New aircraft rises 'like a balloon'

[sandworm101]

Most of the mentioned use cases involve high altitudes. Higher altitudes = higher winds. The air is smooth up there but it does move. For instance, the upper level winds above my head right now are pushing 130knots. This thing will have to do more than glide gently up and down if it wants to maintain station at 10km+, airliner altitude.

[saulrh]

Go higher. If you search for "high altitude wind" you'll get info from 20,000 feet, which is not at all the same as 20,000 meters. Past a point, the thinning atmosphere actually means less coupling and wind speed decreases. You'll note that tiny quote halfway through about it being difficult to get up to the required altitude of 20km. That's because the average wind speed bottoms out around 5 meters per second at an altitude between 20km and 25km [1]. Add in the thinning air reducing drag and, yeah, a solar-powered balloon can absolutely stationkeep at that altitude. Here's a wiki page with more links: https://en.wikipedia.org/wiki/Geostationary_balloon_satellit...

[1] https://www.researchgate.net/figure/Average-wind-speed-in-th...

[kbenson]

I was wondering about this too. Then again, I don't know the air density difference. 130 knots at half the density (not that I know if half density is a feasible figure) would impart something like half the force, I imagine. Then again, lower density affects the ability of craft that use density for lift to operate.

[ChuckMcM]

Yup, that has been the Achille's heel of these types of vehicles. One work around is to have a bunch of vehicles and have them move to altitude, stay over the area of interest as long as possible and then change to a lower altitude without the winds to move back to the head of the line.

[TheLoneAdmin]

Apparently the craft is powered entirely by solar power, plus batteries, to work at night. A solar powered craft cannot maintain 130 knots.

[jpm_sd]

The same method of altitude control, using a compressor and an internal "ballonet", is used on Google Loon.

[hirundo]

With the soaring price of helium, I wonder what it costs to fill up that gas bag and how quickly it leaks out. And at what point filling it up costs more than the "almost expendable" aircraft.

In the novel/film Contact the character S.R. Hadden lives in an airliner that rarely lands. With a larger Phoenix that lifestyle could become available to somewhat less wealthy billionaires. Maybe it could eventually become an atmospheric variation of seasteading.

[ttyl0125]

According to the article, the Phoenix has a reversible hydrogen fuel cell on board. Just a guess, but maybe it's filled with helium on the ground (for safety purposes),then generates hydrogen (from electricity and water) once aloft to replace any lost helium?

[jacobush]

If helium gets really expensive, they could switch to hydrogen. Maybe even switch inflight, by replenishing lost helium with hydrogen. Maybe by hydrolysis. For a plane operating in remote areas at altitude, the explosion risk is not an issue.

[everdev]

> Maybe it could eventually become an atmospheric variation of seasteading.

It's like a miniature version of the Venus cloud city idea, but here on Earth.

[astazangasta]

There are no really great lifting gases. Steam is ok but must be kept hot. H2 is dangerously explosive. Vacuum is the best (a so-called "null ship") but no known material can maintain the hull pressure under vacuum.

[kevinmchugh]

I believe Hadden lives on a space station in both movie and book.

[neom]

For those curious, University of the Highlands and Islands is in Inverness, Scotland. Quite a bit north of Edinburgh and Glasgow.

[ZeroGravitas]

That's the main campus but part of the concept is for it to be distributed over most of the Northern part of the country, including, as the name suggests, the islands:

https://www.uhi.ac.uk/en/#campuses

[tim333]

The solar powered blimp in the photos looks too slow to stay in one place on a somewhat windy day, which would be necessary if it's a satellite replacement.

[larrydag]

I'm curious if it can achieve the 20km altitude. I would bet weather would be a significant factor with keeping it aloft and on course.

[foxyv]

I remember a proposal for one of these balloon gliders by NASA. Except on an entirely different scale. Be cool to see how it works out.

[agumonkey]

I'd love a fleet of small lighter than air balloons for city coasting

[sarbaz]

This is exactly how submarines work

[evgen]

Submarines use a prop for forward motion and are almost never 'gliding' using their planes. The purpose of the wings on this craft are similar to the variable-buoancy underwater drones that are out there, when the craft is rising the wings are trimmed to cause forward motion and then when it is descending they are trimmed in the other direction to continue forward motion.

[NikkiA]

What decides if it's an airship or not is not whether it has wings, but whether it's lighter than air. This thing is lighter than air, thus it is an airship.

Yet more terrible writing by the BBC.

[ajross]

Uh, cite for that? Sorry, that's ridiculous pedantry. It's very reasonable to call the thing an airship, or an aeroplane (something done in the article only once, and in the context of a sourced quote justifying the distinction no less). I'm aware of no dictionaries or professional categorizations this article violates. It's a device that spans the boundary, and the article is literally about that, as the technology is (well, sorta) interesting.

Why is lack of adherence to your personal aeronautical jargon preferences a criterion for "terrible writing"? And why is this the top comment in the topic? Come on folks.

[kjhughes]

"The central fuselage is filled with helium, which makes it buoyant so it can ascend like a balloon."

"And inside that there's another bag with compressors on it that brings air from outside, compresses the air, which makes the aeroplane heavier and then it descends like a glider."

[lordnacho]

Sounds like it's an air submarine. The description of the variable buoyancy sounds pretty much like what a submarine does.

[andrelaszlo]

I might be misunderstanding things but it sounds like the "breathing" (compressing atmospheric air) gives it variable density? I guess it makes it a sometimes-an-airship.

[MagicPropmaker]

It's both heavier and lighter! There's a compressor that can bring air in from the outside and make it heavier than air, and then this air can be released making it lighter again. This is explained in the article. It really is something new.

[mothsonasloth]

University of the Highlands and Islands is considered a bit of a second rate institution in Scotland.

A nice bit of publicity for them none the less.

Hopefully they can develop this more and more. Scotland needs a boost to Aerospace after we got another Space port last year

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