With a programmable transmitter such as the NX10, you can have as much flexibility as you like.
The suggestions in the manual and the the transmitter setups that you can download from Horizon are created by the people who design and test the BNF planes. A lot of people become dependent on the downloadable setups and never learn how to program their transmitter, and that's unfortunate because you'll miss out on a lot of features of the radio if you don't learn how it works. I understand why that feels like they're "forcing you down a specific path", but if you compare those setups across many planes, they're actually quite inconsistent.
Some background...
The switch assignments in RealFlight for the InterLink DX mimic a lot of the traditional settings for things going back for a couple of decades. Spektrum's history is rooted in how JR radios worked. If you were to pick up a 1st generation DX8, it really did force you down a certain path because each switch had a name (not "A", "B", "C", etc.) and could only do certain things. The traditions represent a cross between airplanes and helicopters.
- Switch A - Gear Up/Down
- Switch B - Transmitter Flight Modes (big on helis, not so much on planes but you might find uses for that with planes too)
- Switch C - Elevator Dual Rate
- Switch D - Flaps
- Switch E - "Aux", sometimes used for the governor switch on helis
- Switch F - Aileron Dual Rate
- Switch G - Rudder Dual Rate
- Switch H - Heli Hold Mode, which made it the standard for airplane throttle cut too
When SAFE came along, that added a wrinkle to the plan in that you now have receiver flight modes. Using a switch assigned to a specific channel, the receiver would change its behavior to change between three different modes. A lot of people use Switch B for that purpose since it's a three-position switch. Why not Switch A? That's a long story...
SAFE originally came out in the form you see it in the AeroScout, with three modes. "SAFE On/Off" is actually misleading, as SAFE is a much bigger collection of functions than a binary on/off setting. SAFE has two ways of controlling the flight. SAFE self-level will use your stick input as a request for a certain bank angle. As long as you hold the stick at a certain percentage, the receiver will try to hold the plane at that percentage of the SAFE bank angle limit. Letting the stick return to center tells the receiver to go back to level flight. The other control is SAFE envelope. In envelope, SAFE lets you fly the plane normally - center stick means keep flying in the same attitude, not necessarily a level attitude. However, if the plane pitches or rolls all the way to the bank angle limit, then the receiver jumps in and stops the plane at the limit and holds it there until you move that stick (ail or ele) back to the center, and then it gives you control back. In SAFE self-level mode, you can also add throttle-to-pitch mix, which is intended to help a beginner control pitch primarily with the throttle stick and to a lesser extent the elevator. Finally, the SAFE feature set also offers Panic Mode. Panic Mode is really just another form of self-level, but it's usually set up as a special mode in the receiver that has smaller bank angle limits and higher SAFE gains so that it forces the plane back to level flight faster. Panic Mode is controlled by a different channel than the regular flight modes.
A real AeroScout uses radio channel 5 to select between Beginner (SAFE self-level) mode, Intermediate (SAFE envelope) mode, and Experienced (no SAFE, only AS3X) mode. On that channel, +100% = Beginner Mode, 0% = Intermediate Mode, and -100% = Experienced Mode. Those are the default % outputs for a three-position switch, so it all works out nicely. Panic is on channel 6, and you must configure that on your radio somehow. Normally it gets assigned to the button or a switch. A value anywhere from +25% to -150% will activate Panic Mode. If you ignore channel 6 and don't do anything to set it up, it will output 0% which is in the range that turns on Panic.
The whole "SAFE On/SAFE Off" thing came along in 2016 when Horizon introduced SAFE Select. SAFE Select how they decided to offer a choice between having SAFE or not having SAFE on BNF planes. True trainers still use the three modes like the AeroScout. Back then, Horizon didn't let us as customers program SAFE on the receivers (AR636's), so the only way to get SAFE was to buy it with that capability. But of course, not all of their BNF buyers wanted SAFE to be active. SAFE Select gives you a way to totally turn SAFE on or off based on how you bind the receiver to the transmitter. If SAFE is available, then you can also set up a switch for "SAFE On" or "SAFE Off" and teach the receiver which channel it's on using a special stick sequencer. Notice that the is "no programming needed" for SAFE Select; you can make these two choices without breaking out programming software and USB cables. That was the point.
The marketing people thought that explaining all three modes for a SAFE trainer were too complicated, and they're not wrong. That's why SAFE Select simplifies the whole thing into On and Off. "SAFE On" is really a mix between Beginner and Intermediate modes. It has self-level like Beginner Mode, and many of their models also have a throttle-to-pitch mix configured in "SAFE On". It's like Intermediate mode in that it offers wider bank angle limits, as the SAFE Select planes are not meant to be someone's first plane. "SAFE Off" is like what it says, with SAFE turned off and only AS3X/AS3X+ active. However, many people would be surprised to learn - because they don't document this - that even in SAFE Off mode, Horizon may be applying rate and expo in the receiver. That depends on the plane, and you really have to dig into the receiver settings to find it. Just like you can get into programming transmitters, you can get into programming receivers and customize all of this stuff too, including SAFE features in the current Spektrum receivers (AR630, 631, 637T, and others).
SAFE Select still has three modes in the receivers. So how does it work? Typically, receiver flight mode 1 is the mode with SAFE self-level enabled. The other two modes are set up to be identical, both with SAFE off. That way, things will work as expected when you use either a two-position switch as Switch A or a three-position switch such as B. When you use a two-position switch, it outputs +100% or -100%, which really corresponds to receiver flight mode 1 and 3 respectively.
Some of the manuals for SAFE Select planes suggest using Switch A since it's a two-position switch, but that messes things up once you have a plane with landing gear. For consistency, many people still use Switch B even with SAFE Select. And if you ever get into programming the receiver yourself, it's typical to use all three modes as SAFE On, AS3X Only, and No Gyro. You probably won't use a two-position switch for the receiver modes if you program it yourself.
Back to dual rate...
That's an age-old debate - using one switch or three. Some people swear by three. They want that much control over the rate for each channel, and the switches are traditionally laid out the way the are so that it's easier to move the switch without moving the hand holding that stick. Some people don't want that complexity and just want one switch for all three. Frankly, you'll find Horizon BNF planes coming with downloadable setups both ways, and it often reflects the preference of the person making the setup. The planes in RealFlight are a mix as well; some use Switch F for all three channels, and some break it out across three switches. Of course, you can program that any way you like to on your radio for your plane. You can use the same switch for rates that's being used for something else - no problem.
In RealFlight, you can use the Aircraft Editor to change the channel that's assigned to each of the three rates. You'll find that on the Radio tab, under Output Channels.
When you're in the Aircraft Editor, keep in mind that you're using RealFlight's channel numbers, not the numbers you see on your NX10. RealFlight typically numbers Output Channels starting with 1 = Aileron, 2 = Elevator, 3 = Throttle, 4 = Rudder. (That's "AETR" ordering. Spektrum uses "TAER" ordering.) The Input Channel numbers correspond to the numbers in the Controller Profile setup. In this case, Input Channel 5 is usually Switch F.
Because it's a computer simulator, it's more complicated to make adjustments like this than it is when you just have a transmitter, a receiver, and an airplane. But it can be done.
