Hi everyone,
With my friend we built a solar powered glider (4m wingspan). Yesterday we made a 7 hours flight with 7800mah battery pack, the total load was 17500mah with solar cells.
It was great BUT, during the day the controler was fighting with thermals to regulate the altitude, what a waste of energy !
I tried to set the maximum sink to zero in TECS params but it didn't work. I'm sure there is a solution to let the plane taking altitude with thermals. The max climb max is set to 0,5m/s and it works great to limit the power and it is enought to lock the alti.
Maybe someone know how to let the plane free to climb but managing an altitude floor.
Replies
Thank you very much, we will work on it.
Congrats !
APM is not really optimized for gliders, especially in the auto modes. I'm using it mostly in FBWA mode ( more details here : http://www.itluxembourg.lu/site/soaring-with-apm-and-ultimate-lrs/ )
Regarding your question about thermals in auto mode, I've noticed that the min/max pitch limits has priority over the TECS.
So here's the idea : set the LIM_PITCH_MIN to the pitch value corresponding to when your glider is just gliding at ideal speed. Let's say it's at pitch = -2°.
Now your plane is in auto mode, circling at 100 m, powered by the motor. Let's say that the pitch = 0° in this situation.
Then the plane enters a thermal : the plane takes 2 meters every second, and the APM want to correct the altitude by cutting the motor and pitching down. But it's not authorized to pitch down by more than -2° (the LIM_PITCH_MIN parameter), so it just cuts the motor, and makes a perfect glide at -2°, while continuing to gain altitude from the thermal. You'll observe that whatever settings you've got in the TECS parameters, APM will first stricly obey to the LIM_PITCH_MIN.
The thermal disappears : the plane continue its glide at -2° with motor off until 100m, loosing very slowly its altitude, and at 100m the APM throttles up again.
Maybe you'll want to change the LIM_PITCH_MIN just before landing but it's not mandatory. May I also suggest that you try to land in FBWA, trim it so that it glides correctly with sticks centered and then it becomes a perfect mode for landing almost hands off.
We will share everything,a youtube channel will show every build steps and tuning. It's powered by 12 li-ion cells (18650) and 48 solar cells C60 sunpower maxeon. APMmicro 2.7, ublox neo8m gps with compass, MPXV7002 analog airspeed sensor and genasun charge controller.
The aircraft was design by Frank Aguerre with predimRc especialy for our needs. We made the wings structure with carbon rodes and 3D printed parts made with my prusa i3.
Paul Meier said:
Wow, amazing, would you share some of the specs of your plane ?
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