
New aircraft rises 'like a balloon' - jdmark
https://www.bbc.com/news/uk-scotland-48013519
======
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.

~~~
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.

~~~
saulrh
> not that I know if half density is a feasible figure

1/15th - .08 kg/m^3 at 20km, 1.2 kg/m^3 at sea level. 20km is _way the heck_
up there. And yes, it does make it difficult to build something buoyant
enough, which is why the use case for this is something like a geostationary
internet balloon rather than for transportation.

[https://www.engineeringtoolbox.com/standard-atmosphere-
d_604...](https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html)

------
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.

~~~
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.

~~~
davnicwil
Excuse the silly question if it is one, but would one option be not a full
vacuum but only marginally lower density of air inside the balloon,
supplemented by solar-powered propellers? Could there be a material strong
enough to handle a minimal density difference to provide enough lift for it to
work?

~~~
jeffreyrogers
Any structure strong enough to withstand the pressure from outside the vacuum
weighs too much to be lifted. At least that's what I read in some aerodynamics
book. Maybe some materials scientist will come along and prove that wrong.

~~~
beamatronic
Can we make many small ones instead of one big one?

~~~
shkkmo
As volumes decrease in size, the ratio of surface to volume increases, make
weight a bigger issue with smaller envelopes (given that surface thickness
would not be able to decrease proportionally).

------
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](https://www.uhi.ac.uk/en/#campuses)

~~~
therein
Just out of curiosity, do you have any relation to the Remarkable Tablet?

~~~
ZeroGravitas
Nope, no connection, both independently named after the character in the Iain
Banks sci-fi novel, I assume.

------
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.

~~~
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.

~~~
PeterisP
Like a hot air balloon which becomes heavier than air or lighter than air by
regulating temperature in order to ascend or descend? That's fancy tech as of
year 1800.

~~~
PhasmaFelis
As long as we're nitpicking terminology, hot air balloons aren't airships
either, they're aerostats. And they certainly don't use their variable
bouyancy to propel themselves in directed flight. Saying this thing is just a
hot air balloon is like saying an airplane is just a glider.

------
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](https://en.wikipedia.org/wiki/Sutherland_spaceport)

