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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

#191

Post by tomxor »

caconym_ wrote: post #150
tomxor wrote: post #47

Earlier quoted context omitted.

[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…

> with a much smaller cost per unit for build, launch and maintenance Somebody further down in the comments estimates $250k in launch costs for each Starlink satellite^[1]. Elsewhere, I found a claim that SpaceX execs said in 2019 that the per-satellite cost was "well below" $500k^[2]. So let's say $400k per satellite including manufacturing and launch, just to pick a number. Once it's in orbit, you need to pay for o…

> OP's article makes the "cheaper" claim with (AFAICT) absolutely nothing to back it up, and the fact is that full size aircraft are not cheap.

It's not a full sized aircraft. 1 small autonomous plane is cheaper than 1 small satellite in general - in almost all respects. The article didn't claim anything beyond this:

> The unmanned glider [...] is cheaper and more environmentally friendly than a satellite.

This is fairly obvious and uninteresting, what is interesting is cost per GB/user/km2, in other words the end result, which is hard for anyone to say with much certainty at this point even with a thorough analysis because nether business has reached scale yet.

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

#192

Post by caconym_ »

tomxor wrote: post #191
caconym_ wrote: post #150

Earlier quoted context omitted.

> with a much smaller cost per unit for build, launch and maintenance Somebody further down in the comments estimates $250k in launch costs for each Starlink satellite^[1]. Elsewhere, I found a claim that SpaceX execs said in 2019 that the per-satellite cost was "well below" $500k^[2]. So let's say $400k per satellite including manufacturing and launch, just to pick a number. Once it's in orbit, you need to pay for o…

> OP's article makes the "cheaper" claim with (AFAICT) absolutely nothing to back it up, and the fact is that full size aircraft are not cheap. It's not a full sized aircraft. 1 small autonomous plane is cheaper than 1 small satellite in general - in almost all respects. The article didn't claim anything beyond this: > The unmanned glider [...] is cheaper and more environmentally friendly than a satellite. This is fa…

> It's not a full sized aircraft. 1 small autonomous plane is cheaper than 1 small satellite in general - in almost all respects. The article didn't claim anything beyond this:

From the picture in the article I'm not sure what else to call it other than "full size". Wiki claims it has a ~90 foot wingspan^[1]. Wiki also claims it has an 11 lb payload capacity, so one imagines a practical version of this concept would need to be be substantially larger in order to carry a useful telecom payload.

(A Starlink satellite is a couch-sized slab weighing over 500 lbs, and one can only assume how much of that is telecom equipment, but it's probably a lot more than 11 lbs. So it seems plausible that you'd need on the order of 10 aircraft of this size, or a single much larger and much more expensive aircraft, to equal the throughput of a single Starlink satellite. None of that sounds cheap.)

Being a UAS doesn't necessarily make it cheaper, either. The MQ-1 Predator, a borderline obsolete ~1500 lb airframe pushed by a ~100 hp air-cooled Rotax, seems to cost governments on the order of 10 million dollars to procure. I'm sure there's a lot of pork in there, but it seems far from obvious that relatively exotic UASs like this one can be procured and pressed into production use for, say, two orders of magnitude less than that.

> This is fairly obvious and uninteresting, what is interesting is cost per GB/user/km2, in other words the end result, which is hard for anyone to say with much certainty at this point even with a thorough analysis because nether business has reached scale yet.

Starlink is already a service you can buy and use, subject to whatever "beta" rollout scheme they're using. They still have a long way to go to realize their scale ambitions, but I think their economics are far more settled than other schemes (like this one).

I do agree that cost per user is the interesting number here, but--as above--it seems far from obvious that this UAS scheme can even be competitive with Starlink, let alone cheaper in any reasonable sense.

^[1] https://en.wikipedia.org/wiki/Airbus_Zephyr

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

#193

Post by dredmorbius »

pault wrote: post #140
onychomys wrote: post #22

Earlier quoted context omitted.

Is there a reason you optimized the amount of starting energy in the battery? I know basically nothing about how solar power works, but surely you'd just fill the battery up to 100% with an extension cord on the ground before launching it?

The battery is too heavy if it's fully charged.

There are actually electrochemical cells which do change mass as they charge and discharge, metal-air batteries. In these, oxygen from the air is the cathode used to reduce the metal anode. But mass gain goes the opposite direction: the batteries are actually heaviest when discharged.

Various metals can be used. Iron is cheap, whilst aluminium-air cells actually offer some of the best performance in kWh/kg of available materials, exceeding that of LiON cells.

https://en.wikipedia.org/wiki/Metal%E2%80%93air_electrochemi...

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

#194

Post by rtkwe »

zdragnar wrote: post #111
mattlondon wrote: post #100

Earlier quoted context omitted.

I've always been kinda fascinated by this solar yacht concept. I wonder now with post-covid remote working options and starlink if you could actually make it work. I do wonder though if sailing the ship is basically a full-time job in itself (navigation channels? Docking at foreign countries? Getting food etc?).

I thought starlink didnt work for mobile connections? I.e. that it had to be registered and operated at a fixed address. That said, unless you are able to drop anchors, I am guessing that you would spend most of your working hours at a dock or with a partner piloting instead.

They've said that the base station will be able to roam at some point in the future and right now it's because they don't schedule the service on an ad-hoc basis so if you're base station isn't in it's expected area it won't get service.

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

#195

Post by Scoundreller »

walrus01 wrote: post #160
Scoundreller wrote: post #142

Earlier quoted context omitted.

I suspect this is why starlink has some base station licenses in eastern parts of Newfoundland. It’s the closest you can get to London before swimming from Contiguous North America.

They also need them there for current architecture up and back service to rural Atlantic Canada.

You’d build more central for that though, no? Otherwise you’re just covering a lot of ocean (until inter-sat links are up and running).

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

#196

Post by HeadsUpHigh »

Cthulhu_ wrote: post #183
goldenkey wrote: post #121

Earlier quoted context omitted.

I learned a few years ago about barnacles, which by virtue of being unaerodynamic and super heavy if you let them form huge colonies on the bottom of your ship, can decrease fuel efficiency severely. I saw how much work maintanence was, I said 'nope!' I guess a house is similar in some ways. Shingles don't last forever, pipes get corroded. The salty sea though, it's a bit more unkind to things, aye?

I don't get why US houses are still built with shingles, they don't seem to last at all. Our houses are generally built with roof tiles (not mine, I've got a flat roof which will need to be redone every 25-30 odd years :/ ) which last for decades and generally only need a few replaced after heavy storms, maybe cleaned up if they look grimy. Pipes are made from plastic and last decades, but they're generally not too h…

Boats also have critical systems such as engines that need maintenance and despite that break often. Esp. on a sailboat, there's nothing more important than the engine and these are usually cooled by salt water.

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

#197

Post by HeadsUpHigh »

ncmncm wrote: post #165
dragonsky67 wrote: post #129

Earlier quoted context omitted.

There is a whole world there I do not know and don't really want to. What a strange world we live in.

Yes. You can think of it as automated stealing. Much of the inequity could be eliminated by imposing a per-transaction tax.

Or you can think of it as HTF trading firms subsidizing 20-60ms internet for the common user. The last couple ms probably mean nothing to you but they mean a lot to them. I guess it depends on what your world view is.

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

#198

Post by walrus01 »

Scoundreller wrote: post #195
walrus01 wrote: post #160

Earlier quoted context omitted.

They also need them there for current architecture up and back service to rural Atlantic Canada.

You’d build more central for that though, no? Otherwise you’re just covering a lot of ocean (until inter-sat links are up and running).

You would cover a lot of ocean but you'd also cover all of rural Newfoundland. I believe there's also a site somewhere in Nova Scotia. Dozens of starlink earth stations are now up and running.

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

#199

Post by Mountain_Skies »

Cthulhu_ wrote: post #183
goldenkey wrote: post #121

Earlier quoted context omitted.

I learned a few years ago about barnacles, which by virtue of being unaerodynamic and super heavy if you let them form huge colonies on the bottom of your ship, can decrease fuel efficiency severely. I saw how much work maintanence was, I said 'nope!' I guess a house is similar in some ways. Shingles don't last forever, pipes get corroded. The salty sea though, it's a bit more unkind to things, aye?

I don't get why US houses are still built with shingles, they don't seem to last at all. Our houses are generally built with roof tiles (not mine, I've got a flat roof which will need to be redone every 25-30 odd years :/ ) which last for decades and generally only need a few replaced after heavy storms, maybe cleaned up if they look grimy. Pipes are made from plastic and last decades, but they're generally not too h…

When I lived in southern California, roof tiles were very common but in the eastern US, it's mostly shingles. I hate to think of what a hailstorm would do to a roof full of tiles. Hail can cause significant damage to a shingled roof but it's much less expensive to replace.

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

#200

Post by Mountain_Skies »

zdragnar wrote: post #111
mattlondon wrote: post #100

Earlier quoted context omitted.

I've always been kinda fascinated by this solar yacht concept. I wonder now with post-covid remote working options and starlink if you could actually make it work. I do wonder though if sailing the ship is basically a full-time job in itself (navigation channels? Docking at foreign countries? Getting food etc?).

I thought starlink didnt work for mobile connections? I.e. that it had to be registered and operated at a fixed address. That said, unless you are able to drop anchors, I am guessing that you would spend most of your working hours at a dock or with a partner piloting instead.

Starlink has to abide by the laws of whatever jurisdiction you are in. There's not many technical reasons why they can't provide roaming service on the seas but there are issues such as if you dock in a country that prohibits Starlink service, they're going to want some system in place to reject your packets. That shouldn't be too difficult but resources must be allocated to making it happen. They probably have other things on their plate now that are a higher priority.
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