How level does SxR receiver have to be?

[Allan Bennett]

I'm installing an S8R receiver in a new model. It's not the first one I've done, but in this model the handiest surface for mounting the receiver is not parallel to the centreline of the aircraft. It's probably about 5 degrees off. Is the 'Offset angle of auto level' adjustment in the PC configuration software the place to take this into account, or will it automatically be taken into account when I do the self check?

The surface to which the receiver will be mounted inverted is sloping downwards towards the nose of the model. If compensation is to be made using the 'Offset angle of auto level' function, will that require a negative angle or positive?

[Denis Watkins]

Try, Allan

To fit the unit level

I set a unit up On silicone sealer and a spirit level before, to compensate for a sloping floor

[Allan Bennett]

Ok, I've made a balsa wedge to make a small horizontal platform to mount the receiver on.

So what is the 'Offset angle of auto level' for? My understanding is that when you do the self check it will take the attitude of the aircraft at that time as being the normal flying attitude for auto-level flying mode.

[Denis Watkins]

Without the wedge, using the sloping floor and

Yes, you can apply offset, but this would permanently apply a push of pull to the elevator, from the gyro, just to fly level.

Always best to have a flying trimmed out model 1st, with a level mount

Then a very small offset can be used to correct any mount discrepeancy

But have never had the need to use offset, these units have worked 1st time

Some of the knife edge lads may use a little offset, as you have the landing gear and cockpit to compensate for

[Allan Bennett]

Posted by Denis Watkins on 02/11/2019 21:47:18:

Without the wedge, using the sloping floor and

Yes, you can apply offset, but this would permanently apply a push of pull to the elevator, from the gyro, just to fly level.

Always best to have a flying trimmed out model 1st, with a level mount

Then a very small offset can be used to correct any mount discrepeancy

But have never had the need to use offset, these units have worked 1st time

Some of the knife edge lads may use a little offset, as you have the landing gear and cockpit to compensate for

The model will be trimmed mechanically to fly straight and level -- the slope of the Rx mounting surface shouldn't affect its flight characteristics unless in stabilisation mode or self-levelling mode the sloping Rx 'thinks' that it should be level because it hasn't been told it's mounted on a slope, which is what I was surmising the 'Offset angle of auto level' is supposed to do.

Anyway, it shouldn't be an issue now that I've installed a wedge to make it as level as I can. Like you, my SxR receivers have worked so far without the need to adjust any parameters, other than going through the self-check routine.

[Martin Harris - Moderator]

My stabilised Jeti receiver initialises at an angle in tailwheel models and then works while I fly in any and every attitude. I don't think a small amount of out of level should affect anything...

Depending on how your receiver functions, you may need to trim the model mechanically to use heading hold.

[Allan Bennett]

Posted by Martin Harris on 03/11/2019 21:26:07:

My stabilised Jeti receiver initialises at an angle in tailwheel models and then works while I fly in any and every attitude. I don't think a small amount of out of level should affect anything...

Depending on how your receiver functions, you may need to trim the model mechanically to use heading hold.

Initialisation is not an issue with the FrSky stabilised receivers so far as I know. The only time you've got to have the model in the correct attitude is when doing a 'self check' (which is initiated by the user during initial setup, not by the act of powering up the receiver), at which point it adopts the attitude of the model as its baseline for self-levelling.

As far as I know the FrSky receivers don't have a heading-hold function -- I've never programmed it or used it, but I stand to be corrected on that.