Solar-powered aircraft flown for nearly three weeks without landing • Hacker News Board

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

#131

Post by bumbada » Mon, Oct 11, 2021, 10:52 PM UTC

pbhjpbhj wrote: post #69

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…

>top speed isn’t that big of a deal when your living on the boat full time.// If you're living on your boat 365 then I imagine avoiding severe weather becomes more important?

This is the reason Weather reports and forecast are so important for people on boats.

Most people living in boats actually live on ports and don't get very far from the coast most of the time.

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

#132

Post by silisili » Mon, Oct 11, 2021, 10:57 PM UTC

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…

Interesting last point...curious why is that? Do they get battered from weather and physically tear, or do they just stretch/thin over time?

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

#133

Post by titanomachy » Mon, Oct 11, 2021, 11:19 PM UTC

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…

Wow, the "Silent Yachts" one has a "fully automated towing kite"! That's not something I've ever encountered before, very clever. Removes the need for an annoyingly tall mast and probably saves a lot of weight as well.

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

#134

Post by sfblah » Mon, Oct 11, 2021, 11:26 PM UTC

runarberg wrote: post #104

Ottolay wrote: post #95

Earlier quoted context omitted.

As a reference a new Cessna 172 is $432,000 [1] and that is not a high tech aircraft. [1] https://www.forbes.com/sites/erictegler/2021/04/28/prices-fo...

This feels like comparing potatoes and pineapples. A new Cessna vs a used Falcon 9 launch hardly seems like a fair comparison. The cost of the rocket is written off as externalized. The actual satellites are not factored in at all. Really what we are comparing here is the cost of an operation vs the cost of an airplane. The economics still seem dubious.

And a Cessna 172 has to be human safe.

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

#135

Post by Ottolay » Mon, Oct 11, 2021, 11:28 PM UTC

JackFr wrote: post #107

Ottolay wrote: post #99

Earlier quoted context omitted.

The U2 was subsonic. Also, un-powered gliders can get up to impressive altitudes. https://www.airbus.com/newsroom/press-releases/en/2018/09/ai...

> The unmanned glider, which is powered by two small propellers, I’m confused by the article and the above comment. Isn’t a glider by definition unpowered?

Checkout [1]. Easier to say "motor glider" or "powered glider" than "powered airplane with glider like configuration".

[1] https://en.wikipedia.org/wiki/Motor_glider

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

#136

Post by jws » Mon, Oct 11, 2021, 11:41 PM UTC

silisili wrote: post #132

jws wrote: post #74

Earlier quoted context omitted.

…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…

Interesting last point...curious why is that? Do they get battered from weather and physically tear, or do they just stretch/thin over time?

They lose their ability to hold their "shape" and become less efficient. This is primarily a concern for people that want to go as fast as possible. I've been perfectly happy with sails after 20 years of light use. I mean, I can see that they don't really have the best shape, but I'm still sailing so all is good.

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

#137

Post by contingencies » Mon, Oct 11, 2021, 11:54 PM UTC

titanomachy wrote: post #133

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…

Wow, the "Silent Yachts" one has a "fully automated towing kite"! That's not something I've ever encountered before, very clever. Removes the need for an annoyingly tall mast and probably saves a lot of weight as well.

A mast provides a predictable center of lift in the boat on two axes, easy to control, handles high winds elegantly. Kite? Not so much. Also, try sailing in to the wind with a kite. May be possible, but very, very slow going. Traditional sail plans strike a balance between functionality at all points of sail, ease of handling and safety. They also have downwind sail options.

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

#138

Post by runarberg » Tue, Oct 12, 2021, 12:02 AM UTC

sfblah wrote: post #134

runarberg wrote: post #104

Earlier quoted context omitted.

This feels like comparing potatoes and pineapples. A new Cessna vs a used Falcon 9 launch hardly seems like a fair comparison. The cost of the rocket is written off as externalized. The actual satellites are not factored in at all. Really what we are comparing here is the cost of an operation vs the cost of an airplane. The economics still seem dubious.

And a Cessna 172 has to be human safe.

Indeed, and the $432,000 is the price on the consumer market. A mass order of Zephyrs by, say, the British Government is sure to land a much smaller price tag per unit then a lone hobby pilot can expect when buying a single airplane.

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

#139

Post by zucker42 » Tue, Oct 12, 2021, 12:08 AM UTC

algo_trader wrote: post #82

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?!

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

What's the usefulness of this or was it just a random example?

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

#140

Post by pault » Tue, Oct 12, 2021, 12:10 AM UTC

onychomys wrote: post #22

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

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.