Help! How to do differential thrust on opentx?

[Battery800]

So I have a tx16s and I’m trying to program differential thrust into my plane. I’m having problems just writing models from my pc so can anyone walk me through the process for the mixes and such?

 

[JasonK]

here is an example were I setup CH3 as one throttle channel and CH5 as the other throttle channel with 25% differential on the throttles. You also want to make sure to setup your fail safe correctly as most receivers will center a channel when in fail safe and you don't want that on a throttle challenge.

Mixers

CH1	I1:Ail Weight(+100%)
CH2	I2:Ele Weight(+100%)
CH3	I3:Thr Weight(+100%) += I4:Rud Weight(+25%) := MAX Weight(-100%) Switch(SF↑) [Cut]
CH4	I4:Rud Weight(+100%)
CH5	Thr Weight(+100%) += I4:Rud Weight(-25%) := MAX Weight(-100%) Switch(SF↑) [Cut]

 

[Battery800]

here is an example were I setup CH3 as one throttle channel and CH5 as the other throttle channel with 25% differential on the throttles. You also want to make sure to setup your fail safe correctly as most receivers will center a channel when in fail safe and you don't want that on a throttle challenge.

Mixers

CH1	I1:Ail Weight(+100%)
CH2	I2:Ele Weight(+100%)
CH3	I3:Thr Weight(+100%) += I4:Rud Weight(+25%) := MAX Weight(-100%) Switch(SF↑) [Cut]
CH4	I4:Rud Weight(+100%)
CH5	Thr Weight(+100%) += I4:Rud Weight(-25%) := MAX Weight(-100%) Switch(SF↑) [Cut]

Thanks

 

[Battery800]

Thanks

here is an example were I setup CH3 as one throttle channel and CH5 as the other throttle channel with 25% differential on the throttles. You also want to make sure to setup your fail safe correctly as most receivers will center a channel when in fail safe and you don't want that on a throttle challenge.

Mixers

CH1	I1:Ail Weight(+100%)
CH2	I2:Ele Weight(+100%)
CH3	I3:Thr Weight(+100%) += I4:Rud Weight(+25%) := MAX Weight(-100%) Switch(SF↑) [Cut]
CH4	I4:Rud Weight(+100%)
CH5	Thr Weight(+100%) += I4:Rud Weight(-25%) := MAX Weight(-100%) Switch(SF↑) [Cut]

Are there any logical switches, global variables and special functions?

 

[JasonK]

Are there any logical switches, global variables and special functions?

not for something simple like this, no. All you need is some mixers setup

 

[Battery800]

not for something simple like this, no. All you need is some mixers setup

Alright then, I’ll try it.
Oh by the way, is there a simulation page with the sliders?

 

[JasonK]

Alright then, I’ll try it.
Oh by the way, is there a simulation page with the sliders?

not sure, I do most of my configuration directly on my radio

 

[Battery800]

not sure, I do most of my configuration directly on my radio

Is this right? I’m not sure how to do the maximum weights

 

[JasonK]

That looks like it would work... what do you mean by "maximum weights"?
Right now the throttle is 100% mixed into both channels and the rudder is 30% to both. Which should work fine.

 

[Battery800]

That looks like it would work... what do you mean by "maximum weights"?
Right now the throttle is 100% mixed into both channels and the rudder is 30% to both. Which should work fine.

I don’t know what the “:= MAX Weight(+100)” means

 

[JasonK]

I don’t know what the “:= MAX Weight(+100)” means

it is an override mix that gives you a throttle kill switch, so instead of add, it is override to set it to zero

 

[Battery800]

here is an example were I setup CH3 as one throttle channel and CH5 as the other throttle channel with 25% differential on the throttles. You also want to make sure to setup your fail safe correctly as most receivers will center a channel when in fail safe and you don't want that on a throttle challenge.

Mixers

CH1	I1:Ail Weight(+100%)
CH2	I2:Ele Weight(+100%)
CH3	I3:Thr Weight(+100%) += I4:Rud Weight(+25%) := MAX Weight(-100%) Switch(SF↑) [Cut]
CH4	I4:Rud Weight(+100%)
CH5	Thr Weight(+100%) += I4:Rud Weight(-25%) := MAX Weight(-100%) Switch(SF↑) [Cut]

So, it works, but smal problem: I found out that I need quite a bit of trim on the rudder(20%) but when I start the motors up, one of them spins at neutral, because of the trim. Right now, I’m just giving as much trim before the motor starts, but it might affect the turning a tiny bit still.

 

[mrjdstewart]

you need to individually set the throttle range on both esc's. i would guess that is your issue. depending upon the controller and the channels used diff thrust can have its little quirks, but yours sounds like and ESC not programing issue.

good luck,

me

 

[JasonK]

So, it works, but smal problem: I found out that I need quite a bit of trim on the rudder(20%) but when I start the motors up, one of them spins at neutral, because of the trim. Right now, I’m just giving as much trim before the motor starts, but it might affect the turning a tiny bit still.

if you need 20% trim on your rudder, go fix the mechanical issue

in the mixes or outputs you should be able to remove trim from effecting the motor outputs.

 

[JasonK]

yes, you can just set this to false in the mixer for the rudder -> motors:

note -> if you do, you won't have any rudder trim in your motor mix