What is propwash oscillation?

Propwash is the low-frequency wobble (roughly 20–60 Hz) that appears when your props fly through their own disturbed air — typically on descents, punch-outs and hard direction changes. It shows in the blackbox as the gyro oscillating around the setpoint even though the sticks are steady.

Is propwash a PID or a filter problem?

Both. You need enough D-term to damp the oscillation, but heavy filtering adds delay that makes propwash worse. The fix is usually cleaner filtering (so you can run more effective D) plus dynamic damping/D_max, not just raising D blindly.

Can I fully eliminate propwash?

You can reduce it a lot, but some propwash is physics. Good filtering, adequate D-term, healthy motors/props and a rigid frame get most quads to where propwash is barely noticeable in normal flying.

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How to Fix Propwash Oscillations

Propwash is that low-frequency wobble on descents and hard stops. It's one of the most common tuning complaints — and one of the most misunderstood. Here's what actually causes it and how to tune it out.

What propwash actually is

When you descend or snap to a stop, your props chop through their own turbulent wake. That disturbed air makes the quad twitch, the flight controller corrects, and if the tune can't damp those corrections fast enough you get a visible 20–60 Hz oscillation. In the blackbox it looks like the gyro ringing around a steady setpoint.

Step 1 — rule out mechanical noise first

Propwash tuning fails when the real problem is noise. Check the FFT: if the gyro is buried in broadband noise, no amount of D-term will help. Fix bent props, worn bearings and loose frames first, then confirm your filters are catching the motor resonance. A clean gyro is the prerequisite.

Step 2 — get D-term high enough to damp it

D-term is what resists the oscillation. Many propwash-y quads simply don't run enough D. Raise D on roll and pitch gradually and re-fly the same test (descents + hard stops). The moment motors start getting hot or the gyro gets fuzzy, you've hit the noise ceiling — back off and improve filtering instead.

Step 3 — use dynamic damping (D_max)

D_max lets Betaflight run a lower base D-term for cool motors and low delay, then boost D only during the fast gyro movements where propwash lives. This is the single most effective propwash tool on modern firmware — it gives you damping when you need it without heating motors the rest of the time.

Step 4 — reduce filter delay

Every filter adds latency, and latency makes propwash worse because the correction arrives late. Once your gyro is clean, walk your lowpass cutoffs up (less filtering) as far as motors stay cool. Less delay = the D-term acts sooner = tighter propwash control. See the filter tuning guide.

Let the blackbox tell you the numbers

The trap with propwash is chasing D and filters in circles. Drone PID Helper reads your descents and hard stops, scores the propwash directly, and tells you whether the fix is more D, dynamic damping or less filter delay — with a CLI diff to apply.

Check your propwash score Read: how to read a blackbox