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" (as per http://forum.nasaspaceflight.com/index.php?topic=36313.msg1301658#msg1301658 Here is a comparison of reported measurements for EM Drives and for the latest report by Fearn, Zachar, Woodward & Wanser.Notice that the force per power input reported by Fearn, Zachar, Woodward & Wanser is several orders of magnitude lower than the "EM drives". Actually it is barely (3.5 times higher) more than the force per power input of a photon rocket:lengths in meterrfFrequency in 1/second (microwave frequency during test)power in wattsforce in milliNewtonsforce per PowerInput in milliNewtons/kWc= 299705000 m/s (speed of light in air)c= 299792458 m/s (speed of light in vacuum) (for Cannae Superconducting)(the difference between c in air compared to c in vacuum is negligible)Note: SmallDiameter for Shawyer's EM Drives obtained from his reported ShawyerDesignFactor .Force/PowerInput of a Photon Rocket = 1 / c(* Cannae Superconducting *)rfFrequency = 1.047*10^9;cavityLength = 0.01+0.004+0.006+0.01 = 0.03;bigDiameter =(22.86-2*(0.00430)) = 0.220;smallDiameter = bigDiameter-2*0.01=0.200;power = 10.5Q = 1.1*(10^7)measured force = 8 to 10measured ForcePerPowerInput = 761.9 to 952.4Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket = 228,400 to 285,500(* Shawyer Experimental *)rfFrequency=2.45*10^9;cavityLength=0.156;(estimated from photographs)bigDiameter=0.16; (given by Shawyer)smallDiameter=0.1025; (obtained from the Design Factor, bigDiameter and frequency provided by Shawyer)Design Factor = 0.497;power = 850;Q = 5900 ;measured force = 16measured ForcePerPowerInput = 18.82Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =5,640(* Shawyer Demo *)rfFrequency=2.45*10^9;cavityLength=0.345;(estimated from photographs)bigDiameter=0.28;(given by Shawyer)smallDiameter= 0.09613; (from the Design Factor, bigDiameter and frequency provided by Shawyer)Design Factor = 0.844;power = 421 to 1200;Q = 45000;(measured force = 102.30 milliNewtons only reported for 421 watts, 243 milliNewtons/kW )measured ForcePerPowerInput = 80 to 243Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =23,980 to 72,830All Brady cases have the following dimensions:cavityLength=0.2286; (provided by Paul March)bigDiameter=0.2794; (provided by Paul March)smallDiameter=0.15875; (provided by Paul March)(* Brady a TM mode*)rfFrequency=1.9326*10^9;power = 16.9Q = 7320measured force = 0.0912measured ForcePerPowerInput = 5.396Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =1,617.2(* Brady b TM mode*)rfFrequency=1.9367*10^9;power = 16.7Q = 18100measured force = 0.0501measured ForcePerPowerInput = 3.000Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =899.12(* Brady c TE mode *)rfFrequency = 1.8804*10^9;power = 2.6Q = 22000measured force = 0.05541measured ForcePerPowerInput = 21.31Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket =6,386.7(* Fearn, Zachar, Woodward & Wanser*)rfFrequency = 39,300;power = 170measured force = 0.002measured ForcePerPowerInput = 0.01176Force/PowerInput of a Photon Rocket =0.003337measured ForcePerPowerInput to the one of a photon rocket = 3.526