit of testing to see what currents the motors are using along with battery life that some folk might find useful (discussed in the following posts). Essentially from what i read the people who had trouble were using the MK system and the motors had drawn over 40A which was the boards current limit for each motor leading to failure of the speed controllers.

My build includes CS8 frame and 2-d gimbal, Wookong M controller, Maytech Opto 55A ESC's, Plettenberg 15-22 motors, I used two power distribution boards as i was concerned that the 8 motors might draw more than the 200A limit of an individual board. Connectors are XT60 from the batteries (2 Thunder Power 5S (18.5v) in parallel) but i found that they were getting pretty hot so i exchanged them for XT150 which have resulted in no heat and therefore less loss.
My ESC's are programmed as follows (note if i had my chance again i would probably choose castle creations pheonix 2 (now that they have multirotor firmware as i have used them previously without failure on helicopters - they also log which is nice when you want to know what is happening).
brake off
battery type - NiCad/NiMh
low voltage cut off Threshold - Low
timing - High
Start - start acc
governor - rpm off
cut off power - reduce
motor rotation (fwd/reverse as required)
Switching freq. - 16Hz

More to follow ........

View attachment 4951

Not as elegant as the herc and others but individual ESC's seemed safe for now
 

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BorisS

Drone Enthusiast
did you test the different timing setting low mid high, or did you start with high ?

Boris
 

remyd

Member
So the biggest concern is the amps these motors can draw and yes they can suck them fast. I rigged up a single motor with a carbon 13x6.5 prop (purchased through aerobot) and measured the amps plugged directly though a futaba receiver. At 100% throttle i measured peak 66amps, but considerably lower in the 20-30's amp range when the throttle was 50-70%. I guess the point is to make sure that the ESC's can cover the max should you need it. Obviously this isn't a real world test and i wasn't sure how the throttle might be limited through a controller such as the Wookong. My second test was to do some bench tests in a full ready to fly configuration. I strapped the CS8 to my kitchen table and hooked everything through the wookong, and logged the amps and pack voltage using eagle tree telemetry gear (note all these tests are on a single ESC and a single battery even though i was using 2 batteries). At 100% throttle through the Wookong controller i only managed a peak of 32 amps so obviously there is some throttle limiting going on in the Wookong. You could hear the difference in prop speed etc when run at 100% directly through a receiver verses the Wookong. Not the graph also shows the battery draw down as the throttle increases. More to follow....


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remyd

Member
just went with high it seemed to work and did note your issues with the V2 prior to testing. Ken suggested auto but they were working fine.
 

BorisS

Drone Enthusiast
if it feels right and than it will be okay. I always tend to start with low and work my way up.

Did you do your throttle test with the WKM in attitude or manual mode. And yes the WKM has a throttle limitation for sure since it is also limited to 6m/1sec climbing rate. Which in my eyes dosent mean though that it won't demand more from the motors once you try to catch the bird from a drop or you try to stop it quickly in a full speed forward flight.

Boris
 

remyd

Member
So the next test was more for battery duration rather than anything else. I wanted to get a feel before going out for a test flight. The graph will show battery draw down and amp draw. The copter was strapped to the table and i am running 13x6.5 carbon props, throttle is 50% just high enough to see the copter light on its legs with a couple of full throttle bursts at the end of the flight, i have 1.75kg of weight on the gimbal. I took the pack down to 18.4 volts from 21v a fully charged 5 cell which took 11min. Interestingly at this takeoff throttle % we are only using a couple of amps, the full throttle at the end showed a peak of 21 amps.

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remyd

Member
All tests were done in attitude mode. The following data that i will put up will be during flight and will include both attitude and GPS modes. My internet connection is slow so the youtube video of the flights is still being uploaded, nothing exciting rather to give an idea of what the data was acquired and for me to remember what the platform looked like with different props. Remember i just want to go up take a few shots and return to the ground safely :). I was amazed how good the GPS hold was now that i have a working antenna. That said i think my LED light is not working correctly as the colour is purple.
 
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remyd

Member
Ok so after some help from Boris and a strange reversed motor which was causing the craft to tilt i sorted things and was ready for some real hovering with my 1.7kg payload and 1.2kg batteries plus the frame and gimbal which i haven't weighed yet (it won't be light the way i have built it :)). Their is a slight head/cross wind. I am still using the 13x16.5 props. Flight time was around 7.5min with the two TP 5S 5000, amp draw in hover is around 19-20 amps. You can see that the pack voltage drops fairly sharply at the 7.5min mark and this time i took them down to 18v. You could go further but at your own peril both for the battery and the craft. I will pop some links to the you tube snippet of the type of flight later.

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remyd

Member
Final test was to change the carbon props to APC 14x4.7's. The great thing about this change was the stability of the craft really improved, with the higher pitch props the craft was a little bit jittery, probably more responsive in a climb or pulling out of a decent but for smooth flight i can definitely say the APC seem much more stable. I am not sure if you will be able to see it on my poor Iphone video but i won't be going back to the higher pitch prop in a hurry. The bonus is less amps are being used with a average of around 18 amps and as a result i got a solid 9min before the battery started to tail off. I have included the single flight results graph along with the graph of the different plots against each other. Anyway hope this is some use to those who have or were looking at the plettenberg motors. These are 15-22 motors (slightly lower KV) which might be different to what others have bought (15-18, or 15-20 from what i can see on this forum)

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BorisS

Drone Enthusiast
its an interesting one since the APC 14 x 4.7 always caused the CS 8 to be very unstable for me, but again i am not using the pletternberg but the standard QCs. The 11 gram 12 x 3.8 cf from MK and the ligther aerobat 13" version were a lot better. Shows again in my eyes that its the prop Motor combo that makes the difference etc.

But what you really should be doing at some point of your test flights is put the gain on your radio. Basic gain pitch and roll on one nob or slider and attitude pitch and roll at another. Basic starting at 150 or what ever you feel safe with and attitude in a arrange that you can take it down to 60 or up to 150 and test fly and change the gains during flight. Some props dodnt work ar lower gains and than all of a sudden you hit the right range and it works a lot better. etc.

By the way very nice info posting from you side, thanks for that !

Boris
 

remyd

Member
Thanks Boris, trying to give a little back after you helped me so much - really appreciated your help and suggestions along the way!
I did up the gains for the test to 140 but yes i agree i do need to dial both sets of props in using a slider and see how the craft copes. It isn't as big an issue for me as i am after stills and likely to only fly in low wind speed but still ......I also want to test a full throttle climb and decent bailout at some point just to be sure about the amps but i am really comfortable after seeing the flight and bench data. Today's test were just to put my mind at ease after much of the discussion of the plettenberg motors etc. Hopefully it will be of use to others who might have a box full of motors and not sure where to go or want to try again with other ESC's or controllers?
 


BorisS

Drone Enthusiast
japp looking better in the ground effect with the 14 x 4.7 I am still positive though if you bring up the basic gains a little that the 13 6.5 aerobot will out perform the 14 4.7 not in flight time but stability.

Concerning the LED and the signals i am a little worried though looks like white flashed. Or a double flash of what ever color although you are already holding height ?

Boris
 

BorisS

Drone Enthusiast
other thing is stability looking onto the bird is one thing. I was wrong a couple times before. When i mounted a go pro and looked at the video afterwards things looked differently. If you want to do that test, hard mount the Gopro though onto the center plate for example not on the gimbal. The gimbal stab fakes the results to the better or worse sometimes.

Boris
 

remy I find that the JXF 14x4 propellers perform the best with my Orbit 15-20 and AUW of 7.4 kilos. Going bigger in prop size with WKm only hurts stability.

Also Graupner 14x8 are nice and seem to outperform the APC and Slowfly shape propellers. 14x8 in Graupner size is simillar to a 13x5 in APC size.

If you find that the stability is not good enough then the only change you can do is try and reflash your esc's with simonk firmware.
 
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remyd

Member
yes Boris - re the lights not sure what is going on but a LED definately looks faulty that said in the breeze today the altitude and GPS hold was rock solid so i think it was all working. I have the 900MHz radio link and ground station so i will have a better look in my next round of testing to see what is going on. I have a go pro on my F450 quad so i will transfer in due course to see the effect of gains and props. I have been told it is best to do the gains in wind rather than in calm conditions as i am unlikely to see much change when the copter doesn't have to compensate as much. Your thoughts?
 


remyd

Member
Also what batteries are you guys running verses flight times (both brand, capacity and C ratings)? I have built this principally to house a Nikon D800 and at other times a 2-d multispec camera mainly for agricutural work. The intention is simply to take a shot of the canopy at heights ranging from 50-100m and then back to the ground so both the stability and flight times are not as critical for me compared to the guys trying to shoot stable video footage. My other gear is a tad on the expensive side. A hyperpsectral camera in a RC plane (12 ft wing span and 10ft long) and a jet turbine 2m helicopter both attached to high spec ground control station, RTK 2cm GPS and attitude sensors operating at 800Hz accurate to 0.01 degrees for pitch, yaw and roll. The radio link has a range of 90km. All good stuff but the people i am working with on the build have taken forever. Better to be safe than sorry but ......
 

BorisS

Drone Enthusiast
personally weight Mah/ ratio and true rating these are the best you can get at the moment. Pricey but worth the cash. The reports that i was reading is that they are also easy going if there is a problem bigger inner resistance as expected etc.

http://www.maxamps.com/products.php?cat=24

have to see if i still have my logs for the lipo

Boris
 

BorisS

Drone Enthusiast
View attachment 4957
don't remember the weight of the copter but think it was with full gear so CS gimbal and a Gh2 stock lens.

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charge discharde logs to see what goes in.

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I have a 4s though probably more possible with 5s 6s and weight wise probably still possible that you take two 11000 Mah in parallel.
And you have to take in account I am flying with 12 3.8

Boris
 

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