The Huffington Post gives the EM drive a spin around the photon drive block.http://m.huffpost.com/us/entry/7489064Update from hackaday about their EM drive.https://hackaday.io/project/5596-em-drive/log/18994-cavity-finished

What is the rationale for the "Spring Force" artifact?I thought @frobnicat had disposed of that issue.Please provide what spring materials you know of that have a substantially different modulus of elasticity E in compression than in tension (this would be useful to experimenters, I guess, to avoid), what is the difference in value for E between compression and tension, and why you think that the spring used by Berca would display a substantial difference in E between tension and compression.The overwhelming number of materials commonly used as springs have practically the same modulus of Elasticity in tension than in compression.With deformations large enough, the issue that comes up is not one of bilinearity between tension and compression, but it is one of nonlinearity. For large deformations spring materials behave with a cubic nonlinearity, but they are still elastic and have same properties in tension and compression.You would have to reach plasticity (permanent deformation) of a metal to exhibit significant differences between tension and compression.

"the chamber walls in the Brady et al. tests a" an issue ?have we forgotten about the tests that Paul March reported with the EM Drive outside the chamber walls?

Quote from: Rodal on 06/04/2015 06:26 PMWhat is the rationale for the "Spring Force" artifact?I thought @frobnicat had disposed of that issue.Please provide what spring materials you know of that have a substantially different modulus of elasticity E in compression than in tension (this would be useful to experimenters, I guess, to avoid), what is the difference in value for E between compression and tension, and why you think that the spring used by Berca would display a substantial difference in E between tension and compression.The overwhelming number of materials commonly used as springs have practically the same modulus of Elasticity in tension than in compression.With deformations large enough, the issue that comes up is not one of bilinearity between tension and compression, but it is one of nonlinearity. For large deformations spring materials behave with a cubic nonlinearity, but they are still elastic and have same properties in tension and compression.You would have to reach plasticity (permanent deformation) of a metal to exhibit significant differences between tension and compression.I think you are overthinking the issue quite a bit here. In Iulian's setup, the spring looked to be in tension. When the deflection of the cantilevered torque arm is downwards, the deflection of the spring increases and the tension would increase. When deflection is up, tension decreases. The force provided by the spring is not a constant in both instances, and is therefore a source of error. ...

Quote from: Star One on 06/04/2015 06:47 PMThe Huffington Post gives the EM drive a spin around the photon drive block.http://m.huffpost.com/us/entry/7489064Update from hackaday about their EM drive.https://hackaday.io/project/5596-em-drive/log/18994-cavity-finishedThey test the Baby EM Drive next week !Oh baby, baby !

Quote from: Rodal on 06/04/2015 05:13 PMQuote from: phaseshift on 06/04/2015 05:01 PMQuote from: Rodal on 06/04/2015 04:56 PMQuote from: phaseshift on 06/04/2015 04:38 PM...So, while I would like to hear updates from Iulian on his progress I would rather not add his 'data' to the table until he says "I think I'm seeing thrust", but not just due to the excitement of the moment.It doesn't matter to me, data in any form is so rare right now. As as long as I realize where it came from, it's fine. Beggars can't be choosers. A couple of months or a year from now I will be picky.

Quote from: phaseshift on 06/04/2015 05:01 PMQuote from: Rodal on 06/04/2015 04:56 PMQuote from: phaseshift on 06/04/2015 04:38 PM...So, while I would like to hear updates from Iulian on his progress I would rather not add his 'data' to the table until he says "I think I'm seeing thrust", but not just due to the excitement of the moment.It doesn't matter to me, data in any form is so rare right now. As as long as I realize where it came from, it's fine. Beggars can't be choosers. A couple of months or a year from now I will be picky.

Quote from: Rodal on 06/04/2015 04:56 PMQuote from: phaseshift on 06/04/2015 04:38 PM...So, while I would like to hear updates from Iulian on his progress I would rather not add his 'data' to the table until he says "I think I'm seeing thrust", but not just due to the excitement of the moment.It doesn't matter to me, data in any form is so rare right now. As as long as I realize where it came from, it's fine. Beggars can't be choosers. A couple of months or a year from now I will be picky.

Quote from: phaseshift on 06/04/2015 04:38 PM...So, while I would like to hear updates from Iulian on his progress I would rather not add his 'data' to the table until he says "I think I'm seeing thrust", but not just due to the excitement of the moment.It doesn't matter to me, data in any form is so rare right now. As as long as I realize where it came from, it's fine. Beggars can't be choosers. A couple of months or a year from now I will be picky.

...So, while I would like to hear updates from Iulian on his progress I would rather not add his 'data' to the table until he says "I think I'm seeing thrust", but not just due to the excitement of the moment.

Quote from: X_RaY on 06/03/2015 09:31 PMQuote from: phaseshift on 06/03/2015 09:12 PMQuote from: X_RaY on 06/03/2015 09:08 PMQuote from: Rodal on 06/03/2015 08:53 PMQuote from: sneekmatrix on 06/03/2015 08:43 PMWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.correct andThe tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.Are you sure that's a net blue shift? The frustum has to gain momentum which means the photon loses energy and red shifts. Is the blue shift something that photon's do when they tunnel?Yes, if there is a potential barrier (cutoff frequency, diameter )most of the photons would be reflected (may be at the sidewall may be at the energy barrier) but some photons able to tunneling that barrier in just zero time, i think than the cavity acts like shorter than it is.The small end looks like it is narrow to the small end. Its more a intuitiv thing, i have the luck to work with conical cavities for special applications. Got network analyser, Spectrum Analyzer, circulator, load, tapered cavities all available and i am able to build conical cavities like a want but in K-Band area I'm just wondering.. if tunneling happens instantaneously (in the literal sense), then there is no time to measure anything - it happens without any dt . Hence, I don't think it can be said that photons increase or decrease frequency during the transition through the barrier.. if there is null time passing, then logically no measurements can take place, from which we can derive a claim about how frequencies of photons might change during a null time transition.

Quote from: phaseshift on 06/03/2015 09:12 PMQuote from: X_RaY on 06/03/2015 09:08 PMQuote from: Rodal on 06/03/2015 08:53 PMQuote from: sneekmatrix on 06/03/2015 08:43 PMWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.correct andThe tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.Are you sure that's a net blue shift? The frustum has to gain momentum which means the photon loses energy and red shifts. Is the blue shift something that photon's do when they tunnel?Yes, if there is a potential barrier (cutoff frequency, diameter )most of the photons would be reflected (may be at the sidewall may be at the energy barrier) but some photons able to tunneling that barrier in just zero time, i think than the cavity acts like shorter than it is.The small end looks like it is narrow to the small end. Its more a intuitiv thing, i have the luck to work with conical cavities for special applications. Got network analyser, Spectrum Analyzer, circulator, load, tapered cavities all available and i am able to build conical cavities like a want but in K-Band area

Quote from: X_RaY on 06/03/2015 09:08 PMQuote from: Rodal on 06/03/2015 08:53 PMQuote from: sneekmatrix on 06/03/2015 08:43 PMWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.correct andThe tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.Are you sure that's a net blue shift? The frustum has to gain momentum which means the photon loses energy and red shifts. Is the blue shift something that photon's do when they tunnel?

Quote from: Rodal on 06/03/2015 08:53 PMQuote from: sneekmatrix on 06/03/2015 08:43 PMWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.correct andThe tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.

Quote from: sneekmatrix on 06/03/2015 08:43 PMWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.

Wouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?

As an onlooker I do often wonder about the possible magnitude of the artifacts.Is it reasonable to think that any configuration of the system could interact with Earth's magnetic field enough to explain the resulting thrust?Could even a dedicated electrostatic "air pusher" taking this basic frustrum form generate these sorts of figures with this kind of power input?Basically, in the worst case scenarios, where the system is explicitly designed to generate the artifacts, what magnitude of artifacts would we see?

Quote from: wallofwolfstreet on 06/04/2015 06:50 PMQuote from: Rodal on 06/04/2015 06:26 PMWhat is the rationale for the "Spring Force" artifact?I thought @frobnicat had disposed of that issue.Please provide what spring materials you know of that have a substantially different modulus of elasticity E in compression than in tension (this would be useful to experimenters, I guess, to avoid), what is the difference in value for E between compression and tension, and why you think that the spring used by Berca would display a substantial difference in E between tension and compression.The overwhelming number of materials commonly used as springs have practically the same modulus of Elasticity in tension than in compression.With deformations large enough, the issue that comes up is not one of bilinearity between tension and compression, but it is one of nonlinearity. For large deformations spring materials behave with a cubic nonlinearity, but they are still elastic and have same properties in tension and compression.You would have to reach plasticity (permanent deformation) of a metal to exhibit significant differences between tension and compression.I think you are overthinking the issue quite a bit here. In Iulian's setup, the spring looked to be in tension. When the deflection of the cantilevered torque arm is downwards, the deflection of the spring increases and the tension would increase. When deflection is up, tension decreases. The force provided by the spring is not a constant in both instances, and is therefore a source of error. ...Overthinking, me ? Nahh DERIVATION OF SPRING STIFFNESS IN TERMS OF FORCE AND DISPLACEMENTFormula from strength of materialsstress = Force /Area (uniform normal stress distribution on the cross-sectional area)strain =displacement/(original length) (definition of strain)stress = E strain (constitutive relationship = linear modulus of elasticity E)Then it trivially follows that:Force =( E * Area/ originalLength ) * displacementForce = SpringStiffness * displacement (a linear stiffness relationship between force and displacement)wherespringStiffness = E Area/ originalLength It doesn't matter whether it is tension or compression if the material has a unique E (which most materials do)It doesn't matter the amount of tension if the material has a linear stress-strain relationship giving a linear EIn essence, if you are worrying about the "amount of tension" affecting the force, then you are positing a material with a nonlinear stress-strain relationship.If we agree that the spring material has a constant modulus of elasticity E, then the SpringStiffness is constant as well:Force = SpringStiffness * displacement (this is known as Hooke's law)then delta (Force) = SpringStiffness * delta (displacement)EXAMPLE: SAME ABSOLUTE VALUE OF DISPLACEMENT IN UPWARDS AND DOWNWARDS DIRECTIONSo let's say that the neutral position is for z (vertical coordinate) = 0F = SpringStiffness z(so z=0 means F=0)for z = + positiveDisplacementpositive Force = SpringStiffness * positiveDisplacementfor z = - positiveDisplacementnegative Force = - SpringStiffness * positiveDisplacementso positive Force = - negative ForceSame displacements up or down translate into same absolute value of force up or downEXAMPLE: DIFFERENT ABSOLUTE VALUE OF DISPLACEMENT IN UPWARDS THAN DOWNWARDS DIRECTIONfor z = + positiveDisplacementpositive Force = SpringStiffness * positiveDisplacementfor z = - (1/7) * positiveDisplacementnegative Force = - (1/7) SpringStiffness * positiveDisplacementso positive Force = - 7 negative Forceor, equivalently,negative Force = - (1/7) positive ForceThat spring force is balanced by the force on the cantilever, which is being measured.In essence, the spring is linear .What is the source of error ?

...I thought “overthinking” was the wrong phrase to use, but now I'm not so sure . You did a great job of accounting for linearities in the above post. You accounted for linearity of the spring force (no complaints here). The deflection of a cantilevered beam is also linear with respect to force applied (so good so far on the linearity front)http://en.wikipedia.org/wiki/Deflection_%28engineering%29. However, there is a non-linearity in the analysis that you didn’t account for, and it ends up justifying my initial remarks. Sin(theta) is not a linear function.

Quote from: wallofwolfstreet on 06/04/2015 06:50 PMQuote from: Rodal on 06/04/2015 06:26 PM...I think you are overthinking the issue quite a bit here. In Iulian's setup, the spring looked to be in tension. When the deflection of the cantilevered torque arm is downwards, the deflection of the spring increases and the tension would increase. When deflection is up, tension decreases. The force provided by the spring is not a constant in both instances, and is therefore a source of error. ......EXAMPLE: SAME ABSOLUTE VALUE OF DISPLACEMENT IN UPWARDS AND DOWNWARDS DIRECTIONSo let's say that the neutral position is for z (vertical coordinate) = 0F = SpringStiffness z(so z=0 means F=0)for z = + positiveDisplacementpositive Force = SpringStiffness * positiveDisplacementfor z = - positiveDisplacementnegative Force = - SpringStiffness * positiveDisplacementso positive Force = - negative ForceSame displacements up or down translate into same absolute value of force up or down...

Quote from: Rodal on 06/04/2015 06:26 PM...I think you are overthinking the issue quite a bit here. In Iulian's setup, the spring looked to be in tension. When the deflection of the cantilevered torque arm is downwards, the deflection of the spring increases and the tension would increase. When deflection is up, tension decreases. The force provided by the spring is not a constant in both instances, and is therefore a source of error. ...

...

Quote from: wallofwolfstreet on 06/04/2015 08:55 PM...I thought “overthinking” was the wrong phrase to use, but now I'm not so sure . You did a great job of accounting for linearities in the above post. You accounted for linearity of the spring force (no complaints here). The deflection of a cantilevered beam is also linear with respect to force applied (so good so far on the linearity front)http://en.wikipedia.org/wiki/Deflection_%28engineering%29. However, there is a non-linearity in the analysis that you didn’t account for, and it ends up justifying my initial remarks. Sin(theta) is not a linear function. Well, the conversation now has shifted from "Spring Error" to you claiming that there is a geometric nonlinearity in Berca's tests.I don't understand your picture and how it may relate to Iulian's test.Whatever it is you are trying to represent by the angle theta, let's say that for Power OFF, you have an angle theta= thetaInitialand that for Power ON, pointing UP you have an anglethetaOnUP = thetaInitial + deltaThetaUPand that for Power ON, pointing DOWN you have an anglethetaOnDOWN = thetaInitial + deltaThetaDOWN(where deltaThetaDOWN is a negative number)then the change going up ischangeUP = Sin[thetaInitial + deltaThetaUP] - Sin[thetaInitial ] =Sin[thetaInitial]Cos[deltaThetaUP] + Cos[thetaInitial]Sin[deltaThetaUP] - Sin[thetaInitial ]for small change in angle deltaThetaUP ~ 0the expansion of the Sin and Cos series give: (see http://en.wikipedia.org/wiki/Trigonometric_functions#Series_definitions )Cos[deltaThetaUP] ~0Sin[deltaThetaUP] ~ deltaThetaUPchangeUP =Sin[thetaInitial] + Cos[thetaInitial] deltaThetaUP - Sin[thetaInitial ] = Cos[thetaInitial] deltaThetaUP the change going down ischangeDOWN = Sin[thetaInitial + deltaThetaDOWN] - Sin[thetaInitial ] =Sin[thetaInitial]Cos[deltaThetaDOWN] + Cos[thetaInitial]Sin[deltaThetaDOWN] - Sin[thetaInitial ]for small change in angle deltaThetaDOWN ~ 0the expansion of the Sin and Cos series give: (see http://en.wikipedia.org/wiki/Trigonometric_functions#Series_definitions )Cos[deltaThetaDOWN] ~0Sin[deltaThetaDOWN] ~ deltaThetaDOWNchangeDOWN =Sin[thetaInitial] + Cos[thetaInitial] deltaThetaDOWN - Sin[thetaInitial ] = Cos[thetaInitial] deltaThetaDOWN So for small deflections of the EM Drive, the effect is also linear:changeUP = Cos[thetaInitial] deltaThetaUP changeDOWN = Cos[thetaInitial] deltaThetaDOWN (where deltaThetaDOWN is a negative number)changeInSin[theta] = Constant * changeInAnglewhere Constant = Cos[thetaInitial]There is no geometric nonlinearity for small forces of the EM Drive, because the force produced by the EM Drive is tiny (fractions of a gram), which also involve tiny changes in displacement, and tiny changes in rotationWe are talking here about very small forces produced by the EM Drive, and hence very small displacements, and very small roatations produced by the EM Drive.Note1, what is involved here is called a perturbation analysis, which is quite common in Physics. Such perturbation is also involved in the analysis for beam bending or shell structures used by engineers when the design a rocket spaceship. Note2, if you are interested in a nonlinearity, involving a thermal instability affecting the EM Drive, then this is an excellent paper that is highly recommended: https://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECT

...To be honest, the fact that you employed a linear approximation to sin for small angles ought to be enough to convince you that there is a geometrical non-linearity.

Quote from: wallofwolfstreet on 06/04/2015 10:32 PM...To be honest, the fact that you employed a linear approximation to sin for small angles ought to be enough to convince you that there is a geometrical non-linearity. You are simply wrong, there is no geometric nonlinearity involved in Berca's measurements because the forces of the EM Drive are extremely small. Good luck and goodbye

Quote from: Rodal on 06/04/2015 10:35 PMQuote from: wallofwolfstreet on 06/04/2015 10:32 PM...To be honest, the fact that you employed a linear approximation to sin for small angles ought to be enough to convince you that there is a geometrical non-linearity. You are simply wrong, there is no geometric nonlinearity involved in Berca's measurements because the forces of the EM Drive are extremely small. Good luck and goodbyeWell I guess there is no convincing you, and I'm sorry to hear that. Nature doesn't make approximations. For no non-zero value of theta, does sin(theta)=theta exactly . Ergo, there is a non-linearity in Iulian's setup with his spring arranged as is. Maybe you don't think it is big enough to warrant a mention on the sources of error page, and that's fine by me. Rest assured though, it is there.

Quote from: phaseshift on 06/01/2015 09:56 PMQuote from: TheTraveller on 06/01/2015 09:17 PMQuote from: phaseshift on 06/01/2015 06:35 PMShort snippet of Ruby code that computes the Shawyer Design Factor the way TheTraveller has in his spreadsheet.def compute_design_factor( small_diameter_meters, large_diameter_meters, frequency_hz, jC) cM = 299705000.0 cf = cM / frequency_hz jCFPI = jC * cf / Math::PI b = Math.sqrt( 1 - ( jCFPI / large_diameter_meters ) ** 2 ) s = Math.sqrt( 1 - ( jCFPI / small_diameter_meters ) ** 2 ) df = (b - s) / ( 1 - b * s ) return df endjC = BesselJ CutoffBefore doing Df or resonance calc you need to know excitation mode TMm,n,p or TEm,n,p and the appropriate BesselJ value as per that mode. BesselJ value is driven by mode TE or TM and the associated m & n values. p refers to the number of 1/2 waves between the end plates. There are 2 tables provided. One for TE mode and one for TM mode. Each is indexed by the selected m & n values.As example to use TE013 mode, use the TE table and the value at the intersection of the m=0 & n=1. = 3.8318 Then adjust end plate spacing or frequency or Df, via altering either/both end plate diameters to fit the desired number of p 1/2 waves between the end plates.Tables attached.And what? The above method coming directly out of your spreadsheet and produces the same values - I had to bounce all over to pull all the cells together and then simplify all the duplicate references - not sure what you're trying to point out - other than for people to use the above tables to pick a value for jC? Yes use the tables, for now, to select the appropriate BesselJ value for the excitation mode.Next version will directly calc the BesselJ value for the selected mode.Ay the heart of the Df equation is the cutoff wavelength, which is driven by the BesselJ value for the selected excitation mode.TE11 has a different Df than TE01 and different again for TM01. There is no one value for BesselJ.Once the mode is selected and resonance is obtained, the physical antenna placement, length & design must be correct to excite the frustum in the mode that the frustum has been designed for.Further to obtain the highest Q possible, the frustum impedance must match that of the Rf generator. To do that will require the physical ability to adjust the antennas local enviroment by some physically adjustable means.I'm working to bring those placement & length calculations and impedance tuning methods to the calculator.As it exists now, there are several more stages to be added.

Quote from: TheTraveller on 06/01/2015 09:17 PMQuote from: phaseshift on 06/01/2015 06:35 PMShort snippet of Ruby code that computes the Shawyer Design Factor the way TheTraveller has in his spreadsheet.def compute_design_factor( small_diameter_meters, large_diameter_meters, frequency_hz, jC) cM = 299705000.0 cf = cM / frequency_hz jCFPI = jC * cf / Math::PI b = Math.sqrt( 1 - ( jCFPI / large_diameter_meters ) ** 2 ) s = Math.sqrt( 1 - ( jCFPI / small_diameter_meters ) ** 2 ) df = (b - s) / ( 1 - b * s ) return df endjC = BesselJ CutoffBefore doing Df or resonance calc you need to know excitation mode TMm,n,p or TEm,n,p and the appropriate BesselJ value as per that mode. BesselJ value is driven by mode TE or TM and the associated m & n values. p refers to the number of 1/2 waves between the end plates. There are 2 tables provided. One for TE mode and one for TM mode. Each is indexed by the selected m & n values.As example to use TE013 mode, use the TE table and the value at the intersection of the m=0 & n=1. = 3.8318 Then adjust end plate spacing or frequency or Df, via altering either/both end plate diameters to fit the desired number of p 1/2 waves between the end plates.Tables attached.And what? The above method coming directly out of your spreadsheet and produces the same values - I had to bounce all over to pull all the cells together and then simplify all the duplicate references - not sure what you're trying to point out - other than for people to use the above tables to pick a value for jC?

Quote from: phaseshift on 06/01/2015 06:35 PMShort snippet of Ruby code that computes the Shawyer Design Factor the way TheTraveller has in his spreadsheet.def compute_design_factor( small_diameter_meters, large_diameter_meters, frequency_hz, jC) cM = 299705000.0 cf = cM / frequency_hz jCFPI = jC * cf / Math::PI b = Math.sqrt( 1 - ( jCFPI / large_diameter_meters ) ** 2 ) s = Math.sqrt( 1 - ( jCFPI / small_diameter_meters ) ** 2 ) df = (b - s) / ( 1 - b * s ) return df endjC = BesselJ CutoffBefore doing Df or resonance calc you need to know excitation mode TMm,n,p or TEm,n,p and the appropriate BesselJ value as per that mode. BesselJ value is driven by mode TE or TM and the associated m & n values. p refers to the number of 1/2 waves between the end plates. There are 2 tables provided. One for TE mode and one for TM mode. Each is indexed by the selected m & n values.As example to use TE013 mode, use the TE table and the value at the intersection of the m=0 & n=1. = 3.8318 Then adjust end plate spacing or frequency or Df, via altering either/both end plate diameters to fit the desired number of p 1/2 waves between the end plates.Tables attached.

Short snippet of Ruby code that computes the Shawyer Design Factor the way TheTraveller has in his spreadsheet.def compute_design_factor( small_diameter_meters, large_diameter_meters, frequency_hz, jC) cM = 299705000.0 cf = cM / frequency_hz jCFPI = jC * cf / Math::PI b = Math.sqrt( 1 - ( jCFPI / large_diameter_meters ) ** 2 ) s = Math.sqrt( 1 - ( jCFPI / small_diameter_meters ) ** 2 ) df = (b - s) / ( 1 - b * s ) return df endjC = BesselJ Cutoff

...I don't particularly agree with the focus and wording (I see the word "amateur" is present in the wiki) for Iulian Berca's experiment, when the same degree of stringent rigor is not dedicated to the tests reported by very small private companies in the UK and the USA and a University in China for their tests in ambient conditions.

After the invention of the EM Drive by Roger Shawyer, Iulan Berca was the first independent electrical engineer to fabricate a working EmDrive and successfully record force from the device.

Do not underestimate the determination of a quiet man.

Quote from: wallofwolfstreet on 06/04/2015 10:44 PMQuote from: Rodal on 06/04/2015 10:35 PMQuote from: wallofwolfstreet on 06/04/2015 10:32 PM...To be honest, the fact that you employed a linear approximation to sin for small angles ought to be enough to convince you that there is a geometrical non-linearity. You are simply wrong, there is no geometric nonlinearity involved in Berca's measurements because the forces of the EM Drive are extremely small. Good luck and goodbyeWell I guess there is no convincing you, and I'm sorry to hear that. Nature doesn't make approximations. For no non-zero value of theta, does sin(theta)=theta exactly . Ergo, there is a non-linearity in Iulian's setup with his spring arranged as is. Maybe you don't think it is big enough to warrant a mention on the sources of error page, and that's fine by me. Rest assured though, it is there. Remember discussing a similar "relevance" issue with dr Rodal (inertial recoils from thermal expansions, yes it's 0, no it's not...). Do you think it is big enough to play a significant role in the apparent up/downward disparity ? What size roughly would have to be the arc span to make such non linearity relevant at, say, even only 1% ? Do you see the arm actually move to such extent ? Personally I had to run numbers before I was convinced that a "not 0" was close enough to 0 to be negligible in practice (and hence null, kind of, at least for the discussion).