Propwash is a standard subject in FPV drone flying, particularly throughout altitude drops and sharp 180-degree turns. It manifests as oscillations or vibrations as a result of turbulent airflow created by a drone’s propellers, considerably impacting flight stability and video high quality. This tutorial will discover what propwash is, what causes it, and how one can reduce it via tuning and configuration changes.
What’s Propwash?
Propwash happens when the turbulent air created by a drone’s propellers interferes with the drone’s flight. This turbulence may cause instability, leading to wobbling or oscillations, particularly throughout maneuvers like sharp turns, speedy descents, or aggressive braking. The impact is usually seen within the drone’s video footage as jello-like vibrations, which will be significantly irritating for pilots aiming for clean and cinematic photographs.
What Causes Propwash?
Propwash is primarily brought on by the interplay of the drone’s propellers with turbulent air. When a drone is in movement, particularly throughout fast maneuvers, the air disturbed by the propellers doesn’t have sufficient time to settle earlier than the propellers move via it once more. This creates a suggestions loop of turbulence that destabilizes the drone.
A number of components could make propwash worse:
- Propeller Design: The form, measurement, and pitch of the propellers have an effect on how air is moved.
- Flight Maneuvers: Aggressive maneuvers enhance the probability of encountering propwash.
- Tuning and PID Settings: Poorly tuned filter and PID settings can exacerbate the consequences of propwash.
- Weight and Body Design: The drone’s weight distribution and body design can affect the way it handles turbulent air.
Tricks to Scale back Propwash
Decreasing or minimizing propwash requires a mix of correct tuning, flight strategies, and {hardware} changes. Listed below are some efficient suggestions.
Guarantee Mechanical Integrity
First, make sure that your quad is mechanically sound:
- Make sure the flight controller is soft-mounted, and mounted securely.
- Test for free screws on the body, motors, and different elements.
- Confirm that no carbon fiber plates within the body are cracked, and the body is as stiff as it may be.
- Guarantee motors are in good situation, bearings are clean, and bells should not free.
Use Low Pitch Propellers
Utilizing high-quality, low-pitch propellers could make a big distinction in dealing with propwash. Whereas higher-pitch props are nice for attaining greater high speeds, lower-pitch props can change RPM sooner, making your drone extra responsive and faster to regulate to air turbulence.
Listed below are my propeller suggestions: https://oscarliang.com/propellers/#Suggestions
Allow RPM Filter
It’s really useful to allow RPM filtering, following this tutorial: https://oscarliang.com/rpm-filter/.
When you have BLHeli_S ESCs, it is best to flash Bluejay firmware onto them. When you have BLHeli_32 or AM32 ESCs, you’re already set for RPM filtering, comply with these guides to configure your ESC for optimum efficiency:
Regulate Filter Settings
As soon as your quad is mechanically sound and operating the newest firmware with RPM filtering enabled, you may wish to attempt these filter changes:
- Disable Gyro Lowpass 1 Filter: This will often be safely turned off with RPM filtering enabled on most quads. It reduces filter delay and improves propwash dealing with. You must do a brief take a look at flight to test if motors get scorching earlier than commiting.
- Scale back Filtering Additional: In Betaflight, go to the PID tuning tab and filter settings. Transfer the Gyro Lowpass filter sliders to the correct (to 1.2 or 1.3) to cut back filtering whereas making certain the quad nonetheless flies properly with out scorching motors.
- High-quality-Tune: When you discover issues at greater values (e.g., 1.5), again the sliders down a bit to seek out the minimal quantity of filtering you may get away with.
Decreasing filtering may also help push PID good points greater with out inducing oscillations, nonetheless, this requires a clear and well-maintained quad, and having the ability to analyse it via Blackbox logs can also be strongly really useful.
Correct PID Tuning
Default PIDs in Betaflight are typically superb, however there’s all the time room to fine-tune propwash dealing with:
- Improve D-Time period: The D-term in your PID settings helps counteract speedy modifications in movement. Greater D acquire may also help scale back oscillations brought on by propwash. Nonetheless, rising the D-term an excessive amount of can result in motor overheating and oscillations, so make changes step by step via correct tuning strategies.
- Regulate P-Time period and I-Time period: An excellent PID acquire requires good ratios between P and D, and between P and I. Due to this fact, when making modifications to D acquire, you also needs to regulate P and I good points to take care of these ratios.
Additional Readings:
Implement Dynamic Idle
Dynamic idle ensures your motors preserve a minimal RPM even in reverse movement conditions, minimizing propwash.
When prop wash happens, the flight controller makes an attempt to stabilize the quadcopter by quickly dashing up or slowing down the motors. With out Dynamic Idle, the minimal RPM your motors can attain is 5.5% by default. In distinction, when Dynamic Idle is enabled, Betaflight can command the motors to drop to 0% RPM, so the vary of throttle the motors can attain when preventing prop wash is far wider. This enhanced braking functionality noticeably improves prop wash dealing with.
I’ve an entire weblog submit explaining what Dynamic Idle is and find out how to configure it: https://oscarliang.com/how-to-enable-and-configure-betaflight-dynamic-idle/
Change the Means You Fly
Aggressive flying typically results in extra pronounced propwash. By training smoother, extra managed maneuvers, you’ll be able to scale back the turbulence created by your drone’s propellers. For instance, when descending, attempt to pitch ahead barely to attenuate air turbulence immediately hitting the propellers, successfully decreasing propwash.
Conclusion
Propwash is a problem that each FPV pilot faces, however with the correct mixture of tuning, {hardware} changes, and flight strategies, you’ll be able to considerably scale back its influence. By understanding the causes of propwash and making use of the following pointers, you’ll be capable to take pleasure in a extra steady flight and seize smoother video footage. Pleased flying!