New Flapping Robot Swims And Flies Like Diving Bird

New Flapping Robot Swims And Flies Like Diving Bird

Engineers from MIT and EPFL in Lausanne, Switzerland, have developed a robot capable of swimming underwater and flapping its way into the air, mimicking the behavior of diving seabirds. The "flapping-wing aerial-aquatic vehicle," known as the FAAV, is designed to transition between air and water, two mediums with vastly different physical properties.

The project was led by Raphael Zufferey, an assistant professor of mechanical engineering at MIT and head of the AURA Lab. Zufferey and his team spent two years developing the vehicle, drawing inspiration from approximately 100 species of birds, such as petrels, gulls, and Atlantic puffins, that utilize their wings for both flight and swimming.

According to Zufferey, water is 1,000 times denser than air. He noted that while birds like puffins can swim at speeds of 3 meters per second and fly rapidly, no one had previously attempted to replicate this in a mobile robotic system.

Engineering the Transition

The robot weighs less than 300 grams — about half a pound — and features a wingspan of not quite three feet. Its design includes a central fuselage housing a battery and a waterproof electric motor, which drives a crankshaft to move the wings. To maintain neutral buoyancy and keep the robot light enough for flight, the team opted for an open body plan where every individual component is waterproofed, allowing water to flood the system.

The wings are constructed from translucent nylon fabric reinforced with carbon fiber struts and coated with hydrophobic nanoparticles to help wick away water. The team tested three different wing sizes: small (60 centimeters), medium (80 centimeters), and large (100 centimeters).

Research conducted in a water tank and at Lake Geneva in Switzerland revealed that the robot functions most reliably with medium-sized wings. The team found that flexibility is essential; wings must be firm enough for flight but flexible enough to minimize flapping amplitude while underwater.

The FAAV departs from biological reality in two primary ways to reduce mechanical complexity. First, it lacks legs. While most diving birds, such as ducks and puffins, paddle their feet to take off from the water's surface, Zufferey and his colleagues discovered that the robot could launch itself into the air without a paddling maneuver.

Second, the team decided against foldable wings, which would have required additional joints and motors. Instead, they relied on wing flexibility. A motorized tail allows the robot to adjust its pitch to dive or climb.

Performance and Mechanics

The robot's flight and swim speeds are similar to those of actual diving birds. When flapping at a frequency of around 5 hertz (five flaps per second), the robot can swim at speeds of almost 1 meter per second and fly at around 6 meters per second.

To transition from water to air, the robot requires a specific configuration. The team determined that the robot should be pitched at 70 degrees, a steep angle that prevents wingtips from hitting the water's surface. To generate the necessary thrust to break the surface and enter the air, the robot must move its wings ten times a second, compared to the five to six times per second needed to maintain flight.

Glenna Clifton, an animal movement biologist at the University of Portland, noted that on a single charge, the robot is estimated to fly for not quite four miles or swim for more than a mile.

Applications in Ocean Science

The researchers, who published their findings on Thursday, July 9, 2026, in the journal Science, believe the FAAV could launch a new class of aerial-aquatic drones. Zufferey envisions the robot being used by marine biologists and oceanographers to monitor remote coral reefs, algal blooms, fish stocks, and coastal erosion.

"Our dream vision is for oceanographers, marine biologists, and members of coastal communities to launch this robot from a boat, or from shore, and it would fly close to the area of interest, such as an iceberg or a port facility, or over a pod of whales,"

Raphael Zufferey, assistant professor of mechanical engineering at MIT, via MIT News

Zufferey added that the robot could dive to collect samples or take measurements and then fly back to deliver data, potentially reducing costs compared to traditional ocean vessels. He aims to equip the device with onboard sensors to facilitate this data gathering.

The project received support in part from a Marie Skłodowska-Curie Actions fellowship grant and involved co-authors from EPFL and Northwest Indian College in Bellingham, Washington.

Moving forward, the research team is working to improve the wing design to allow the robot to turn in addition to flapping. They also plan to test the vehicle's performance in turbulent conditions, including wind and choppy waters.