karla

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #15 on: December 03, 2019, 08:53:17 am »
@theothercliff
Thanks a lot, i am just not there yet, but hope to catch up and use your list.

I've later built the MiniTalon with analog airspeed sensor too.

May I ask where and how you installed the pitot tube on that wing frame?
Cant really spot it in the pictures you posted.
What considerations you went through?

Asking since I am getting a bit inspired to install one myself on a similar wing (ZOHD Talon Rebel GT, long name  ::) ).
It does have a v-tail and thus a rudder function, unlike the mako.
« Last Edit: December 03, 2019, 08:57:58 am by karla »

jdl

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #16 on: December 03, 2019, 11:03:36 am »
I've installed the pitot tube on the right wing of MiniTalon, some 15-18cm away from the fuselage. I've followed the info and advices in the MT dedicated thread in rcgroups, especially these of mark_q. He also has an excellent MT dedicated site:
http://www.itsqv.com/QVM/index.php?title=X-UAV_Mini_Talon_Build_Compilation

If your pitot tube is all-metal one, you can make use of this 3d-printed mount:
https://www.thingiverse.com/thing:1887194

Mine pitot tube was different design so I installed it with hot glue and a plastic screw for additional strength. Never had problems with it, the hot glue holds it perfectly, just had to be very cautious aligning it correctly. I'll make a close-up photo of the pitot tube on the wing later and I'll post it here...

This position of the pitot tube is considered to offer minimal disturbances in the airflow and thus minimal errors. It is safe on landings, too.





I've burried the sensor and the hoses in the foam, in the wing. Only the cable goes into the fuselage.



Here is the post about my MT build:

https://www.rcgroups.com/forums/showpost.php?p=39982936&postcount=13905

There are tons of useful info in the MiniTalon thread in rcgroups, worths reading it all. I guess you can find interesting ideas for your build of ZOHD Talon Rebel GT there.

karla

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #17 on: December 03, 2019, 11:37:19 am »
OMG, thanks a lot for sharing all this!
Q: I notice you have a small gps unit that do not have an external mag in it, right?
So, where do you mount your external mag?

jdl

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #18 on: December 03, 2019, 12:20:06 pm »
Nowhere  :)
Not using external mag at all.

On the MiniTalon I'm using Revo's internal mag, works flawlessly. There are not power lines passing too close, all cables are twisted and I get (almost) no alarms, no matter how much thrust I give. In fact, the situation is way better compated to the ZMR250 quadcopter and Z-84 plane that have auxmags installed.

I've rarely seen in the telemetry logs mag warnings, not critical reds, and the rate of their occurance is comarable or lower than the rate of the identical warnings in the logs from Z-84 (that uses external mag).

karla

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #19 on: December 03, 2019, 12:22:04 pm »
sooo good to hear that!
I will take a bet the internal mag also will work on the Rebel GT.

jdl

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #20 on: December 03, 2019, 12:49:13 pm »
I guess so. ZOHD Talon seems to have (looking the photos on the web) spacious internals to allow good separation betheen FC and power lines.

Even if internal mag turns to be unusable on the final build stages, you can always replace the GPS with Naza clone and use its own mag for auxmag. Weight penalty is almost insignifacant..

f5soh

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #21 on: December 03, 2019, 06:02:46 pm »
You can also give a try to Complementary+GPSOutdoor, without mag.

Re: Position hold on a fixed wing - Altitude control mystery
« Reply #22 on: December 03, 2019, 08:17:39 pm »
Cool !

Hmmm...  This is about fixed wing GPS flight modes.  I have never tried this without a mag.

So does "next" (or even 16.09??) use the "fixed wing constraint" to do GPS flight modes on fixed wing without a mag?  (It assumes that it is pointed in the direction that it is traveling?)  I have just assumed that it used mag.  I need to read code more completely.  :)
« Last Edit: December 03, 2019, 08:51:18 pm by TheOtherCliff »

jdl

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #23 on: December 04, 2019, 02:11:06 pm »
@karla
Here are some photos of how the pitot tube is mounted on my MiniTalon wing. I've measured 18.5cm from the base of the wing, so approx. 20cm from the fuselage.


karla

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Re: Position hold on a fixed wing - Altitude control mystery
« Reply #24 on: December 05, 2019, 02:42:32 am »
This sounds better and better :)

@jdl very clear, thanks.
@f5soh interesting, I will try setting Complementary+Mag+GPSOutdoor and see what it does.
@theothercliff good questions!