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Solar-powered aircraft flown for nearly three weeks without landing

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Re: Solar-powered aircraft flown for nearly three weeks without landing

#41

Post by [deleted] »

spijdar wrote: post #32
mkr-hn wrote: post #28

Earlier quoted context omitted.

Batteries are heavier when fully charged. Takeoff weight matters. It's not much heavier, but it might be enough to affect things at this scale. edit: remember the context. This is about an abstract optimization to find the minimum viable aircraft.

I can't tell if this is satire or not, but taken in good faith, how? A fully charged battery would necessarily have more mass than a fully depleted battery, but the difference should be so tiny as to be immeasurable. Or am I wrong? We're essentially talking about the sum weight of a bunch of electrons, which are extremely light. There's no other exchange of matter going on when charging/discharging a battery, just th…

[deleted]

Re: Solar-powered aircraft flown for nearly three weeks without landing

#43

Post by andrepew »

j245 wrote: post #11
sokoloff wrote: post #2

Related (in at least one dimension): https://www.airspacemag.com/daily-planet/airborne-for-64-day... Cessna 172 flown for 64 days, 22 hours, 19 minutes and 5 seconds.

Neat - but not interesting from a technological stand point.

Over 1500 hours of continuous operation is quite a feat. Components like magnetos have service schedules much shorter than that.

This also ignores all the unexpected issues that pop up in aviation. My only experience with Cessna 172s are rentals which are treated like crap - those planes need something looked at like every 50 hours.

Re: Solar-powered aircraft flown for nearly three weeks without landing

#44

Post by enchiridion »

jermaustin1 wrote: post #39
rrss wrote: post #31

Earlier quoted context omitted.

what kind of batteries are meaningfully heavier when charged? are you just talking about like E/c^2?

A water/gravity battery comes to mind. Definitely not the answer you are looking for, but an answer none the less.

Depends on your definitions. Is the water pumped considered part of the battery before it’s elevated?

Re: Solar-powered aircraft flown for nearly three weeks without landing

#46

Post by Ottolay »

tpmx wrote: post #23

Probably/unfortunately not really a Starlink competitor, right? They don't specify the "cruising" altitude, but I assume it's ~10 kilometers at most, probably less? Airbus would need quite a few of these in order to build a global internet connectivity service then. Edit: https://en.wikipedia.org/wiki/Airbus_Zephyr says ~20 km. Starlink sats (will) operate at ~540-570 km: https://spaceflightnow.com/2021/04/29/spacex-…

The U2 operated at over 20km, so maybe the altitude is higher.

I suspect the greater issue is vehicle cost, lifetime, and safety. A starlink satellite is much smaller (and as result cheaper) and is rumored to have a 5+ year lifetime. Also, at end of life it burns up in the atmosphere. No worry about pushing the life on a component and having it crash and kill someone as a result.

Re: Solar-powered aircraft flown for nearly three weeks without landing

#47

Post by tomxor »

tpmx wrote: post #23

Probably/unfortunately not really a Starlink competitor, right? They don't specify the "cruising" altitude, but I assume it's ~10 kilometers at most, probably less? Airbus would need quite a few of these in order to build a global internet connectivity service then. Edit: https://en.wikipedia.org/wiki/Airbus_Zephyr says ~20 km. Starlink sats (will) operate at ~540-570 km: https://spaceflightnow.com/2021/04/29/spacex-…

[EDIT] remove redundant info

> Airbus would need quite a few of these in order to build a global internet connectivity service then.

Yes it would require more units, but with a much smaller cost per unit for build, launch and maintenance. That's where it will start to get interesting: Which will have the lowest cost per GB, per user, per square km of coverage etc?

I suspect even if it's cheaper it would still remain less global, since having massive swarms of these would probably be even more of a logistical nightmare than starlink. i.e they would supplement other technology... which is pretty much what Airbus is quoted suggesting in the article.

Re: Solar-powered aircraft flown for nearly three weeks without landing

#48

Post by phnofive »

hellohntoday wrote: post #42

I'm assuming the flights were achieved mid summer when they days are longest and it can't yet operate outside this window. If this is the case, shame they don't just admit this up front

Perhaps they are aware of eatrh's axis and will move operations to the southern hemisphere? Or adjust the drone's speed to stay in sunlight?

Re: Solar-powered aircraft flown for nearly three weeks without landing

#49

Post by jermaustin1 »

enchiridion wrote: post #44
jermaustin1 wrote: post #39

Earlier quoted context omitted.

A water/gravity battery comes to mind. Definitely not the answer you are looking for, but an answer none the less.

Depends on your definitions. Is the water pumped considered part of the battery before it’s elevated?

The pumping of the water would be "charging" the barrel of water, I guess.

Re: Solar-powered aircraft flown for nearly three weeks without landing

#50

Post by endymi0n »

tehjoker wrote: post #37

I wonder how the engine can keep operating for such long periods of time without maintenance!

This stuff is pretty sturdy. The lifetime of brushless electric motors used in this kind of dirtless environment is basically the lifetime of the bearing used and can usually be measured in years of nonstop operation without any modification already.
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