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DX7 Programmable Mixing

What does the offset value do?

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Peewhit07/01/2010 18:53:57
795 forum posts
264 photos
I am setting up a four servo wing (slope soarer) with crow braking on the throttle stick and need to use the programmable mixes in a big way - five out of the six to be exact.
The offset value is confusing me no end as I do not know what it does.
The book says that it is to "redefine the neutral position of the slave channel".
Could someone translate this into simple English please?
Peewhit09/01/2010 18:47:08
795 forum posts
264 photos
Had a play and think I have it sorted.
The offset value seems to redefine the neutral or zero position of the MASTER channel, not the slave.
For example, when using a throttle stick for crow braking with stick back for crow on:-
The default zero position of the throttle stick is it's mid point and with a programmable mix of throttle (master) to elevator (slave),  the top %age value set to 0 and the bottom %age set to 100, the throttle stick will not start to move the elevator until it's mid point or zero value.
An offset value of +100% sets the zero value of the throttle stick to the top.
Hence it proportionally moves the elevator as soon as you start to pull it back.
In other words, the offset value defines the point at which the master channel starts to move the slave.
Richard Neve 113/11/2012 12:00:17
4 forum posts

Hi Peewhit, just found this post after searching for an answer to your exact original question and I think you've answered it very effectively. Thank you

Frank Skilbeck13/11/2012 13:52:04
4736 forum posts
101 photos

It's use is on the flaps on 4 servo wings where you want to use a little reflex (i.e. up) flap for speed, a small amount of down for thermal (on the flap switch/slider) and a lot of down on crow braking, by offsetting the centre you can use all the available servo travel.

On the Multiplex Cockpit you set up the flaps on the flap slider and the throttle stick controls the spoilers (i.e. up aileron), but by mixing spoiler to flap you get crow braking. You can also mix aileron to flap using the flight phases so you can have full span ailerons as well. Offset is useful as you don't have to "waste" a lot of flap servo travel, say you want 60 deg down travel and 10 degree up, by offsetting the centre you can use the full servo travel for the 70 degree movement but the offset centre is with the flap surface at 0 degrees. So you'd set the flap position with the servo centered to be at 25 degrees down (i.e. half travel) and then use the offset to move them to the center so the flaps are level.

Chris Bott - Moderator13/11/2012 14:39:37
6837 forum posts
1429 photos
1 articles

Peewhit have you had a look at the downloadable setups from Spektrum. You may be able to modify one of those?

I have used the Radian Pro one and it only uses 3 mixes for 3 position flap, 3 camber positions and crow. You'd have to reassign stuff to the throttle channel, but I think that's all.

PS did you know that of the different mix to aileron options?

e.g. Mix flap to LAIL and both ailerons will move the same way. Alternatively if you mix flap to RAIL, the two ailerons will move in opposite directions.

Peewhit13/11/2012 19:03:58
795 forum posts
264 photos

Hi Richard and glad to be of help.

Thanks Chris. I did not know of those.

My original post was nearly three years ago and I have since upgraded to a DSX9 which runs my six servo slope soarers beautifully.

For those who have a DX7 and want to set up a full house sloper using a six channel receiver, this program works very well

Spektrum DX7 Program For Four Servo Wing

Gives flaps linked to ailerons for increased roll rate, ailerons linked to flaps for full wing camber, and crow braking (using the throttle stick) with elevator compensation.

This program is based upon setting the ailerons as flaperons

The instuctions are for a 6 channel receiver.

If using a 7 channel receiver you can substitute Aux2 for GEAR which then leaves the GEAR channel free.

Please note that the programmable mix numbers used MUST be exactly as stated, as 5 and 6 give a different effect to 1,2,3, and 4


Enable flaperon mixing

Right aileron to AIL channel

Left aileron to AUX1 channel


Disable gear switch by setting gear servo travel to 0%,0%

Right flap to GEAR channel

Left flap to THROTTLE channel

Set up PMIX5 as THROTTLE master to GEAR slave with setting of 100%,100%

This links both flaps together.

Crow braking

PMIX1 throttle master to elevator slave for crow braking elevator down compensation.

Rates are top 0%, bottom – whatever you need for your required down elevator compensation.

Offset value +100%. This sets the “mid point” of the throttle to stick full up and crow is activated by pulling the throttle stick down.

PMIX2 throttle master to flap slave. As the ailerons are set up as flaperons, the flap channel controls the ailerons as flaps. This gives both ailerons up movement for crow braking.

The throttle stick drives the left flap directly and as the flaps are linked by PMIX5, both flaps will move when the throttle stick is moved.

Full wing camber

The ailerons are set up as flapperons – use the flap system setting for the correct amount of camber and reflex, operated by the 3 postion flap switch.

Set the aileron travel first.

PMIX3 flap master to throttle slave this is the flap movement for camber and reflex.

As the flaps are linked by PMIX5, both of them will move.

Flaps moving with ailerons

PMIX4 aileron master to gear slave – moves right flap with ailerons.

PMIX6 aileron master to throttle slave – moves left flap with ailerons.

Chris Bott - Moderator13/11/2012 20:41:18
6837 forum posts
1429 photos
1 articles

Clever stuff Peewhit.

Just forr clarity:- I completely missed the OP date. My note apples to DX8 and DX7s and probably not the original DX7.

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