KaseyRC

I'm new to RC and computer radios. Have been flying a trainer with a standard 4 channel radio. I've purchased a DX7 with AR7000 receiver's to put in my trainer as well as a Sig Mayhem 3d plane.

I'm confused about mixing and how and when to setup it up.

Also the Mayhem is very touchy to stick movement. I've setup Exp on all controls with 100% on each switch as position 0, and normal on position 1. Is 100% too relaxed. Should it be 50% instead?

How do you know when and how to setup mixing? Ail>Rud and so on.

I've searched around but I'm unable to find answers to my questions. Maybe we can gather enough information to make this a sticky for others in the future.

Thanks,

Kasey

Rodney

I am not familiar with the DX7 but, when comparing to other brands, most people use 20 to 50% expo. If a Futaba or Hitec it is negative expo, if JR it is positive to soften response around center stick. I would think 100% would be very hard to use as that would mean essentially no control movement near center stick with it snapping full over as you reached the end position. Do not confuse expo with dual rates as, when you say 100%, I'm inclined to think you are adjusting dual rates.

KaseyRC

Rodney,
Thanks for the response.
I setup 100% expo. I think I'll back it down to 50%. I get full motion of the servo, but the greatest deflection as when the stick goes beyond half way point.

How do I setup the Ail to Rud mixing?

Does anybody know of a good reference somewhere I the internet that has some sample setups? I don't want to trash my plane because I setup my radio wrong.

Thanks,

alan0899

G'day Kasey,
Set your Dual Rates, elevator, ailerons & rudder, low rate, to 50% or 60% of high rates, this will reduce the throw of the control surfaces, & make it much less sensitive, forget about expo until you are happy with the way the planes flys.
If you need expo, add it later, in case you don't know, you can have a low rate, with no expo, & a high rate WITH expo, or visa versa, but set up the plane using your rates first, then play with expo.
Exponential, only softens the feel around centre of stick travel, but once you move the stick past the expo point, you get linear movement, & bang, you find the plane is too sensitive.
In the case of the DX7 it is positive Expo you need not negitive, be aware.
You should only need rudder/aileron mixing with high wing slow flying aircraft, like a J3 Cub, & so on, your tainer won't need it, you may need to use 2 servos for the ailerons on you Mayhem, in which case you would set the wing type to Flapperon, & plug your right aileron into "AIL" slot & your left aileron into "AUX1", your ailerons will now work properly.
Read you manual, on the DX7, & talk to guys at your club, if you need any more info on mixing.

KaseyRC

Allan,
Thank you for your reply. I already setup the Mayhem for Flapperon. I'm going to change my DR to 50% for low rate as you suggest. and put Expo back to zero. As for reading the manual, the manual for the DX7 is horrible. The JR S400 has a better manual. But the S400 is not a computerized radio.

When do you setup mixing and for what reasons.

BaronSchwab

Mixes help keep the plane flying straight on knife edge passes. When you apply rudder on knife edge sometimes the plane will either pull towards the canopy or push away and mixing rudder to ail will eliminate this problem.

Some people like to mix ail to rud to coordinate turns as on a full scale aircraft.

If you are unsure on how to mix or how much to mix, talk to an experienced pilot at your club. He can help you. Ask him to fly your plane and mix what is necessary and to keep test flying it until it is good. He may not be familiar with your radio but if he had computer radio experience he will be able to figure it out and show you how he did it.

Zeeb

My Feedback: (41)

Well not to put too fine a point on it, but IMHO the most important mixes have not been mentioned....

While flight control mixing is useful for various conditions and is most commonly thought of as the actions mentioned already, I think you might find that being able to do a mix for throttle cut on shutdown, as well as a throttle up mix for flying are quite useful mixes as well.

Granted the DX-7 does have a throttle recovery feature that can be used to shut down a glow model, but I'm not really fond of that particular method as I'm used to using a tx switch with my gassers for shutdown. There are those guys who do like I used to, click in some throttle up trim just before takeoff and then you have to remember to click it back to land, or at least my Funtana doesn't want to land if the idle RPM is too high. So after being shown the switch activated throttle up trick, or what I call "Flight Idle" like a full scale turbine by the gasser guys, I find both mixes to work quite well.

As for flight control mixing to affect dynamic stability, there's nothing wrong with asking about it now, but the why will become clear as you get more experience...[8D]

You'll find that some mixes like the dual elevator servos must use one of the six mixes available. Be aware that if you are mixing flight controls, only #5 and #6 mixes on the DX-7 have the capability of trim following.