Researchers Create Drone that Flies and Dives

An exciting new development by researchers in the United States of an unmanned, fixed-wing aircraft, capable of traveling through the air and also underwater, promises to provide scientists with the means of watching, monitoring and tracking wildlife above and below the ocean.

A team of researchers from North Carolina State University, with funding and assistance from Teledyne Scientific, have come up with the EagleRay XAV, the first unmanned, fixed-wing aircraft which can repeatedly move between sky and sea.

The project initially started in 2014 when a team of scientists at NC State’s Department of Mechanical and Aerospace Engineering won a research contract from Teledyne, by 2016 the team led by Assistant Professor Matthew Bryant had developed a fully operational prototype and published their results in 2017.

According to Ph.D. student  Warren Weisler who was involved in the EagleRay project, just maintaining aerial surveillance uses a large amount of energy, and the EagleRay is able to conserve energy by spending some of its time in the water.

Weisler says a good example of the unique ability of the EagleRay might be the tracking of a large pod of fast-moving dolphins from the air, when the pod stops to feed the EagleRay can loiter in the water and resume flight when the dolphins move off.

William Stewart, another NC State Ph.D. student who worked on the project says the EagleRay could also rapidly move underwater sensors from location to location, and perform underwater monitoring that most unmanned aerial vehicles are unable to do.

As sonar only works underwater,when searching for a sonar target, the EagleRay could fly to a site, submerge to take sonar readings, and then resume flight to take readings elsewhere; an aircraft would have to drop ‘sonobuoys’ to collect sonar data.

Stewart says an important feature regarding the EagleRay design is that it is scalable and  models can be made larger or smaller according to their intended function, and depends on the size of the desired payload,desired operation time and other demands.

The current model of EagleRay weighs 12.6 pounds, has a wingspan of 59 inches and is 55 inches long; It has a dual-use propeller, powered by an electric motor, that propels it through both air and water.

Weisler says they are currently developing a custom controller for the EagleRay, as existing controllers are not designed for a vehicle that transitions from air to sea and back again – they’re designed to be one or the other.

The researchers are also refining a dynamic model of the EagleRay, for use in simulations that can be used for training purposes, to predict performance under various conditions and to refine the vehicle design.

They say the project has been extremely challenging and rewarding but seeing it fly during field trials was” exhilarating”.

Co-principle investigators on the project were Professors Kara Peters, Ashok Gopalarathnam, and Larry Silverberg.

The paper, “Testing and Characterization of a Fixed Wing Cross-Domain Unmanned Vehicle Operating in Aerial and Underwater Environments,” is published in the IEEE Journal of Oceanic Engineering. Weisler is lead author of the paper. Co-authors include Stewart, Bryant, Peters, Gopalarathnam and Mark Anderson of Teledyne.