Dual-motor tailsitters

Another servo and hinge assembly that will work for smaller builds.

https://www.foxtechfpv.com/15kg-large-torque-180-degree-digital-servo.html

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Caution, to reach an angle of 180° with this servo you need PWM from 500 to 2500μs

Post #902 addressed a “work around”. Are there 180 degree servos with dual output shafts operating within the default pwm range?

Do slomo video, replay and count cycles then recalc to real speed.

My “full 3d printed Tail Sitters”, almost ready for final assembly, wingspan 130cm.
This is a prototype printed in PLA, the final version will be different and printed in ABS or ASA.
As we know automatic landing with Tail Sitters becomes critical in windy conditions.
I think my suggestion can be the solution to the problem:

Good flights!

Marco

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Hi Marco, This is what I do when I fly manually and what I program when using autopilot. It is however not the case with rth… having it automatic would be awesome and save many propellers ! :smile:
Ps: I’m curious to see what you reach with 3d printing, other initiatives I’ve seen were fails: too heavy or too weak… Compared to hot wire profile+fiber… What îs your structure weight at the moment ? good luck ! :four_leaf_clover:

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At the moment the weight is 900g, but the final version it should not exceed 600g.
The advantage of 3d printing is resistance, it is really solid, and that changes can be made easily.
The possibility of being able to produce spare parts with little expense is a good thing.
As resistance it is payable to a composite structure.
I’ve already brought these 3d printed frame to an extreme fligh, without the autopilot:

Marco,
Very nice project. I hope we will get soon update and a video.
According to my experience, I agree wind resistance is better when wind comes from the side. But the question of pitch and yaw control remain critical as the wing need a lot of authority to withstand gusts during the descent. I mean it is not easy to keep a constant yaw and surprisingly, during the descent the yaw is the most difficult axis to control. I had a crash some days ago when I tried to land my wing in around 15 knots of wind because the yaw axis was uncontrollable and in that case the wing drift with the wind until a tree came… Now I have increased Q_A_RAT_YAW_P to the limit and this is better. From hardware point of view, large ailevons, vector thrust, low aspect ratio and high power to weight ratio have to be considered.
Attitude of the wing could be a primary source of information to get the wind direction.
regards,
pierre

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I agree, so during my tests I was really low with the descent speed, not over 30/40 cm/sec.
When this prototype will be able to carry out a completely automatic mission I will certainly publish a video that documents it.

Wingtra in windy conditions

Wow, this landing blows me away!! Total awesomeness.

Would be interesting to know if this one just got lucky or if its repeatable.
Would be cool to get that code in AP.

Wingtra works very well on transitions, they are very soft.
We hope to achieve the same performance in Ardupilot, higher would be the top! :slight_smile:
I don’t remember if they use a proprietary code or if it is PX4.

Hey guys, I am having a sort of “flat spin Issue” with my Tailsitter in QStabilize mode.
I’ve noticed it porpoises during forward flight too. I have tried moving around the CG and it is definitely in the nose heavy area, it gets worse when I move the CG back.
Also with a 5mph wind at my back it is very difficult to fly into the wind in Qstab mode, is there A way I can get more control authority?

Logs

Any help Would be Greatly appreciated.

Hi, the two things I see are 1 elevon motor tilt mismatch cut back on your elevon throw a lot and #2 cover your rudders as it needs some yaw stability even bigger rudders? I think you are very close to a nice airplane… hope this helps

Thanks, but I am lost, what does this mean?

what’s happening is when the airplane accelerates = more airflow… the elevons work more and the system senses it and corrects with tilt and elevons, drops the nose and does it, again and again, you have too much elevon but easy to fix by reducing elevon throw till it stops… probably less than 1/2 that you have now… it will still have enough control because you have motor tilt and that is very powerful. with my setup, the elevons work to keep the wing parallel especially in yaw… watch the video in roll/yaw

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also, the flat spins are caused by the t/e moving up faster than the l/e with lots of induced drag from the overcontroled elevons with no airspeed and no rudders…no yaw control= flat spin

others suggestions:

If I am correct, your flat spin issue begin around line 95. As far I understand, the yaw follow what the pixhawk demand. The pitch is an other story and I dont understand why the pixhawk demand 0 pitch from line 96.
Also at the beginning of the log there is a message concerning compass (switching to compass 1 then to compass 0) I have never seen before !
Are you sure that all your calibrations are corrects ?
While flying do you check EKF status ?
Can we get your parameters, it seems to me that there is not enough authority from your vector thrust. what throw do you have ?

Yeah, not sure exactly what this is about, I get “BAD AHRS” messages until I get a message that says something like IMU is using GPS0 then all errors go away. I thought I was in the clear

I believe so.

No, how would one check, and is it not available in the log after flight?

Uploaded .param and 2 more flight logs that both resulted in flat spins.

From 800 to 2200 PWM that I have set, it is nearly 180degrees, I hardly see them go that far though unless it is flat when landed.

looks like power loss at transition for a moment? maybe transition while climbing keeping some a/s no idea why the power sag some programming thing??