Propwash is a typical problem in FPV drone flying, particularly throughout altitude drops and sharp 180-degree turns. It manifests as oscillations or vibrations because of the 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 decrease it by way of 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 could cause instability, leading to wobbling or oscillations, particularly throughout maneuvers like sharp turns, fast descents, or aggressive braking. The impact is usually seen within the drone’s video footage as jello-like vibrations, which may be notably irritating for pilots aiming for easy and cinematic pictures.
What Causes Propwash?
Propwash is primarily attributable to 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 cross by way of it once more. This creates a suggestions loop of turbulence that destabilizes the drone.
A number of elements 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 chance of encountering propwash.
- Tuning and PID Settings: Poorly tuned filter and PID settings can exacerbate the results of propwash.
- Weight and Body Design: The drone’s weight distribution and body design can affect the way it handles turbulent air.
Tricks to Cut back Propwash
Lowering or minimizing propwash requires a mix of correct tuning, flight strategies, and {hardware} changes. Listed here are some efficient ideas.
Guarantee Mechanical Integrity
First, be certain that your quad is mechanically sound:
- Make sure the flight controller is soft-mounted, and mounted securely.
- Examine 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 easy, and bells are usually 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 here are my propeller suggestions: https://oscarliang.com/propellers/#Suggestions
Allow RPM Filter
It’s beneficial to allow RPM filtering, following this tutorial: https://oscarliang.com/rpm-filter/.
You probably have BLHeli_S ESCs, it’s best to flash Bluejay firmware onto them. You probably have BLHeli_32 or AM32 ESCs, you’re already set for RPM filtering, observe these guides to configure your ESC for optimum efficiency:
Regulate Filter Settings
As soon as your quad is mechanically sound and working the newest firmware with RPM filtering enabled, you would possibly need to strive these filter changes:
- Disable Gyro Lowpass 1 Filter: This may often be safely turned off with RPM filtering enabled on most quads. It reduces filter delay and improves propwash dealing with. It’s best to do a brief take a look at flight to examine if motors get sizzling earlier than commiting.
- Cut back Filtering Additional: In Betaflight, go to the PID tuning tab and filter settings. Transfer the Gyro Lowpass filter sliders to the suitable (to 1.2 or 1.3) to cut back filtering whereas guaranteeing the quad nonetheless flies effectively with out sizzling motors.
- Nice-Tune: For those who discover issues at greater values (e.g., 1.5), again the sliders down a bit to search out the minimal quantity of filtering you may get away with.
Lowering filtering may help push PID positive factors greater with out inducing oscillations, nevertheless, this requires a clear and well-maintained quad, and with the ability to analyse it by way of Blackbox logs can also be strongly beneficial.
Correct PID Tuning
Default PIDs in Betaflight are usually superb, however there may be all the time room to fine-tune propwash dealing with:
- Improve D-Time period: The D-term in your PID settings helps counteract fast modifications in movement. Greater D achieve may help cut back oscillations attributable to propwash. Nonetheless, growing the D-term an excessive amount of can result in motor overheating and oscillations, so make changes steadily by way of correct tuning strategies.
- Regulate P-Time period and I-Time period: A really perfect PID achieve requires good ratios between P and D, and between P and I. Due to this fact, when making modifications to D achieve, you also needs to alter P and I positive factors to keep up these ratios.
Additional Readings:
Implement Dynamic Idle
Dynamic idle ensures your motors preserve a minimal RPM even in reverse circulate 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 way wider. This enhanced braking functionality noticeably improves prop wash dealing with.
I’ve a complete weblog submit explaining what Dynamic Idle is and the way to configure it: https://oscarliang.com/how-to-enable-and-configure-betaflight-dynamic-idle/
Change the Approach You Fly
Aggressive flying typically results in extra pronounced propwash. By working towards smoother, extra managed maneuvers, you possibly can cut back the turbulence created by your drone’s propellers. For instance, when descending, attempt to pitch ahead barely to reduce air turbulence instantly hitting the propellers, successfully decreasing propwash.
Conclusion
Propwash is a problem that each FPV pilot faces, however with the suitable mixture of tuning, {hardware} changes, and flight strategies, you possibly can considerably cut back its affect. By understanding the causes of propwash and making use of the following pointers, you’ll be capable of take pleasure in a extra steady flight and seize smoother video footage. Joyful flying!
