Difference between revisions of "Experimental Results"

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The cavity length is estimated as 0.317 to 0.187.  The larger number takes into account the full length of the cylindrical part of the EM Drive Demo and the smaller number corresponds only to the length of the truncated cone section.  Please notice that the Demo has a variable length actuated by a gear mechanism, in order to tune the cavity to achieve resonance  http://www.wired.com/images_blogs/dangerroom/images/2008/09/24/emdrive_2.jpg .</ref> || None || 2.45*10^9 ||  421-1200|| 45000 || 102.30 || 80-243 || 23980 - 72830
 
The cavity length is estimated as 0.317 to 0.187.  The larger number takes into account the full length of the cylindrical part of the EM Drive Demo and the smaller number corresponds only to the length of the truncated cone section.  Please notice that the Demo has a variable length actuated by a gear mechanism, in order to tune the cavity to achieve resonance  http://www.wired.com/images_blogs/dangerroom/images/2008/09/24/emdrive_2.jpg .</ref> || None || 2.45*10^9 ||  421-1200|| 45000 || 102.30 || 80-243 || 23980 - 72830
 
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|NASA Brady et.al. a ||TM212 <ref name="brady">Mode shape is noted as TM211 in Brady et.al.'s report.  However, calculations show that TM211 should take place at a significant lower frequency and that this mode must have been TM212. Notice that Brady et.al. b took place practically at the same frequency as [http://forum.nasaspaceflight.com/index.php?topic=36313.msg1327177#msg1327177 March TM212 test in vacuum]</ref>||Ambient || 0.2286 || 0.2794 || 0.15875 || ||  extruded HDPE relative permitt. =2.26@3GHz|| 1.9326*10^9 ||  16.9||7320 || 0.0912|| 5.40 ||  1620
+
|NASA Brady et.al. a ||TM212 <ref name="brady">Mode shape is noted as TM211 in Brady et.al.'s report.  However, calculations show that TM211 should take place at a significant lower frequency and that this mode must have been TM212. Notice that Brady et.al. b took place practically at the same frequency as [http://forum.nasaspaceflight.com/index.php?topic=36313.msg1327177#msg1327177 March TM212 test in vacuum]</ref>||Ambient || 0.2286 || 0.2794 || 0.15875 || ||  extruded HDPE relative permitt. =2.26@1-3GHz|| 1.9326*10^9 ||  16.9||7320 || 0.0912|| 5.40 ||  1620
 
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|NASA Brady et.al. b ||TM212 <ref name="brady"/>||Ambient|| 0.2286 || 0.2794 || 0.15875 || || extruded HDPE relative permitt. =2.26@3GHz|| 1.9367*10^9 ||  16.7|| 18100 || 0.0501|| 3.00 ||  899
+
|NASA Brady et.al. b ||TM212 <ref name="brady"/>||Ambient|| 0.2286 || 0.2794 || 0.15875 || || extruded HDPE relative permitt. =2.26@1-3GHz|| 1.9367*10^9 ||  16.7|| 18100 || 0.0501|| 3.00 ||  899
 
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|NASA Brady et.al. c ||TE012 ||Ambient|| 0.2286 || 0.2794 || 0.15875 || ||  extruded HDPE relative permitt. =2.26@3GHz|| 1.8804*10^9 ||  2.6|| 22000 || 0.0554|| 21.3 ||  6390
+
|NASA Brady et.al. c ||TE012 ||Ambient|| 0.2286 || 0.2794 || 0.15875 || ||  extruded HDPE relative permitt. =2.26@1-3GHz|| 1.8804*10^9 ||  2.6|| 22000 || 0.0554|| 21.3 ||  6390
 
|-
 
|-
|NASA March et.al. ||TM212 <ref name="Mode Shape verification">This test is the only reported test that has verified the mode shape with experimental measurements.  A thermal camera was used that showed the same temperature profile as predicted from induction heating resulting from mode shape TM212</ref> ||5*10^(-6)|| 0.2286 || 0.2794 || 0.15875 || ||  extruded HDPE relative permitt. =2.26@3GHz|| 1.9371*10^9 ||  50|| 6726 || 0.055|| 1.10 || 330
+
|NASA March et.al. ||TM212 <ref name="Mode Shape verification">This test is the only reported test that has verified the mode shape with experimental measurements.  A thermal camera was used that showed the same temperature profile as predicted from induction heating resulting from mode shape TM212</ref> ||5*10^(-6)|| 0.2286 || 0.2794 || 0.15875 || ||  extruded HDPE relative permitt. =2.26@1-3GHz|| 1.9371*10^9 ||  50|| 6726 || 0.055|| 1.10 || 330
 
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|-
 
|[[Iulian_Berca|Iulian Berca]] Tests 3 & 3.1 (averaged w/up/down directional effects subtracted) <ref>See http://www.masinaelectrica.com/emdrive-independent-test/.  Because of the high profile nature of the tests, they are included here merely to give a rough comparison to the more scientifically rigorous tests. The measured thrust in this table is an average of multiple runs in tests 3 and 3.1, subtracting out the likely effects of hot air.  @deltaMass calculated the net thrust for the EmDrive across both test.  See [http://forum.nasaspaceflight.com/index.php?topic=37642.msg1384709#msg1384709].</ref> ||TM212<ref name="Iulian Mode Shape">Iulian Berca used the same dimensions as NASA's truncated cone, but without a dielectric. Mode shape is predicted to be TM 212 according to NASA's COMSOL FEA analysis 2/6/2014 by Frank Davies NASA/JSC/EP5 (2.458 GHz) and to Rodal's exact solution calculation (2.423 GHz). Actual mode participation depends on the spectrum of frequencies excited by the magnetron, the geometrical placement of the RF source in the EM Drive, and the number of eigenfrequencies in and near the magnetron's spectrum </ref>  ||Ambient ||0.2286 || 0.2794 || 0.1588 || || None || 2.45*10^9 (magnetron) ||  800 || n/a || 2.3 || 2.8 || 850
 
|[[Iulian_Berca|Iulian Berca]] Tests 3 & 3.1 (averaged w/up/down directional effects subtracted) <ref>See http://www.masinaelectrica.com/emdrive-independent-test/.  Because of the high profile nature of the tests, they are included here merely to give a rough comparison to the more scientifically rigorous tests. The measured thrust in this table is an average of multiple runs in tests 3 and 3.1, subtracting out the likely effects of hot air.  @deltaMass calculated the net thrust for the EmDrive across both test.  See [http://forum.nasaspaceflight.com/index.php?topic=37642.msg1384709#msg1384709].</ref> ||TM212<ref name="Iulian Mode Shape">Iulian Berca used the same dimensions as NASA's truncated cone, but without a dielectric. Mode shape is predicted to be TM 212 according to NASA's COMSOL FEA analysis 2/6/2014 by Frank Davies NASA/JSC/EP5 (2.458 GHz) and to Rodal's exact solution calculation (2.423 GHz). Actual mode participation depends on the spectrum of frequencies excited by the magnetron, the geometrical placement of the RF source in the EM Drive, and the number of eigenfrequencies in and near the magnetron's spectrum </ref>  ||Ambient ||0.2286 || 0.2794 || 0.1588 || || None || 2.45*10^9 (magnetron) ||  800 || n/a || 2.3 || 2.8 || 850

Revision as of 12:22, 5 June 2015

Forces, Power, Frequency, Mode shapes, Testing Conditions (ambient or partial vacuum) and Dimensions

The current best estimates for the parameters of various test articles run by public research institutions (NASA Eagleworks), very small private companies (SPR Ltd., Cannae LLC.), and independent engineers/researchers, is here, along with the reported forces. Note that complete dimensions are not known in most cases, and some had to be determined via indirect methods (e.g., estimation from photographs). See Building for details on drives built by do-it-yourselfers.

Credit to Dr. Rodal and others for the great effort in compiling these. Please note some caveats for this data, at that link.

Description Mode Shape[1] Pressure (Torr)[2] Cavity Length (m) bigDiameter (m) smallDiameter (m) Shawyer Design Factor Dielectric Frequency (Hertz) Input Power (W) Q [3] Force (mN) Force / PowerInput (mN/kW) Force/Power Multiple of Photon Rocket
Cannae LLC, G. Fetta, Superconducting[4] Ambient 0.03 0.220 0.200 None 1.047*10^9 10.5 1.1*10^7 8-10 761.9 - 952.4 228400 - 285500
SPR Ltd, R. Shawyer, Experimental Ambient 0.156 0.16 0.1025 0.497 [5] relative permittivity =38 2.45*10^9 850 5900 16 18.82 5640
SPR Ltd, R. Shawyer, Demonstration Ambient 0.317 to 0.187 0.28 0.17027 0.484[6] None 2.45*10^9 421-1200 45000 102.30 80-243 23980 - 72830
NASA Brady et.al. a TM212 [7] Ambient 0.2286 0.2794 0.15875 extruded HDPE relative permitt. =2.26@1-3GHz 1.9326*10^9 16.9 7320 0.0912 5.40 1620
NASA Brady et.al. b TM212 [7] Ambient 0.2286 0.2794 0.15875 extruded HDPE relative permitt. =2.26@1-3GHz 1.9367*10^9 16.7 18100 0.0501 3.00 899
NASA Brady et.al. c TE012 Ambient 0.2286 0.2794 0.15875 extruded HDPE relative permitt. =2.26@1-3GHz 1.8804*10^9 2.6 22000 0.0554 21.3 6390
NASA March et.al. TM212 [8] 5*10^(-6) 0.2286 0.2794 0.15875 extruded HDPE relative permitt. =2.26@1-3GHz 1.9371*10^9 50 6726 0.055 1.10 330
Iulian Berca Tests 3 & 3.1 (averaged w/up/down directional effects subtracted) [9] TM212[10] Ambient 0.2286 0.2794 0.1588 None 2.45*10^9 (magnetron) 800 n/a 2.3 2.8 850
California State Univ., Fullerton, Fearn, Zachar, Woodward & Wanser - piezoelectric MET thruster[11] Partial Vacuum ? 39300 170 22000 0.002 0.01176 3.526

Environmental pressure unit: 1 Torr = [math]\cfrac{1}{760} [/math] of a standard atmosphere.

Comparison to Photon Rockets

For a perfectly-collimated photon rocket, the force per power input is as follows:

Photon Rocket Force / PowerInput (mN/kW) = 0.003337

If the results above are validated, the EM Drive would greatly exceed that ratio.

Notes and references

  1. Mode shapes for the EM Drive truncated cone geometry are given according to the closest mode shape for a cylindrical geometry, instead of given by the eigenparameters of the truncated cone eigensolution (for example, using the wavenumber). The reason for this is two fold: 1) There is no standard convention on how to number mode shapes for a truncated cone, and 2) the truncated cone geometry used by the EM Drive researchers has been close to a cylinder: the cone angles have been relatively small. Therefore the mode shapes resemble those of a cylinder. TM means "transverse magnetic": a mode shape where the magnetic field is in the azimuthal, solenoidal direction and the electric field is in the transverse and longitudinal direction. TE stands for "transverse electric": a mode shape where the electric field is in the azimuthal, solenoidal direction and the magnetic field is in the transverse and longitudinal direction. The subscripts m,n,p in TMmnp and TEmnp, stand for the mode shape quantum numbers in the azimuthal (m), transverse (n) and longitudinal (p) directions respectively.
  2. This field denotes whether the test was performed in ambient conditions (hence the field labeled as "Ambient") or in a partial vacuum. When the researcher has provided the pressure in the partial vacuum condition, this is given in the units of Torrs.
  3. Quality factor of resonance: a measure inverse to damping: the higher the Q, the lower the damping. Infinite Q corresponds to zero damping. Critical damping occurs for a value of Q = 1/2.
  4. Completely different shape from the other EM Drives: this is not a truncated cone, but instead it is shaped like a pillbox with a circular cross-section. Results were posted in the Cannae webpages. Page is no longer available, but an archived version as of 2 November 2012 is available at archive.org:[1]
  5. UK Patent Application GB 2 334 761 A, date of publication 01.09.1999, application No 9809035.0, date of filing 29.04.1998
  6. Forum posts by @phaseshift, @Rodal, and @Rodal - The Design Factor is reported as 0.844 in at least three of Shawyer's references; however using a Design Factor = 0.844 gives a much smaller diameter in conflict with the ratio of the small diameter to the big diameter shown in the picture of the Demonstrator in Shawyer's publications, so it is assumed that was an unintentional typo (0.844 instead of 0.484, which results in a small diameter that agrees with the published image). The smallDiameter shown here was recalculated from the revised Design Factor (0.484). The cavity length is estimated as 0.317 to 0.187. The larger number takes into account the full length of the cylindrical part of the EM Drive Demo and the smaller number corresponds only to the length of the truncated cone section. Please notice that the Demo has a variable length actuated by a gear mechanism, in order to tune the cavity to achieve resonance emdrive_2.jpg .
  7. 7.0 7.1 Mode shape is noted as TM211 in Brady et.al.'s report. However, calculations show that TM211 should take place at a significant lower frequency and that this mode must have been TM212. Notice that Brady et.al. b took place practically at the same frequency as March TM212 test in vacuum
  8. This test is the only reported test that has verified the mode shape with experimental measurements. A thermal camera was used that showed the same temperature profile as predicted from induction heating resulting from mode shape TM212
  9. See http://www.masinaelectrica.com/emdrive-independent-test/. Because of the high profile nature of the tests, they are included here merely to give a rough comparison to the more scientifically rigorous tests. The measured thrust in this table is an average of multiple runs in tests 3 and 3.1, subtracting out the likely effects of hot air. @deltaMass calculated the net thrust for the EmDrive across both test. See [2].
  10. Iulian Berca used the same dimensions as NASA's truncated cone, but without a dielectric. Mode shape is predicted to be TM 212 according to NASA's COMSOL FEA analysis 2/6/2014 by Frank Davies NASA/JSC/EP5 (2.458 GHz) and to Rodal's exact solution calculation (2.423 GHz). Actual mode participation depends on the spectrum of frequencies excited by the magnetron, the geometrical placement of the RF source in the EM Drive, and the number of eigenfrequencies in and near the magnetron's spectrum
  11. [3]Forum post by @Rodal - Included here because Prof. Woodward's device is also a propellant-less concept, and because Paul March (NASA) maintains that Prof. Woodward's Mach Effect theory might also be, in his opinion, an explanation for thrust for the EM Drive.