An article An Airplane With No Moving Parts appeared over at IEEE Spectrum: MIT researchers have used ion drive—until now a purely space-based system—to fly a model plane a short distance indoors.
There's quite a lengthy video about the invention of this device here featuring Steven Barrett, associate professor of aeronautics and astronautics at MIT:
The article also says "... Ion drive was first demonstrated 101 years ago by famed rocketeer Robert Goddard, and it’s now routinely used in space, for instance to reposition satellites."
Here's the dubious link for that.
Goddard's rockets never reached outer space (he died in 1945).
As it turns out US Patent 3,130,945 describes exactly the device shown at IEEE Spectrum. Here's the single claim from this 1964 patent:
"1. IN COMBINATION WITH FLYING APPARATUS COMPOSED OF A STRUCTURE SUPPORTING DISCHARGE ELECTRODES FOR CAUSING ADJACENT AIR MODULES TO BECOME ELECTRICALLY CHARGED SPACED FROM A GRID OF ELECTRICAL CONDUCTING MEANS FOR NEUTRALIZING THE CHARGE ON ELECTRICALLY CHARGED MOLECULES WHOSE CHARGE WAS CAUSED BY SAID DISCHARGE ELECTRODE AND MEANS FOR APPLYING A HIGH D.C. POTENTIAL BTWEEN SAID ELECTRODES AND SAID GRID TO CAUSE AIR TO MOVE FROM SAID ELECTRODES TOWARD SAID GRIDS TO PROVIDE A PROPULSION FORCE FOR SAID FLYING APPARATUS, AND ANTENNA MEANS FOR USE WITH RADIO FREQUENCY ENERGY SIGNALS, SAID ANTENNA COMPRISING A PLURALITY OF ELEMENTS WHICH SERVE ALSO AS PART OF SAID STRUCTURE FOR THE FLYING APPARATUS BY BEING CONNECTED ELECTRICALLY TO ONE TERMINAL OF SAID HIGH D.C. POTENTIAL TO ASSIST IN PROVIDING PROPULSION FORCE FOR SID APPARATUS."
I was intrigued by this article because I actually know quite a bit about this.
You see, about 47 or so years ago building ion-powered mechanical devices wasn't that uncommon.
I couldn't say where I got the idea from exactly, perhaps some variant of this Popular Mechanics article (I was not a fan, I read Radio Electronics and Popular Electronics and followed "Carl & Jerry quite closely). I did not think it up myself, of that I am sure, the details are apparently lost to time.
(Lest you think I am kidding look up the Badger State Science Fair from the early 1970's - if you can find it. Voice activated locks, Plasma. Lasers. Computers. All manner of things taken as "modern" today.)
Being 12 years old and living in rural Wisconsin didn't leave much room for entertainment. Grandpa had an endless supply of electronics mags so that's what I turned to.
Unlike the IEEE article there weren't any well-to-do donors to fund the project so creativity was required.
First off a high-voltage power supply was required, at least 20kV.
The best source for this were abandoned TVs by the side of the road. I specifically remember a DuMont TV I picked up one day while driving somewhere with my dad. Something along these lines:
In the olden days TV's often had schematics pasted onto the inside back cover. This made it easy to see if it contained all the parts you needed.
Before you could build a 20kV power supply out of tubes you needed aa 250vDC power supply to run the tubes. This was easy because all TV's at the time contained such a DC power supply. All you had to do was strip down the TV to remove the chassis. Then strip the chassis down to remove the parts you didn't need leaving the 250vDC supply (usually a couple of transformers, a couple of rectifier tubes (5U4's), a couple of big caps and miscellaneous parts.
Next step was to convert the horizontal sync portion of the circuitry into a free-running multivibrator. Something along these lines:
I used two distinct tubes and had to learn RC math to calculate the frequency needed. Then you extracted the "flyback" transformer and tapped off the 20kV line:
Next you attach a pin pointing up off the tap. Of course, you insulate things well: I used acrylic plastic my father brought home from job sites or clients.
When fired up, aside from the screaming flyback (no doubt because my frequency calculations were off), there is the distinct sound of ionization and a definite "wind."
Finally you bend up some wire like this:
Set it on the pin (the pin stuck through the loop) and watch it spin!
The whole apparatus probably weighed 25 pounds and plugged into a wall outlett so there was no chance of flight but the principles were there (it would take another 40 years for batteries to catch up).
It this weren't fun enough I learned how to build capacitors out of tin foil and acrylic. The tin foil would convulse on discharge.
There's quite a lengthy video about the invention of this device here featuring Steven Barrett, associate professor of aeronautics and astronautics at MIT:
The article also says "... Ion drive was first demonstrated 101 years ago by famed rocketeer Robert Goddard, and it’s now routinely used in space, for instance to reposition satellites."
Here's the dubious link for that.
Goddard's rockets never reached outer space (he died in 1945).
As it turns out US Patent 3,130,945 describes exactly the device shown at IEEE Spectrum. Here's the single claim from this 1964 patent:
"1. IN COMBINATION WITH FLYING APPARATUS COMPOSED OF A STRUCTURE SUPPORTING DISCHARGE ELECTRODES FOR CAUSING ADJACENT AIR MODULES TO BECOME ELECTRICALLY CHARGED SPACED FROM A GRID OF ELECTRICAL CONDUCTING MEANS FOR NEUTRALIZING THE CHARGE ON ELECTRICALLY CHARGED MOLECULES WHOSE CHARGE WAS CAUSED BY SAID DISCHARGE ELECTRODE AND MEANS FOR APPLYING A HIGH D.C. POTENTIAL BTWEEN SAID ELECTRODES AND SAID GRID TO CAUSE AIR TO MOVE FROM SAID ELECTRODES TOWARD SAID GRIDS TO PROVIDE A PROPULSION FORCE FOR SAID FLYING APPARATUS, AND ANTENNA MEANS FOR USE WITH RADIO FREQUENCY ENERGY SIGNALS, SAID ANTENNA COMPRISING A PLURALITY OF ELEMENTS WHICH SERVE ALSO AS PART OF SAID STRUCTURE FOR THE FLYING APPARATUS BY BEING CONNECTED ELECTRICALLY TO ONE TERMINAL OF SAID HIGH D.C. POTENTIAL TO ASSIST IN PROVIDING PROPULSION FORCE FOR SID APPARATUS."
I was intrigued by this article because I actually know quite a bit about this.
You see, about 47 or so years ago building ion-powered mechanical devices wasn't that uncommon.
I couldn't say where I got the idea from exactly, perhaps some variant of this Popular Mechanics article (I was not a fan, I read Radio Electronics and Popular Electronics and followed "Carl & Jerry quite closely). I did not think it up myself, of that I am sure, the details are apparently lost to time.
(Lest you think I am kidding look up the Badger State Science Fair from the early 1970's - if you can find it. Voice activated locks, Plasma. Lasers. Computers. All manner of things taken as "modern" today.)
Being 12 years old and living in rural Wisconsin didn't leave much room for entertainment. Grandpa had an endless supply of electronics mags so that's what I turned to.
Unlike the IEEE article there weren't any well-to-do donors to fund the project so creativity was required.
First off a high-voltage power supply was required, at least 20kV.
The best source for this were abandoned TVs by the side of the road. I specifically remember a DuMont TV I picked up one day while driving somewhere with my dad. Something along these lines:
In the olden days TV's often had schematics pasted onto the inside back cover. This made it easy to see if it contained all the parts you needed.
Before you could build a 20kV power supply out of tubes you needed aa 250vDC power supply to run the tubes. This was easy because all TV's at the time contained such a DC power supply. All you had to do was strip down the TV to remove the chassis. Then strip the chassis down to remove the parts you didn't need leaving the 250vDC supply (usually a couple of transformers, a couple of rectifier tubes (5U4's), a couple of big caps and miscellaneous parts.
Next step was to convert the horizontal sync portion of the circuitry into a free-running multivibrator. Something along these lines:
I used two distinct tubes and had to learn RC math to calculate the frequency needed. Then you extracted the "flyback" transformer and tapped off the 20kV line:
Next you attach a pin pointing up off the tap. Of course, you insulate things well: I used acrylic plastic my father brought home from job sites or clients.
When fired up, aside from the screaming flyback (no doubt because my frequency calculations were off), there is the distinct sound of ionization and a definite "wind."
Finally you bend up some wire like this:
The whole apparatus probably weighed 25 pounds and plugged into a wall outlett so there was no chance of flight but the principles were there (it would take another 40 years for batteries to catch up).
It this weren't fun enough I learned how to build capacitors out of tin foil and acrylic. The tin foil would convulse on discharge.
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