Following the first full-scale testing of its solar-powered Aquila drone back in July, Facebook described the event a success. Well, turns out that wasn't entirely true, with the aircraft crashing on the landing and the right wing taking on a bit of damage. This was obviously less than ideal, but the upside is Facebook now has some thoughts on how to better build a drone fit for the purpose of bringing the entire world online.

Its mammoth wingspan (greater than that of a Boeing 737), light weight (around a third of an electric car) and huge array of solar panels aside, Aquila is a little different than most other aircraft. Built by Facebook with a view to broadcasting the internet to regions that currently lack access, it doesn't carry traditional take-off and landing gear, for one.

Instead, Aquila takes off using a bespoke dolly structure that propels it along the runway. It then lands on skids on the bottom of motor pods. Well, it's supposed to anyway. After staying aloft for 96 minutes and gathering a bunch of useful data, a structural failure in the right wing just seconds before landing caused the drone to crash to the ground at a speed of 25 knots (28 mph).

The company was unable to reveal details about the crash due to a review by the National Transportation Safety Board, but that restriction has now been lifted after the board released its findings.

The wing failure seems to have been brought about by strong wind conditions, which pushed the aircraft above its glide path and caused the autopilot to respond by lowering the nose to correct the trajectory, in turn, exceeding its normal speed of 25 mph (40 km/h).

According to Facebook, this could have been avoided with more drag, allowing the aircraft to descend more steeply. It could have also been prevented if the autopilot prioritized airspeed, rather than altitude. To this end, the company is now working on a second-generation Aquila that will feature a spoiler or airbrake to afford it the necessary drag for steeper, slower descents and autopilot that is programmed to sacrifice altitude tracking in favor of limiting airspeed, if the situation calls for it.

Facebook hopes that one day Aquila aircraft will soar for 60 to 90 days at a time and use advanced laser communications to bring high-speed internet to the some four billion people that currently go without. Such a grand undertaking means that the company will have to make some pretty serious breakthroughs along the way, and it also means that its first spill probably won't be its last.

Source: Facebook, National Transportation Safety Board

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