Soaring/Gliding for Planes

@Bastian Thanks for sharing your file. At the moment I thermal very happy with my 3,5 m. F5j Cirrus with a Matek 765 wing and ARSPD sensor. The software is performing great. Often 2+ hours flights on a single 200 meter start and flat terrain. Difficult to keep below the allowed 300m hight and within LOS. It took me quit some testing with the settings to get it working.
BUT:
I started about 2 years ago with a Radian Pro and never got it thermalling very well. Happily I started with the Cirrus!! But on returning to the Radian I compared the parameters through Compare Params in MP Full Parameter Tree. I also reread all the posts. Checked the soar parameters with the Spread sheet tool from @Samuel_Tabor (thanks for that). Not tried the MatLab tool from @sonicdahousecat, but will ask my son for help.
What also could help me and others as well are:

  1. A working .param set as a reference for several different gliders to compare just in case of difficulties.
  2. Or a table of specific soar parameters also for a range of gliders, so that I could quickly find a specific parameter for my plane by interpolating or eyeballing in the table. More or less like the standard settings for normal planes in the WIKI.

While learning I have some larger gliders waiting.

Hi Bastian, I’m happy you are enjoying your Lentus with the soaring feature.

I had a look at your posted log.
The bank angle is limited quite often by the stall prevention feature while circling:


I didn’t smooth the airspeed, that’s why it doesn’t fit exactly.

You can find the calculation for the roll limit here in the code:
ardupilot/Attitude.cpp at master · ArduPilot/ardupilot (github.com)

If I understand it correctly, the roll limit is calculated by the (simplified) equation:
image
We can rearrange equation to AIRSPEED_FBW_MIN:
image
And calculate AIRSPEED_FBW_MIN parameter to allow a bank angle of e.g. 45° at 12m/s:
image
You can try AIRSPEED_FBW_MIN = 10 instead of 11 or disable stall prevention to get tighter turns.

Hello Sonicdahousecat.
Thank you for your contribution, I am very interested.

The truth is that I have a problem that I don’t know how to solve.
I have the same configuration of Ailerons and Flaps, and the problem that I observe is that the SERVO TRIM AUTO = 1, produces a trim of the 2 Ailerons up about 5 mm, that is to say that instead of trimming with an elevator, it does with the ailerons.
I have tried various DSPOILER_OPTS settings, but I still have the same problem.

I need you to tell me what version of Ardupilot you are using, and if possible, put your .param.
I am running V4.1 Beta5, and I suspect that this has something to do with my problem.

I really think I have it easy, I use the same plane as you, a Lentus, just a little heavier, because it has the retractable train, and therefore, if I put the same version as you, and the same .param, it has it works just as well as you.

I have to make some small changes in your .param, because I carry another type of GPS, and another type of ARSPD, in addition to Telemetry, but that is all easy.

Thanks for everything, I wait for your news with anxiety, to see if I can solve this.

Greetings and happy flights.

I imagine that if I am flying in Termica very well, with the ailerons raised both, 5 mm, when I take them in place, everything will be much easier, and with much more performance.

@Bastian On both my Radian and Cirrus I am using the flaps on a direct channel. On the Radian using 1 channel and 2 channels used by the Cirrus. On the Tx set to the Tht stick for full deflection (+/- 80 deg. deflection) and mixed on a slider for reflex/normal/thermal. (-3 … +10 deg.) On the FC: Setup/Servo Output/RCIN5 and on Config/SERVOx_FUNCTION = 55. Not optimal, but surrended when programming the spoiler options. It worked but took much time to configure. Still working on that. The Cirrus is thermalling extremely well if switched to THERMAL mode, the Radian not, probably a faulty parameter. On both planes:
ARSPD_FBW_MIN = 9
SOAR_THML_BANK = 30
NAVL1_PERIOD = 17
Using ArduPlane V4.1.0beta5(b32e0ab8) and a MatekF765-Win.

Hi Bastian, I had a similar issue.

In my case, both flaps were trimmed up by about 5mm after a flight with SERVO_AUTO_TRIM enabled.

I had the impression that the ailerons were trimmed correctly and moved both flaps back down by exactly the same amount with SERVOx_TRIM so that I wouldn’t change the roll moment again.

Unfortunately I was not able to find the corresponding code. But I found this thread: SERVO_AUTO_TRIM both ailerons up

Maybe we can ask @iampete to take a look at the logs.

I’m running at the moment V4.1 Beta5 too.

Hello Hello sonicdahousecat.
Yes, it would be interesting to ask @iampete to take a look at the logs.
Pass me if you are so kind, the .param you currently use, in the Lentus.
Thanks.

Here is my actual param Lentus.param (22.2 KB)

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Thanks sonicdahousecat.
It is of great help for me, to be able to compare your .param with mine.
Greetings.

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Sonicdahousecat.
Check this parameter, RTL_RADIUS = 0.
I take it to 60, in your case with 0, if it ever comes home, it may end up screwing up.
Well there are always other securities, but I would put it at 60 m.
All the best.

Hi Bastian, RTL works fine for me. If RTL_RADIUS is zero then WP_LOITER_RAD is used.

The blue line is RTL mode.

@ Samuel_Tabor and other, I need some help to find the reason why my Radian crashed (flight #157) a few weeks ago. While my Cirrus is thermalling very well, the Radian never did. I did compare all the settings and could not find the reason.

I was flying in FBWB towards SOAR_ALT_CUTOFF when I suddenly decided to land. So I switched to MANUAL and suddenly it looked like the plane stalled and spiralled downwards without any reaction. So I switched to FBWA in the hope it would stabilize, but it did not. Halfway down I triggered the flaps , but nothing happened. The flaps are direct out on CH3 + CH4. SERVO3_FUNCTION = 55 (and 4) while flaps are on CH5. The AirSpeed (CTUN.AS) stayed roughly at 18 m/sec but varied as the plane spiralled. The POS.ALT line was not influenced by the flaps at all. It looked like the flaps did not function at all. Down from 180m. in 10 sec.

The Radian can be repaired, but is now to be replaced by an ArtHobby Silent. As I wanted to reuse the electronics the cause of failure it is important to me. Hardware failure or some overlooked setting?

I get an error uploading the .bin file.

Thanks for your hints.

Maarten.

Again error uploading. Is 41 MB too large??

Yes, is too big. Use https://www.transferxl.com/ or similar services to upload larger files and then link this here.

@MagicRuB Hi Tom. Just dropped you a file again. Was intended for @Samuel_Tabor (see post #417) but could not upload normally.
Thanks. Maarten.

Reinhard, thanks for the information. Looked at transferxl and wetransfer but saw no possibility to make it public. So used an old link to MagicRuB. Hopes it still works.
Maarten.

Hi Maarten,

I had a look at the log. I can’t see any obvious issues with the actions of the system. It looks like either the stall was just not recoverable using the control loops, or there was a hardware failure e.g. failed servo.

Hi Samuel, thanks for looking at my log!
The servos functioned right after the crash and today I have tested them with my servo tester. All working well, be it that the aileron servos are rough and sloppy after 200-300 hours of use.


But my AirSpeed (red line, m/s) looks strange to me. When I switched to Manual in an upslope at 180 m(green line, m), the motor stopped and speed came down to 3 m/s. Here the plane probably stalled and I switched to FBWA to recover, should not have done that. The ailerons went full from right-left-right-stayed there. So explaining the spiralling down.

What puzzles me is the analog AirSpeed (red). At 16.32.58 it suddenly jumped from 8 m/s to 21 m/s and stayed very erratic after that.

Conclusion:

  1. Maybe my analog sensor is not working well, explaining the bad thermalling in the past. I will replace it for a digital one.
  2. It probably stalled all way down, not recovering as per Arduplane manual has been warned.

Lessons learned:

  1. On THERMAL a good AirSpeed sensor is needed.
  2. If in dire straits switch to MANUAL if STALL_PREVENTION =1. Not to FBWA.

Maarten.

If someone else want to look at the file:
To download look at post #166 for file:
157 10-10-2021 4-33-06 PM.bin

Thanks for any help, Maarten.

Hello all,

I would like to start with soaring and I’m willing to buy the Phoenix 2400 to start with and after everything goes well I will implement it on a F5J glider.
The FC is Omnibus F4 Pro, my problem is that I don’t know what to define in servo function in arduplane for a “Full house” glider with all the F5J functions (Crow, flaps, ailerons, etc.).

I will be happy for any help.
Thank you very much
Rotem