Real flying fish are already great… but now scientists have come out with a robot inspired by them! That’s right, a flying fish robot now exists and it can travel an impressive 26 meters (85 feet) through the air after take-off, from underwater!
Engineers from Imperial College London developed it in the hopes that it will be able to assist in the event of an environmental catastrophe. Their innovative creation could collect water samples following floods, oil spills, or nuclear disasters, for example. Details about it have been published in the academic journal Science Robotics.
Raphael Zufferey, an aeronautical engineer who worked on the device, said:
These kinds of low-power, tether-free robots could be really useful in environments that are normally time and resource-intensive to monitor, including after disasters such as floods or nuclear accidents.
The biggest challenge with developing such a robot was how to create enough force for such a small machine to be able to take off from the water. Lead researcher Mirko Kovac explained:
Water-to-air transition is a power-intensive process, which is difficult to achieve on a small-scale flying vehicle that needs to be lightweight for flight. We have used water-reactive chemicals to reduce the materials that the robot needs to carry. Since the chamber fills passively and the environmental water acts as a piston, we can create a full combustion cycle with only one moving part, which is the pump that mixes the water with the fuel.
Their solution? The device is able to swim and fly by using a simple combustion system that pushes water out as a jet and propels the robot up. The propulsion technique they designed is so effective that the robot is even able to fly out of choppy waters, meaning it could be used to collect water samples in difficult environments.
As reported by IEEE Spectrum:
The AquaMAV combines combustible power and water in order to propel itself. The drone contains calcium carbide powder. When mixed with water, the drone creates acetylene gas, which then gets funneled into a combustion chamber along with air and water. When ignited, the mixture then explodes, forcing the water out of the combustion chamber and propelling the drone into air.
After having figured out the problem of providing adequate thrust, there was a second challenge that needs to be solved to conquer the water-to-air transition with a fixed-wing robot. Then the third main challenge was the overall design of the robot itself because the optimal design and balance for the robot is quite different in each phase of operation. They describe these two challenges in the paper as such:
For the vehicle to fly in a stable manner during the jetting phase, the center of mass must be a significant distance in front of the center of pressure of the vehicle.
However, to maintain a stable floating position on the water surface and the desired angle during jetting, the center of mass must be located behind the center of buoyancy.
For the gliding phase, a fine balance between the center of mass and the center of pressure must be struck to achieve static longitudinal flight stability passively. During gliding, the center of mass should be slightly forward from the wing’s center of pressure.
The engineers took their flying fish out for testing in a lake and in a wave tank to check its abilities in different conditions. They had also tested it previously in the lab. In all the different scenarios the robot was successful. The trials of the launch and flight technology went well and now they have moved on to the next phase of development. The team hopes to eventually build a system that can be used in the real world to help in difficult situations where it would be too dangerous for a human to go.
