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

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

#71

Post by rektide » Mon, Oct 11, 2021, 7:00 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…

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

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

#72

Post by runarberg » Mon, Oct 11, 2021, 7:01 PM UTC

Ottolay wrote: post #46

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.

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.

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

#73

Post by tpmx » Mon, Oct 11, 2021, 7:03 PM UTC

btilly wrote: post #63

tpmx wrote: post #52

Earlier quoted context omitted.

With Starlink soon having ~global coverage, why bother transporting, launching and servicing these aircraft for a one time thing? I don't see the benefit. Will also be really hard to reach low prices for end user terminals with this approach. Very high quality visual/signals surveillance seems like a much more obvious market fit.

First, Starlink has limited bandwidth per square mile. Therefore it cannot conceivably provide telecommunications for densely populated areas. Second, all you have to do is make these aircraft compatible with cell phones. So your target population already has "end user terminals" literally in hand. Third, this is not a one-time need. Local disasters happen fairly regularly, and sometimes can be predicted in advance.…

Pretty good points. Starlink can't do 2G/3G/4G/5G with mobile phones on the ground, ~550+ km away, of course.

They should probably look into partnering with e.g. Ericsson Response (https://www.ericsson.com/en/about-us/sustainability-and-corp...).

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

#74

Post by jws » Mon, Oct 11, 2021, 7:07 PM UTC

Retric wrote: post #56

Tepix wrote: post #34

Earlier quoted context omitted.

Why wouldn't you use the wind energy also? It's a lot of fun, readily available and a lot cheaper…

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 care about performance.

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

#75

Post by esel2k » Mon, Oct 11, 2021, 7:09 PM UTC

pvarangot wrote: post #27

kwertyoowiyop wrote: post #25

It’s so depressing to read that one proposed mission for this plane is…monitoring oil spills.

I worked on a satellite imaging startup. For this kind of stuff usually oil and gas and large scale agriculture are the first ones to show interest. They don't need great resolution or revisit times and their assets span over very big areas so monitoring from the ground/sea or with small drones is really expensive.

Depends on the appplication. An NDVI analysis or determining vast crop / growth problems yes but if you want to check for disease this is often done by drones to have higher resolution. I could imagine doing regular field visits with these planes and avoid the high labor costs of drone management/flying.

Sources: I work in a big agtech company with satellite imagery. PS: We should connect.

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

#76

Post by markl42 » Mon, Oct 11, 2021, 7:13 PM UTC

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?

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

#77

Post by KineticLensman » Mon, Oct 11, 2021, 7:14 PM UTC

jjcm wrote: post #54

Tepix wrote: post #34

Earlier quoted context omitted.

Why wouldn't you use the wind energy also? It's a lot of fun, readily available and a lot cheaper…

From the images on the site it looks like it deploys a sailing kite in addition to the solar powered engines.

Oh hi jjcim. Another cool research project from where I used to work. [0] Back in the day, the development building had a great view of the runway during the Farnborough air show and my pals on the Zephyr project would give me a shout if anything interesting was taking off.

[0] https://en.wikipedia.org/wiki/Airbus_Zephyr

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

#78

Post by j245 » Mon, Oct 11, 2021, 7:14 PM UTC

OJFord wrote: post #16

j245 wrote: post #11

Earlier quoted context omitted.

Neat - but not interesting from a technological stand point.

Is it not? I don't imagine such sustained flight, continuous operation of all the equipment and engine for so long, would've been a design consideration. Presumably there's a number, I just doubt it's tens of days, so isn't it interesting that it was achieved?

This record was set ~3 months after someone else did it for 50 days.

From an engineering stand point, performance of components or materials are always assumed to be much worse than actual and the forces / conditions they are subject to overestimated, with further factors of safety applied on top. This is how it should be. It also means properly designed things will carry on working better than you expect (on average).

It’s not interesting (to me) from a technological stand point compared to the solar UAV because flying up and down the same road with a truck refuelling you is not useful, and if others (e.g. Military, NASA) could be bothered to do it - they would probably do a better job relatively easily.

To me - It’s the same as building the worlds longest domino trail. You could beat the previous record by 1 million dominos which is neat but.. what have you proven, and why does it matter ?

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

#79

Post by teraflop » Mon, Oct 11, 2021, 7:15 PM UTC

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.

It's a good idea, in principle. But according to the sources I could find, to get enough gravitational potential energy to equal the electrical capacity of Zephyr's batteries, you'd have to lift the entire craft by about 70km.

https://www.aviationpros.com/engines-components/aircraft-air...

https://en.wikipedia.org/wiki/Airbus_Zephyr

I can imagine you'd want to take advantage of gravity to a certain extent, but it seems a bit tricky to estimate how much. Presumably there's a particular altitude at which the aircraft's overall efficiency is at a maximum. Deviating from this altitude allows you to store a bit of extra energy (which means you can get away with a smaller battery) but you don't want to deviate too far, or you'll lose more energy to various inefficiencies than you're saving. And you probably need to keep some electrical reserve power anyway, in order to be able to actively navigate away from unfavorable winds.

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

#80

Post by kbenson » Mon, Oct 11, 2021, 7:19 PM UTC

Asmod4n wrote: post #70

kbenson wrote: post #64

They're hoping to get six months flight eventually out of a propeller craft. I can't help but wonder what we could eventually get out of a solid state craft.[1] They mention batteries in this article when referencing that six months target, but I have to assume servicing the propellers is important as well. 1: https://www.engineering.com/story/how-the-worlds-first-solid...

You got a small typo there.

Lol, thanks. :)