Drones

MIT's gasoline-powered UAV targets five-day flight endurance

MIT's gasoline-powered UAV tar...
A team of MIT students successfully tested a prototype gasoline-powered UAV that can potentially stay aloft for five days at a time
A team of MIT students successfully tested a prototype gasoline-powered UAV that can potentially stay aloft for five days at a time
View 4 Images
The entire team that developed this new UAV design
1/4
The entire team that developed this new UAV design
The team examining one of the carbon fiber wings
2/4
The team examining one of the carbon fiber wings
The first prototype test flights involved launches from the roof of a car
3/4
The first prototype test flights involved launches from the roof of a car
A team of MIT students successfully tested a prototype gasoline-powered UAV that can potentially stay aloft for five days at a time
4/4
A team of MIT students successfully tested a prototype gasoline-powered UAV that can potentially stay aloft for five days at a time

When it comes to flight endurance for an unmanned UAV, the Qinetiq Zephyr still reigns supreme with a flight of over 336 hours, but its solar-powered, high-altitude design doesn't make it suitable for many applications. A team of engineers at MIT has developed a cheaper UAV design that has the ability to stay aloft for up to five days at low-altitudes on a single tank of gasoline, potentially offering communications support in areas struck by natural disasters.

The long-duration UAV is powered by a 5-hp gasoline engine, weighs under 150 lb (68 kg) and features a glider-like design with a 24-ft (7.3-m) wingspan. As well as being designed to carry communications-support payloads of up to 20 lb (9 kg), the UAV could offer a cost-effective platform for general environmental monitoring.

"These vehicles could be used not only for disaster relief but also other missions, such as environmental monitoring," says R. John Hansman, one of the leaders of the MIT project. "You might want to keep watch on wildfires or the outflow of a river."

The team examining one of the carbon fiber wings
The team examining one of the carbon fiber wings

The team initially investigated the idea of using solar energy to power the aircraft, but soon realized a fossil-fueled engine would have much more functionality considering the emergency-relief applications being targeted.

"[A solar vehicle] would work fine in the summer season, but in winter, particularly if you're far from the equator, nights are longer, and there's not as much sunlight during the day," Hansman explains. "So you have to carry more batteries, which adds weight and makes the plane bigger."

The team computer-modeled a design for the gasoline-powered UAV using a software tool called GPkit, which was developed by the other leader on the project, Warren Hoburg. GPkit is a tool that takes specific constraints and then models optimal design dimensions for a vehicle. Unlike other similar software tools, which are fairly limited in terms of the number of constraints that can be considered, Hoburg's system can process around 200 constraints simultaneously.

The ultimate design, determined by the software for optimal flight duration, was constructed from lightweight materials such as carbon fiber and can be easily taken apart for shipping, allowing for quick delivery to disaster zones. The software emulations also predict the design will be able to fly at altitudes of 15,000 ft at any latitude in up to 94th-percentile winds (only six percent of flights would encounter winds that are too strong), for more than five days.

The first prototype test flights involved launches from the roof of a car
The first prototype test flights involved launches from the roof of a car

Having built a prototype last year, this year the team developed a launch system that consisted of a basic metal frame that attaches to a car roof rack. With the UAV sitting atop the frame, the car or truck accelerates to the UAV's optimal takeoff speed and the remote pilot angles the aircraft upwards, which causes the fastener to automatically release and sends the UAV skywards.

The team is yet to test the UAV under long-distance endurance conditions, but early short-run prototype flights conducted in May proved successful. However, these test flights required the aircraft's weight to be reduced from 150 to 55 lb (25 kg) so as to comply with FAA regulations for small unpiloted craft. Despite success in launching, flying and safely landing the prototype, the team says there are other factors that need to be considered for longer, multi-day test flights, such as ensuring there are enough people to monitor the aircraft for the duration of the flight.

"There are a few aspects to flying for five straight days," Hoburg says. "But we're pretty confident that we have the right fuel burn rate and right engine that we could fly it for five days."

Source: MIT

2 comments
MD
commendable work... I know that this isn't a technical forum, (question to team) Would(n't) a hybrid power plant deliver greater mission endurance?(.) If a 5hp motor is required for climb performance but only 2-3hp for on-station duty, a 2hp (say) optimised motor, coupled to a parallel electric (BLDC etc) unit with hybrid (high energy density and+ high power delivery) storage sized for climb energy required, could allow for more than 5hp peak in the same (mass) package or a lighter package overall. - Solar recharge while onstation would be elegant, though a jettisonable auxiliary power plant/storage (recoverable/glide to home etc.) would also be an option if weight saving trumps other needs. lol. We are talking 5 days here, an over spec'd IC motor will be inefficient (relatively speaking) running at partial throttle for 5 days... Multiple other configs could deliver of course, that is the beauty of distributed propulsion/ flexible power management. Available if needed. (half jk)
chase
I don't know that i would have chosen gas/fossil fuels. There has to be something else much more suitable. Something is being overlooked.