06 February 2013

Full trailing edge mix with the DX7

According to this excellent UK forum post, just by picking the correct two of the six free mixers, one is able to program to Spektrum Dx7 for crow (butterfly), full trailing edge aileron and full trailing edge camber for a four servo wing utilizing a 6 channel receiver:

Four servo wing full trailing edge mix for Dx7 
Detail re use of P Mix 5 and 6 for Dx7 trailing edge mix

Just in case the forum link should die at some stage, some extracts of this useful chat are pasted below, with appreciation to the modelflying UK forum:

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 instructions 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.

Had a bit of luck - well a lot of luck really- in setting up my Typhoon slope soarer in that I managed to achieve crow breaking, ailerons moving with flaps for full wing camber, and flaps moving with ailerons for increased roll rate.

There was one  puzzling thing which worked very much to my advantage so today I "borrowed" the receiver and battery from my Fusion and investigated.

Programmable mixes 5 and 6 are different to 1, 2, 3 & 4 in that the trim levers will adjust both the master and slave servos. 
There is another benefit of this feature.

With a mix set up on either 5 or 6, and a further mix on 1, 2 , 3 or 4 set up with the master of the first mix as slave, then both master and slave of the first mix are activated by the second mix. 

As an example, the flaps of my slope soarer are set up on the throttle and gear channels with p-mix 5 linking them together (throttle master and gear slave)  so that both flaps move from the throttle stick.

The ailerons are set up as flaperons so that they work off the three position flap switch to alter wing camber.

I have p-mix 2 with flap master to  throttle slave which links the ailerons (working as flaperons on flap channel) to flaps (on throttle and gear channels) to give full wing camber.

 Because the throttle and gear are linked on p-mix 5, and p-mix 2 has the throttle (p-mix 5 master) as slave, both flaps move together.

I originally discovered this by pure accident and it saved me a very valuable p-mix.

It only works if the first p-mix is on 5 or 6 and the second p-mix is on 1, 2, 3 or 4.