Scientists Develop Self-Propelling Phoenix Aircraft That Inhales Air (bbc.com) 90
dryriver writes: The BBC reports on a 50ft long and only 120kg heavy blimp-like UAV aircraft that is designed to fly at 70,000 feet, is entirely solar powered, uses variable-buoyancy for propulsion, and can essentially stay airborne in a self-powered way until it experiences mechanical or electrical failure. The Phoenix varies its buoyancy continuously using a helium-filled fuselage that also has an interior air sack that works a bit like a lung. It can inhale air and compress it on demand, making the aircraft temporarily heavier than air, and expel the inhaled air through a nozzle at the back of the aircraft, making the aircraft lighter than air again, creating some extra forward propulsion in the process.
The Phoenix -- which is a simple, cheap-to-build aircraft that its designers describe as "almost a disposable aircraft" -- could one day act as a satellite replacement flying at 70,000 feet. It may also be used for surveillance purposes or to release micro-satellites into earth orbit. The Phoenix has already completed short test-flights of 120m inside the hangar it was built in. This YouTube video shows just how gently the Phoenix rises into the air, hovers in place, and lands again. Unlike drones that need to land, refuel and then take to the skies again, the Phoenix may stay in the air for very long periods of time, landing only for periodic maintenance of its electrical and mechanical components.
The Phoenix -- which is a simple, cheap-to-build aircraft that its designers describe as "almost a disposable aircraft" -- could one day act as a satellite replacement flying at 70,000 feet. It may also be used for surveillance purposes or to release micro-satellites into earth orbit. The Phoenix has already completed short test-flights of 120m inside the hangar it was built in. This YouTube video shows just how gently the Phoenix rises into the air, hovers in place, and lands again. Unlike drones that need to land, refuel and then take to the skies again, the Phoenix may stay in the air for very long periods of time, landing only for periodic maintenance of its electrical and mechanical components.
Re:Jellyfish drifting (Score:5, Informative)
Wouldn't this be drifting in the jetstreams like a jellyfish? May it could use the shifting winds to navigate like a hot air ballon does.
The Phoenix flies at 70,000 feet, higher than either the polar jets at 30,000–39,000 ft (nine–twelve km) or the subtropical jets are at 33,000–52,000 ft (10–16 km).
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Re:Jellyfish drifting (Score:5, Informative)
Out of interest, how high do the jellyfish drift?
To the high tide line, of course.
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"Float like a jelly bird? Let's go right now!" - Famous movie line.
Station keeping (Score:5, Interesting)
If you launched enough of these you could saturate the sky and not really need to worry about stationkeeping as a new one would drift in to a cell as other's exited on average and maintained in that equilibrium with just a little extra effort.
This would make a grea way to show ads for pepsi, or to allow facebook to stream videos direct to your cell phone form orbit while the visually track what you are doing.
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That would be a way to reduce global warming as well, reflecting sunlight back up into the sky.
More blimps (Score:2)
https://theintercept.com/2017/... [theintercept.com]
Flaming Bird (Score:3)
Who names a blimp a 'phoenix'? Oh, the humanity!
At least it uses helium. I'm wondering how fast it can propel itself, though.
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Simple: It's shaped like a huge manatee.
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Go US, that saved us the cost of a bomb!
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OK, yes, there were a couple of "burning" problems with earlier blimps, but we're at least reasonably sure that we solved those.
The Hindenburg was actually a dirigible (rigid interior frame) not a blimp, but the German's bad engineering with regard to static control and choice of flammable materials contributed a lot to the disaster, as well as the use of hydrogen.
It can inhale air and fart (Score:2)
sorry, could not resist...
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Sure you can. But, with enough force to propel you in a particular direction?
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Maybe in space...
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Yes but the air is going to be quite thin and that seems like it would directly impact their method of operation. I'm sure they've done the math and theory but I wonder if the practical implementation will actually pan out.
Advantages of the variable-buoyancy propulsion? (Score:2)
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and expel the inhaled air through a nozzle at the back of the aircraft, making the aircraft lighter than air again, creating some extra forward propulsion in the process.
They probably minimize the buoyancy changes to minimize energy expenditure which means expelling relatively little air from the rear so it probably does not contribute significantly to the propulsion.
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Great explanation... BBC should have consulted you.
I wonder what the max payload of these blimps would be... and would payloads scale up economically with larger blimps? I feel like that would be a basic question anyone looking to deploy sensors or communications would need to know. The article says they have to scale up to reach the desired altitudes, but says nothing specific about payload weight/size.
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It's basically the same reason why airplanes are more efficient than helicopters.
Airplanes use a bit of power to drive themselves forwards, but rely on a wing to provide lift to keep them up. The wing is more efficient at generating lift than a downward-directed fan/prop/rocket/whatever.
A buoyancy glider uses the same principle flipped: it generates lift (or sink) and uses a wing to translate that into forward thrust. Again, the large fixed wing is more efficient than the small spinning ones.
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A down-pointed fan is also a spinning wing (more than one, actually). If you read my post carefully, I took some care to refer to the means of generating vertical lift with general terms.
A helicopter with sufficiently large, well-designed blades could theoretically generate lift as efficiently as a fixed wing. The problem is, the chopper blades would have to effectively BE airplane wings, and that's generally proved somewhat impractical.
Not Orbit (Score:3, Informative)
"It may also be used for surveillance purposes or to release micro-satellites into earth orbit."
^ The article directly contradicts this summary claim. There are no plans to accelerate this thing to orbital velocity, which is about 30 km/s and would be absurd to expect from this. The claim of the designers is that it's an alternative to going to orbit. Perhaps it can achieve the goals of some subset of microsatellites so that they don't have to go to orbit.
Re: Not Orbit (Score:4, Interesting)
Not terribly practical. Most of the energy of achieving low Earth orbit is in reaching orbital velocity -- roughly 10x the speed of a high speed rifle bullet. There are advantages to designing an orbital launch vehicle that starts above most of the atmosphere. You can use a vacuum optimized rocket nozzle design and don't have to overcome aerodynamic resistance. But there's a proven solution to getting an orbital launch vehicle over most the atmosphere -- a first stage, which now can be reusable.
It's *conceivable* that an airship platform might be advantageous to a reusable first stage, certainly from an environmental point of view, but it's only likely to be competitive if it were somehow operating on a massive scale. That makes it an interesting engineering problem, but not something that will be pragmatic in our lifetimes.
There was also a company about a decade ago that was pursuing an airship to orbit scheme. The idea was to have a huge stratospheric balloon platform from which superlight airships could be launch; the airships would use buoyancy to achieve altitudes sufficient to employ ion thrusters, and then spend days or even weeks to achieve LEO. They had a DoD contract, but I suspect the military was more interested in the balloon platform than in the airship to orbit scheme.
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Re: Not Orbit (Score:4, Informative)
The rocket equation says no.
A conventional rocket has to accelerate its fuel and its payload. A projectile system just has to accelerate the payload.
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"It's *conceivable* that an airship platform might be advantageous to a reusable first stage, certainly from an environmental point of view, but it's only likely to be competitive if it were somehow operating on a massive scale. That makes it an interesting engineering problem, but not something that will be pragmatic in our lifetimes."
It could be quite pragmatic in our lifetimes if commonalities amongst these ships and an assortment of applications were exploited to make their manufacture a commodity opera
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The article stated that the micro-sats would be released at a high altitude, where they would accelerate to orbit.
Clearly the micro-sats would need their own propulsion, but that would be much less that would be required from ground level.
Re:Not Orbit (Score:5, Informative)
That is a common misconception: that once you get to high altitude, you are practically in orbit. Being in orbit requires velocity, and velocity requires a huge energy input - much more than just getting up to 10s of kilometers of elevation.
A different slashdot commenter has summed it up as the 6-6-6 rule [slashdot.org]: Mach 6 at 60,000 ft altitude is a whopping 6% of the way to orbit.
Let's say you are aiming for low earth orbit: altitude 300 km and velocity about 7.72 km/sec. The potential energy for reaching orbital altitude is approximately m * g * h, or mass * 3e6 [J/kg]. The kinetic energy is 1/2 * m * v^2, or approximately mass * 3e7 [J/kg]. In other words, you have to put in 10x as much energy getting the object up to orbit velocity as you do in raising it to orbit altitude.
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This is also a common misconception. You can't analyze rockets by computing kinetic energy. You must compute delta-v. For launching, there are also gravity and aerodynamic losses.
Accelerating *up* is considerably harder than accelerating in other directions, if that acceleration is applied over some significant period of time. And trimming off a few percent of the *final* energy required can translate to a lot more of the *total* energy required, due to the nonlinearities in the rocket equation. It's like b
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True. Even for an actual satellite, you can get reasonably significant fuel savings by launching from high altitude. Enough that Paul Allen sunk a whole bunch of money into it. SpaceX also considered the concept, but decided that the complication and restrictions (like size) weren't worth the fuel savings.
I expect the "we can also launch satellites" thing is just tacked on though. A long duration autonomous high altitude blimp has lots of uses by itself.
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That may be true, but you haven't actually put numbers to it. How much do you save by first lofting your rocket to 60,000 ft altitude? Or: but differently, how much more payload can you pu
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It's an interesting exercise to work the whole thing out. I've got a stuff to do today, unfortunately. But as a rough indication, you can look at the impulse provided by each stage in a Falcon 9.
First stage: 7607 kN for 162 s = 1,232 MNs
Second stage: 934 kN for 397 s = 371 MNs
The first stage is also about four times the mass of the second stage as well. You certainly couldn't replace the whole first stage with an air launch system, especially a stationary one like a blimp, but it does illustrate that delta
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Oblig. (Score:3)
So, has it been weaponized yet?
Re: Oblig. (Score:2)
The blimp was developed by military contractor Stirling Dynamics. It _is_ a weapon prototype.
https://www.stirling-dynamics.... [stirling-dynamics.com]
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Dammit, I should have known better. Post hoc weaponization is so last century!
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This is an american forum. I'm not american. Pillock. And will you ever learn to get your apostrophes right?
Weaponising dinkel wheat (Score:2)
its spelt weaponised
How would one turn dinkel wheat [wikipedia.org] into a weapon?
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spud guns.
Changing the balloon's surface: black and white (Score:2)
It's an old idea, but they could have a way to change the outside surface between black and white, to absorb more or less sun heat, to alter the temperature and the density of the lifting gas. It might be more efficient than compression.
Buckminster Fuller gave us Cloud Nine: city-sized tensegrity spheres. https://en.wikipedia.org/wiki/... [wikipedia.org]
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Perhas a layer of eInk?
obligatory... (Score:1)
Self propelling, inhales air (Score:2)
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Nothing like a jet engine. A jet engine requires fuel for a start.
This is basically a blimp, but with a solar powered pump to suck in or expel air and thus vary its mass. Heavier than air and it descends, lighter than air and it ascends.
The expelled air also provides a little bit of propulsion, but the main way of getting around will be like a hot air balloon. Move to an altitude where the wind is going the same way you want to go.
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more like a glider (Score:2)
I won't believe it until (Score:1)
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Unless it's on the cover of Popular Mechanics then I don't believe it exists.
Right idea, wrong magazine [youtube.com]
Low cost satellite alternative? (Score:2)
Why helium (Score:3)
In this unmanned application, why the need to use increasingly scarce helium? Hydrogen is cheaper and would work even better.
Of courage, you wouldn’t want to call it the Phoenix if it used hydrogen.
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Ummm... no. The reason helium doesn't seem scarce is because the U.S. is pissing away its reserve, artificially lowering the price. The low price means natural gas producers have no incentive to collect it, further exacerbating the problem. Reality will soon catch up with the helium market. Also, because a hydrogen molecule is much larger than a helium atom, hydrogen diffuses through small cracks and solid materials much slower than helium, making it easier to contain, not harder.
TFA is wrong about one thing (Score:2)
Phoenix is an unmanned aerial vehicle (UAV) designed to stay in the air indefinitely using a new type of propulsion.
Actually, variable-buoyancy propulsion is a very old type of propulsion. Solomon Andrews' [wikipedia.org] "Aereon" airship used it in the 1860s.
Stays airborne ... until it doesnn't (Score:2)
Umm .... like any aircraft it "... can essentially stay airborne in a self-powered way until it experiences mechanical or electrical failure. "
Not sure what there is to see here.