Servers by jDrones

Nimbus Tricopter VTOL

(Greg Covey) #384

Hi Michael,

The FoxTech setup uses SERVO9_FUNCTION = 75 and the original conversion by Kris (the diagram you posted) uses SERVO9_FUNCTION = 76. Both ways work…you just need the appropriate servo plugged in.

As for the compasses, my recommendation is to only use the external primary compass or you may go nuts!

Thanks for posting your findings!

(Michael De Leon) #385

Thanks @GregCovey. Will work on it again this week, i was curious about FBWA, havent tried transition to this mode from vertical to forward. Does the transition need a throttle management or i just put it in mid stick and let the autopilot do its job during its transition?

(Greg Covey) #386


Normally, mid-stick is probably fine for the Nimbus. However, it is dependent on your plane and setup. You can read more details here. On the FireFLY6 VTOL, I found that raising the throttle created smoother transitions. On my FX79 Quadplane, mid-throttle works great!


Note that holding level pitch does not mean the plane will hold altitude. How much altitude a plane gains or loses at a particular pitch depends on its airspeed, which is primarily controlled by throttle. So to gain altitude you should raise the throttle, and to lose altitude you should lower the throttle. If you want Plane to take care of holding altitude then you should look at the FlyByWireB mode.

(Michael De Leon) #387

Thanks for the inputs @GregCovey

what pixhawk are you using?

(Greg Covey) #388

Pixhawk v2.4.8 which is really a Pixhawk 1.

(Musa Wilmar) #389

i only use 1 compass instead of many compass to avoid ERROR COMPASS VARIANCE

(Michael De Leon) #390

Thanks for this @Musa_Wilmar . I have answer from foxtech. kinda logical. The aircraft fly fast. Seems there assesment is that it was over shooting with the target orientation. IDK if this is correct can someone verify this thanks.

@GregCovey thanks for replying.

Will do some test again. Will try to fly it manual and stabilze, Ive tried it flying in vertical with windy condition in qloiter, i have no issue flying it and transition from fixedwing @ 15-20ms .

My main concern is fixedwing. Its a very fast system.

(Musa Wilmar) #391

i think u can minimize the over shooting with reduce the WP radius and the cruise speed… i think 30m WP radius and 16m/s cruise speed is close enough for me…

this is my last full auto pilot test video…

(Atico) #392

Hi Musa, you can change these parameters to avoid it …



(Michael De Leon) #393

Thanks for the info. Will get back to you guys once ive done testing

(Graham D) #394

Had a quick AUTO flight today but it did something a little unexpected. The waypoint (#2) after the 30m transition point was at 60m but the aircraft had only reached 45m by that waypoint and it’s airspeed was just around 10m/s (36km/h), so a little too slow and the aircraft was wallowing a bit. Only nearing waypoint 4 the altitude reached 60m and then suddenly the aircraft sped up to 18m/s (64km/h) before slowing to 13m/s (47km/h), it’s cruise speed.
So why so slow all the way to 60m? The aircraft has enough power to climb at easily 13m/s+ yet it flew so slowly to reach 60m?

(Ryan) #395


Thanks to you and everyone on here I have gotten my new vehicle hovering! My last one was transitioning great and then crashed so I rebuilt it… I’m now having some issues with the transition. It starts into transition then goes into like a flat spin and kinda flips over… I feel like it’s not getting up to speed in the transition even though airspeed sensor says it is…

Do you have to have an airspeed sensor to switch into FBWA and transition?

How can I tell if my airspeed sensor is reading properly? When I plug it into i2c, the accelerometers are moving around…

Can you share your firmware file, I have a new one and don’t know how to download it! Also can you share latest v2 Param file for the upgraded servos from fox tech!

Thanks again for all the help!!!


(Greg Covey) #396

Hi Ryan,

The default air speed ratio should work fine for you but you can always calibrate it using the procedure here. Also, make sure that you have tested that the AS sensor is enabled correctly in Mission Planner. I usually have it displayed in the HUD and blow into the pitot tube to watch the number go up.

Having an AS sensor installed should enhance the transition performance but you can always try it initially without the AS sensor being enabled. Also, double-check that your control surfaces are compensating in the correct direction in FBWA mode on the ground. Hopefully, some of the others in our group can add some suggestions.

Due to health reasons, I have suspended my hobby testing. I hope to get back to enjoying this great hobby some time this summer. Cheers!

(Ryan) #397


I hope your health is getting better! Thanks for responding!

I tried to transition the vehicle without the airspeed sensor on board, and still had the same issues… I swapped tilt servos to the new fox tech ones, and made sure they are pointed forward in FBWA. The vehicle hovers great, but once I transition it like yaws and rolls over…

Here are my questions:

When I change over to the new fox tech tilt servos do I need to change any parameters? I made sure the end points are adjusted for motors to point straight out, and is it ok if my pwm is 2250 on MAX?

In forward flight do the motors do thrust differential for yaw?

Can you put motors/servos on either main or aux ports? I changed my servo functions, but I didn’t know if it would matter which side of the pixhawk 2 i plugged into… I have a BEC pro from Castle powering the tilt servos and wing servos (HV), but have the signal lines plugged into the AUX 1,2,3,4

  • Ryan
(Greg Covey) #398

Hi Ryan,

Thanks for the well wishes!

You shouldn’t need to change parameters (other than endpoints) just by installing the FoxTech servos. The reason that you are using a PWM of 2250 is that you likely didn’t test your servo arm positions (up and forward) with a servo tester before mounting them mechanically. As long as you can hover well then it is probably fine.

The motors do not currently perform differential yaw in forward flight unless it is a new feature that was added. You can use either OUTPUT or AUX ports.

My suspicion is that your forward flight control directions for ailerons and/or V-tail are incorrect for the Pixhawk stabilization. Perhaps you could post a short ground video in FBWA mode showing the aileron and v-tail movements for the radio sticks and then the FC stabilization.


(Michael De Leon) #399

Hello guys,
Just an update on my work with the Nimbus from foxtech.
Got ten flights on it and no crash. the 1st two was crucial and need to transition to tricopter.
3rd flight and so on i get the hang of it.
Flight modes are qloiter, fbwa and cruise. Flies great but still need to remove that error compass variance. Im using 1 compass only. This happen when i turn. Foxtech advise that during bank and tail wind the system tends to speed up that whats causing the error. ive tried lowering the max roll limit and was able lessen the tight turn.

Im impress with 15ms cruise speed. Tuned airspeed sensor.

Issues need to resolve now when it turns the altitude drops 3-5mtrs. I have already the parameters for this to play with my next test.

Flying it Mission is great. Just need to figure out how it will loiter during RTL and not to engage tricopter mode in high altitude.

Cheers guys thanks for the help.

(Michael De Leon) #400

Also im impress landing it from 30mtr alt fixedwing to tricoper. It glide down to its transition speed and break when it reaches it. have some perfect transition. Some are scary like it would fall from its tail. But now im 100% confindent flying it FBWA to Qloiter.

(hans bert) #401

Hope you get well soon!
You are doing great work Greg!

1 Like
(Michael De Leon) #402

Hello Guys. Just an update.

We did production flight for the nimbus using the MAP-A7R.
5km distance from home point. I was impress with the taranis x9d. We still have signal even in 5km range without any long range module.

The air frame can handle 25ms speed.

We did an overshoot of 150 for it to turn and shoot the flight lines better.

What we wanted now to adjust is the tail wag and when we use rudder the aircraft seems yawing like a robot. Not as smoothly as a Quad.

During RTL the aircraft tends to transition to Qloiter. Is there radius fence for this?

I also need help on analyzin our logs during our last mission yesterday.

  • The system airspeed and ground speed went up fro 16 target airspeed to 25ms.
  • Altitude drops from target altitude.
    -Flightmodes become Uknown and Avoid.
    This all happen when the mission start at. During its approach to AOI. it was cruising on its target airspeed.
    Here are the BIN and Tlog from the PC.

(Greg Covey) #403

Hi Michael,

Cool report! What receiver are you using? An X8R? How does it feel to have so much money in a camera in the air? It reminds me of my Cinestar clone days. :slight_smile:

Use the RTL_RADIUS parameter to determine when an RTL will change to QRTL.

I’m looking forward to testing my Nimbus VTOL soon!