I have been wanting to start this thread for following reasons:-

(a) A lot of newbies have been PMing me for understanding certain mixes

(b) Some classified a simple radio as complex one as it is beyond them to program, i found this lack of understanding, baffling , the reason i realized was that the manual is not good enough.

(c) Most importantly, many were/are not using the radio to its fullest capability, i have seen people using a 'V-tail' mixer flying with a computerized radio, a clear indication of lack of understanding

(d) Some heli fliers have shocked me by flying some advanced heli on a stock setup, we could discuss that too

Disclaimer

The mixes that i would discuss here would be generic, the names for it in some radios could be different, we could discuss that as i finish the thread.

Value addition to mix and how have you been using them, is most welcome ( I know a friend of mine used Elevator DR to drop a towing banner, ingenuity!!)

What is a mix ?

Very simply put, Signal sent to specified/different (cross or not crossed) channels of your receivers to let your servo/s act in  particular programmed fashion

Servo Centering

Some Radios allows you to fine-tune the CENTER or neutral position of all flight control servos. After hooking up your controls and mechanically centering all linkages to the  approximate positions, invoke this FUNCTION to arrive at particular servo that you need to centre.

Warning
Servo Centering command is to “Fine-tune” the exact position of the control surface when the transmitter control is in neutral.
Using a large amount of electronic centering adjustments will decrease the total throw available for that channel (because it is servo limited, mechanically). In particular, centering adjustments greater than + or - 50% will tend to make the extreme stick position on one end less responsive, due to reduced throw a that end

EXPO (EXPONENTIAL)

Most Radios allows you to choose two/three (or more) settings for Exponential throw for each of the primary flight channels, Elevator, Aileron and or Rudder.

Exponential throw is primarily used to “soften” or decrease the control stick sensitivity of a control around the neutral
point. With Exponential disabled, a servo will move in an amount proportional to the amount of control stick deflection, i.e., 50% stick deflection will result in 50% servo travel; 75% stick deflection will result in 75% servo
travel.

Remember

Exponential settings DOES NOT change the amount of travel available at 100% stick deflection, but rather it changes the amount of the servo travel that will occur with stick deflections less than 100%. The first 25% of stick deflection may be set to result in only 10% of total servo throw making the control less sensitive around neutral. See image
If you have used Exponential functions before, you will want to start with a small amount of Exponential (10 to 20%) to
determine wheather you like this sort of control response. Exponential is most useful where strong control response is
desired at extreme stick positions but softer response to small stick movement is desired in order to make very accurate
small corrections to flight path.

Setting the Exponential with a positive number will make servo movement soft in some radio and the opposite (Futaba) in some radio BE CAREFUL of that.

Dual Rate, D/R adjustments allow you to switch from your “standard “ control deflection to a reduced amount of throw by simply flipping a switch. The Actual speed of signal processing and servo movement are not affected by the Dual Rate settings, only the amount of total throw available is reduced from the total throw.

Dual Rate settings for Aileron and Elevator and or Rudder could be programmed. It is important to understand that the term “Dual Rate”  The Dual Rate setting can be varied from 0 to 150%. Default for Dual Rate 1 is 100%. I recommend you leave first setting at default setting and only reduce the setting for Dual Rate 2 & or 3, add some expo to sullen the center and you are good to go

Warning

Prior to taking off your model, check the position of both of your Dual Rate switches to make sure they are in the position you want!

EPA (END POINT ADJUSTMENT)

All radios  allows you to adjust the “End Points”, or limit of the servo travel for all flight channels. In general, it is best to use as close to 100% servo throw as possible. This allows for the best possible resolution and centering of all control surfaces. However in some cases it is not possible to use full servo movement such as those instances where short control horns must be used because of aircraft design considerations, or with fixed length control horns such as a throttle arm.

Assume we want to adjust the EPA of the Elevator channel servo. To electronically do so, The EPA of the Elevator channel can be adjusted from 0% to 150%. You can increase or decrease the amount by using the (INC+) or (DEC-)
function keys. By moving the elevator stick up and down, you will see the throw has increased, ensure that the neutral position is attained by the servo upon release the stick.

WARNING

Increasing EPA reduces Resolution and sometimes disturbs the Neutral point, depending on the setup increasing EPA would bring you to a mechanical stop of the surface and you could over load and consequently BURN the servo

Throttle Curve

The Throttle Curve function allows you to vary the amount of servo travel in relation to the movement of the throttle control stick at different points throughout the entire range of deflection of the throttle servo. Multi point custom-programmable Points ensure an extremely precise Throttle Curve to suit any situation.

For example, many glow and gas engines are very non-Linear, meaning that when the throttle control stick is at half, the engine is not at half power. In addition, many times the difference between three-quarter power and full power is almost indistinguishable. By adjusting the Throttle Curve, you can change the way the engine reacts to power based on the position of the throttle control stick. For example, you can change the Throttle Curve so that three-quarter stick feels like three-quarter throttle.

The Throttle Curve function is also extremely useful when setting up a twin-engine aircraft. In a twin-engine aircraft, it can be difficult to achieve the exact same throttle response for both engines. Some transmitter allows you adjust the Throttle Curve for the Right and Left engines separately.

For example, you can change the Throttle Curve on one engine to match the response of the other engine, from idle all the way to full throttle. The Throttle Curve function can be programmed separately for each of the Engines. An Input and Output display, along with a graph, that help visualization is generally present in such radios.

Remember

You need to be alive to the way engine and aeroplane responds to your throttle inputs, believe me throttle curve is extremely useful when doing 3D aeros and absolutely essential flying Nitro/Gas Helis

THROTTLE HOLD

The Throttle Hold function allows you to set a specific position that particular throttle throttle servo in a multiengine aeroplane, will Hold and not respond to the throttle control stick. This function is only used when flying twin/multi engine aircraft. Most Transmitters allows you program Throttle Hold for the Right or the Left engine separately.

For example, you can set Throttle Hold at idle for the right engine. After starting and tuning the right engine, you can use the Throttle Hold function to Hold the right engine at idle while you start, warm-up, and tune the second engine. The Throttle Hold function can be programmed separately for each of throttle servos.

WARNING

Keep in mind that it's possible to set the Throttle Hold lower than the throttle End Point Adjustment. For example, with the throttle End Point Adjustment set to -100% and the Throttle Hold set to -150% the servo will move -150% when the Throttle Hold is Activated. Throttle Hold lower than your throttle End Point Adjustment is not recommended, else there is a chance of over driving your control linkage and burning / damaging your servo/hinge.

THROTTLE CUT

The Throttle Cut function allows you to set a specific position that the throttle servo will move to. The Throttle Cut function is primarily used to shut down your engine after flight.

For example, if your engine idles when the throttle control stick is at the -100% position, you can set the Throttle Cut to -120% to shut down your engine when the Throttle Cut function is activated. Some transmitters allows you to program the Throttle Cut percentage values for the Right and the Left engines independently to take into account any differences between throttle linkages. The Throttle Cut function can be programmed separately for each of the throttle servos.

Some Radios like the 14MZ 18MZ you can set below what throttle position cut should function, this prevents engine cutting accidentally when the throttle is above preset value (Typically very slightly above idle)

WARNING

Keep in mind that it's possible to set the Throttle Cut lower than the throttle End Point Adjustment. For example, with the throttle End Point Adjustment set to -100% and the Throttle Cut set to -150% the servo will move -150% when the Throttle Cut is Activated. Throttle Cut lower than your throttle End Point Adjustment is not recommended, else there is a chance of over driving your control linkage and burning / damaging your servo/hinge.

IDLE DOWN (THROTTLE IDLE DOWN)

The Idle Down function allows you to set a specific position that the throttle servo will move to. The Idle Down function is similar to the Throttle Cut function, MAIN DIFFERENCE however, whereas the Throttle Cut function is designed to be used to shut down your engine, the Idle Down function is designed to be used to set your engine to a specific idle speed that is different from the idle speed provided when the throttle control stick is pulled all the way back, yet still maintain the full range of throttle travel. For example, you can set one idle speed that you use during normal flight using the throttle trim switch, then you can program a slower idle speed using the Idle Down function for use during landing or when you want your aircraft to stay in position while idling on a paved runway. The Idle Down function can be programmed separately.

WARNING

Keep in mind that it's possible to set the Idle Down lower than the throttle End Point Adjustment. For example, with the throttle End Point Adjustment set to -100% and the Idle Down set to -150% the servo travel will increase in that direction when Idle Down is Activated. Idle Down lower than your throttle End Point Adjustment is not recommended, else there is a chance of over driving your control linkage and burning / damaging your servo/hinge.

AILERON DIFFERENTIAL

The Aileron Differential function allows you change the ratio of the Up to Down movement of each aileron.

For example, many aircraft exhibit a yaw tendency due to adverse aileron drag ( Read Here for explanation of  Adverse Aileron Drag)when the ailerons are used. Although this can affect any aircraft, it's noticed mostly on high-wing aircraft and aerobatic aircraft. The Aileron Differential function can be used to eliminate the yaw tendency by adding more movement to the upward moving aileron than the downward moving aileron.

For example, if your aircraft tends not to stay in a straight line during rolls, you can adjust the Aileron Differential to make the aircraft roll more axially and therefore in a straight line.

Remember

Although the Aileron Differential settings can be made even if your model uses only one aileron servo, it is of no use.  the Aileron Differential function is intended to be used when your model features two separate aileron servos (one or more servo controlling each aileron). When only one aileron servo is used, changing Aileron Differential percentage values is essentially the same as changing End Point Adjustment. Prior to setting the Aileron Differential, you should ensure that each aileron is moving UP and DOWN the same amount.

basic mixes are done, before we proceed to flaperons ailevators and heli mix, you could ask questions and we could discuss mixes specified here

Gusty sir,

1. A practical usage of Expo's wherein the rates are larger closer to the center (typically called negative, but positive on some systems)

2. . sounds like the V-tail is flying the radio. Am I missing something there?

1. I always use expo, to soften response close to stick neutral, esp on a high throw aeroplane you need a soft centre for precision manoeuvrings. this is also called Stick Gearing or Non_Linear mechanism in real aeroplane (even real aeroplane too has Expo, so to say)

2. Let me explain this, guy flying a Xeno with a Futaba 7C had a V Tail mixer in his Xeno. When i asked him why, he gave me that "Holier than Thou" look and must have thought "wanker !! doesn't even know this. "

My bad i missed the question. To Counter an over restrictive gyro, you could use larger movement at close to centre in certain manoeuvres esp in helis

Also, Some heli pilots (Tariq does it i heard) restrict their full throttle movement with a throttle expo with high centre and zero movement after 65-70% throttle.

1. got that  .

2. probably he was trying a 'ruddervatoreronottle' config or something

PS: That mix for restricting throttle sounds innovative, and useful for a person like me, who flies a helicopter like a plane, 'cut the throttle to land' types...lol

Great thread Gusty... tons of valuable information.

I will try to chip in to see if I can add some value.


Throttle Cut where there is no Throttle Hold function is also a good function in electric planes to restrict motor from accidental start. It can be used as a safety switch. I have this programmed in all my electric planes. In some transmitter like the 18MZ, 8FG and 14SG there is also a great feature called "MOTOR Function" which can be used as a safety feature in electric planes to avoid accidental start of the motor.

Also for gas engines I prefer to have an optical or electronic kill switch over a mechanical (throttle servo) engine kill. It will still work to kill the engine in case of a throttle servo failure.

Also while mixing two channels there is a high possibility to overdrive a servo in case a mix is active. It is important to setup limit on that channel so the mix does not throw the servo over it's available limit when the mix is active.

Example: I have full flaps and a mix of ailerons go up (spoileron) in my landing configuration (airbreaks). The ailerons go 50% up in this configuration and while in high rates, I need full right (100%) aileron. In this situation the mix will provide a throw of 150% which will exceed the limit but the limit setup in in End Points will not let it go beyond 135%. The 135% can be adjusted accordingly.

The 135% in the picture (example) below is the limit.

Thanks Salam, i have flagged that as warning !!

any more issues, doubts you could raise ! else we will get on with further mixes

one generic warning I'd like to put forth chief, mixes shouldn't be changed with receivers on and connected to aircrafts, especially if one is flying multicopters. Although a little care should make this warning redundant

AILERON DIFFERENTIAL ANOTHER EXPLANATION

This is probably the most important advanced feature you will want to program into your transmitter. Aileron differential offers a way to get your plane to roll in a more axial fashion; program in more up-aileron than down-aileron. The downward-deflected aileron creates more drag than the upward-deflected aileron, and that induces a yaw during a roll. To test for this, fly your plane downwind and directly away from you. Pull it to a 45-degree upline and roll it once. If the nose is yawed slightly after the plane has completed the roll, the plane needs aileron differential. To compensate for this differential, a scale aerobatics design such as an Extra will usually require approximately 2 degrees more up-aileron than down-aileron. You may need different amounts of up- and down-aileron for right and left rolls.

A couple of point to the above for newcomers...

Aileron differential can only be programmed if you have separate aileron servos. Aileron differential can also be setup mechanically by angling the servo arm towards the leading edge and attaching the pushrod. (assuming
servo at bottom of wing) With the above method you can achieve aileron differential even with a single aileron servo(use a disc on the servo or one of those star shaped wheels) If you want ultimate precision then you will need the two servo
programmable tx option

hi
i have a turnigy 9 ch
i need to pair my rear wheel servo with my rudder without using a Y connector.....
how do i pair servos with the programming??    

plz help