Trainer Mode¶
TRAINER provides rate control with pitch and bank angle limits, without self-leveling. It is the closest Wingflight equivalent to the behavior Spektrum calls SAFE Intermediate or Envelope mode. This is a behavioral comparison, not an implementation of Spektrum's proprietary controller.
Flying with Trainer¶
Inside the configured limits, the sticks command rotation rate as in normal stabilized rate flight. Use aileron to establish a bank, center it to stop commanding roll, and apply opposite aileron to roll out. Centering the sticks does not command wings-level flight or capture an ATT HOLD target.
Near a limit, Trainer uses the current gyro rate to anticipate overshoot and intervenes against commands that would carry the aircraft farther out. If an angle is already beyond the limit, it commands a return toward the boundary. Pilot input that helps return remains available.
Trainer uses the normal rate PID controller. Each axis keeps normal I-term decay while its rate command passes through unchanged, including stronger pilot input back into the envelope. I-term decay is suspended only on an axis whose command the limiter is changing, so it can sustain the correction at the limit.
| Mode | Stick behavior | Centered sticks | Pitch/bank envelope |
|---|---|---|---|
| ANGLE | Commands an attitude within the configured angle limit | Commands level flight | Limits the requested attitude |
| TRAINER | Rate control inside the limits | No deliberate self-leveling | Intervenes near/beyond the configured limit |
ANGLE is therefore closer to SAFE Beginner/Angle Demand; TRAINER is closer to SAFE Intermediate/Envelope. See Spektrum's SAFE setup guide for its distinction between angle demand and envelope protection.
Setup¶
- Enable and calibrate the accelerometer. The firmware only offers TRAINER when an accelerometer is available and trainer support is built in.
- Assign TRAINER to a switch range in Modes. If an older Configurator hides it, enable Expert Mode. Updated Configurators show TRAINER without Expert Mode.
- Set Gain, Bank angle limit and Pitch angle limit in Profiles → Trainer (angle limits). Save the TRAINER assignment first so its Profiles panel appears.
- In the Ethos suite, assign TRAINER under Controls → Modes and adjust Gain, Bank and Pitch under Flight Tuning → Advanced → Flight Modes → Acro Trainer. The suite requires MSP API 22.04 or newer; update the firmware snapshot alongside the suite. ANGLE and ATT HOLD have separate tools in the same menu.
- In EdgeTX, Profile – Various exposes the independent limits with API 22.4 firmware. Its older-firmware support retains shared limits.
With MSP API 22.4 firmware and updated clients, ANGLE and TRAINER each have independent limits: bank 10–90° and pitch 10–75°, symmetric in both directions. These match the configurable ranges documented for SAFE angle demand and envelope protection. They do not reproduce Spektrum's proprietary control algorithm or guarantee identical flight response.
Existing profiles retain their shared limits until an axis is changed. On a fresh setup, TRAINER inherits 20° for both axes and ANGLE inherits 55°. There is no universal SAFE default to copy across different aircraft. A legacy shared pitch limit above 75° remains effective until overridden; new explicit pitch limits are capped at 75°.
Trainer Gain controls correction strength when the limit is exceeded;
its default stored value is 75. Firmware also provides the CLI setting
acro_trainer_lookahead_ms (default 50 ms) for predictive intervention.
CLI and compatibility¶
The per-profile settings are angle_roll_limit, angle_pitch_limit,
acro_trainer_roll_limit and acro_trainer_pitch_limit. 0 means inherit
angle_level_limit or acro_trainer_angle_limit, respectively. Nonzero
values use a minimum effective angle of 10°, with the axis maximum above.
The shared settings remain available for older clients and CLI backups.
The new values are stored separately, so upgrading does not reset PID profiles. They follow profile selection, copying and reset. Updated clients show the effective angles and preserve inheritance when an axis is not edited. Older clients cannot edit the independent limits; their shared-limit changes affect only axes still inheriting. Upgrading the Configurator/Ethos suite is therefore recommended when using independent limits.
Use non-overlapping switch ranges for ANGLE and TRAINER. These are alternative modes, not layers: ATT HOLD and ANGLE each take priority over TRAINER when their mode switches overlap. Selecting ANGLE and TRAINER together does not add Trainer limits to Angle mode.
Limits of the protection¶
The angle boundary is a control objective, not a guarantee that the aircraft cannot cross it. Momentum, wind, tuning and available control authority can cause overshoot. Pitch-angle limits do not measure angle of attack or prevent stalls, and Trainer does not manage throttle, altitude or terrain clearance.
Trainer's angle correction does not depend on the airborne estimate or motor output, so cutting throttle does not disable its limits during a glide.