INAV (Inertial Navigation Assisted Vehicle) is a popular flight control firmware used in fixed-wing drones, multirotors, and other unmanned vehicles, emphasizing GPS-assisted navigation features. One of INAV’s standout features is its On-Screen Display (OSD), which provides real-time flight data directly on a pilot’s screen, making it easier to monitor flight metrics, navigate, and manage battery usage. The OSD (INAV OSD_Speed_Source) is invaluable to pilots, giving them immediate access to data on altitude, distance, speed, battery voltage, GPS coordinates, and more.
The “OSD Speed Source” in INAV refers specifically to the setting that determines how speed data is displayed on the OSD. This choice of source is crucial for accuracy and depends on a pilot’s specific setup and flying needs. INAV’s OSD speed source setting can utilize data from different sources, primarily from GPS or the pitot tube (airspeed sensor), and can also use ground speed or airspeed as needed. Each option has unique advantages and limitations, depending on the type of flight or environment. This article will explore INAV OSD speed sources, their configurations, and best practices for selecting and using them.
Understanding Speed Sources in INAV
INAV’s OSD provides multiple options for speed sources that pilots can configure based on their requirements – INAV OSD_Speed_Source:
- GPS Ground Speed: This is the speed relative to the ground, derived from GPS data. It accounts for factors like wind but doesn’t reflect the airspeed (the speed relative to the surrounding air). GPS ground speed is ideal for general navigation, especially when wind conditions are not a significant factor.
- Airspeed (Pitot Tube): The pitot tube measures airspeed, which is the speed of the drone relative to the air. This speed is crucial for fixed-wing aircraft that require a minimum airspeed to stay aloft. Airspeed measurements are generally more accurate for aircraft performance but can be affected by sensor calibration and atmospheric conditions.
- Hybrid Speed (Combined Ground Speed and Airspeed): INAV also offers a hybrid option that combines GPS and airspeed data to give a more comprehensive speed measurement, accounting for wind and other factors.
Each of these speed sources has distinct applications, and understanding when and how to use them is key to maximizing performance and flight safety.
Importance of Choosing the Correct Speed Source
The choice of speed source affects not only the accuracy of the data displayed on the OSD but also how the vehicle behaves in autonomous flight modes. Incorrect speed settings can lead to inefficiencies (INAV OSD_Speed_Source), such as higher battery consumption or even potential flight instability in certain conditions. Pilots need to be aware of how speed data impacts their flight, especially when using advanced navigation modes like return-to-home (RTH), waypoint missions, or altitude hold.
GPS Ground Speed
What is GPS Ground Speed?
GPS ground speed is the speed of the vehicle relative to the ground, as determined by GPS satellites (INAV OSD_Speed_Source). This measurement is independent of wind and air density, providing a straightforward and reliable measurement that is easy to interpret for general navigation. Since GPS ground speed doesn’t account for wind speed, it may not always accurately reflect the true speed of the vehicle in relation to the surrounding air.
Pros and Cons of Using GPS Ground Speed
Pros:
- Accurate in Calm Conditions: In environments with little to no wind, GPS ground speed provides a reliable measure of the drone’s movement.
- Readily Available: GPS data is widely available on most drones without requiring additional sensors.
- Consistent Across Altitudes: GPS-based measurements are generally consistent regardless of altitude, provided the drone maintains a clear view of the sky.
Cons:
- Not Accurate in Windy Conditions: GPS ground speed does not account for wind, so it may overestimate or underestimate speed when flying into or with the wind.
- Not Suitable for Fixed-Wing Takeoffs and Landings: Fixed-wing aircraft need accurate airspeed data to ensure they stay aloft, especially at low speeds and during takeoff or landing.
Applications for GPS Ground Speed
GPS ground speed is commonly used for multirotor drones and other vehicles that fly low and don’t require the precise speed measurements essential for aerodynamic control. It’s ideal for drones that don’t use fixed wings (INAV OSD_Speed_Source), where airspeed isn’t as critical. GPS ground speed is also suitable for casual flights, photography, and filming, where simplicity and reliability are prioritized over exact speed measurements.
Airspeed (Pitot Tube)
What is Airspeed?
Airspeed measures the vehicle’s speed relative to the air surrounding it. This data is typically obtained from a pitot tube, a sensor that calculates airspeed by measuring the pressure difference between moving air (dynamic pressure) and stationary air (static pressure). Airspeed is especially important for fixed-wing aircraft because it indicates whether they are moving fast enough to generate the lift required to stay aloft – INAV OSD_Speed_Source.
Pros and Cons of Using Airspeed
Pros:
- Critical for Fixed-Wing Stability: Airspeed is essential for fixed-wing aircraft, especially during takeoff and landing, when precise speed control is vital.
- Accounts for Wind Conditions: Unlike GPS ground speed, airspeed reflects the true speed of the vehicle relative to the air, accounting for wind influence.
- Improved Battery Efficiency: Fixed-wing aircraft can use airspeed data to optimize their power usage, as airspeed directly correlates to lift generation.
Cons:
- Requires Additional Sensor: A pitot tube or other airspeed sensor is required, which adds weight and complexity to the drone setup.
- Needs Calibration: Airspeed sensors must be calibrated accurately; otherwise, they can deliver inaccurate readings.
- Subject to Environmental Influence: Factors like air density, altitude, and temperature can affect airspeed measurements.
Applications for Airspeed
Airspeed is primarily used in fixed-wing drones or aircraft that require precise speed control for flight stability (INAV OSD_Speed_Source). It is essential for scenarios where the pilot needs to maintain consistent flight conditions, such as long-range flights, high-altitude missions, and situations with variable wind. Airspeed data also helps in executing smooth takeoffs and landings.
Hybrid Speed (Combined Ground Speed and Airspeed)
What is Hybrid Speed?
Hybrid speed is a combination of GPS ground speed and airspeed data, providing a more comprehensive understanding of the vehicle’s movement. This approach uses GPS to calculate ground speed while simultaneously using airspeed to understand how the vehicle moves relative to the surrounding air (INAV OSD_Speed_Source). Hybrid speed data is helpful in scenarios where both airspeed and ground speed are important for maintaining stable flight, such as in turbulent or high-wind environments.
Pros and Cons of Using Hybrid Speed
Pros:
- Adaptable to Complex Conditions: Combines the benefits of GPS ground speed and airspeed, making it ideal for varied environments with unpredictable wind conditions.
- Accurate for Autonomous Modes: Hybrid speed provides a balanced measure, which can enhance the accuracy of autonomous flight modes like RTH and waypoint missions.
- Suitable for Mixed Use: Works well for both multirotor and fixed-wing aircraft that may switch between flying in calm and windy conditions.
Cons:
- Complex Data Processing: Requires both GPS and airspeed sensors, increasing the complexity of the setup.
- Additional Hardware Required: Needs both GPS and a pitot tube or similar airspeed sensor, which can add weight and power consumption.
Applications for Hybrid Speed
Hybrid speed is suitable for drones that operate in mixed environments or perform various tasks requiring both GPS-based ground speed and accurate airspeed measurements (INAV OSD_Speed_Source). This setup is particularly useful for long-range flights and autonomous missions that might experience variable wind conditions.
Configuring INAV OSD Speed Source
Setting up the correct OSD speed source in INAV is essential for displaying accurate speed data on your OSD and ensuring smooth operation during flight. Here’s how to configure the speed source in INAV (INAV OSD_Speed_Source):
- Connect to INAV Configurator: Open the INAV Configurator software on your computer and connect your flight controller.
- Access the OSD Settings: Go to the OSD tab in INAV Configurator, where you can configure what data appears on your screen during flight.
- Choose Speed Source: In the OSD tab, locate the “Speed Source” option. The available choices will be:
- GPS for ground speed
- Airspeed for pitot tube-based measurements
- Hybrid for a combination of both GPS and airspeed.
- Adjust Layout and Settings: Arrange your OSD layout to display speed information in a way that suits your flight needs. Customize the layout to show additional data such as altitude, distance, battery voltage, and navigation details.
- Test and Calibrate: Before your flight, test your setup to ensure that the speed source works correctly. For airspeed sensors, calibrate them based on the manufacturer’s instructions to avoid inaccurate readings.
- Save and Deploy Settings: Once configured, save the settings to the flight controller, ensuring they will be retained when the drone is powered off.
Best Practices for Using OSD Speed Sources in INAV
Choose the Appropriate Speed Source for the Flight Type
For multirotors and casual flights, GPS ground speed is usually sufficient (INAV OSD_Speed_Source). However, fixed-wing pilots and those flying in varying wind conditions may benefit from using airspeed or hybrid speed sources.
Calibrate Sensors Regularly
If using airspeed or hybrid settings, make sure to calibrate the pitot tube or airspeed sensor frequently to maintain accurate readings (INAV OSD_Speed_Source). A well-calibrated sensor ensures safety and efficiency, particularly during takeoffs and landings.
Monitor Battery Usage
Different speed sources can impact battery life, especially if extra sensors are involved. Pilots should monitor battery consumption and plan their flights accordingly, as airspeed sensors can draw additional power.
Test in Different Conditions
It’s a good practice to test your selected speed source in varying weather conditions to understand how it responds. This will give you confidence in its reliability and help you decide if adjustments are needed.
Adjust OSD Layout for Visibility
Make sure the speed data is easy to read on your OSD layout, especially if you’re flying with FPV goggles or a monitor. Large, clear fonts and simple layouts can make a significant difference in real-time decision-making during flight.
Conclusion
The INAV OSD speed source setting is a crucial feature that allows pilots to customize how speed data is collected and displayed during flight. Understanding the differences between GPS ground speed, airspeed, and hybrid speed sources is essential for achieving accurate and reliable data. The choice of speed source can affect flight performance, battery consumption, and navigation efficiency, especially when using advanced autonomous modes.
By configuring and calibrating the correct speed source, pilots can improve their flight experience and make data-driven decisions, whether flying a multirotor drone in calm conditions or a fixed-wing aircraft through variable winds. Ultimately, INAV’s flexibility with speed sources allows for versatile applications across a range of drone types and flight environments.
FAQs
1. What is the default speed source in INAV?
The default speed source in INAV is usually set to GPS ground speed, which works well for multirotor drones and general navigation.
2. When should I use airspeed as the speed source?
Airspeed is ideal for fixed-wing aircraft that rely on precise speed data for stable flight, especially during takeoffs and landings.
3. What is hybrid speed, and when is it useful?
Hybrid speed combines GPS ground speed and airspeed, providing a more comprehensive speed measurement. It’s useful for flights with variable wind conditions.
4. Do I need a pitot tube for airspeed measurements?
Yes, a pitot tube or similar airspeed sensor is required to measure airspeed accurately. This hardware measures the pressure difference to determine speed relative to the air.
5. How do I change the OSD speed source in INAV?
You can change the OSD speed source in the INAV Configurator’s OSD settings by selecting either GPS, airspeed, or hybrid options.
6. Can I use GPS ground speed for fixed-wing flights?
While GPS ground speed can be used, it’s not ideal for fixed-wing aircraft, as it doesn’t account for wind, which can affect the aircraft’s ability to maintain stable flight.