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May 23, 2007
Alien craft? doubt it... but...!
This is so bizarre.
It looks like, but isn't, some kind of extra terrestrial craft. I don't know if it's a photoshop effort or if it is a real thing created by some rich geeks.
But then again, it apparently looks like some 'tech' from the upcoming MICHAEL BAY transformers moxie...
There are also other photos on Flickr especially the comments on this photo
Some talk of sitings from a few years back
Scanning through the comments on the Flickr stream the words 'hall effect thruster', 'electromagnetic' and 'lifter' popped out in this comment from NASAnerd1947 - the comment seems to hold the best explanation of the mechanics of the how of such a craft, but unfortunately not the why :)
I'm not an expert on faking digital images, but I have studied the field of electric and electromagnetic propulsion as a professional aerospace engineer. If the object is real, the explanation put forward by robert3clemens is pretty much right on. This would be an example of an endoatmospheric Hall-effect thruster. The curved electrodes on the top would be charged to a high positve voltage. Since they are arranged in a radially symmetric manner, they would create a radially symmetric electric field gradient that goes to zero in the middle. Any positive ions in the air (nitrogen, oxygen, etc.) in the vicinity of and interior to the electrodes would therefore be forced radially inward. No central electrode would be necessary. Electrons would of course be attracted to the electrodes and collected on their surfaces. Since the positive ions are tens of thousands of times more massive than the electrons, virtually all of the momentum flow is carried by the positive ions. A superconducting ring or rings inside the donut shaped annular shell would be arranged so as to create circular magnetic field lines centered around the symmetry axis. There are a couple of different winding geometries that would work. As the ions move radially inward, they cross the magnetic field lines at essentially right angles. The Hall effect says that charged particles crossing magnetic field lines will receive an acceleration that is proportional to the size of the magnetic field and at right angles to both it and the velocity vector of the particle. If the velocity of the particle is radially inward and the magnetic field line is tangential, then the particle will be accelerated downward and through the hole. This is the slingshot effect that robert3clemens was talking about and can increase the size of the ion wind by an order of magnitude. Usually the limiting parameter on an ion wind thruster is the very low level of ionization in normal air (a few hundred per cc). There simply aren't very many charged particles around to "grab" with the electric field, and this is why ordinary "lifters" don't have enough thrust to get themselves and their power supplies off the ground. Theory and experiment show that this can be dramatically improved by artificially boosting the ion concentration in the air. This can easily be done with ultraviolet radiation; I wouldn't be surprised if there weren't some excimer lasers pointing upward, interior to the electrodes.The electrodes on the top are curved because they follow the stream lines of the ion wind; they define what is known as the "stream tube". Since air molecules flow radially inward between and around the electrodes, the volume of air flow increases as you move axially downward to the annular hole; that's why the stream tube is bigger at the entrance to the annular hole than it is at the top.
Hall effect thrusters have been used in space for decades. In that case, you have to bring your working fluid with you (usually Xenon or some other noble gas). Here, the air is the working fluid. One of the problems that all Hall effect thrusters have to deal with is charge build-up. What you're doing in the vicinity of the curved electrodes is stripping electrons off and accelerating the positively charged ions downward. Therefore you've got a positivley charged column of air moving away from the device. If you didn't do anything about that, you would eventually build up a pretty good charge separation that would tend to kill the thrust and also possibly cause destructive arcing or sparking. That's where the "paddles" or "wings" come in. I think their first purpose is to serve as electrodes that recombine the electrons with the downward flowing ion wind and thereby neutralize it. In order to do that, you need a lot of surface area, because the natural conductivity of the air is low. I think they also serve a secondary purpose of steering the thrust vector of the ion wind. If you supply a slightly different electron current to each of an opposed pair of paddles, you will pull the column of positively charged air to one side or the other. The different photos of what is probably the same device ("Chad's", Lake Tahoe, and now Capitola) have different numbers and configurations of paddles. However, the one thing they all have in common is that they all have a minimum of two pairs of paddles, diametrically opposed to each other. This always allows control of pitch and roll. They also appear designed to have a large surface area in contact with the air at the exit plane of the thruster. If this is a real object, I would guess that whoever built it is experimenting with different models of paddles. For one thing, the long paddles appear to have hinges where they join the body of the "donut". This implies that they are designed to be folded up to make storage or transport of the object easier. The short paddle with six corona discharge needles on it looks like it might not have to be stowed.
The superconducting coil or coils serve two purposes, as robert3clemens alludes to. First, they provide the very strong magnetic field necessary to produce the Hall effect; second, they are an energy storage medium. Superconducting magnets are capable of being charged and discharged extremely fast and have very low internal losses. Depending on the quality of the superconductor material, the energy density can be equal to or greater than primary lithium batteries. The main power consumption would for supplying the current necessary for maintaining the high voltage on the top curved electrodes, and "pumping" the collected electrons down to the paddles
We are not the first to think about this. The attractiveness of a purely electrically fueled aircraft with no moving parts is self-evident. The intellectual history of Hall effect (or magnetohydrodynamic) endoatmospheric thrusters goes back at least to the 1950's, when a great deal of classified work was done in the area. What makes it feasible today is the availability of "high temperature" superconductors on an industrial scale (pioneered, I might add in Silicon Valley, which appears to be at the epicenter of these sightings).
All of this says that these devices, if real, were built by otherwise ordinary, but extremely well educated and well informed human beings with a few tens of millions of dollars to play with. A discussion of where the original idea for this kind of vehicle came from will be left for another day.
OK, so why are these things being flight tested over Capitola and Lake Tahoe, instead of Edwards Air Force Base or China Lake Naval Weapons Test Center, or Area 51? Good question, it seems pretty risky. Actually, we don't know they didn't fly around Area 51 or China Lake, first. If these things were built by one of the usual suspect aerospace contractors for a government Agency, they almost certainly would have been tested at a restricted flight test center first. Maybe they have already undergone preliminary testing and they are now getting ready to move into the operational phase and they are intended to operate in the mountains and near the sea. If that's the case, we shouldn't assume that the flights are occurring without the knowledge of Homeland Security Department and other agencies. Maybe the Agency that built them wants to determine what fraction of sightings will be conveniently dismissed by skeptics as hoaxes. On the other hand, any number of dot-com millionaires and billionaires live within a fifty mile radius of Capitola. One of them could have decided to build something like this out of petty cash. In that case, they would not necessarily want or need access to a government test site. Still, flying something like this inside continental airspace without permission would be illegal most places and pretty cheeky, even for a dot-commer.
Why isn't there a video? Again, how do you know there isn't? Absence of evidence is not evidence of absence. I often see such comments along the lines of "If I had seen something like this, I would have taken a perfectly focused and professionally produced video and instantly published it everywhere in order to satisfy the curiousity of random skeptics bent on character assassination." The facts are otherwise. Anyone who has ever spent any quality time investigating UFOs or other cryptic phenomena knows that only a tiny fraction of witness sightings ever get reported to anybody outside the immediate family. First of all, exactly who are you supposed to report it to? There is no official collection point for this kind of story. Second, and probably more important, what's the motivation? In most cases you simply bring down accusations of being an idiot, a fraud, or both.
Posted by dottie at May 23, 2007 11:59 PM
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