# FPV Radio Controller Setup: Dual Rates, Throttle Curves, and Mixing
Your radio controller is the physical interface between your brain and the drone. Properly configured rates, throttle curves, and channel mixing make the difference between a quad that feels locked-in and one that fights you. This guide covers radio-side tuning for OpenTX, EdgeTX, and ELRS radios.
## Dual Rates and Expo on the Radio
While Betaflight handles rates on the flight controller side, radio-side rates and expo provide an additional layer of control — especially useful for fixed-wing FPV and fine-tuning stick feel per model.
### What Dual Rates Do
Dual rates reduce the maximum stick output to a percentage of full travel. A 70% rate means full stick deflection only outputs 70% of the channel range.
| Rate Setting | Stick Feel | Best For |
|—|—|—|
| 100% (default) | Full travel, fastest response | Racing / freestyle |
| 70-85% | Softer, reduced maximum throw | Cinematic / precision |
| 50-70% | Very soft | Beginners / fixed-wing |
### Expo (Exponential)
Expo softens stick response around center without reducing maximum throw. High expo = gentle near center, aggressive at edges.
| Expo Value | Center Feel | Edge Response |
|—|—|—|
| 0% | Linear | Linear |
| 20-30% | Soft center | Full speed at edges |
| 40-50% | Very soft center | Aggressive at edges |
| 60%+ | Extremely soft | Very sharp at edges |
## Throttle Curves
A linear throttle curve means 50% stick = 50% throttle output. For many FPV builds, this is not ideal. Custom throttle curves compensate for motor power characteristics and personal preference.
### Common Throttle Curve Strategies
| Curve Type | Use Case | Effect |
|—|—|—|
| Linear (default) | All-around | Direct 1:1 mapping |
| Soft bottom | Freestyle / racing | More resolution at low-mid throttle for precise hovering and proximity control |
| Aggressive top | Cinematic cruising | Faster response at high throttle for punch-outs |
| Throttle cut at bottom 5% | Safety | Prevents accidental spin-up; requires deliberate arming |
### Setting a Custom Throttle Curve (EdgeTX)
1. Go to **Model Setup → Mixes → Thr**
2. Edit the mix and select **Curve**
3. Create a custom curve: e.g., points at (-100, -100), (-50, -60), (0, -20), (50, 30), (100, 100)
4. This creates a “soft bottom” curve — fine control at low throttle
## Channel Mixing for Advanced Setups
### Flaperons / Spoilerons on Fixed Wing
Mix aileron and flap channels for configurable wing profiles:
“`
CH2 (Aileron) += CH6 (Flap) weight 30%
CH6 (Flap) += CH2 (Aileron) weight 30%
“`
### Pan/Tilt Camera Gimbal Mixing
Mix head tracker channels to camera gimbal servos:
“`
CH7 (Pan) = TR1 weight 100%
CH8 (Tilt) = TR2 weight 100%
“`
## Switch Configuration Best Practices
| Function | Switch Type | Channel |
|—|—|—|
| Arm | 2-position (SA or SF) | AUX1 (CH5) |
| Flight Mode | 3-position (SB or SE) | AUX2 (CH6) |
| Buzzer | Momentary (SH) | AUX3 (CH7) |
| Turtle Mode | 2-position | AUX4 (CH8) |
| Pre-arm | Momentary | Logical switch |
## Recommended Radio Gear
A quality radio with smooth hall gimbals and flexible EdgeTX programming makes all the difference. The RadioMaster TX16S and Boxer series — available at [uavmodel.com](https://uavmodel.com) — offer full EdgeTX support with ample switches, color touchscreens, and precision hall-effect gimbals for fine rate and curve tuning.