What happens when you cross an albatross and a sailboat? According to researchers at US MIT, that ends in a hybrid, robotic glider that combines the best of the land and air worlds. The team developed a glider that hovers like a bird and skims over the water like a sailboat. Except that the this sail/plane needs less wind than an albatross to stay in the air and goes 10 times faster than a sailboat.
The albatross is a clever piece of aeronautical engineering - its physiology makes this bird a long-distance glider. Its long, tapered wings can reach a wingspan of over 3.5 metres. Powerful curves and tendons ensure that the wing can also be held in the same position for long periods of time. Covering distances of 10,000 km is no exception for the bird. In doing so, the bird cleverly exploits the different speeds between air layers. By moving from a high, faster layer of air to a lower, slower one, the bird can accelerate without using its wings.
We find a similar principle with the sailboat: it moves at the interface of two different media, air and water. The big difference with the albatross is that it already benefits from very small differences in wind speed, while the sailboat needs more. The MIT researchers wondered whether the positive properties of both could not be accommodated in one means of transport.
The result is a drone-like glider weighing less than 3 kg that has a wingspan of 3 metres and a knife-shaped keel that can be stabbed into the water. Furthermore, the craft/plane is equipped with GPS, measurement sensors, autopilot function and ultrasonic altimeter. This allows precise control of the altitude relative to the water. This allows the boat/plane to move just above but also allows the keel to be tucked just under the water. This way, the boat/plane can hover in strong winds and benefit from the air layers while the keel can be lowered when the wind decreases to regain more speed. With this combination of techniques, a speed 10 times greater than that of a sailboat can be achieved, while the 'range' compared to an albatross is increased by a factor of three.
In addition to a wing and keel, the drone-like Albatross has a triangular sail for on the water. According to the researchers' calculations, the sail/plane can reach a speed of 20 knots (37 km/h) in winds blowing at 6 knots (9.3 km/h).
The researchers hope the ship/plane will provide a solution to better monitor large areas of the ocean that are currently inaccessible or at high cost. This will help track the impact of climate change on these parts of the ocean. Images of a test flight can be found below.
