Dynamic D

Dynamic D varies the D-term between a base D value (active during calm, smooth flight) and a higher D Max value (active during fast moves and propwash). It lets you keep D low enough to avoid motor heat and noise in cruise, while still having strong damping available when the quad needs it, e.g., during hard flips or in propwash.

Dynamic D has been available since Betaflight 4.3. It is enabled by default.

How It Works

In calm flight, D stays at the D value. When the quad detects fast movement, D rises toward D Max. Two signals independently trigger the boost — whichever is stronger wins:

1. Gyro signal — detects actual quad movement: fast flips/rolls, propwash oscillations, vibration from a bent prop. Sensitivity is set by D Max Gain.
2. Setpoint signal — detects stick input before the quad has moved, allowing D to rise earlier and anticipate the move. Contribution is set by D Max Advance.

A 10 Hz low-pass filter is applied to the gyro signal before boost calculation. This introduces a brief delay, which is intentional — the boost ramps up toward the end of a flip rather than immediately, so it doesn't dampen the quad's initial responsiveness to your input.

When D Max is set to 0, Dynamic D is effectively disabled and D stays constant at the base D value.

Tuning in the Configurator

Dynamic D settings are on the PID Tuning tab. The PID sliders show Damping (D Gains) (base) and Dynamic Damping (D Max) (peak) for each axis. In the PID Controller Settings section, D Max Gain and D Max Advance control the boost response.

Step-by-step approach

1. Disable Dynamic D first. Set D Max for roll and pitch to 0 in the PID table. Fly and find your optimal D with constant damping — this is your baseline.

2. Re-enable and set D Max. Once you have a good base D, set D Max to 20–30% above D as a starting point (e.g. D = 30 → D Max = 38–40).

3. Adjust D Max Gain. Default (37) is conservative and safe for most builds. Raise toward 45 on very clean freestyle builds; lower toward 20–25 for racing or noisier setups.

4. Check D Max Advance. Default (20) is intentionally low — enough to take the edge off overshoot on hard moves without adding noticeable delay. Set to 0 for racing. Higher values (up to 60–80) cause D to rise earlier but introduce more delay; only explore this if gyro-triggered boost alone doesn't control overshoot on very responsive builds.

5. Verify with logs or motor temperature. After any change, do a short hover and check motor temperature. If motors are significantly hotter, reduce D Max Gain or lower D Max.

When to Use Dynamic D

Freestyle / cinematic — Great for propwash control. Set D to your comfortable cruising value and D Max 20–40% higher to absorb propwash. D Max Gain of 35–45 works well on clean builds.

Racing — Responsiveness matters more than propwash control. Keep D Max Gain at or below the default (37) so D stays near the base value during normal flying and only peaks on hard moves. Some racers disable Dynamic D entirely for predictable, constant D.

Hot motors / noisy build — Set D lower than you otherwise would (reducing noise and heat in cruise), then set D Max higher proportionally to recover damping during fast moves where it's most needed.

When Not to Use Dynamic D

If your build is noisy (bent props, loose hardware, dirty motors), a high D Max Gain will cause D to spike whenever there is vibration, pushing toward D Max continuously. Either lower D Max Gain significantly or disable Dynamic D until the build is cleaned up.

CLI Reference (2025.12)

Variable	Default	Range	Configurator label	Description
d_roll	30	0–250	D (roll)	Base D on roll — active in smooth flight
d_pitch	34	0–250	D (pitch)	Base D on pitch
d_yaw	0	0–250	D (yaw)	Base D on yaw
d_max_roll	40	0–250	D Max (roll)	Peak D on roll — reached during fast moves and propwash
d_max_pitch	46	0–250	D Max (pitch)	Peak D on pitch
d_max_yaw	0	0–250	D Max (yaw)	Peak D on yaw
d_max_gain	37	0–100	D Max Gain	Boost sensitivity — higher values push D toward D Max more quickly and aggressively
d_max_advance	20	0–200	D Max Advance	Setpoint contribution to the boost trigger — higher values cause D to rise earlier when sticks are moved

These are profile-specific settings.

Debug Logging

To inspect Dynamic D in Blackbox:

set debug_mode = D_MAX

Channel	Content
[0]	Gyro factor — contribution of gyro to boost (%, relative to D Max Gain)
[1]	Setpoint factor — contribution of sticks to boost (%, relative to D Max Advance). The larger of [0] and [1] determines boost level.
[2]	Actual active D gain on roll (instantaneous)
[3]	Actual active D gain on pitch (instantaneous)

A well-tuned Dynamic D setup shows [2] and [3] sitting near D in smooth flight, rising to near D Max during hard flips and propwash, and returning quickly.

Version History

The variable naming has changed significantly across firmware versions. If you are migrating from an older tune, note the following:

Firmware	Configurator "D" label	Configurator "D Max" label	CLI base D variable	CLI peak D variable
4.2 and earlier	D (constant)	—	d_roll	—
4.3–4.5	D (base)	D Max (peak)	d_min_roll	d_roll
2025.12+	D (base)	D Max (peak)	d_roll	d_max_roll

The Configurator's labels ("D" for base, "D Max" for peak) were consistent from 4.3 onward. However, the underlying CLI variable names were swapped relative to the labels until 2025.12, when the firmware was updated to align with the Configurator's mental model.

Migrating a 4.5 tune to 2025.12:

• Your old d_roll value (which was peak D) becomes d_max_roll
• Your old d_min_roll value (which was base D) becomes d_roll
• d_min_boost_gain → d_max_gain
• d_min_advance → d_max_advance