New Record For Solar-Powered Autonomous Flight: 28 Hours Without Refueling

Hallie Siegel describes a new and impressive achievement for solar-powered flight: keeping a drone aloft for more than a full day. From the article: To actually pull it off has required a fair bit of innovation in flexible solar cells, high energy density batteries, miniaturized MEMS and CMOS sensors, and powerful processors ... but researchers at ETH Zurich have just recently managed to keep their unmanned UAV aloft for 28 hours without any fuel, building on their previous record by over an hour. Having more than 24 hours of endurance is important because overcast skies can inhibit recharging and poor weather or high winds can affect power consumption.

Comments

Good achievement, but

[Kohath]

But why not just use a lighter-than-air vehicle and stay aloft for months?

Re:Good achievement, but

[fnj]

But why not just use a lighter-than-air vehicle and stay aloft for months?

Airships only exceed optimized airplanes in transport efficiency for extremely large sizes and severely limited speeds. Solar/battery airplanes can already exceed one diurnal cycle, so there is no reason in principle why they themselves cannot stay aloft for months.

Airships are subject to problems that do not apply at all to airplanes. A major one is that they are subject to serious lift variations due to varying degrees of heating differential to the surrounding atmosphere. This can only be countered via engine power or by expenditure of ballast and valving of gas. This has traditionally been the ultimate limit to their endurance, which has never exceeded 11 days in practice.

Re:Good achievement, but

[Kohath]

Makes sense. How about a hybrid approach with a lighter-than-air vehicle shaped to generate lift? Does the extra size needed for the lighter than air gasses cause more loss from drag than it saves by reducing the energy needed to stay aloft?

Re:Good achievement, but

[4wdloop]

Using solar energy to compress the gas instead of leaking it?

Say impact

[Anonymous Coward]

I have found the word "impact" is great for people who don't know the difference between affect/effect. Works great when I review resumes, too (If the job requires a good command of English, "impact" for anything but a molar or crater=fail).

*affect power consumption

Re:Say impact

[Anonymous Coward]

I'm glad you will never review MY resume...

Learners Dictionary / Impact

Question

[fnj]

If the craft can fly for greater than one diurnal cycle, why cannot it fly indefinitely?

Re:Question

[Anonymous Coward]

I assume it started with batteries that were full, and used a mixture of battery juice and solar to stay afloat. But the batteries eventually ran dry.

Re:Question

[Anonymous Coward]

Nope, RTFA, batteries had higher charge at the end of the 28 hour flight than at the start.

Re:Question

[radarskiy]

Two cloudy days in a row.

Affect not effect

[Anonymous Coward]

Sorry to be fussy but such an error cannot go unremarked. Sounds like poor weather and high winds generate power, helping the airplane fly longer! Should be:

"poor weather or high winds can affect power consumption".

Anyway, well done Rafz RC Model Club.

Fuel.

[rickb928]

I do not think that word means what you think it means.

28 hours?

[rmdingler]

Pssshh! Is that all?

Re:28 hours?

[Anonymous Coward]

I agree, unmanned flight should easily be able to keep up with a manned flight that runs on battery and solar power.

Small difference between 28 hours and many weeks

[Dr. Spork]

If the current generation of solar powered drone stays up for more than a day, the next generation might stay up for weeks. Basically, what this shows is that we're pretty close to the threshhold where incoming photovoltaic energy over 24 hours matches the energy needs to keep the thing flying. Just a bit more optimization could mean that the thing takes in more energy than it uses, and then it can basically fly until something wears out. All kinds of interesting things then become possible.

Not a record, not even close

[Anonymous Coward]

Qinetiq Zephyr flew for "336 hours and 22 minutes (2 weeks / 14 days)".

I'm pretty sure I remember a similar but much longer flight, but I can't find the details. Regardless, 28 hours isn't very impressive compared to 336.

Re:Not a record, not even close

[radarskiy]

From the article:
"thereby setting a new *Swiss* endurance record for unmanned solar-powered flight, and improving upon the previous internal record (ASL’s Sky Sailor) by a over an hour."
(emphasis mine)

So the summary overstates the record by most of a planet.

Re: not a record

[Anonymous Coward]

>I'm pretty sure I remember a similar but much longer flight, but I can't find the details. Regardless, 28 hours isn't very impressive compared to 336.

I thought someone put a solar flight up for something like almost a year a few years back.

Unmanned UAV?

[PatientZero]

As opposed to a manned unmanned aerial vehicle?

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