Rethinking Wind Measurement for UXVs: How Ultrasonic Wind Sensors Outperform Pitot Tubes on Drones, USVs, and Autonomous Systems

Pitot Tube vs. FT Ultrasonic Wind Sensor for UXVs

UAVs and UAMs tend to cruise at lower airspeeds than other aviation. Additionally, UAV and UAM platforms that must slow down for package delivery or transition between horizontal and vertical flight require precise measurement at low airspeeds. FT acoustic resonance sensors maintain accuracy from 0 to 75m/s (145 knots). UXVs are highly-vibrational platforms producing intense noise; acoustic resonance is the only ultrasonic technology which is immune to vibrations and noise.

Pitot Tube Airspeed Systems: How They Work and Where They Fall Short

A pitot tube airspeed system measures fluid flow speed by comparing stagnation (total) pressure — the pressure of air forced into the tube as a vehicle moves — with static pressure from the surrounding atmosphere. The difference represents dynamic pressure, which can be converted to airspeed using Bernoulli's principle (Anderson, Fundamentals of Aerodynamics, 2016). Pitot tubes have long been the standard for measuring airspeed in aviation and are also adapted for marine applications such as speed-through-water (STW) logging.

However, for UXVs and autonomous platforms, pitot systems present several operational challenges. At lower airspeeds typically below 40knots, the pressure differential measured by pitot systems becomes very small, making pitot measurements more susceptible to error and noise. In contrast, acoustic resonance wind sensors maintain accuracy and responsiveness in this low-speed regime.

Clogging Risk: Dust, insects, or debris can obstruct the tube openings, leading to inaccurate or lost readings; an issue highlighted by the Federal Aviation Administration in their Advisory Circular 43-6D (2017).

Icing Hazard: Frozen pitot tubes can lead to unreliable or lost airspeed data, an initiating factor in accidents such as Air France Flight 447.

Limited Vector Capability: Pitot systems primarily measure forward airspeed; obtaining full wind vectors (direction and crosswind components) requires additional sensors or assumptions. 

Maintenance Requirements: Pitot systems typically require periodic calibration, cleaning and inspections; burdensome especially in remote or inaccessible installations.

These challenges do not negate the fundamental utility of pitot-systems as they remain an important instrument in aviation. In the context of remote, unmanned platforms, these drawbacks can make it useful to supplement pitot systems with additional sensing technologies.

FAQs 

Q1: What are the operational limitations of pitot tubes in remote or autonomous systems? 

Pitot tubes can ice over, clog, or fail in dusty/sandy environments. They require frequent cleaning and calibration, which is impractical for remote or autonomous operations (Federal Aviation Administration, Advisory Circular 43-6D, 2017).

Q2: How do ultrasonic wind sensors improve mission safety?

FT wind sensors deliver real-time, accurate wind speed and direction with no moving parts, enabling better autopilot control, safer landings, and improved mission success rates (WMO Guide, 2023).

Q3: Are FT wind sensors suitable for small UAVs?

Yes. FT wind sensors are lightweight, compact, and have low power draw, making them ideal even for small fixed-wing or VTOL drones.

Q4: Can FT wind sensors be used on helicopters?

Yes. FT sensors are frequently deployed on rotary-wing platforms during test and evaluation flights, where precise wind measurement is critical. They are not certified for use on commercial passenger aircraft.

References and Further Reading:

ArduPilot Documentation - Airspeed Sensors
https://ardupilot.org/plane/docs/airspeed.html

Anderson, J.D. (2016) Fundamentals of Aerodynamics (6th ed.) New York: McGraw-Hill. ISBN: 978-1260456547.

Federal Aviation Administration (2017). AdvisoryCircular 43-6D: Altitude Reporting Equipment and Transponder System Maintenance and Inspection Practices. Retrieved from
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43-6D.pdf

NASA Glenn Research Center - Pitot Tube Theory https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/pitot-static-tube-speedometer/ (Accessed October 2, 2025)

World Meteorological Organisation (2023). Guide to Instruments and Methods of Observation (WMO-No.8). Geneva, Switzerland. Available at: https://library.wmo.int/records/item/41650-guide-to-instruments-and-methods-of-observation (Accessed October 2, 2025)