It’s been mere months after Facebook announced the termination of the Aquila program. And it has now decided to open-source the design methods of the aircraft.
What is ‘Aquila?’
For those of you who aren’t familiar with Aquila, I will dedicate a small time.
“Aquila,” which is the Latin term for eagle was a solar-powered drone developed by Facebook to bring internet to remote, isolated areas. Or to act as a relay station to provide internet access. It was developed at Facebook’s Connectivity Lab and its prototype was constructed by an England-based company called Ascenta. Facebook acquired Ascenta in 2014. Aquila’s maiden voyage first took place on 28th June 2016, and then another flight was taken place on 22nd May 2017 after a few modifications.
Later on, in the same year, Facebook partnered with Airbus to further develop Aquila. And to work on the project, HAPS (High Altitude Platform Station) in addition. However in June this year, it was announced that Facebook would stop building its own aircraft and instead opt to continue working with Airbus on HAPS connectivity in general.
After presenting two papers on the multidisciplinary optimization, or MDO-based technology at the American Aeronautics and Astronauts (AIAA) aviation conference, Facebook open-sourced the design framework of Aquila, as FBHALE, Facebook High Altitude Long Endurance.
The need for MDO in this case:
Battery technology has had an increased progression, so as solar-cell efficiency and composite materials. They have made solar-powered, uninterrupted flying quite easier than before, but performing with as little power as possible is still hard. Especially in such harsh conditions as the winter solstice, which still demands way higher aircraft performance.
This means we have to maximize aerodynamic performance (lift to drag ratio) and minimize structural mass. Which results in the maximization of energy storage capability. But the problem we face at this point is that increasing aerodynamic performance can affect badly to the overall structural weight, and vice versa. So the MDO design framework is to look for the best design that can achieve the requirements by addressing those challenges earlier.
As part of this, they had outlined a few modelling techniques.
- Aerodynamic performance modelling
- Structural performance modelling
- Integrated performance calculation
HAPS is one of the important building blocks for global connectivity today. And by open-sourcing the framework, Facebook hopes that aircraft designers would be able to not only improve on it but even use it for different applications.