This looks too good to be true, and it probably is, but it’s worth pursuing.
And since when is thrust rated in “grams”?
38 thoughts on “Reactionless Drive?”
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This looks too good to be true, and it probably is, but it’s worth pursuing.
And since when is thrust rated in “grams”?
Comments are closed.
It’s not impossible, just infinitely improbable.
So you are saying Douglas Adams predicted this?
He’s wrong, actually. It’s not infinitely improbable at all. The odds against it are exactly (exactly, mind you) a million-to-one against. Yielding, of course, a 9-times-in-10 chance of occurring.
Think Pratchett, not Adams.
And since when is thrust rated in “grams”?
Never. At best you can use grams force i.e. gf. The SI unit is the Newton (N).
http://www.wired.co.uk/news/archive/2014-08/07/10-qs-about-nasa-impossible-drive
Wired recently put a Q&A up which clarifies a lot of questions people have had.
This is the second time someone says the thing works. The first time it was some Chinese researchers. We have heard these sorts of claims of reactionless drives several times before. I guess the bona fide test will be someone using it to propel satellites in space. If it does work it should open up solar system exploration by leaps and bounds.
Is this a ring current in a magnetic field thing?
Yes, as soon as I saw it I thought of the “Dean Drive” from the 1960’s.
http://www.jerrypournelle.com/science/dean.html
Of course, as pointed out by the famous editor John W. Campbell, if it works any nuclear submarine could be turned in a spaceship capable of going to Mars and beyond. In fact the June 1960 issue of Astounding had a picture on its cover showing just that.
https://crotchetyoldfan.files.wordpress.com/2008/09/1960-astounding_science_fact_and_fiction_196006.jpg?w=500
It will be interesting to watch it play out. It does sound too good to be true, but IF it works this time it will make rockets as out of date as balloons… It would also have huge military implications and change warfare as much as the internal combustion engine did.
I can see an in-space application for this but can you generate enough thrust vs stack weight for this to work inside an atmosphere?
“Reactor sizes range up to ~500 MWt (about 165 MWe) in the larger submarines”
“A specific thrust of 9.92 kN/kW was predicted with an acceleration limit of 0.5m/s/s.”
-> 1.6 GN.
Ohio displacement: 16.7Gg
I get 95 m/s/s. The ‘acceleration limit’ would seem to -not- include the efforts to counter gravity. So… 9.8 + 0.5 -> can lift an Ohio. The weight of the -device- isn’t in the stock weight of the Ohio, but there’s tons of stuff to jettison before you get down to “bare power plant and shell”. (In fact, the whole “How does this cavity rotating around the center of the earth affect things” is one of the WTF points for me.)
As a former gold crew member of the Ohio (E-div)…I never thought I would see displacement listed in gigagrams.
The cover is from 1960, so you would need a sub from that era, perhaps the Triton (SSRN586) 🙂
Also since you wouldn’t need the torpedoes in space, or missiles, you could probably added an another reactor to the ship 🙂
You might need them when you encounter the Russian and Chinese nulcear subs 🙂
I don’t get the sense anyone really has the foggiest on “What in the heck is actually going on” beyond the direct “We do this, and this happens” interpretation.
I’d really like this device operated with a CERN-like sensor array around it.
Are there design documents around? The couple papers I tracked down were of the type “Investigations with a Black Box” with no design other than the representational trapezoid.
I’m just wondering if they’re overlooking something, such as creating any kind of magnetic field which will creates a measurable torque, which is what makes a compass needle work.
This is one of those cases where I’m highly skeptical and also hoping I’m wrong.
A true reactionless drive, even one with a thrust-to-weight that makes it useless for an Earth-to-Orbit launch system, would be by far the greatest invention of the space age. It would change everything. Just the impact on satellite lifespans alone would be profound.
A little over 20 years ago, a paper in Physical Review Letters caught my attention. It reported experimental results showing that gyroscopes lost weight when spun vertically in a right hand direction. No weight effect was present with left-hand spin. The weight loss was also proportional to spin rate. Three different gyroscopes (differing in rotor mass and material) were used, and the results were the same with all. Moreover, the effect was the same when the gyros were inverted. It took 21 months of peer-review to clear the paper, in a journal which normally published 4-8 weeks after submittal. But it did appear. A rebuttal paper, written by a guy who had thrown a gyroscope on a scale and detected not effect, was published within weeks. I never did hear a convincing reason for the experimental results, but have also never heard of them being repeated.
After looking at the “Cannae Drive” website, I think this will prove to be something similar.
Put it in a triple cubesat, toss it from ISS, see what it does.
Can anyone estimate what sort of reflectivity they’d get out of ‘state of the art’ microwave mirrors? I mean, if only -one- photon was inserted, how far (on average) would it bounce?
Is that the key criteria keeping this in the microwave region?
“And since when is thrust rated in “grams”?”
You see this kind of thing all the time in the British media. They’re so keen not to use Imperial (ie, English) measurements that they just blindly translate into French, regardless of whether it’s to the correct units or makes any sense (ridiculously precise values are another common result of this: reports of “91.4 centimeters” of snow, for example, because a press release said “3 feet”). The BBC are the worst culprits, but it doesn’t surprise me to see Wired UK at it too.
http://ntrs.nasa.gov/search.jsp?R=20140006052
Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the “null” test article).
That about sums it up.
I, too, would love for this to be true, but I suspect what we have here is Cold Fusion 2.0.
I suspect the Dean Drive is a better analogy. It’s kind of funny that, the more sensitive the instruments, the smaller the effect. As Doug Jones suggested, put it in orbit and see what happens.
This is why decreasing launch costs is so important. If launch costs were low all sorts of stupid ideas could be tested in orbit and some might actually produce good results.
If what’s actually going on is some weak interaction between the experimental apparatus and the Earth’s magnetic field, even on-orbit testing won’t necessarily settle the issue.
I’ve been reading about this device for more than a decade. New Scientist ran a article about it in 2006 and ESA also looked at it before then, while BAe in Stevenage also ran some tests but found nothing significant.
I note that in this case they built two test article and that “[T]hrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust”, which immediately suggests that the measurement errors were too large to say for sure that thrust was actually produced.
Carl Sagan once said that “extraordinary claims require extraordinary evidence” and this is far from extraordinary. I really do hope the device works but, at the moment, I’m not holding my breath.
I doubt they’re doing what they think they’re doing, because the device is a simple piece of metal operating in the microwave region.
If there was a real, not-yet-understood effect that produces almost a Newton of thrust from a kilowatt of power, then RF engineers certainly didn’t know about it, and thus didn’t take extreme pains to avoid it in all the waveguides and antennas on our satellites, which hurl out kilowatts of radiated power. If the effect is real, it would be highly unlikely that the present satellite systems weren’t at least producing several micro-Newtons of thrust by accident, and since we didn’t care if an antenna was wildly off-axis to a satellite’s center of mass, all our communications satellites should have slowly started to tumble, then expended all their reaction control propellant trying to compensate for the mysterious microwave thrust, not to mention the huge effect such a thrust would have on their orbits.
But that didn’t happen, so I’ll note that it is easy to accidentally make a high-power circuit that’s also an electric motor or electromagnet. It’s so easy to accidentally do it that we always bolt the components down so nothing moves. (It’s also easy to accidentally turn any high-gain audio amplifier into a bad FM radio if you’re prototyping on it next to a 100 kW broadcast tower, but that’s something everybody figures out on their own.)
A few years ago I was doing some controls on a small scissors lift mounted on the back of a little electric maintenance truck, designed for changing light-bulbs in an aluminum plant. The platform had to be mostly fiberglass so the truck wouldn’t get flipped on its side from the invisible, propellantless forces you encounter when you park next to a pot with 300,000 amps DC running through, where shovels can be ripped right out of your hands. But of course there is an equal and opposite force being exerted on the pot of aluminum.
They’re measuring forces on their drive system using a torsion balance, so they’ve managed to build a rotor. By Newton’s first law, their rotor is being acted upon by an external force. By Newton’s third law, there’s some other body experience and equal and opposite force, so what I’d do is try to identify the stator. An easy way to do that is to take all their carefully calibrated lab equipment and shielding that surrounds the test article, and suspend it all from a tall ceiling with wire or string roughly 13 feet long, which should turn everything in the room into a pendulum. Then adjust the length of each string so each piece of equipment swings with a period of exactly four seconds. Then turn the thruster on and off every two seconds and see which pieces of equipment start swinging. Those would be the stators.
Now that sounds like a good experiment. Cheaper than sending it up into space to test it, too.
Ed,
If I recall G. Harry Stine proposed something similar to test the Dean Drive, but it never happened because Norman Dean became paranoid about his invention being stolen. Hopefully it will be used to put this new invention to the test.
Even if it works, is it really worth all the excitement? Will it in a practical sense have a significant advantage over an electric rocket?
Here are my two assumptions, the first is that the device actually works, the second is that the thrust generated per power applied is not significantly different from the curve we see with electric rockets we are familiar with.
If so this ‘reactionless drive’ really doesn’t change the picture very much as far as manned flight within the solar system. It would have some advantages over electric rockets but suffer from some of the same limitations that apply to an electric rocket spacecraft, such as low acceleration and the need for a nuclear energy electric power source.
Admittedly a working self-contained reactionless drive does open up exciting potential for a robotic interstellar mission.
The advantage is you would need no reaction mass at all. So unlike an ion-drive which needs xeon or argon or whatever as a reaction mass you could, for example, produce all the requirements for propulsion using some solar panels which do not need any refueling. The propulsion would be low-thrust just like for ion-drives so it would take a long time to get up to speed but for robotic probes that is not a big problem.
Kilowatts fed into a high Q microwave resonator? My first guess would be photon pressure through the feed line. One of many artifacts more easily removed if the RF generator is built into the test article inside a Faraday cage.
Even if it works that does not turn a nuclear sub into a space ship (not referring to the obvious.) The ocean is a huge heat sink. A reactor with enough power would probably melt your ship.
You would only need the highest power level of your reactor to produce enough thurst (> 1g acceleration) to get to orbit; maybe just a few minutes worth of the high power; once your in orbit, you can get by with low thurst with presumably much lower power output from your reactor. In other words you would run the reactor (fission or fusion) at highest power levels to acheive orbit, hopefully just a few minutes; after that ratchet it down, applying thrust at right angles to spiral out from the earth.
For those interested, John G. Cramer, Ph.D., who has been writing about different space drive proposals since the 1980’s has an interesting column in the July-August Issue of Analog (written in January) on some ways they might possibility work without violating the laws of physics. Should make interesting reading 🙂
http://www.npl.washington.edu/AV/altvw173.html
Is it Space Drive Time?
[[[In this column I’ll consider two promising space drive developments that may be coming into fruition, one involving Mach’s principle and the other proposing to “push against the quantum vacuum” for propulsion. The formidable roadblock for the space drive concept is Newton ’s 3rd law of motion, a form of the law of conservation of momentum. In conventional rocket propulsion, a space vehicle can only be propelled forward and can only increase its forward momentum if propellant with an equal and opposite incremental momentum is expelled backwards as exhaust. No form of internal motion, no shaking, bumping, spinning, or orbiting of interior masses, no tilting or twisting of eccentric internal flywheels, can produce any net momentum change in the overall object. Something must go backwards out the back if something else is to go forward.]]]
If it works that’s good news and doesn’t really depend on understanding it.
If it violates physics, that’s better news because it means we are about to understand physics better.
Anyway, if what you want is just to be able to maneuver in earth orbit without reaction mass, you can do that already with a long wire (reacting against the local magnetic field). Implementation is not too easy (lessee, step 1: deploy this kilometers-long wire in a straight line normal to the orbit.) Does not work for interplanetary, but then you can’t have everything, and it has the benefit of working in the real world.
Long straight objects in orbit would tend to align normal to the orbit due to tidal effects.
It should be pointed out that a device that violates conservation of momentum in any reference frame will also violate conservation of energy. So this is actually a putative perpetual motion machine of the first kind.
My guess on the error? Make one side of the device slightly warmer than the other and difference in air pressure will generate “thrust”. The abstract said they tested it at ambient atmospheric pressure (although I am told the paper says something different, which is very odd and another reason to be cautious about the whole thing.)