I'm not sure i'm doing good..

I 'm flying with an apm 2.5, rx frsky, tx turnigy 9x.

I saw the video of Mark Harrison on youtube ( https://www.youtube.com/watch?v=r7B0Sfyb6Uo ) explaining how to setup your failsafe setup on your frsky. I did it too..It workds ! nice !

In the manual of the apm 2.5,, the failsafe is explained of an other way : https://code.google.com/p/arducopter/wiki/AC2_Failsafe?wl=en

Do i have to make the setup of the apm 2.5 like explained in the manual if i already follow the instruction of Mark Harrission (seup on the RX) ?

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You can follow Mark's instructions. The FrSky can set PWM values for all channels. A setting with neutral stick input I.e centered and with the mode set to LAND or RTL, is the same as you doing that on your TX.

Some receiver's only support fail safe on throttle. This is when setting the PWM values in MP helps, as this is what the APM will use when that event occurs. I know Futaba has throttle Only FS.

When you use FrSky failsafe to set the throttle below 975, to trigger the failsafe in APM the advantage is that the APM will not go back to the current stick positions when signal is restored. It will stay in LAND or RTL until you do a mode change.

If using RTL as a failsafe,,you must make sure you have a good sat lock before taking off, otherwise the copter will not know the correct place to return too

When you follow mark's instruction, you will put the the failsafe @ 50% throttle and wil use the RTL mode..Done !

How do you use the failsafe on apm 2.5 below 975 when your throttle goes to 50% in failsafe mode? 

How do you use the failsafe on apm 2.5 below 975 when your throttle goes to 50% in failsafe mode? 

You need to temporally need to set the limits on your CH3 to emit a PWM pulse at 950, You can verify these on the green bars screen in MP. Then you set the failsafe as Mark showed (press the f/s button on the RX)

When you enable throttle fails safe parameter in APM now. When you turn of the RX it will send out a PWM of 950 (essentially not throttle) the APM reads this as a failsafe and switches to RTL. When you come back into range, the FS is not cancelled until you change the mode. ie. toggle from stab position and back again.

When you follow mark's instruction, you will put the the failsafe @ 50% throttle and wil use the RTL mode..Done !

Yes it's simple, but soon as you come back into range and the FrSky receiver gets the signal, it will change mode back to what you had been using before, ie. stabilize. essentially stopping at your range limit. You can regain control and fly it home, but it won't RTL completely. (I'm not syaing you should change from this, just making sure you understand the implications of each option, you decide if this or the APM mode suits your needs)

Sidenote: I like your ariel placement device, I would suggest the one in the horizontal plane is place in the forward direction so it's further away from the GPS unit to reduce interference with it.

Why do you say temporaly ?

When you set the limits at 950, do you have to use a special mode? Of you let it in stabilize?

Since you don't want that in normal operation, the throttle minimum should be a normal 1000 PWM value. It's only when you lose signal will the output from the RX output 950 and then that triggers the FS

What Bill said, with fewer words. :)

Receiver with fail-safe setting on all channels:

- Set throttle F/S position to 50%

- Set mode channel F/S position to RTL

Receiver with fail-safe on throttle only:

- Adjust throttle end-point down to lowest possible position (<975)

- Store low throttle position as the fail-safe position

- Adjust throttle end-point back to default for normal usage, to prevent accidental triggering of fail-safe in flight

i want to use the apm and i'am interested in the fail-safe on throttle only

i'm using the ttrim on the tx to go on a very low position (984)

i fix my fail-safe position with my rx

i do the trim up to the normal position (1100)

when i'm looking to the radio calibration an put the tx off i have a value who change between 983 and 984 and the RTL is NOT going ON.

Where do i make a mistake?

default It needs to be less that 975 for example 970 to trigger. If you cannot get any lower than 983, you could set the FS_THR_VALUE to 990, for example, and then it will work (983 < 990). You can set FS_THR_VALUE in the Advanced Parameters section the Configuration part of MP

Trim is not the way to go. You want to change channel end-points. End points is the total range for the servo and on Futaba for example the default is +-100% with the option to change it up to +-140%. Different radios has different names and schemes for this, but the result is the same.

So set the throttle end-points for maximum range, and only use trim to get even lower if necessary.

it works ! thanks !

I too am having a hard time figuring this out.  First, off, I have a Frsky system.  I assumed I would not have to set any F/S setting on the receiver?  Perhaps I am wrong... I bound my radio/rx at -150%/+150%, then returned to normal travel (100%) and have it set up in MP correctly.  

I.E.- My minimum throttle is 995 with throttle stick off.  My FS PWM value is 925, and when I shut my radio off, it goes to 900. This triggers the F/S and puts my plane into RTL.  However I get no throttle.  I assumed that I could set a F/S throttle setting in MP somewhere but I cannot?

I tried to adjust my Ch 3 (throttle) min PWM value to say 40-50% but then it activates at any flight mode other than manual?  I am quite confused.  

Another question, is how will an airspeed sensor effect this, as I have one, but I am new to APM yet, so to keep it simple I do not want to use it for the time being, but I would like to set a F/S setting to RTL, and a airspeed setting above stall, and have the APM run the throttle in F/S mode, is this possible as well?  Thanks in advance!!!! 

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