Thanks for the website feedback - for the sake of clarity, our test flights with the sub-scale aircraft have all been at lower altitudes. The stratosphere is the next step and we plan to fly there next summer!
Love the enthusiasm - it's definitely a very fun project to be working on!
Discussed a few of your questions elsewhere in the comments, but here are some thoughts on scaling laws:
Over-simplifying a bit for the sake of brevity: In general, for larger aircraft structural mass scales up more quickly than wing area (check out “indoor free flight models”). By using a span-loaded structure (i.e. having weight distributed along the wing span to match the way lift is spread over the wing) you can avoid some of these constraints and have an approximately constant structural mass fraction.
The aircraft is actually very quiet - it needs to be very aerodynamically efficient so it doesn't require much thrust. You can’t really hear it in flight, but I’m no audio engineer - so I don't know how useful microphones would be. Genuinely curious about this so if you have any pointers let me know!
Wow, very cool! I've watched plenty of races at the Nurburgring but never stopped to think about how I was receiving the video feeds! If you have any contacts there I'd love to speak to them.
Yes, FB were trying something similar to this with Aquila. We actually used to work with a few people on that project, it sounds like the all composite flying-wing design was a bit of a challenge for them. I also understand they weren’t providing internet direct-to-device, just as backhaul for cell towers, which proved to be a difficult business case. In the end they partnered with Airbus on some projects, but I don’t know what came of that.
Quite a lot has changed in the past decade. Li-ion Battery energy density has roughly doubled, solar tech has come a long way (both in efficiency, but also production scale/costs for commercial silicon cells), and there’s been a wave of improvements for miniaturized drone/UAS hardware. On top of that, there’s 50 years of existing research into solar flight - we’re lucky that we can learn from that!
The aircraft is able to climb under its own power. We have a diurnal energy cycle - charging the battery up through the day and deploying battery energy in the night. If we launch in the morning with a full battery, we have a whole day's worth of extra solar power to use to climb up to altitude.
Winds will be a bigger issue than energy when climbing. Up at 20 km (70k ft.) winds are quite calm, but we need to ascend through more turbulent winds as we climb. We’re sizing our MVP around this.
Winds up to 20 km are NOT quite calm. They can max out to 60 m/s at height of 10 km, which is more than 3 times than enough to blow a solar aircraft far-far away. You have to choose proper meteo conditions for climbing and descending and plan the trajectory taking into account those winds to be able to land at a given place.
I've been analyzing GFS data a couple of years ago for similar project. The problem is that lack of energy demands to design a really low speed aircraft for low densities that you can find in stratosphere. At 10 km winds are stronger than in stratosphere and density is higer.
You can find the results in https://journals.sagepub.com/eprint/GVXWXDABPE6A8PNRGTBU/ful....
The whole aircraft model probably is not like yours and is subject to many conservative estimates, but I am pretty much sure that wind model is accurate in this publication and generalizable to different regions.
This is a concern for us. As with many disruptive technical advancements (e.g. in Nuclear or AI), there are many ways our technology can be used - both good and bad. It's important to us that what we do is ethical - that means supporting and pursuing use cases with huge positive societal value like rural connectivity or wildfire monitoring. With that said, there are definitely ethically-questionable use cases for this technology and I don’t underestimate how difficult it will be to navigate. We certainly have no intention of monitoring civilian populations and haven’t spoken to any police forces about what we’re doing.
I'm glad to hear that, I hope you stick to those principles if the police or military come calling. They have deep pockets and your investors will want their 100x.
Making their plane military-approved would be extremely costly and frankly it probably wouldn't work. There have been a lot of people commenting about the military clearly wanting this and taking over the project, but what makes a plane like this possible is not having the same requirements as military aircraft.
My biggest concern would be weight & power. This plane only works if it stays light and doesn't use a lot of power. If the military wanted this for live video or EO/IR, how would that communicate with ground sensors? KU satcom, UHF? Will it have IFF onboard, will it meet all the no-single-point-of-failure requirements? Everything the military requires will start using up a ton of power and adding a ton of weight. I get people always think these things will be used for evil, but it isn't exactly easy to take something civilian and suddenly ship it off to some USAF squadron.
