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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

#81

Post by Ph0X »

bagels wrote: post #66

To fly through the night, you need energy. I'm wondering if it's more efficient to store it in the batteries, or as stored kinetic energy by flying to a high altitude and descending through the night.

Assuming you didn't care about the path, could you also take some optimal path where you go east to west to prolong the days, then go west to east to shorten the nights. Could probably play with south/north too depending on the time of the year to get longer days. Or maybe you can go far enough to the pole where it's always day.

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

#82

Post by algo_trader »

gusgordon wrote: post #13

For those curious about the physics of these aircraft, here's an analysis I did of the same concept. The goal is to determine the smallest aircraft configuration that can indefinitely sustain flight: https://github.com/gusgordon/atmospheric_satellite#readme

nice analysis

Is it feasible to operate these at lower altitudes?

e.g. can we have solar/air drones posted every 100 miles of interstate highway?!

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

#83

Post by philk10 »

markl42 wrote: post #76
JCM9 wrote: post #40

In 1958 two guys flew a Cessna 172 nonstop for 64 days without landing. They refueled mid-air via a truck that drove under them during a low pass.

how did they um...."defuel" their bodies and such in the air?

https://news.ycombinator.com/item?id=18158207

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

#84

Post by spookthesunset »

philk10 wrote: post #83
markl42 wrote: post #76

Earlier quoted context omitted.

how did they um...."defuel" their bodies and such in the air?

https://news.ycombinator.com/item?id=18158207

Summary: they pooped into plastic bags and tossed them overboard.

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

#85

Post by p1mrx »

luma wrote: post #33
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 you're being serious. You are technically correct, but also incredibly wrong in suggesting that the increased weight would be substantial enough to impact anything measurable. Depending on the size and capacity of the cell, you might see a difference due to general relativity on the order of nanograms. see: https://physics.stackexchange.com/questions/34421/does-the-m...

A nanogram saved is a nanogram earned.

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

#86

Post by mariusseufzer »

rektide wrote: post #71
stareatgoats wrote: post #24

This is great and points to how solar in some cases already can facilitate continuous operation without the need for refueling of planes, boats, cars, you name it. Expect this to grow as battery and solar cell tech develops further. My favorites atm are the yachts that are capable of sailing just about anywhere in the world without a drop of fuel. The price is prohibitive, but considering that you might not need a ho…

anyone else think it would be super damn fun building solar floating homes like this?

I'd be down haha - When do we start?

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

#87

Post by Johnny555 »

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

They ran the 18 day flight test in September, so not the dead of winter, but also not on the longest summer days:

A solar-powered aircraft has completed an 18-day test flight offering hope it could be used to create internet access for billions of unconnected people around the world...The test flight touched down in Arizona on September 13.

https://www.thenationalnews.com/world/the-americas/2021/10/1...

Phoenix has about 12.5 hours of daylight on Sept 13th. (compared to ~14.5 hours on June 21st, ~10 hours on Dec 21st.

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

#88

Post by ethbr0 »

runarberg wrote: post #72
Ottolay wrote: post #46

Earlier quoted context omitted.

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.

I’m a bit puzzled by the economy here. Is creating, lunching and orbiting a satellite really cheaper then flying an airplane? Is it really cheaper to have a decommissioned satellite totally burn up in the atmosphere then reusing parts of an airplane to fix another, recycle unusable parts and put the rest in a landfill? The economics here just seem wrong.

USD2021$15M per Falcon 9 launch (re-used, assuming first launch was paid for by a customer) [0]

60 Starlink satellites per Falcon 9 launch [1]

= + USD2021$250,000 in launch costs per satellite (+ manufacturing / ops costs)

[0] https://www.elonx.net/how-much-does-it-cost-to-launch-a-reus...

[1] https://space4peace.org/starlink-gears-up-to-launch-nearly-1...

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

#89

Post by einpoklum »

jermaustin1 wrote: post #49
enchiridion wrote: post #44

Earlier quoted context omitted.

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.

I'm sure this will work great for powering an aircraft, too. You could just let it all hang from an anchor at the highest point in the battery :-P

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

#90

Post by lstodd »

jws wrote: post #74
Retric wrote: post #56

Earlier quoted context omitted.

Sails have several major downsides, most notably they take up a lot of deck space and cause a boat to tilt to the side. If you’re regularly sailing long distances it’s much faster but top speed isn’t that big of a deal when your living on the boat full time. Other options like kites and wind turbines can work well but they all all significant upfront costs as well as ongoing maintenance issues. Spending that same mon…

…cause a boat to tilt to the side… This is a net positive. The alternative is to roll back and forth with the waves. It’s much nicer with the sail up and ata bit of a heel. Also, just to throw this in, one of the world cruising sailing couples which wrote for the magazines switched to a diesel powered boat as they aged and found that they spent less of fuel than they had on new sails. Sails are consumables if you car…

The alternative is a catamaran.

Your point on the diesels still stands. Properly designed cats are unsinkable and don't readily capsize, but not weathering a storm is worth every penny invested in diesels. Besides one needs them in marinas anyway.

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