Imagine if someone like a stranded climber needed food, but could initially only be reached by drone. Scientists have developed a proof-of-concept system to deliver this food to them, in the form of a drone with edible wings.
First of all, there are already different groups using multicopter drones to deliver food parcels from stores or restaurants to customers’ homes. Why not just use one?
Well, although these drones have enough battery life to be used in cities, they might not be able to cover the long distances that would be needed to deliver food to people lost at sea, in the wild or in other remote locations. A longer-range fixed-wing drone would be better for this purpose, although according to scientists from the Swiss research institute EPFL commercial models can usually only carry around 10-30% of their own mass. as payload.
In order to increase this percentage, an EPFL team led by postdoctoral researcher Bokeon Kwak set out to design a partially edible fixed-wing drone. And no, it wouldn’t be reusable – it would make a one-way trip to the person in need, providing them with food until they could be reached by rescuers.
Scientists focused their efforts on the wings, as they typically take up the most volume on a fixed-wing drone. If providing food weren’t an issue, these wings would normally be made of a light but strong material like expanded polypropylene (EPP) foam. After some experimentation, it was decided that puffed rice cakes offered a good edible alternative, as their mechanical properties are similar to those of EPP.
In order to construct the rectangular wings, the puck-shaped cakes were laser cut into hexagonal pieces, which were then glued together along the edges using an edible gelatin. Cornstarch and chocolate have also been tried as adhesives, but gelatin has proven to be stronger. Once assembled, the wings were covered with an inedible removable plastic, to protect the rice cake material from moisture.
The resulting model has a wingspan of 678mm (26.7in) and it does indeed fly – at a speed of 10m (33ft) per second – and carries 50% of its own mass as edible payload. Additionally, researchers estimate that it could carry 80 grams of water in an onboard container.
Its two wings contain a combined 300 kilocalories of food energy, which is roughly equivalent to one serving of breakfast. Needless to say, a larger version – or several smaller drones sent to one location – could deliver a greater amount. Further research will focus on making more parts of the drone edible and increasing the nutritional value of the edible material.
“Until now, the amount of food that existing drones could carry has been limited to the payload,” the team said in a paper presented last week at the IEEE/RSJ International Conference on Intelligent Robots and Systems ( IROS) in Kyoto. “However, an edible drone can significantly overcome this payload limitation, through the recreation of certain body structures with food materials.”