There are some fast drones on the market but few hold a candle to MIT's 'rocket drone' project. This drone, called the Firefly, tops out at Mach 0.8 speeds -- approximately 614 mph (988 kph). The zeppelin-shaped drone is meant to launch from a companion fighter jet in order to collect data or serve as a distraction for an enemy's weapons.
The drone itself only weighs two or three pounds and comes equipped with a small engine. Once deployed from the accompanying aircraft, it opens its wings and then flies around completing its task before being discarded.
The project comes from MIT's AeroAstro group, "America's oldest and most respected university aerospace program," the group noted on its website. One of the researchers involved in developing Firefly's unique build is Tony Tao, a PhD student. Tao noted that the unconventional drone doesn't seem logical on the surface, but ultimately, the unique build of the drone is what has made it successful.
The project stemmed from a challenge presented by the United States Air Force. They tasked the team with developing a UAV no bigger than 2.5 inches wide (6.35 cm) and 17 inches long (43.18 cm) that could fly at Mach 0.8 speeds for longer than two minutes.
"We use this burn-rate suppressant, which—via chemical decomposition—cools the flame and changes the flame structure so that it actually burns slower," Tao said in an interview with MIT Technology Review back in August. "You don’t usually want to put a fire extinguisher inside of your fire, but that’s exactly what we’re doing."
That slow burn is what allows Firefly to outlast other rockets of that size. Thanks to the burn-rate suppressant, Firefly can cruise at rocket-level speeds for up to three minutes. Comparable rockets of that size would only last for a few seconds without the burn-rate suppressant. Firefly's motor also burns fuel from the aft end forward. This sends the exhaust traveling through a nozzle made of a graphite/ceramic composite. The drone's top is what holds the payload (if there is one), avionics, and its flight control equipment. The bottom half of the small drone is what holds the retractable wings and the narrow tail for maneuvering.
"There was no vehicle with this speed, at this size, that could deploy off an aircraft,” John Hansman, MIT professor of aeronautics and astronautics, said to Aviation Week. “It is too small for a turbine and too fast for electric, while a pulse-jet presents thermal problems."
The Firefly rocket drones have yet another element that sets the project apart. Each Firefly is 3D printed out fo titanium to its exact specifications. This makes it one of the first 3D-printed rockets to fly in the world.
MIT is no stranger to developing drones, especially military-grade drones. In January, MIT developed autonomous swarming drones for the Pentagon. Just like Firefly, these Perdix drones will also be launched from a fighter jet and sent out to accomplish their mission.
While Perdix made its debut in January with public testing, the Firefly team said its about a year away from being able to safely flight test the drone. They're currently finalizing engine burn tests and temperature testing on electronics.