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Launch HN: Radical (YC W23) – Autonomous high-altitude solar aircraft

news.ycombinator.com

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Re: Launch HN: Radical (YC W23) – Autonomous high-altitude solar aircraft

#111

Post by lijaf »

the__alchemist wrote: post #66

Looks amazing! So many potential applications. Does it use PX4, Ardupilot, a customized version of these, or custom firmware? What sort of MCUs and ground station? Are you using an all-in-one electronics sort of unit, or distributed systems (eg CAN nodes, LRUs or w/e) How are you solving the RF communications, ie what sort of range are you getting, and what frequency/transmitters/power level? What sort of range do yo…

Looks like they are using Mission Planner in their video, suggesting Ardupilot.

Re: Launch HN: Radical (YC W23) – Autonomous high-altitude solar aircraft

#115

Post by crabbone »

pierrekin wrote: post #104
pierrekin wrote: post #80

Earlier quoted context omitted.

I worked on this at Facebook very briefly. I believe the project was called Aquila internally. I worked with a famous engineer who joined Facebook from a well known british aircraft manufacturer. He was an aerodynamics expert and was trying to solve the problems of flutter and other dynamic instability in the extremely large, high aspect ratio, lightweight composite wing. I wasn't officially told this, but I believe…

I am possibly wrong about small details, and would appreciate corrections. So when I joined the project, the physical aircraft was based in the USA, but the software team for the autopilot was based in the UK. For some reason - I think it was the very high altitude capability - the USA considered the autopilot to be munitions. When I first joined the project, there was this bizzare situation where it turned out to be…

Re' sending an entire aircraft over the ocean vs. sending software over the internet: you'd be surprised, but it's still often the case.

I worked for a storage company that made a long-distance replication product (i.e. a program that allows one to store their data both locally and far away in a reasonable time-frame). We were contacted at some point by a movie production company which had this problem of moving the "raw" footage from the place it was filmed to the place it was supposed to be edited, and because it would take ages over the Internet, they'd use an airplane to fly it between the sites.

In general, it's a known phenomenon in the storage industry and as technology advances gets rebranded from "Boeing loaded with CD-ROMs", to loaded with hard-drives, to loaded with USB sticks etc. In other words: Internet is slow, if you want to move a lot of data, as in it has very low bandwidth.

Re: Launch HN: Radical (YC W23) – Autonomous high-altitude solar aircraft

#116

Post by t0mas88 »

Leherenn wrote: post #105

How do you deal with temperature (roughly -60°C/-70°F)? Do you heat the batteries? What about icing? It might be too cold for it at that altitude?

Icing doesn't happen below about -40 C because moisture in the air at those temperatures becomes ice crystals which don't freeze to aircraft. At least not to aluminum normal aircraft. No idea whether it's the same for a solar drone.

Re: Launch HN: Radical (YC W23) – Autonomous high-altitude solar aircraft

#117

Post by t0mas88 »

rolling_robot wrote: post #103

I am curious how are you planning to cope with aeroelasticity issues in near-earth turbulence. Given low air speed, low wing loading, and huge aspect ratio this is going to be an issue. I suspect that most of the previous projects failed because of these issues combined with tight requirements on very light-weight structures.

Indeed. Very high aspect ratio wings could be hard to make strong enough at very low weight to survive climbing through the lower parts of the atmosphere.

Some convective activity could help the climb, but it would add a lot of turbulence for the first 30,000ft or so.

Re: Launch HN: Radical (YC W23) – Autonomous high-altitude solar aircraft

#119

Post by jthomaslm »

CaveTech wrote: post #98
jthomaslm wrote: post #57

Earlier quoted context omitted.

Wildland forest fires were actually the inspiration for this technology! A year ago Seattle had the worst air quality in the world for a few days, which piqued my interest in the area. Speaking to people in the USFS we learned about the challenges of getting real-time high-resolution data, and realized that an ultra long endurance drone would be a great way to get this.

Any idea how big an effect air quality has on cell efficiency? Do cells work with diffuse light or is 20km high enough to be unaffected?

Flying at 20 km should place us above cloud cover and fire smoke, but the cells do work surprisingly well in diffuse light. Ensuring that we use imaging sensors that can cut through the smoke will be key (most likely LWIR or MWIR)

Re: Launch HN: Radical (YC W23) – Autonomous high-altitude solar aircraft

#120

Post by cyrieln »

creyes12345 wrote: post #18

I was peripherally involved with a similar project a few years ago. They got bought out by Facebook. This was before Aquila. There’s a good reason why most airplanes look and behave alike: because it works. Technology choices like flying wings (not used here) or twisting wings (used here) are a “code smell” to my computer programmer nose. To me, nothing is sexier than good reliable technology that works. Smart invest…

Low weight and high aerodynamic efficiency are crucial. You naturally end up with high aspect-ratio wings which tend to be more flexible than conventional aircraft wings. In order to keep aero-elastic effects under control, multiple tailplanes can help to stabilize the structure, and provide roll control at the same time - we’re not set on this technology though, ultimately our analysis tooling will drive this design decision.

Batteries are heavy, but if you want to conduct long endurance flights - greater than a few days, then realistically they are the best option.

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