DX6i for differential thrust - impossible? - RC Groups
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Aug 11, 2008, 02:43 AM
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DX6i for differential thrust - impossible?

I've been trying to program my DX6i for differential thrust. My idea was to put one motor on throttle and one on rudder. Then mix like this:

Mix 1: Throttle -> Rudder 100% 100%
Mix 2: Rudder->Throttle 100% 100%

What I found is that the rudder motor works as expected, but the throttle motor doesn't seem to do anything differently. That is, the rudder channel doesn't affect the throttle.

Any ideas? Anyone get differential thrust working on the DX6i, maybe with a V-tail mixer?


PS: working on this:
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Aug 11, 2008, 08:29 AM
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diff thrust on dx6i


it's easy when you know how:

turn on dual airelons in wing type
mix throttle to flaps (aux) d +100 u +100
reverse airelon (not flap)
can set 100% differential to stop one motor slowing when turning (other motor speeds up).

Connect one motor (via esc1) to rec airelon, and the other (via esc2) to rec aux. Dont forget to disconnect one of the red wires (centre) from the plug or you'll blow your reciever.

you'll need to play around with dr, travel adjust, and expo, to suit your model. It's easy to create wild oversteer.

Aug 11, 2008, 08:31 PM
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Brilliant, thanks! I've been playing with it and had both ESCs on different batteries with their BECs connected to the receiver... sounds like that's not such a clever idea.

I'll give this a try tonight.

Problem though: this is going to be an elevon bird. I want rudder connected to differential so I can use elevator/ailron for the elevons. Any ideas for how to make that work?
Aug 12, 2008, 01:23 AM
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Mix 2: Rudder->Throttle 100% 100%
The reason why this mix doesn't work is the dx6i software has a bug. And as a result throttle can't be used as a slave.
Aug 12, 2008, 02:25 AM
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Kwok - thank you! That explains the problem I'm seeing. That stinks, though.
Aug 12, 2008, 12:07 PM
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closer... but still not quite there

by using the v-tail wing type in addition to what I said above, you can get a bit closer:

turn on v-tail wing type (keep dual airelons)
connect airelon1 to rec elev and airelon2 to rec rudd

airelons will be left stick instead of right, elevator right stick as usual, and you can't use differential on the airelons as that's routed to the other channels.

The problem is essentially that there's no provision for twin engine setups on any trannys I've seen, which I find surprising. Surely even if diff steering is not required then there would be the need to balance motor output?

Last edited by el_tel; Aug 12, 2008 at 12:16 PM.
Aug 12, 2008, 07:18 PM
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It sounds like the dx6i could ALMOST do it except for that darn firmware bug.
Aug 14, 2008, 03:05 AM
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yeah, you're right. I think the DX7 can do it.
Mar 15, 2009, 10:29 AM
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Dick Adams's Avatar

U.P to El-Tel!

El-Tel, if I am following what you are doing, do you end up with the differential throttle steering on your right stick?

Having trouble thinking this through!

In a 3 flight control channel flying boat, I put the rudder on the aileron channel output so I am flying on the right stick. So that wouldn't work on a rudder elevator ship? If I am following, your setup could work on an aileron ship, or no?


Mar 15, 2009, 12:04 PM
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richard hanson's Avatar
As I mentioned in your other post - you need two channels (one foreach motor - *modified by the throttle )
ther is nothing wrong with the DX6i-
* or modified by the rudder
Last edited by richard hanson; Mar 16, 2009 at 09:05 AM.
Mar 15, 2009, 09:34 PM
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Dick Adams's Avatar

Redux, et al...

Richard, I tried to follow what you wrote in my earlier thread, but couldn't follow all of it! When I asked some follow up questions, I didn't hear back from you. I reread it and still am having problems.


Here's one part that you wrote that still throws me now that Horizon has confirmed a programming bug:

"If rudder is master- throttle can INCREASE or DECREASE as rudder is moved left OR right."

What's wrong with the Dx6i according to Horizon, not me, is that the throttle channel cannot be a slave!

The reason I posted on this thread is that work arounds were being discussed. Do you have a work around for the Dx6i bug that doesn't require making throttle a slave?? I would love to hear it and try to understand it if you do.

I am new to mixing and computer radios, but am an old dog who still tries to learn new tricks.


Mar 15, 2009, 09:56 PM
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Hello Dick Adams,

I didn't see your last post, until I went back to that old thread to reread what "richard hanson" wrote again. All I can say is, none of it makes any sense to me and I am not a noob. It's easy enough for him to me wrong by providing the proper DX6i settings.

Mar 16, 2009, 08:04 AM
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Dick Adams's Avatar

Mornings are a good time to fish!

Good morning, Kwok!

Well, glad to see it's just not me. But Richard tried to write a mixing primer for me, and the center power off thing did turn on a light and got me a step closer to understanding this stuff. You thought a primer wasn't needed.

I keep proving that it is!

Let's see if Richard will take the bait.


Mar 16, 2009, 08:58 AM
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richard hanson's Avatar
Why solve it for you - that would spoil your fun!
two ouputs -one for each motor is needed .
a master which modulates each is also needed.
here is a picture of a more involved mix
A-rudder deflection moves both halves of air brake as a normal one piece iem
B- low engine settings open airbrake porportionately (power setting increases spread of halves)
C-elevator is trimmed down porportionately (trim) as brake is deployed
It all worked as noted I did this one 10 years ago using a JR10 tx
Someone else has also posted what looks to me like a working setup for the DX6i- but I have not tried it. I think it was basically, two throttle outputs modulated by the rudder channel.
Last edited by richard hanson; Mar 16, 2009 at 09:08 AM.
Mar 16, 2009, 01:27 PM
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Dick Adams's Avatar

Mission Impossible Assignment Accepted!

Hah! A mystery assignment with clues. I am game. But the rules are:

1. only 2 mixes allowed (as that is all the Dx6i has!), and
2. throttle can't be slave, and, last
3. can't have a weird result, like my present "lame duck" mix of throttle to rudder that requires the reflexes of a cat and the memory of an elephant, both of which, trust me, I lack


Had my Tx packed up to ship back for the stick pot inspection, but will unbox and tackle this tonight.



Ps: Richard, are you sure enough about this to bet something really valuable, like a 6 pack of good beer??
Last edited by Dick Adams; Mar 16, 2009 at 09:16 PM.

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