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New aircraft rises 'like a balloon'

bbc.com

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Re: New aircraft rises 'like a balloon'

#41

Post by ttyl0125 »

hirundo wrote: post #5

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…

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?

Re: New aircraft rises 'like a balloon'

#42

Post by kjhughes »

NikkiA wrote: post #31

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.

"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."

Re: New aircraft rises 'like a balloon'

#43

Post by [deleted] »

astazangasta wrote: post #6
hirundo wrote: post #5

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…

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.

[deleted]

Re: New aircraft rises 'like a balloon'

#44

Post by saulrh »

kbenson wrote: post #18
sandworm101 wrote: post #17

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.

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.

> 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...

Re: New aircraft rises 'like a balloon'

#45

Post by MagicPropmaker »

NikkiA wrote: post #31

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.

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.

Re: New aircraft rises 'like a balloon'

#47

Post by lordnacho »

NikkiA wrote: post #31

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.

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

Re: New aircraft rises 'like a balloon'

#48

Post by PeterisP »

MagicPropmaker wrote: post #45
NikkiA wrote: post #31

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.

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.

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.

Re: New aircraft rises 'like a balloon'

#49

Post by sfotm »

MagicPropmaker wrote: post #45
NikkiA wrote: post #31

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.

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.

How would a more traditional airship descend, if not by becoming heavier than the air surrounding it?

Re: New aircraft rises 'like a balloon'

#50

Post by jwilli »

MagicPropmaker wrote: post #45
NikkiA wrote: post #31

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.

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.

It's new because it is being done in the atmosphere. I work with Autonomous Underwater Vehicles (AUV) which have employed this method of propulsion for at least a decade. For AUVs the variable buoyancy is achieved by having an expandable bladder of fluid which can be contacted to allow ballast to enter or expanded to expel ballast. Check out Slocum gliders if you are curios
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