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  1. 01 Aug '14 19:27
    In the 1970s a high school classmate of mine was all excited about something he had read about: the Dean drive, a "reactionless drive" that supposedly converted rotary motion within a device into linear acceleration of the device. "Imagine how revolutionary this is going to be for spaceflight!" he said.

    I told him it sounded like a pure scam to me. He didn't like that. I think time has proven that he was wrong about it.

    Now I see on the Net something called a Cannae drive----
    http://www.pbs.org/wgbh/nova/next/space/improbable-thruster-seems-work-violating-known-laws-physics

    Supposedly something like a microwave cavity is producing a tiny thrust.

    What do you think about the authenticity of this?
  2. Standard member DeepThought
    Losing the Thread
    01 Aug '14 19:42
    Originally posted by Paul Dirac II
    In the 1970s a high school classmate of mine was all excited about something he had read about: the Dean drive, a "reactionless drive" that supposedly converted rotary motion within a device into linear acceleration of the device. "Imagine how revolutionary this is going to be for spaceflight!" he said.

    I told him it sounded like a pure scam to me. ...[text shortened]... icrowave cavity is producing a tiny thrust.

    What do you think about the authenticity of this?
    He's not the only person to produce cavity drives. What they all have in common is that they won't work. This is bunk.
  3. Standard member wolfgang59
    Infidel
    01 Aug '14 22:08
    Originally posted by DeepThought
    This is bunk.
    NASA should have asked you first before wasting money on testing it!
  4. Standard member DeepThought
    Losing the Thread
    02 Aug '14 00:24
    Originally posted by wolfgang59
    NASA should have asked you first before wasting money on testing it!
    Maybe they have a vacancy for a debunker?
  5. 02 Aug '14 07:44 / 4 edits
    DeepThought is right; it is almost certainly nonsense.

    The headline says it all:

    "Improbable Thruster Seems to Work by Violating Known Laws of Physics"

    I am guessing here that the vague word "Seems" here comes from people who don't quite understand how to take proper account of error of measurement (they are only talking about "30-50 micronewtons" dependency in their measurement. Which is more likely; -that they made a tiny error in their measurement or that they have broken the laws of physics? )
    Although I wouldn't totally dismiss the idea from the outset without first looking at any evidence, it would be extremely unlikely that they have found a way of breaking any known laws of physics.
    If they had, by now someone would have most probably already won a huge Nobel prize for it and it would be an extremely big deal making sensational news and we would all certainly know about it!

    Their claims isn't helped by "...In the paper, NASA seemed reluctant to dive into the drive’s mysterious physics. They wrote nothing to suggest how, exactly, the force was produced...."
    And Fetta explanation of how it works is pretty poor.
  6. Standard member sonhouse
    Fast and Curious
    02 Aug '14 12:51 / 1 edit
    Originally posted by humy
    DeepThought is right; it is almost certainly nonsense.

    The headline says it all:

    "[b]Improbable
    Thruster Seems to Work by Violating Known Laws of Physics"

    I am guessing here that the vague word "Seems" here comes from people who don't quite understand how to take proper account of error of measurement (they are only talking about "30-50 mic ...[text shortened]... how, exactly, the force was produced...."
    And Fetta explanation of how it works is pretty poor.[/b]
    If there is any real thrust produced, it might just be electrons escaping.

    I remember the corona thruster made by a scientist buddy I knew when I was 13, high voltage produced a corona discharge onto an s shaped wire with a small loop in the center that could rotate around another conductor, using something like an indian bead for support. With 15,000 or so volts applied, the wire would spin around its support.

    I remember seeing the same thing on a much larger scale at the high voltage lab at cal tech where our HS class visited one day, a million volt version of the same thing but the wire was about 2 meters long, also S shaped and it spun around due to the discharge into open air.

    Don't know if it would work in a vacuum though. If it did, you would have instant electric rocket but that would not violate any laws of physics, the thrust would come exactly the same as any other rocket, mass ejected out of the ass end and accelerating in the opposite direction just like a regular rocket.

    30 micronewtons of thrust could come from something like that. The dimensions shown on the device, I assume are meters? Inches? Don't know.

    1 newton is equal to about 102 gram force units so 30 micro newtons would be about 1/300th of a gram force. Nothing to write home about.

    Remember, the Voyagers leaving the solar system were going off course for some unknown reason? So they finally figured out there was IR emission from the atomic power supply giving a tiny thrust that was throwing a curve into the flight path.

    IF there is real thrust from this device, they may find something similar. 1/3 of a MILLIGRAM of thrust could come from electrons leaving the device or simple IR from heating. IF there is anything at all to this thing.

    Even if it does produce 1/3 of a milligram of thrust, I wouldn't pin my hopes of the space program on it till it could be proven to upgrade that thrust level.

    For instance, the Vasimir rocket which uses actual fuel just accelerated with magnetic and electric forces would produce MAYBE 1/20th of a G of thrust which gets you to Mars in a month as opposed to more like 8 months with regular rockets.

    So to get 1/20th of a G with this thing, you could only have the total weight be 1/15th of a gram. Not exactly useful at this stage of the game. My guess is it is just excess IR or a few electrons flying out the ass end just like a rocket IF there is anything to this thing at all.

    How do you even measure 300 micrograms of force in that thing anyway? Have it on a long string and see the deflection? Any idea of the geometry of such a measurement?
  7. Standard member sonhouse
    Fast and Curious
    03 Aug '14 03:01
    Originally posted by sonhouse
    If there is any real thrust produced, it might just be electrons escaping.

    I remember the corona thruster made by a scientist buddy I knew when I was 13, high voltage produced a corona discharge onto an s shaped wire with a small loop in the center that could rotate around another conductor, using something like an indian bead for support. With 15,000 or ...[text shortened]... Have it on a long string and see the deflection? Any idea of the geometry of such a measurement?
    Was thinking about how to show if electrons were leaving, it would seem simple just to probe the voltage, depending on what RF was fed to it, to see if there was some kind of voltage bias, dc wise.
  8. 06 Aug '14 07:07
    http://xkcd.com/1404/
  9. Standard member sonhouse
    Fast and Curious
    06 Aug '14 09:17
    Originally posted by twhitehead
    http://xkcd.com/1404/
    A new report, claiming NASA confirms thrust:

    http://www.gizmag.com/cannae-reactionless-drive-space-propulsion/33210/?utm_source=Gizmag+Subscribers&utm_campaign=87b7d4c0ab-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-87b7d4c0ab-90238410