Servers by jDrones

Nimbus Tricopter VTOL

(Ryan) #203


When I am trying to use QLoiter it is drifting and sort of toilet bowling… I have done multiple compass calibrations, and it hovers perfect in Qstabilize!!! What do i need to look at to fix this? What can I look at in my log? I want to transition asap, but need to get QLoiter working… Any ideas?


(Greg Covey) #204


You can check the number of satellites and hdop reading. You want more than 10 satellites and an hdop reading of less than 2, preferably closer to 1. You can also post a log (.bin file) for us to look at. The Wiki section below has some good information. Where did you mount your compass?

Diagnosing problems using Logs

(Graham D) #205

…Also look at where your power wires run, if they’re under the Pixhawk then that could be the cause. And keep the compass away from the battery.
I had to move our compass right to the back of the fuselage only then did the compass issues go away.

(Chris ) #206

Hi Guy,

Thanks again for the advice.

good news and bad news.

Good news my nimbus is a fair bit more locked in after updating the PID Settings I got from you guys.
Bad news this just highlights my throttle issue more…still not getting enough power to maintain a level head-height hover…I will pop fox tech an email asking for some guidance on the issue



(Ryan) #207


I put it in the same spot like you described, and it seems locked in! I also cleaned up the power wiring underneath in the fuse so that probably helped as well… I flew it today and had GPS status 4 and 18 sats… Im using the HERE 2 module. It did much better today, felt very locked in!

Only other question I had was, when I take off and get half a meter off the ground the yaw hops a little… It still does this after I moved the GPS/Compass and did a calibration. It’s very slight, but it never does it again after that one time! Its only at take off… I will look into it more, but didnt know if you guys had seen this.


(Greg Covey) #208


I have seen that on several of my VTOLs. Not sure if it is ground effect or something else. I usually just rudder it back over to where I want it and it seems fine.


If you could post a log from that test, we might be able to spot something.


(Graham D) #209

I suspect that’s an EKF switch over, seen it too.

(Ryan) #210

Anyone on here have a list of tuning parameters for transition? I looked on the tilt-rotor page for it specific to tilt-rotors… haven’t found much… I think we should make a master list of what parameters do what for the transition and how you can fine tune it! Any thoughts guys?


(Greg Covey) #211

Can’t hurt so I’ll start. The numbers for each parameter are from Gordon’s V2 file.

ARSPD_FBW_MIN,14 (The ARSPD_FBW_MIN is required to go beyond Q_TILT_MAX and complete the transition.)

Q_TILT_MAX,45 (This is the maximum angle of the tiltable motors at which multicopter control will be enabled. Beyond this angle the plane will fly solely as a fixed wing aircraft and the motors will tilt to their maximum angle at the TILT_RATE)
Q_TILT_RATE_DN,50 (This is the maximum speed at which the motor angle will change for a tiltrotor when moving from hover to forward flight. When this is zero the Q_TILT_RATE_UP value is used.)
Q_TILT_RATE_UP,200 (This is the maximum speed at which the motor angle will change for a tiltrotor when moving from forward flight to hover)
Q_TRANSITION_MS,3000 (Transition time in milliseconds after minimum airspeed is reached)

where x is the tilt rotor(s), determines motor up or down position:
SERVOx_MAX (maximum PWM pulse width in microseconds)
SERVOx_MIN (minimum PWM pulse width in microseconds)

(Chad Frazer) #212

Hey LiquidForce, check to make sure your props are not mounted upside down. You might also have a loose magnet in a motor. I know you already calibrated your ESCs but do it again and check to make sure your transmitter doesn’t have a bias (trim on transmitter is ZERO). Check prop balance. Check wiring for nicks. Double check that you have the correct prop diameter and pitches. Check that the nuts holding the props onto the motor are tight and torqued properly. Smell the motors, if you smell an acrid odor then the winding coating has broken down and you must replace the motor. Check that the motors are firmly mounted as an odd angle during use will scew a lot of performance. Spin the motors with your finger (power not applied anywhere in the system) and put your ear to it, if you hear clicks then you might have a bad bearing, unseated magnets in the motor bell or a misaligned shaft. Most likely though, if all of those are correct then you have a bad parameter somewhere.

If those fail, use a sledgehammer until nothing works, that’ll fix the problem.

(Chris ) #213

First off let me say thank you all for the advice and possible solutions.

So I have finally managed successful a QPlane hover. nice and stable on the altitude and pretty locked in with the PID settings you recommended.

I emailed foxtech for some assistance with the matter and the reply was a simple “sorry we don’t offer support if you purchase the parts and assemble yourself.”, I wish I knew this before I bought everything but at the same time I am glad I now know before I waste further cash there on mapping cameras etc…

The other bonus about this is that it gave me the push I needed to try different props and motor config. I pulled a set of T-Motor U1 motors off a large quad and installed it on the nimbus, I also used a pair of T-Motor 14" carbon fibre props. I adjusted the max travel for the tilt servo so the prop could not strike the wing. Tested with my heavier 5S 12400Mah lipo and was hovering well at 50% throttle value with loads of power to spare.

Is anyone here having success with the Sunny Sky X4112S-9 485 kv with a wooden 13x8 prop??

(Greg Covey) #214

Hi Chris,

Keep in mind that a VTOL is a design with compromises. Unless your plan is to hover a great deal for demos, the goal is normally to hover as little as possible. That being said, the power system design should favor forward flight. So when you use a 14x? t-prop, I suspect that you will not have sufficient pitch for good forward flight…hence the need to use a 13x8 prop. The Gemfan 13x8 wooden props fit the Sunnysky and Foxtech 3520 KV520 M6 motor shafts perfectly.

This combination was used on the Foxtech V1 setup so presumably it was successful.

Here is a summary of various combinations:

Nimbus Plane

  • 2x Motor: 4112 480KV or 4112 KV400
  • ESC: Hobbywing 40A

The FoxTech V1 used the following combination which should match Graham’s setup.

  • 2x Sunnysky 4112 KV485 (front)
  • 1x Sunnysky 4112 KV400 (rear)
  • 3x ESC: Hobbywing 40A
  • 1x Pair 1380 Wooden Propeller
  • 1x 1655 MARKII Matte Propeller(CW)

The FoxTech Nimbus VTOL V2 setup has changed several times but currently uses this setup:

  • 2x Foxtech 3520 KV520
  • 1x Foxtech X5008 KV330
  • 1x Hobbywing XRotor 40A ESC
  • 2x Hobbywing XRotor Pro 50A
  • 1x Pair 1380 Wooden Propeller
  • 1x 1755 MARKII Matte Propeller

My current setup uses a combination of V2 front and V1 rear components:

  • 2x Sunnysky 3520 KV520 (front)
  • 1x Sunnysky 4112 KV400 (rear)
  • 3x ESC: Hobbywing 40A
  • 1x Pair 1380 Wooden Propeller
  • 1x 1655 MARKII Matte Propeller(CW)

(Chris ) #215

Hi Greg,

Thanks for the reply,
Yeah my main reason for locking in the hover at this point is to make sure I have enough grunt to arrest a decent when I transition back to QPlane…with the 4112 KV 485 and the wooden 13x8 prop I originally received this is simply not possible in my location (sea level Cape Town SA). it doesn’t have enough power for sure. it doesn’t even have enough power hover at head height. the wooden props I have (not Gemfan) (I forget the name and am currently away from home) seem too heavy for the the motors and they can’t get the rpm up as quickly as required. this is also my assumption as to why the motors are getting so hot?

I am happy to try 13x8 carbon props on my AC and believe this may help a little however the height of the 4112 motors seem a problem for clearance on the wing. I am assuming the 3520 KV520 is the longer motor therefore giving better clearance…

off hand I cannot exactly remember hence me leaving it out but I think you are correct the 14’ is probably something like a 14x5 or maybe even slightly less. 14x4,8

I understand the VTOL concept is a game of give and take but for sure without a doubt in my mind I will crash this unit when I transition back to QPlane with the 4112 kv 485 it doesn’t have enough power even at full throttle to arrest a fast decent. if I transition above like 300ft I may possibly be lucky if all goes well but I have spent too much time and money (mainly time) on this to loose it on its first transition, right now I am not confident…

I see for all above combinations they use a wooden prop however a buddy of mine purchased his directly from Foxtech PNP and it arrived with carbon props for front and back motors??

The main role I need the unit to work in is plane however due to landing limitations on site the VTOL is the only option to complete the works that this is required for

(Atico) #216

About the direction of rotation of the rear propeller, Foxtech uses CW, however Arduplane advises CCW. It seems that both options are valid.

But what do you think is more effective?

(Greg Covey) #217

Hi Atico,

It appears not to matter as long as the front two rotors are opposite for forward flight. The vectored yaw uses motor tilt so motor speed differential is not needed.


(Greg Covey) #218

I added some decals to my Nimbus before starting my camera mounts. The red and black stripes underneath should help with visibility. I had ordered larger ArduPlane decals from the swag shop but they sent ArduSub decals instead so I used a smaller one and a tribute to Harry Potter. On to camera mounts…

(Wasim Akram) #219

How much weight does your decals add? About the wings on the Nimbus VTOL, is there any flex (or twist) on the wings? Has anyone tried reinforced it with a covering of some sort to minimise the flex. I’m just curious, and I hope that’s okay :wink:

(Greg Covey) #220

Hi Wasim,

Ask any question you like. I don’t know what the weight of the decals were but consider them negligible. The Nimbus (and Crossfire) wings are a great design. The wings are stiff, have no flex, and, easy to assemble without any tools. The tail and the nose are the same way so the design is really meant for easy transport. Other designs in this category are the ZOHD nano Talon and E-flite Opterra.

(cala2) #221

Greg: how the nimbus fix the wings to fuse? Thanks

(anon94298870) #222


The wings and v-tail both attach with these little latch like structures.

One is on the top and the other is on the bottom of the wings. they work quite well and have never had mine come off yet.