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Comment by ep103 | Hacker News Reader

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.

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There have been theories for over a decade that the B2 includes a technology like this: http://starburstfound.org/electrograviticsblog/?p=21

(Edit: Here's the farthest-back link I can find, allegedly from 1993(!): http://www.bibliotecapleyades.net/ciencia/ciencia_flyingobje....

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...

A radar-shielding plasma shield sounds a bit like having a speaker wall to mask conversations.

Welcome to 'anti-sound':

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

If the 'wail' is carefully tuned to the original forces dragging on the craft it might actually work.

More like a sonic absorber.

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.

[1] https://en.wikipedia.org/wiki/Plasma_antenna

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.

"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.

Yeah, they do. The magic keyword is apparently "RCS enhancer".

F117: https://books.google.com/books?id=WaedCwAAQBAJ&lpg=PA65&ots=...

F22: https://www.reddit.com/r/askscience/comments/128js1/how_do_w...

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.)

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 also remember something like this. I just checked, this is a old idea, there is a patent (US 3507348 A) from 1970

From what they're saying in this article, it seems like they're just using it to push air around in the right spots, ionization is a byproduct.

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.

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