To bad your neighbor or good friend isn't a spinner...
I may have a very shallow grasp of what can be done or not with microwaves (at what practical efficiencies) but isn't it possible to use a hollow waveguide and interrupt it for 1mm or so, I mean a waveguide with a fixed part linked to wall plugged RF amp, and a mobile part (coaxial with rotation). Would the leak be too big ? Is a waveguide simply not appropriate for efficient power transmission ?As I understand (weakly, feel free to educate me) RF is "transverse" (E and B orthogonal to propagation) so maybe any power RF wireless transmission scheme might show intrinsic torque between mobile part and fixed part (waveguide or antenna), no ? This could be mitigated by sampling at various relative orientations, or by having a freely rotating part (full 360°) to integrate and even out any orientation dependency ...I wonder if a light enough "carousel" mounted on a sapphire cup bearing (near point like contact) could have low enough stiction to measure 10ľN or so at ends of arm. See attached picture for the overall idea. Alternatively instead of a dry point like contact use a "floater bearing" in water (or liquid metal or low vapor pressure oil for vacuum compatibility). Probably high viscosity but no stiction.Let it spin, measure thrust from acceleration profile first, then from equilibrium speed against viscosity. Check for periodic dependency of signal relative to angle of rotation (as "real" signal part wouldn't depend on that). Make the whole system as symmetric as possible around the axis (cylindrical walls around...).
Quote from: frobnicat on 11/17/2014 09:25 am...Need to change the direction of the thrust and the direction of rotation in your pictures: pic... it should be pointing the other way around, towards the bigger end, thus the rotation should be clock-wise in your picture.
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What's a spinner?
I'm just noting you can't skimp on the balance and vacuum and have people take your findings seriously. Paul March had propellantless thrust in his extra bedroom in 2003-4 and no one took it seriously because he had no vacuum.
Quote from: aero on 11/17/2014 02:40 amTo bad your neighbor or good friend isn't a spinner...What's a spinner? I mean, what do I know. I'm just a magazine publisher.
Just want to make sure (given the flipping of thrust arrows above that just happened) that the emdrive (if it actually works) flies through the air pointy end first, right? Is the sign of thrust flipped in reaction less engines and I didn't get the memo?Given the way the "thruster" is mounted in his space plane and the direction for cavity acceleration here:http://www.emdrive.com/iac2014presentation.pdfThe signs for thrust are flipped in his presentation.
Anyone else in build mode now? I'm gathering materials now, rf connectors and the like. @Ron Stahl:QuoteI'm just noting you can't skimp on the balance and vacuum and have people take your findings seriously. Paul March had propellantless thrust in his extra bedroom in 2003-4 and no one took it seriously because he had no vacuum. I'm not trying to be taken seriously. I'm not even taking this seriously. Building one is just for my enjoyment. I don't have access to a vacuum, nor will I spend more than a few bucks on this setup. What I'm going to do since I don't have vacuum, is put the test article inside a sealed container, pack it with tissue or foam to act as an air baffle and to distribute heat around evenly, and put that on the torsion balance.Next subject:Here's another emdrive theory paper I found:https://hal.archives-ouvertes.fr/hal-01074608/documentThis guy says he can make it better even.
If NASA is also defining thrust in the opposite direction to jet engines and rocket engines, why is NASA using this wrong definition? Shouldn't NASA at least get this right?Wasn't the movement of NASA's torsional pendulum towards the big end?This adds to the confusion in these papers which makes anyone skeptical of the subject matter...
See how NASA defines the thrust direction here (@35 minutes) towards the short end, consistent with Shawyer's spreadsheet, opposite from the dielectric located at the long end:
....@RodalQuoteSee how NASA defines the thrust direction here (@35 minutes) towards the short end, consistent with Shawyer's spreadsheet, opposite from the dielectric located at the long end:That stuff about Cannae above....doesn't follow. We're talking about Shawyer's design here.
Next subject:Here's another emdrive theory paper I found:https://hal.archives-ouvertes.fr/hal-01074608/documentThis guy says he can make it better even.
Quote from: Mulletron on 11/18/2014 04:31 pmNext subject:Here's another emdrive theory paper I found:https://hal.archives-ouvertes.fr/hal-01074608/documentThis guy says he can make it better even.Although fantastic as it seems, we ought to bide our time until some empirical evidence can be gathered to support or refute. Working with metglas foils at room temperature would certainly be easier than cooling YBCO film with liquid nitrogen, in an attempt to get an amplified effect.Seems tough to find pricing information on metglas 2714A. Here is a datasheet and an invite for a price quote:http://www.metglas.com/products/magnetic_materials/2714a.aspHere is some relatively inexpensive metglas tape on ebay, but no indication of it being 2714A.http://www.ebay.com/itm/Metglass-nanocrystaline-tape-for-MEG-generator-power-transformers-inverters-/321587303340?_trksid=p2054897.l4275Lining the inner cavity of a small test article with such material might be a next step in our exploration.