I think the plasma region has a different kinematic viscosity than the un-ionized region. This should change the Reynolds number (ratio of inertial to viscous forces), and that should profoundly affect things like flow separation, turbulence onset - lots of things that matter in flow over airfoils.
There's been work on kinematic viscosity changes due to plasma effects in plasma torches, but I can't provide links right now.
It will be interesting to see how this holds up in real flight conditions: icing, bug splat debris on electrodes, low pressure at high altitudes, and how much electrical power is needed to sustain the benefits. Cool work.
One guess could be (as the WP article above seems to imply) that kinetic energy that would normally go into turbulence instead goes into ionizing the neutral gas (i.e. surrounding airflow). That would transfer kinetic (turbulence) energy into electrostatic energy, and thereby of course reduce turbulence.
Another guess: the article says the plasma actuators can create weak flows, so a small push of air toward the trailing edge of the wing would create enough of a vacuum to re-attached the flow.
>A scaled-down gale blows over a flat plate set inside the tabletop wind tunnel. Despite the low lighting and hazy Plexiglas view portals, we can clearly see the frenzied fluttering of streamer ribbons, called telltales, in the field of little wind vanes that carpets the exposed test surface inside.
I'm really bothered by this style of journalism which feels the need to start off every story with an in media res narrative instead of just telling you the most important points and working its way down like a traditional newspaper article should.
I don't care about the scene at the wind tunnel you visited while researching this story. Tell me about the plasma wings.
I see this more and more and also find it tiresome. I stop reading and go straight to the HN comments. At least then I'll more quickly learn what the damn article is about.
I took Journalism as an elective and fell in love. I use knowledge gained many times a day, and have much deeper insight into what I consume. I highly recommend anyone who hasn't do yourself the favor of taking a Journalism class. I felt like Neo- I could see the code of the matrix and was no longer fooled by all the fake stuff surrounding me.
edit- I could also form a deeper appreciation for the truly amazing Journalists out there. Diamonds in the rough.
You are very interested in the subject, so this seems unnecessary.
Most people are not, and need to be hooked. That's what starting a story like this is intended to do. It's the same reason that so many movies and TV shows start with an action scene and then circle back to start the exposition.
It's surprising that even with the energy it takes to generate a plasma strong enough and in enough quantity to achieve the desired effects, it can still result in an estimated 25% energy savings. It goes to show how much energy just deals with drag in the current system.
>> It's surprising that even with the energy it takes to generate a plasma strong enough and in enough quantity to achieve the desired effects, it can still result in an estimated 25% energy savings. It goes to show how much energy just deals with drag in the current system.
You've made an assumption that they are taking the energy required to create the plasma into account in their aerodynamic efficiency calculations. I didn't see any indication of the power required to produce the plasma, much less that number of power already required to fly. I did see the suggestion of using it on electric planes or wind turbines where larger amounts of electric power are readily available - one can interpret that availability as a convenience (high voltages and power are already there meaning less complexity) or an oversight (we're just neglecting the energy required). Nowhere in the article is this directly addressed. It would not surprise me if the truth were somewhere in between - it takes a lot of power, but saves even more.
I've seen a similar situation in the hybrid car world when making certain comparisons.
There is a huge gap between ~600mph vs much lower speeds of electric planes or windmills. As to energy requirements, it's likely fairly low in large part due to the expected altitude of 30,000+ feet. But also because the goal is stabilizing the airflow.
PS: Drag force is velocity ^2; energy lost to drag Drag force * Distance or v^3.
Do we know if there's a lot or a little lost electricity that is generated as a result of the main engines running? I know cars waste a bunch of electricity (which is how hybrid batteries charge themselves when driving).
> Do we know if there's a lot or a little lost electricity that is generated as a result of the main engines running?
That's not how it works. Car use an alternator instead of a generator because it lets them control how much electricity to make regardless of the speed at which the alternator spins. They basically vary the strength of the magnet in the alternator.
If they didn't the effect of "extra electricity" is a higher voltage, which would obviously be bad.
> I know cars waste a bunch of electricity (which is how hybrid batteries charge themselves when driving).
Hybrid batteries mostly save energy by capturing wasted energy when braking and when going downhill. Charging batteries from the engine makes the engine consume more gas.
> Hybrid batteries mostly save energy by capturing wasted energy when braking and when going downhill
Only for some workloads. A remarkable portion of the efficiency gain in hybrid vehicles is due to letting the ICE run at only the most efficient portion of the torque and power curves. In my experience (10 years in a Prius) regenerative braking is a distant second.
The waste energy in a regular car is not electricity, it is mostly simply heat. Instead of heating up a brake-disc by clamping it with calipers and pads an electric car or a hybrid will engage the motor by allowing it to be driven by the car instead of the other way around. The resulting energy at the output terminals of the motor is rectified and used to charge the batteries.
So when you brake your regular car you lose some heat to the environment, you don't 'waste a bunch of electricity'.
Cars and planes don't "lose" electricity when their engines are running; otherwise their batteries would be constantly overcharged. Hybrid cars just have more powerful alternators.
Hybrid cars don't necessarily have an alternator in the sense that an all gasoline car does-- for example, Toyota's hybrid system uses a pair of motor/generators (electric motors which can be configured to generate power too) connected to each other and to the gasoline engine through a planetary gearset.
Electric motors and alternators are mostly equivalent, the difference is that the diode assembly on a car alternator would stop you from using one as a motor. Otherwise, they are roughly identical.
That you don't find a 'traditional' alternator in an electric or hybrid car is simply because the electric motor doubles in that role when required.
Almost all electric motors when spun will generate power, you'd have to do some work to get one not to generate power when driven.
AC induction motors are the most common type of motor for anything other than small electronics and turning one by hand will not generate any output power. They are definitely not identical to an alternator. The armature of an induction motor doesn't have an associated magnetic field so turning it won't generate any power in the windings.
Permanent magnet motors are the only motor that will generate power if you just pick one up and turn it by hand, and they are quite rare (and expensive) at scales larger than a RC toy motor
Lift requires energy, usually kinetic, like the forward motion of an aeroplane being converted to lift (and drag) via the wings, or the blades of a helicopter pushing air down, or real hot and fast gases pointed downwards (think harrier jump jet).
A blimp, on the other hand, relies on buoyancy for lift, so yeah, in that case, given an altitude at which it's stable, to maintain velocity it only needs to add enough thrust to counteract the drag created by its forward movement.
Yes it is correct. Lift always creates drag. You can think of drag as the work necessary to gain lift. When lift is generated, it produced what is called induced drag[0]. Induced drag and parasitic drag, which is the drag generated from the aircraft structure itself, are where all the energy goes in unaccelerted flight.
I think we're interpreting op differently. No, not all the energy added to a heavier than air aircraft (thrust) in straight-n-level flight* is used to counteract drag. Yes, where there is lift, there is induced drag. But the kinetic energy being added to maintain velocity is also being used for lift.
Imagine if the airfoil on an aeroplane were replaced with a symmetrical airfoil mounted with no angle of incidence. Thrust could be reduced because there's less drag from no lift. No lift, no induced drag, only parasitic drag, and the plane starts to lose altitude. Would you agree that not all the energy added to straight and level flight goes towards counteracting drag?
*where a' and v' are zero, and where for argument's sake, the thrust vector is perfectly horizontal
edit: by a' I mean change in vertical airspeed, by v' i mean change in true airspeed.
No, that's a non sequitur. An aircraft that doesn't produce lift requires less energy input, but that's not because lift requires energy -- it's because when there is no lift, the aircraft is gaining kinetic energy by losing potential energy.
If lift requires energy, then where would that energy go?
I think ppl are equating energy with force. Airspeed, altitude, and fuel are forms of energy, kinetic, potential, and chemical, respectively. Lift, drag, thrust, and weight are forces. We're talking about a heavier than air aircraft in cruise right now, and the contention is over whether all the energy added to the aircraft if used to counter drag.
Simple example: consider a helicopter in cruise. Fuel is burned to produce thrust. There is an insignificant component of that thrust vector pointed orthogonal to the vector of velocity. Since drag by definition acts along the same vector as velocity, not all the energy is being used to counteract drag.
Back to an aeroplane in straight and level, since that's a more interesting example. Let's assume that the direction of travel of the aircraft is normal to the plane of the propeller, so thrust is acting on the same plane as drag, in this idealized situation. Energy is added to the system in the form of thrust created by the prop. Said thrust is used to maintain the amount of kinetic energy of the aircraft. At the same time, this kinetic energy is being transformed into both lift and drag by the wings (and elevators, depending on how far aft the cog is) ergo not all the energy added to the system is used to counteract drag.
To explain it in yet another way: As long as you maintain your height no energy is used for lift, as energy is equal to force integrated over distance. Like as standing on a table requires no energy ;) However, an airplaine isn't standing on anything and the lift force is generated by pushing air downwards and this is what consumes energy.
A car or a train that drives with a constant velocity has constant kinetic and potential energy (assuming level ground). Therefore all energy that is consumed to maintain the status quo is spent to counteract drag.
A plane however pushes down on air instead of solid ground and accelerates it downwards. So not only does the fuel heat up the system due to drag, some of the energy accelerates quite a chunk of air.
Now you can argue that 'moving air' is nothing else than turbulence that takes a bit longer to dissipate and is therefore just another form of drag ;)
This is a bit like the debate on whether it's the current or the voltage that kills, with lift-to-drag ratio being resistance. You are right in the physics sense in that drag alone is enough to calculate instantaneous fuel consumption, but to calculate range you already need to consider mass ratios and lift.
Interesting point, sfc (specific fuel consumption) is only really density altitude and humidity dependant, since it's only calculated on a per engine basis, but a fixed wing aeroplane's range can be greatly affected by the weight and balance of the plane, ie whether the elevators need to be adding upward or downward pressure to the tail section to maintain a cruise attitude
I am not a physicist, but, doesn't fighting gravity by way of lift mean that at cruise altitude the plane is still fighting gravitational acceleration constantly? Drag is friction, right?
The relationship between drag and lift is complicated. They're ultimately both the same phenomenon: pressure differentials introduced by dynamic fluid flow. You cannot have lift without drag, and you cannot have drag without lift [1].
That being said, this is fluid dynamics, where nothing is simple. Some of drag could be loosely described as friction, but not all of it. Think of what you feel while you're swimming, or sticking your hand out of a car window. It's like something is actively pushing against you, like you're catching a ball or something -- which you wouldn't normally call "friction". On top of this there are temperature effects, turbulence, ... and so on. And, most of these are actually at least somewhat coupled to each other.
Anyways, though at the end of the day it may be technically accurate (in certain contexts) to say that all of the power consumed at level flight is going to drag, it's also disingenuous; a bunch of that drag is the direct result of needing to generate lift to fight gravity.
[1] Admittedly this is a somewhat loose interpretation of the word "lift" but when you get down to the nitty gritty details like this I don't think "lift" is any more than a semantic construct to denote "useful drag". But the lift created to help control Apollo command capsules during reentry is a good example of this: by altering the angle of attack, thereby introducing highly asymmetric drag, the capsules "generated" lift to ease reentry angles.
The power required to fly at constant altitude and speed is velocity multiplied the force of drag.
Energy is consumed to exert a force over a distance, but we're not moving against gravity ("constant altitude"), so no energy is directly expended to fight gravity.
Now, that argument cheats a little, because there is a relationship between lift and drag: compare induced drag (drag created as a result of producing lift) to parasitic drag.
Consider a helicopter nearly hovering, but moving forward at a walking pace.
To maintain the hover and prevent the helicopter from falling out of the sky, the engines are consuming large amounts of power. To move it forward at a sedate pace only requires a small expenditure of energy to overcome drag.
If it was on wheels, a human could push it across a hangar with little effort. A human definitely could not hold a conventional helicopter in the air by lifting or by pedaling to turn the rotors.
The reactive force lifting the helicopter should not be thought of as drag.
Are you actually claiming that a helicopter doesn't use any energy to hover in place? Your argument describes the work done on the helicopter (or plane), but not the work the helicopter does on the air, which it pushes downward considerably. So, too, does an airplane's wings 'push' air downwards. Contrast to the vehicle sitting on the ground, where the ground is incompressible and no work is done on it.
Keeping an object at a constant altitude requires force, but it doesn't necessarily cost any energy. For example, there's no energy being expended keeping my coffee cup elevated, just a table exerting a force.
From my admittedly limited understanding of aerodynamics, a plane's engines are only fighting against drag to keep the airspeed up, and it's the airspeed passing by the wings that generates lift -- if engines are necessary to generate lift, gliders and kites wouldn't be able to work at all.
There's more too it than that. The airfoil causes a net downwash, and via newton we know the acceleration of that mass of air will cause an upward force. The finer details of this are something a lot of textbooks get wrong. Wikipedia's article about it is pretty good.
With a kite the wind is the engine, the string allows the kite to use it. Or you can run on a windless day.
With a glider the tow plane or ground tow rope provides the initial energy to get to altitude, giving the glider potential energy. As it glides that potential energy is converted to kinetic energy. The pilot uses their knowledge and skill to glide to places where they can gather more energy from updrafts of various sorts. I think it's really amazing how after that initial injection of energy, it's just all just skill and ambient energy.
I can't seem to find anything in google, but I remember reading about something similar some ~10 years ago for military aircraft. Apparently there were experimental fighter jets that had large ionizing beams of some sort shooting in front of the aircraft? The claim was along the lines of by ionizing the air in front of the craft, it significantly reduced the drag the plane experienced flying through that pocket of air moments later.
I'm having a hard time finding articles on it, but it sounds so similar to this article.
Alas, it's full of anti-gravity and over-unity and other such rubbish, but the bit about the B-2 using electrostatic discharge to shape the airflow around it certainly does sound like what's being referenced in the OP. Almost make me wonder whether anti-gravity etc. aren't simply smokescreens to fuzz up the S/N ratio of leaks about legitimately cutting-edge technologies.)
The B2? A stealth aircraft equipped with an array of pulsing electrodes strong enough to move air? I haven’t read anything about this, but I assume that these things are extremely loud radio emitters.
Allegedly it creates a plasma shield which has a radar-shielding effect, in addition to reducing drag (and maybe actually moving the air). But yeah, you'd think that the RF signature would be unmistakable...
Drop the plasma. What is has are, potentially, some directional antennas capable of attacking inbound radar. But imho it doesn't have even that. This is 1980s/90s tech. It's a quiet bird, as opposed to something like and EW/weasel jamming platform. I doubt it does anything active. Now it may have some conductive material meant to absorb and play tricks with RF, giving the appearance of some magnetic shield, but I don't think it is deliberately broadcasting, at least not in any omnidirectional way remotely similar to a force field.
One active trick is does do, and has been confirmed by ATCs all over the place, is transmit transponder data as if it were a commercial aircraft while in civilian/peaceful air space. This prevents enemy spies from detecting a mission launch and direction, but has raised concerns amongst legal minds. It's akin to a soldier wearing civilian cloths while travelling behind the lines ... but such principals seems to be falling by the wayside these days.
The goal of stealth is to avoid detection. The goal of active jamming is to obscure the specific location of something and prevent targeting, either by blanking enemy sensors or presenting false targets. That is contrary to the goal of not being detected.
> It's akin to a soldier wearing civilian cloths while travelling behind the lines ... but such principals seems to be falling by the wayside these days.
That has always been an acceptable ruse de guerre, so long as the soldiers change back into their proper uniforms before engaging in any combat actions.
It's not illegal. The issue is that any vehicle transporting troops, armed troops, is a valid military target. They aren't meant to hide amongst civilians. A military aircraft pretending to be a civilian is daring the enemy to start shooting at civilian aircraft. Not illegal, just wrong. You would never see a US naval vessel identify itself on radio as a cruise ship, but that is essentially what the B2 does on every combat mission.
(At least those flown from north america, I don't know what they do when flying from the other bases.)
"Directional antennas for attacking inbound radar" is essentially what all jamming does. You send emissions of your own that mess up the returns from the radar. This can be as simple as just blasting noise to make the return indistinguishable from the noise, but the ability to send "false" returns has been around for quite a while. I wouldn't be surprised to hear that they could send an out-of-phase signal to cancel the pulse (like noise-cancelling headphones), but the catch would be that the signal probably wouldn't be perfectly cancelled except in a specific direction (back towards the source) and you could probably detect that. As such I would be surprised to see it on the B-2.
The other thing is that when stealth aircraft are in civilian space they attach/deploy radar targets that give the aircraft a perceptible return for safety's sake. Un-deploying a radar target would look the same on radar as deploying a "stealth field" so that could be an origin of the rumor...
They don't 'deploy' anything. There are no radar reflectors. They just turn on their transponders and anti-collision gear (ACAS). Civilian radar doesn't generally detect reflected energy. It just listens for transponders, which are infinitely more powerful than any reflections. Turn those off and civilian ATC is practically blind whether you are a stealth bomber or 747.
Plasmas are electrical conductors. The electric field of an incident radar wave couples to electrons and ions that compose the plasma and drives currents. This ends up dissipating the radar energy as heat. It's the same result as if the radar hit a poor electrical conductor like carbon-loaded plastic: not much reflection (cause of poor conductivity), but creation of internal currents that dissipate radar energy as heat. It's a resistive dummy load for the radar energy.
This plasma-as-conductor thing can lead to some really interesting antennas. [1] Fill a long plastic tube with an easily ionized gas, and connect the output of your radio transmitter to it. When you want to transmit, ionize the gas column with a high voltage, low current discharge. Voila, you have a nice conductive column to radiate your RF from. Finished with transmission, switch off ionization power. Antenna is then electrically gone. Very important if you're on a battlefield, being hunted by things that can find antennas made out of metal. Your plasma antenna can be there and gone in a millisecond. Phased-array models exist, too.
I'm glad I'm not the only one who was googling for that. I remember two different popular science or mechanics article with that headline. One that had something to do with plasma cloaking, and the other was using plasma for a heat shield...similar to the actuator concept. Again, seems my google-foo has failed...
I think the difference between then and now in terms of making this a viable technology is the presence of computers fast enough to process the shape of the incoming airmass and shape the plasma to compensate. I would imagine the calculations required are fairly intensive.
I believe that is different. IIRC, that theory was about shooting ionizing radiation in front of the vehicle to reduce air density.
This is using tiny, precise plasma "fans" plus a lot of computational fluid dynamics to direct the airflow on a small scale. And it's not a very bad idea.
Helicopters use complex and expensive mechanisms to articulate rotor blades.
If plasma can eliminate hinges on wings hopefully it can also be used to dramatically simplify the helicopter design.
That'll be a real breakthrough.
In a helicopter if your engine stops working, you start falling. Falling produces wind on your rotor blades and causes them to spin faster. Blades spinning faster makes you to stop falling. This effect is called autorotation and you control it by varying the pitch of your rotor blades. Autorotation means that you don't automatically die if your engine fails.
With plasma actuators (also quadcopters), battery faliure means death.
"Corke and his team reported that the wind tunnel test item, which used “new actuators that developed 20 times more thrust while consuming 100 times less power, produced a 65% drag reduction.” The Notre Dame researchers have found that introducing a small oscillation whose waves move perpendicular to the air flow path can halt the onset of the so-called near-surface flow instabilities that lead to turbulence."
Sounds like it's already a real breakthrough. After this it may just be a problem of imagining where to put this stuff.
I think the point is that while it's a minor change for classic aircraft (replace some flaps with a plasma actuator system because it's more energy efficient). In helicopters it is a radical simplification and will drop the price and complexity of the key flight system by an order of magnitude.
Will it have a similar effect on quads both small and large? I keep waiting for people sized quad or octocopters so hopefully this makes them more efficient.
Manned multicopters have already happened. [1] MIT has also demonstrated a variable pitch quadcopter. [2]
If they can use plasma laminar detachment and reattachment to somehow simulate a variable pitch propeller, while still getting some weight savings over a design with multiple swashplates, then yes I think it should help the quadcopter design scale up to larger propellers. That's a big if though, since to simulate a negative angle of attack I'm guessing your propeller design would have to be pretty inefficient with all plasma turned off.
I'm not entirely sure why you want this though, since the single large rotor is more efficient. There was a novel design a few years ago with one large rotor for lift and three smaller ones to counter torque and provide control. [3]
Its one thing to reduce vibration and fatigue. But increasing stability is a two-edged sword. If the plasma actuator fails, suddenly at 500MPH you're less stable. And no device is foolproof, especially one that requires high voltage. A lightening strike, an engine failure and the plane won't fly?
> A lightening strike, an engine failure and the plane won't fly?
How is this different from every other fly by wire system?
And it's not only electronics, when the hydraulics fail on a plane you also lose all control surfaces.
I rather have a solid state system that merely requires voltage to operate than the complex system of moving parts, linear actuators, hydraulic actuators, and fly by wire electronics that is currently required.
> How is this different from every other fly by wire system?
In a fly-by-wire system, low-voltage electricity is used to carry information. Batteries and redundant lines can handle almost any conceivable fault.
In a plasma wing, high-voltage electricity is used to alter the airfoil. Battery backups may be infeasible (or too heavy) for the voltages required. Or the ion generator itself may fail.
> I rather have a solid state system that merely requires voltage to operate than the complex system of moving parts, linear actuators, hydraulic actuators, and fly by wire electronics that is currently required.
The current systems also have millions/billions of hours of proven flight time, as well as the knowledge gleaned from thousands of crash investigations. I'd rather fly on a current system. Also, a plasma aircraft could certainly have a fly-by-wire control also.
> The current systems also have millions/billions of hours of proven flight time, as well as the knowledge gleaned from thousands of crash investigations. I'd rather fly on a current system. Also, a plasma aircraft could certainly have a fly-by-wire control also.
That same reasoning could have been (was?) used against fly-by-wire systems. Why add this additional complexity of a system that does not have the millions of flight hours of the old system.
Just like most aviation tech it probably will first be used by the military for something crazy and then slowly come down to civilian usage. (I imagine the air force commanders would like to have their tanker/radar/non stealth planes have 25% longer flight time/range)
Just guessing, but the industry likely migrated to fly-by-wire because of some quantifiable benefit, either from software-aided stability correction, or reduced risk of a mechanical failure. Maybe they proved that its less likely for FBW to fail than it is for a cable to snap ?
I'm not against using plasma, btw. I'm just saying if one were built today, I'd prefer to trust existing designs until they have a decade or more of testing done.
Perhaps the system could be used to enable the manufacture of very agile but very cheap weaponized drones. Then future battlefields might look like an arcade game, with purple plasma streaks zooming in crazy paths towards their targets.
Presumably the plane's stability without plasma wings would the same as on previous designs--with the exception of military fighter craft, who face a stability vs maneuverability trade-off, there are no benefits to making a civilian craft less stable.
> there are no benefits to making a civilian craft less stable
(Slightly) less fuel consumption? That's for longitudinal stability influenced by center of gravity. [0][1][2]
> Most airplanes are designed so that the wing's center of lift (CL) is to the rear
> of the center of gravity. This makes the airplane "nose heavy" and requires that
> there be a slight downward force on the horizontal stabilizer in order to balance
> the airplane and keep the nose from continually pitching downward.
So moving CG aft decreases stability but also decreases induced drag (drag produced by producing lift) because the downward force required to keep the nose up is reduced, which in turn requires less total lift and a lower angle of attack.
Yes, I also thought about this danger too when reading it. Also, assuming the savings are real, that means the aircraft would take on less fuel. Then, if the actuator fails and the craft is reduced to flying the old, less-efficient, way, it may be in trouble - e.g. in trans-atlantic flight or in conditions where there's no easy landing nearby, since your fuel consumption rises dramatically.
You can mitigate that by keeping enough fuel on board for a non-ionic flight. You'll use it in the next couple of flights, but will pay for the additional fuel used to move the fuel. That should still leave you out ahead.
That technology was adopted by airplane manufacturers in the '70s---it's the contrails. (The side effects of those are just a happy accident.) All that stuff about ticket prices based on oil prices? It's a scam. They don't use any fuel.
Should have been more funny if I hadn't argued for 30 minutes last year with someone who honestly believed this and was trying to sell this to a younger somewhat gullible (it seems) friend of mine.
The guy who tried to convince us was well spoken, serious, in a middle management position and seemed to have swallowed it hook, line and sinker himself.
300% range increase on a drone size vehicle, huh? Imagine the application to conventional jet travel. This would revolutionize the industry, letting jets fly far further than they currently can.
Jean-Pierre Petit have been talking about this for many years, but has been considered a sweet lunatic. The fact he is a UFO believer didn't help, but it's too bad they discarded all his ideas because of it.
Hats off to all those sci-fi stories that described future aircraft as enclosed by glowing silhouettes of various colors. We're living in the future :0)
What happens when it rains? Wouldn't moisture increase the electrical conductivity of air to the point of defeating such devices, or at least radically increasing the energy required? And if that is true, wouldn't random differences in local moisture at various actuators on different parts of the plane, say while approaching a wet runway, result in randomized effects?
I'd say that rainwater isn't all that pure, but setting conductivity aside, what about basic heat? Plasma is hot, very hot. Rain, liquid water, is very cold. To keep the plasma you would have to vaporize the water. That requires massive energy. And the amount of water on a wing is insane. Even if not on the leading edge, lots of water flows along the wing surfaces. At 300km/hour it would be like randomly pouring buckets directly on the plasma shown in the OP. I doubt it could be made stable enough without heating the entire wing red-hot.
There are cold plasmas. Some of these "non thermal" plasmas have been used to disinfect wounds. It's odd to see a column of ionized air exiting a tube and impinging on bare skin, but it's one application in development for cold plasmas. [1]
Serious question: ignoring issues with O3 toxicity, could you strap a plasma wind generator to the front of a car to create downforce and reduce air resistance?
Thinking through it I suspect the numbers don't line up for it to be feasible/economic but I've often wondered how we could displace the air in front of a vehicle without impeding the vehicles travel in doing so.
If it makes you feel better, they've been dealing with electrical failure for years now. Each engine generates enough to power the airplane. Additionally, there are backup batteries and backup generators on board.
The 757/767 even has a pop-down turbine as a last resort.
Worst case, the power capacities of these systems needs to be beefed up. And like you hinted, flying a large plane without hydraulic power is practically impossible anyways. It's not a huge leap from that to plasma actuators.
I didn't get that from the article. I think the idea is less of replacing conventional actuators completely, and more covering the the physical actuators with a layer of plasma to mitigate non-efficient airflow before it hits the actuator.
For now you're right, but for the future... From the article:
> The technology could even replace traditional wing flaps, he says. Although the plasma-actuated “flapless” or “hingeless” wings are currently only suitable for smaller aircraft such as drones or UAVs, Erfani believes that further development could make the technology viable on larger, faster planes.
I don't think that's the concept. It's a solid wing with no moving parts and lift is modified solely by the plasma emitters. The entire wing's surface is still a solid material, it's just the plasma is modifying how the air behaves around it causing change in lift.
Even with the low vacuum the hyperloop's air resistance is still considerable at the speed it's going. That's why Musk's original white paper suggests a big fan in the front to move air from the front to the back the vehicle. So there still would be a substantial element of airflow.
Question: Would that lead to some unfavorable chemical reactions that create undesirable molecules that we don't want to have in the atmosphere? It's an incredibly tiny effect per plane, but over time and given the amount of planes... so obviously only a problem for stable molecules that remain up there for a long time. I had the subject in a chemistry lecture, but it's been quite a while so I don't remember any details.
Not really. Ozone is the primary byproduct of producing a plasma in our atmosphere, and it is really only a problem when it is released at lower altitudes. Releasing it in the upper atmosphere where jets usually cruise would be harmless, if not beneficial to the existing ozone layer.
Not to mention the fact that any byproduct produced by a plasma would be infinitesimal compared to the amount of NOx produced by jet engines.
Probably. Oxygen and Nitrogen react quite a bit in the upper atmosphere where there is plenty of sunlight to initiate reactions. There is a litany of byproducts that can be produced, including NOx.
It would produce a lot of ozone probably, which is harmful to humans at ground level. But exactly what you want to put into the upper atmosphere as it protects from harmful radiation, see ozone hole.
I don't see this being much of an issue. Most aircraft kind of throw efficiency out the window while they are taking off/landing. You don't WANT overly aerodynamic wings at take off because you want exaggerated lift at the cost of drag. It wouldn't make sense to use the plasma until you are at a stage in the flight where you are more concerned about efficiency, i.e. cruising.
If they would succeed with "flapless" design it would be then different story.
I was wondering if this technology would help with reusable rockets. But what you've wrote and what I found about aerodynamics of rockets makes me think that it would not be that helpful.
I thought most commercial flights were above 20km, where the bulk of the ozone layer is? Edit: Oh you mean the takeoff and landing parts of the flight. Good point.
My question was more about other compounds, for example those involving fluorine (https://en.wikipedia.org/wiki/Fluorine#Atmosphere). I have not asked about F specifically because that is known and in decline (I think), but there may be other things in the air that specialists know better.
Shipping runs on oil sludge - the vilest, most polluting substance used anywhere. 6000 cargo ships produce more air pollution than half the rest of the world. So when prioritizing things to fix...
But isn't price still an issue with those new aircraft?
I've thought many times about trying to get my pilots license but have always been dissuaded by the thought that the only general aviation plane I can imagine being able to afford would be from the 1970's or earlier. If they're well maintained they seem to last forever. What's the incentive to spend many times more money for aircraft with those newer, cleaner engines, especially for beginning pilots? Would something like a "cash for clunkers" program for airplanes be feasible?
I bought into a very well maintained grumman tiger, which with a sliding canopy is still damn awesome compared to "modern" planes (most certified designs you can buy date back to the 60's, with the exception of cirrus who is now unsurprisingly selling the most new planes).
