tacx

My Feedback: (1)

Hi All,
I have a new dx7, and have been familiarizing myself with its functions. The manual has a lot to be desired when it comes to giving examples of the diff. functions. Couple things I don't understand..

1. What exactly is "dual-elevator mixing"?

2. In the mixing section it states you can "mix a channel with itself"??? That makes no sence to me.

Thanks for any help

BuschBarber

My Feedback: (2)

Most larger aircraft have separate Elevator Halves, each controlled by a separate servo. This is instead of using a Forked Pushrod or joining the Elevator Halves with wood or wire. You could, of course, use a Y Harness to connect the two Elevator servos, but then you would have to deal with Reversing one of the servos. Reversing circuits tend to have the Neutral shift often, forcing you to have to readjust the Reversing circuit pot or adjust the linkage every few flights.

Many prefer connecting each Elevator servo to a separate channel and mixing the channels with Elevator as the Master. It depends upon the radios programming how you handle the mixing. I believe that with the DX7, you use one of the Programmable Mixers. A common mix would be Elevator (Ch3) and Aux2 (Ch7).

When you mix the same channel with itself, it is usually done to set up some kind of Switch Assignment or for some other purpose. There are so many undocumented uses for Programmable Mixers. The Tx manual just tells you how to enter data into parameter fields but it does not give you scenarios that you can solve by using Programmable Mixers.

Don EdBerg used to publish 3rd party books describing how to program a Futaba computer radio and how to use multiple programmable mixers to solve various scenarios. He never really published anything for JR.

Horizon does have published addendum that can answer some of these questions, but forums like RCU are probably the next best step.

JR radios have traditionally put Flaps on a 3 position switch, by default. This was true with my XP8103 and XP9303.

On my Futaba 8AUPS and 9CAP, you had to use multiple Programmable Mixers which I had trouble doing without the help of someone like Don EdBerg.

I guess the two companies had different philosophies as to what the customer wants in a radio.

tacx

My Feedback: (1)

Thanks Rich,

I understand now about the "dual elevator mixing". I just never thought that anyone would want to plug each elevator servo into a diff. channel. I have a U-CAN-DO with seperate elevator servos, but they are y-harnessed into the elev. channel. The reversing is solved because on the U-CAN-DO the servos are mounted on each side of the fuse with one arm up and the other arm down. I guess if one had a plane that had a diff. servo set up the mixing would be helpful.

Tom

BuschBarber

My Feedback: (2)

The H9 Ultra Stick used to have a procedure, in the manual, for setting up a Futaba 8AUPS, and other radios, to enable all the features of the aircraft. Each Aileron half, Flap half, and Elevator half had a separate servo hooke up to a different channel.

You could use the Flaps as Flaps or they could be combined with the Ailerons to make Giant Ailerons. The Elevators could be used as Elevators or combined with the Ailerons as Tailerons and Elevators. There was a condition called Butterfly, or Crow, where you could pop the Ailerons up, as Speed Brakes, Drop the Flaps, and just like a parachute, the aircraft would abruptly halt and drop on the runway after a dive.

You have so much more control over each control surface when you mix channels. I know guys with Biplanes who have all 4 Aileron servos on separate channels.

You could use a JR Matchbox to connect up to 4 servos to one channel and control Direction, Neutral, and End Points, for each channel, but that would cost an extra $60. If you have enough channels on your Tx, it does not cost you anything more.

I have an H9 P47-150 with a servo in each Main Retract. I put them on separate channels, mix them, and slow on down so it looks more scale.

I have a jet that has a separate servo for Nosewheel Steering. I mix Nosewheel with the two Rudders and I easily trim the Nosewheel with SubTrim, without having to fool with the mechanical linkage.

tacx

My Feedback: (1)

Thanks Rich,
I just started into the hobby at the beginning of last year, so I'm still on a big learning curve. When I was a kid, and that was a loooong time ago LOL, I flew a control line plane. This is a whole diff. ballgame!!! Thanks for the help.

Tom

BuschBarber

My Feedback: (2)

I flew Control Line planes from 1956-1978 when I bought my first RC radio.

AWorrest

My Feedback: (5)

One good way of setting up a throttle kill is to use a program mix and mix the throttle with itself with a ratio of -100%. Assign the mix to one of the switches. You also have to use a negative offset. I don’t have a DX7 handy but on the 9303 a value of -168 or more works. I use this for my electrics as it gives a solid low throttle when the switch is pulled and it doesn’t move with the trim. This is definitely a safety asset.

I haven’t done it myself but some people will mix a control surface with itself as a way of having more than two dual rates.

Allan