Nimbus Tricopter VTOL

Thanks for the inputs @GregCovey

what pixhawk are you using?

Pixhawk v2.4.8 which is really a Pixhawk 1.

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

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.

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

this is my last full auto pilot test videoā€¦ https://www.youtube.com/watch?v=gOE-ZaLpVMM

Hi Musa, you can change these parameters to avoid it ā€¦

Q_TRANS_DECEL

Q_LOIT_BRK_ACCEL
Q_LOIT_BRK_JERK
Q_LOIT_BRK_DELAY

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

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 itā€™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), itā€™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?

Greg,

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 itā€¦ Iā€™m now having some issues with the transition. It starts into transition then goes into like a flat spin and kinda flips overā€¦ I feel like itā€™s not getting up to speed in the transition even though airspeed sensor says it isā€¦

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 aroundā€¦

Can you share your firmware file, I have a new one and donā€™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!!!

Ryan

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!

Greg,

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 issuesā€¦ 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 overā€¦

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 didnā€™t know if it would matter which side of the pixhawk 2 i plugged intoā€¦ 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

Hi Ryan,

Thanks for the well wishes!

You shouldnā€™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 didnā€™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.

Cheers!

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.

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.

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

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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.


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.

Iā€™m looking forward to testing my Nimbus VTOL soon!

Cheers!

Hello Greg, It comes with an X8R reciever with pcb antenna.
The feeling is SCAREY!
Update on adjustment of parameters for the tricopter was successful. We adjusted base on the given Q_RAT you guys were discussing. Tail wag was gone.
We disable the Q_RTL because this was more convenient for us RTL in fixedwing mode so it will just circle around the home point and RC Operator will control it to land.

I havent tried auto take off and landing with mission. I still need to verify on how the mission planning works on AUTO with TAKE OFF and Landing on VTOL. Can anybody help me on this?

Hi Michael,

Maybe I can help here a bit.

We also do missions with a vtol. Not the nimbus, but our own design. Anyway, we started with auto take off and landings. But after a while, we found a better solution.

The reason being that no matter how well you plan and look the weather forecasts, itā€™s never the way you expect. So we ended up always changing the flight plan to take off against the wind and landing against the wind. And guess what, after 1 hour flight, the wind direction changed and had to land manually anyway.

So our procedure now is as follows:

We plan the mission as per mission requirements. Regardless wind direction. No auto tale off, no auto landing. First way point always almost straight above our home position and at 100 meter altitude.

Take off in qhover, at 15 meter altitude change to fbwa and climb to 100 meter. Switch to auto and he will find his way.

Last way point is at 100 meter altitude, regardless mission altitude and again almost straight above home position. As soon as the pilot feels comfortable, take over in fbwa and approach landing. We try to get between 15 to 30 meters. Switch to QHOVER when close to landing area and landing.

Of course you need a reasonable experienced pilot.

But for us this sequence has proven to work very well. No need to think about wind and weather conditions.

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we do it exactly the same way. no auto takeoff and landing, due to heavy wind :stuck_out_tongue:
very good post anthony!

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