Betaflight profiles and modes

Summary¶

libdrone uses Betaflight PID profiles and rate profiles selected together by the SB rate switch, giving three flight states: training/low-speed, normal, and sport. Position 1 links a throttle-capped PID profile with soft rates — a gentle, forgiving mode for learning to fly and for any operation where a lower top speed is wanted. Because the throttle cap and the soft rates switch together, "position 1" means slow-and-calm on every aircraft. Switching is instant in flight with no reboot. A low top speed can also matter for regulatory reasons depending on how and where you fly — whether it does is a question for legal-and-regulatory; this atom covers only the mechanism.

Concept¶

PID profiles vs rate profiles, and why they are linked¶

Betaflight separates two independently switchable configuration sets:

PID profiles (up to 3) store PID gains, filter settings, and throttle limiting. The throttle limit is what caps maximum speed — a rate profile cannot do this.

Rate profiles (up to 3) store stick sensitivity (rates, expo, RC smoothing). They change how twitchy or gentle the sticks feel, but they do not cap speed.

A beginner "calm" mode needs both at once: a throttle cap so full stick does not rocket the aircraft away, and soft rates so stick inputs are forgiving. libdrone therefore links the two: selecting the rate-switch position also selects the matching PID profile, so one switch movement changes both together. This is configured in Betaflight so that rate profile and PID profile track each other.

Important: the throttle cap (speed limit) lives in the PID profile, not the rate profile. If the profile link is misconfigured, the rates will soften but the speed will NOT be capped. The worst case is "training mode is faster than expected" — verify the link on the bench (see Procedure). If you are relying on a speed ceiling for a regulatory reason, the requirement and whether it applies is a matter for legal-and-regulatory; do not assume this mechanism makes any operation legal.

The three SB positions¶

As a first-time pilot you should spend your entire early sessions in position 1, in Angle mode (SD up). Move to position 2 only once hovering and basic manoeuvres are comfortable. Position 3 is for much later.

Low-speed / training mechanism (PID Profile 2)¶

The cap is THROTTLE_LIMIT_TYPE SCALE with THROTTLE_LIMIT_PERCENT. The sticks still reach 100 % of their range, but actual motor output is scaled down. This is a simple, zero-latency mechanical cap that holds regardless of GPS or FC state — if GPS is lost, the cap remains.

For SCRAP (training): start at throttle_limit_percent = 55. There is no target speed to calibrate to — pick a value that feels controllable and lower it if the aircraft still gets away from you. This is about learning, not a number.

For Pro (calibrated speed ceiling): if an operation requires a specific maximum ground speed, calibrate the cap so peak GPS speed stays a clear margin below that target. Fly a straight pass at full throttle in calm conditions, read peak GPS speed, and adjust. The calibrated value varies with battery charge, payload weight, and conditions — calibrate on the day and document the value with the payload weight used. Whether such a speed limit is required for your operation is a question for legal-and-regulatory, not an assumption to make here. See throttle-limiting for the full mechanism.

Angle mode for beginners (SD)¶

The SD switch selects flight mode: Angle (up) self-levels — release the sticks and the aircraft returns to level. Acro (down) does not self-level and holds whatever attitude you set. A first-time pilot should learn in Angle: it is far more forgiving and lets you focus on position and altitude before adding attitude control. Angle mode requires the accelerometer enabled in Betaflight (it is on by default). Move to Acro only deliberately, much later in the piloting-progression.

Reference¶

PID Profile 2 — throttle cap overlay¶

Apply on top of the base configuration. Paste in CLI:

profile 2
set throttle_limit_type = SCALE
set throttle_limit_percent = 55
save

SCRAP: 55 % is a sensible training start; lower if needed. Pro: calibrate to GPS speed ≤ 4.8 m/s (see Procedure), then save the value.

Linking the PID profile to the rate switch¶

Configure Betaflight so rate-profile selection also selects the matching PID profile, so the SB switch moves both together. Verify the link on the bench before flying — the cap must follow the switch, not just the rates.

Rate profile starting values¶

# Rate profile 1 — training / low-speed (soft, forgiving)
rateprofile 1
set roll_rc_rate = 70
set pitch_rc_rate = 70
set yaw_rc_rate = 70
set roll_expo = 25
set pitch_expo = 25
set yaw_expo = 20

# Rate profile 2 — normal
rateprofile 2
set roll_rc_rate = 90
set pitch_rc_rate = 90
set yaw_rc_rate = 80
set roll_expo = 15
set pitch_expo = 15
set yaw_expo = 10

Rate profile 1 uses lower rc_rate and higher expo than profile 2 — both make stick response gentler around centre, which is what a learning pilot wants.

Procedure¶

Verifying the profile link on the bench (props off)¶

1. Connect to Betaflight Configurator, battery connected, props removed.
2. Set SB to position 1. Confirm the active PID profile is 2 and the active rate profile is 1 (shown in Configurator).
3. Set SB to position 2. Confirm PID profile and rate profile both change to the normal pair. If only the rates change and the PID profile does not, the link is not configured — fix before flying.
4. In position 1, briefly run the motors up (still props off) and confirm in the Motors tab that output is capped below the position-2 maximum.

Calibrating the cap for the day (Pro, if a speed target applies)¶

1. Select SB position 1 (low-speed).
2. Fly outdoors in calm conditions. Make a straight horizontal pass at full throttle away from the pilot.
3. Note peak GPS speed from OSD or post-flight Blackbox.
4. If peak speed > your target: reduce throttle_limit_percent by 5.
5. If peak speed is well under target: increase by 5.
6. Repeat until peak speed sits a clear margin below the target. Save in Profile 2 and document the value with the payload weight used.

Switching in flight¶

The SB position can be changed at any time; the new profile pair takes effect immediately with no glitch or reboot. Verify the active position before arming — configure the profile number as an OSD element so it is visible in the goggles.

Rationale¶

Why training and speed-ceiling are the same switch position¶

A beginner needs a slow, forgiving mode to learn in. Some operations need a speed-capped mode for operational or regulatory reasons. Both are the same mechanism — a throttle cap plus soft rates — so libdrone makes them the same switch position rather than two separate controls. The pilot learns "position 1 = slow and calm" on SCRAP as a first-time flyer, and that exact habit carries straight to Pro. One muscle memory serves both the learning curve and any later speed-limited operation. Whether a given operation requires a speed limit is a regulatory question — see legal-and-regulatory.

Why throttle scale rather than GPS-based speed limiting¶

Betaflight does not implement GPS-based speed limiting in standard operation — GPS speed feedback would need an outer loop at the GPS update rate (10 Hz), incompatible with tight PID timing. Throttle scale is a simple, reliable, zero-latency cap that guarantees motor output cannot exceed the set level regardless of GPS or FC state. It is fail-safe: if GPS is lost, the cap remains active.

Connections¶

requires: - betaflight-setup related: - edgetx-model - betaflight-gps-rescue - lipo-batteries - pid-proportional-term - throttle-limiting - legal-and-regulatory - piloting-progression leads_to: - betaflight-gps-rescue - throttle-limiting