Servers by jDrones

Nimbus Tricopter VTOL

(Graham D) #303

Those are very small props! Some here are using 14x8’s on the front and 17x5 on the rear. Also some are using a larger motor on the rear.
I see in both your crashes the plane was moving backwards quickly which seems to imply the rear motor at least does not have enough power? Note: your hover power should be at least 700-800W.

(Musa Wilmar) #304

what if i use 14x5.5 Carbon Fiber Propeller on front and 17x5.5 for rear is it ok? or i use 15x5.5 on front

(Graham D) #305

Foxtech used props with a higher pitch on the front, ie 13x7 or 14x8 for better performance at the faster speeds of forward flight, so 5.5" pitch might be too low for the fronts. I don’t remember what Kv motor is on the default Nimbus but you can look it up. The rear is different from the front motors and thus can use a larger prop. You can try 15x5.5 on rear but not ideal for the fronts.

(Musa Wilmar) #306

noted… i will find it first… a little bit difficult to find a pair 14x8 prop

(Greg Covey) #307

Musa is using 3520 720Kv motors instead of the 3520 520Kv motors we are using up front so there needs to be some caution on selecting the prop size. His Kv is higher.

By using the Foxtech or SunnySky 3520 520Kv motors, the Gemfan wooden props fit right on the M6 adapter. The props come in CW and CCW versions and have a higher pitch for plane forward flight. Remember that you are only hovering for short periods and flying for long periods.

(Musa Wilmar) #308

maybe i can down size a little bit for front… let say 13x08?

(Greg Covey) #309

Yes, it says that for a 3520 720Kv motor, a 12x6 prop is good for a 6s battery so I would try the 12x8 wooden prop…or a 12x8 prop that has both CW and CCW versions.

(Musa Wilmar) #310

thank you @GregCovey, unfortunately i can’t find it at local store here… i have to wait it around 3 weeks for purchasing it overseas…

(Musa Wilmar) #311

@GregCovey, @Graham_Dyer i think i found what the problem on my test log #4
the key is in minute 0:47 and minute 1:33
the sound like barking, is because the motor choked up, here is my scenario :

  1. when it’s Qstab takeoff throttle increase gradually from low to high until it’s fly and ready to transform to plane
  2. when it’s complete fly in stab mode, rear motor is off
  3. when it’s back to qstab again ready to vlanding, rear motor turn back ON and JUMP to HIGH SPEED (not gradually increase)
  4. when rear motor jump to high speed the result is motor choked up / not running smooth
  5. after it’s crash the motor back to low speed and run normally again

sooo… i test this scenario by put high throttle direct to rear motor from stop… and the result is same like when it’s crash… barking and choked up…

in previous maiden flight (test log #3) i was succeed test full cycle flight from vertical taking off, stabilize flight until vertical landing using Xrotor 40a ESC (even using only 1045 propeller for all), but in the same day one of my xrotor 40a is error. so i fix it by replace all esc using 60a opto ESC and like u all know it’s turn become disaster in my next flight attemp…

so… what is still question to solve is, ether it’s because the AMP different (40A to 60A) or it’s because it’s OPTO ESC…

(Greg Covey) #312


It looks like the motor becomes out of sync with the ESC. What model is your 60A ESC?

Why did you select the 3520 720Kv motor instead of the 3520 520Kv motor that we are using?

(Musa Wilmar) #313

I’m using ZTW SPIDER 60A OPTO ESC… and why i use 720KV is just because i have stock motor for that and curious whether is it run or not using this motor… curiosity it turned out to be expensive hehehehe
but it seems like it you guys already have the best configuration on it… so next time i will built the right one…

(Greg Covey) #314

I think you are close to having it work but need to adjust parameters in the ESCs, if possible. The older ZTW Spider 60A Opto ESCs used SimonK and the newer ones use BLheli One-Shot. I am not familiar with changing the parameters.

You could try just swapping out the rear ESC with a Hobbywing XRotor 40A ESC…or swap all 3 ESCs since they are inexpensive. Remember that the hover current is about 30amps total using the 520Kv motors or about 10amps for each ESC. The reports have these ESCs running cool temperature. So your higher 720Kv motors will draw more current but probably still be a good match for the XRotor 40A ESC.

Food for thought…

(Musa Wilmar) #315

i think, i will back to xrotor 40a rather than messing with parameter…

(rollys) #316

Personally, all this is pure conjecture until you can present log from a flight for analysis. You’re still not able to say what the battery voltage and current draw were when the back transition completed. Gauging from all the videos’ audio, you seem to have all the voltage during takeoff but not there in the back transition.

Good luck.

(hirobo) #317

Has anyone managed to make flight takeoff, mission and rtl completely autonomous?

(Matthew ) #318


Is correct that a log would be very helpful to help determine your issue, but they are also onto something about not having the voltage to get back from fixed flight. With VTOL’s you have to add an extra little bit of voltage in the battery or once you transition your voltage no matter what battery we used would usually dip very rapidly when switching back to hover. The obvious reason is you have gone from 1 motor to a total of 5 in some cases but yours it back from 2 to 3 with a decent bit more amp draw. I have seen this with a vtol I built a while back, you can’t try and squeeze out every last voltage from a VTOL bat unless you run dual system. Especially so if you try and use li-ion for all, they just cannot handle to amp draw. I have seen this with the one I built as well where you can pour the throttle to it and it will just sink to the ground, should possibly look at the voltage draw when you went from FW to MC mode, bet its dipping down to low, also might want to see what the low voltage cutoff is for your esc, if you cannot do that then i’d look into some esc’s that allow you to program such.

(Graham D) #319

Yes, I’ve done it quite a few times.

(hirobo) #320

Is this Nimbus good for mapping aero with micasense?
Or sign another wing?
I want to map about 180 hectares per flight

(Musa Wilmar) #321

yes u’r right… unfortunately i have problem with log… i don’t have any log on my every flight… maybe there is some miss setting or else on my pixhawk… however i do another way to analyze it for now… at least it help me to know some of the gauge to match with the flight characteristic…

i do have try re setting the log parameter and format my sd card but the log seems didn’t work… maybe i have to swap my pixhawk FC to fix this…

(Greg Covey) #322


Try using a different sd card and make sure that it is a good quality class. I use the SanDisk - Ultra PLUS 16GB microSDHC UHS-I Memory Card in all my Pixhawk v2.4.8 FCs.

I didn’t see any issues in your video Log #6. All three flights looked good.