No, no toaster elements allowed.
Quote from: OttO on 06/10/2015 02:13 pmQuote from: SeeShells on 06/10/2015 02:03 pm It can measure thrust by its vertical Z displacement up or down Do you plan to put in it toaster resistors to measure the infrared influence No, no toaster elements allowed.I will be using a plastic container to keep any magnetic components from the EMdrive acting on the side walls. And don't laugh as this will work fine and it is inexpensive.
Quote from: SeeShells on 06/10/2015 02:03 pm It can measure thrust by its vertical Z displacement up or down Do you plan to put in it toaster resistors to measure the infrared influence
It can measure thrust by its vertical Z displacement up or down
Quote from: TMEubanks on 06/10/2015 01:23 pm...The chart posted above does NOT seem to include atmospheric drag (which dramatically changes orbital lifetimes etc. at low altitudes). Note that most cubesat launches are at 300 - 400 km - the ISS is 330 km, and that is probably the easiest platform to launch from. A cubesat is 0.1x0.1 meter (1U), so its area is 10^-2 m^2. Its mass will be ~ 1 kg. Assume 0.1 N/kW or 10^-4 N/W or ~ 5 x 10^-5 N for a 0.5 W drive. That means we want forcing to be(ideally) << 5 x 10^-3 N/m^2 to be sure a thrust observed is actually from the thruster. (If drag is large, then you will never be able to model it well enough to say that <thrust - drag> is actually meaningful.)Solar radiation pressure is 4.5 (absorption) to 9 (reflection) micro N / m^2, so radiation force will be < 10^-7 N, which is fine and can be ignored. (For LEO, the radiation pressure from the Earth is also substantial, and hard to model as it depends on cloud albedo, but it will be < solar and so also can be ignored). Drag at altitude depends heavily on the solar activity, and thus the solar cycle (which brought Skylab down). We are near peak right now, which is bad, but in 2 or 3 years or so things could be a lot better. See this prediction:http://en.wikipedia.org/wiki/Solar_cycle_24#/media/File:Solar_cycle_24_sunspot_number_progression_and_prediction.gifLooking at the old Harris-Preister model atmosphere (see Figure 2 of http://stk.com/downloads/support/productSupport/literature/pdfs/whitePapers/A%20Critical%20Assessment%20of%20Satellite%20Drag%20.pdf ) we would want the altitude to be > 300 km. At 400 km, Harris-Preister drag prediction is 3 x 10^-4 N/m^2, which might be OK, but is a little too close for comfort for me. That says to me that a CASIS launch of a test from Station would not be adequate, but a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials. (For various reasons, get-away specials basically never seem to be available for launches to GEO and higher.)Also note that a 600 km circular orbit is about as high as you can go with a reasonable expectation of a 25 year post mission lifetime for a cubesat, which is needed to meet IADC guidelines on limiting space debris :http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2011/8_Leveque_Orbital_Decay.pdfThank you Marshall, this is an excellent explanation as to why nobody has reported launching the EM Drive yet to the International Space Station or such a low Earth orbit. Launching it to a low orbit where it would be subject to air drag would just serve to continue the present state of uncertain experimental results at ground level, but at a low earth orbit would mean a much higher cost, where the experimental uncertainty of the ground tests with the EM Drives is such that there is no scientific demonstration that an EM Drive force that can be used for space propulsion is being measured, since the experimental variations and uncertainty overwhelm the present results.It is still fortunate that one can rescue some positive news from this, that launching at >500km circular orbit would be fine and that still qualifies for relatively low rates [but this rules out the International Space Station is definitely out since its orbit is too low 417 km] :Quote a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials That's about the orbit of the Hubble Telescope, isn't it ? (559 kilometers)
...The chart posted above does NOT seem to include atmospheric drag (which dramatically changes orbital lifetimes etc. at low altitudes). Note that most cubesat launches are at 300 - 400 km - the ISS is 330 km, and that is probably the easiest platform to launch from. A cubesat is 0.1x0.1 meter (1U), so its area is 10^-2 m^2. Its mass will be ~ 1 kg. Assume 0.1 N/kW or 10^-4 N/W or ~ 5 x 10^-5 N for a 0.5 W drive. That means we want forcing to be(ideally) << 5 x 10^-3 N/m^2 to be sure a thrust observed is actually from the thruster. (If drag is large, then you will never be able to model it well enough to say that <thrust - drag> is actually meaningful.)Solar radiation pressure is 4.5 (absorption) to 9 (reflection) micro N / m^2, so radiation force will be < 10^-7 N, which is fine and can be ignored. (For LEO, the radiation pressure from the Earth is also substantial, and hard to model as it depends on cloud albedo, but it will be < solar and so also can be ignored). Drag at altitude depends heavily on the solar activity, and thus the solar cycle (which brought Skylab down). We are near peak right now, which is bad, but in 2 or 3 years or so things could be a lot better. See this prediction:http://en.wikipedia.org/wiki/Solar_cycle_24#/media/File:Solar_cycle_24_sunspot_number_progression_and_prediction.gifLooking at the old Harris-Preister model atmosphere (see Figure 2 of http://stk.com/downloads/support/productSupport/literature/pdfs/whitePapers/A%20Critical%20Assessment%20of%20Satellite%20Drag%20.pdf ) we would want the altitude to be > 300 km. At 400 km, Harris-Preister drag prediction is 3 x 10^-4 N/m^2, which might be OK, but is a little too close for comfort for me. That says to me that a CASIS launch of a test from Station would not be adequate, but a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials. (For various reasons, get-away specials basically never seem to be available for launches to GEO and higher.)Also note that a 600 km circular orbit is about as high as you can go with a reasonable expectation of a 25 year post mission lifetime for a cubesat, which is needed to meet IADC guidelines on limiting space debris :http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2011/8_Leveque_Orbital_Decay.pdf
a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials
Quote from: SeeShells on 06/10/2015 02:22 pmQuote from: OttO on 06/10/2015 02:13 pmQuote from: SeeShells on 06/10/2015 02:03 pm It can measure thrust by its vertical Z displacement up or down Do you plan to put in it toaster resistors to measure the infrared influence No, no toaster elements allowed.I will be using a plastic container to keep any magnetic components from the EMdrive acting on the side walls. And don't laugh as this will work fine and it is inexpensive.Are you making a comment there as you appear to be testing it in a dustbin.
Quote from: SeeShells on 06/10/2015 02:03 pmNo, no toaster elements allowed.Silly as it seems I think it would be a cheap and strong way to prove that the thermal effect are not a problem.Put on the resistors to red hot and measure. If the Z displacement is inferior that the one with EM...
Why not just launch 2 in tandem? One without an EM thruster and get real baseline data comparing the two orbits? Eliminate a lot of unknowns in your test.Shell
Quote from: Star One on 06/10/2015 02:57 pmQuote from: SeeShells on 06/10/2015 02:22 pmQuote from: OttO on 06/10/2015 02:13 pmQuote from: SeeShells on 06/10/2015 02:03 pm It can measure thrust by its vertical Z displacement up or down Do you plan to put in it toaster resistors to measure the infrared influence No, no toaster elements allowed.I will be using a plastic container to keep any magnetic components from the EMdrive acting on the side walls. And don't laugh as this will work fine and it is inexpensive.Are you making a comment there as you appear to be testing it in a dustbin.No comment here and I'm sorry it had to be a Trash can, but it is cheap, strong, non-ferrous plastic and the right size. I know some here will say ... And if it doesn't work just put it out by the curb.
Quote from: Prunesquallor on 06/09/2015 06:51 pmQuote from: Prunesquallor on 06/08/2015 07:58 pmQuote from: deltaMass on 06/08/2015 05:44 pmRe. the recent flyby reference to the Aachen group's Baby EmDrive and CubeSats, I'm reminded that their team leader has already flown a couple of amateur space missions with an outfit called PoqetQub (from memory). This is a NASA forum, so presumably packed to the brim with orbital mechanics specialists!! So... what value of k (N/W) is needed to get EmDrive up from LEO, O Experts?ETA: On reflection that's a dumb question Any positive k value will do.You would have to determine what constitutes an orbit change that is outside the natural decay forces. Cubesats don't have much power, so they may not get much thrust. Would a retardation of orbital decay convince anyone? That is a tricky deal, because orbit decay is sensitive to upper atmosphere expansion/contraction, which is affected by solar activity, etc.If the thrust was significantly greater than the decay forces, you can use something like the Edelbaum approximation to determine the altitude change you should see with constant, tangential acceleration. If there is interest, I'll run some quick parametrics to see what that might be.Here's some analysis of what kind of orbital raising one could expect given constant, tangential, in-plane orbit thrust acceleration starting from a 600 km circular orbit (an average CubeSat altitude). It is not dependent on the type of thruster.Now if one wanted to apply this to a CubeSat with a little bitty EM Drive, here is how the numbers might stack up:Typical CubeSat available power: 0.5 Whttp://www.diyspaceexploration.com/power-system-budget-analysis/Typical CubeSat mass: 1.3 kghttp://en.wikipedia.org/wiki/CubeSatNow, choose your assumed EM Drive efficiency and compute acceleration. For example if you want to assume 0.1 N/kW, your acceleration would be (0.1 N/kW)*(0.5 W)*(0.001 kW/W)/(1.3 kg)/(9.81 m/s2/g) = around 4 micro-gs.You can then look at the chart, find the 4 micro-g line and see the altitude gain as a function of thruster on-time. You can decide for yourself if you want it to have constant thrust at constant power or if you want compute the time you think the universe will let the thruster operate and see how high it will get.The chart posted above does NOT seem to include atmospheric drag (which dramatically changes orbital lifetimes etc. at low altitudes). Note that most cubesat launches are at 300 - 400 km - the ISS is 330 km, and that is probably the easiest platform to launch from. A cubesat is 0.1x0.1 meter (1U), so its area is 10^-2 m^2. Its mass will be ~ 1 kg. Assume 0.1 N/kW or 10^-4 N/W or ~ 5 x 10^-5 N for a 0.5 W drive. That means we want forcing to be(ideally) << 5 x 10^-3 N/m^2 to be sure a thrust observed is actually from the thruster. (If drag is large, then you will never be able to model it well enough to say that <thrust - drag> is actually meaningful.)Solar radiation pressure is 4.5 (absorption) to 9 (reflection) micro N / m^2, so radiation force will be < 10^-7 N, which is fine and can be ignored. (For LEO, the radiation pressure from the Earth is also substantial, and hard to model as it depends on cloud albedo, but it will be < solar and so also can be ignored). Drag at altitude depends heavily on the solar activity, and thus the solar cycle (which brought Skylab down). We are near peak right now, which is bad, but in 2 or 3 years or so things could be a lot better. See this prediction:http://en.wikipedia.org/wiki/Solar_cycle_24#/media/File:Solar_cycle_24_sunspot_number_progression_and_prediction.gifLooking at the old Harris-Preister model atmosphere (see Figure 2 of http://stk.com/downloads/support/productSupport/literature/pdfs/whitePapers/A%20Critical%20Assessment%20of%20Satellite%20Drag%20.pdf ) we would want the altitude to be > 300 km. At 400 km, Harris-Preister drag prediction is 3 x 10^-4 N/m^2, which might be OK, but is a little too close for comfort for me. That says to me that a CASIS launch of a test from Station would not be adequate, but a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials. (For various reasons, get-away specials basically never seem to be available for launches to GEO and higher.)Also note that a 600 km circular orbit is about as high as you can go with a reasonable expectation of a 25 year post mission lifetime for a cubesat, which is needed to meet IADC guidelines on limiting space debris :http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2011/8_Leveque_Orbital_Decay.pdf
Quote from: Prunesquallor on 06/08/2015 07:58 pmQuote from: deltaMass on 06/08/2015 05:44 pmRe. the recent flyby reference to the Aachen group's Baby EmDrive and CubeSats, I'm reminded that their team leader has already flown a couple of amateur space missions with an outfit called PoqetQub (from memory). This is a NASA forum, so presumably packed to the brim with orbital mechanics specialists!! So... what value of k (N/W) is needed to get EmDrive up from LEO, O Experts?ETA: On reflection that's a dumb question Any positive k value will do.You would have to determine what constitutes an orbit change that is outside the natural decay forces. Cubesats don't have much power, so they may not get much thrust. Would a retardation of orbital decay convince anyone? That is a tricky deal, because orbit decay is sensitive to upper atmosphere expansion/contraction, which is affected by solar activity, etc.If the thrust was significantly greater than the decay forces, you can use something like the Edelbaum approximation to determine the altitude change you should see with constant, tangential acceleration. If there is interest, I'll run some quick parametrics to see what that might be.Here's some analysis of what kind of orbital raising one could expect given constant, tangential, in-plane orbit thrust acceleration starting from a 600 km circular orbit (an average CubeSat altitude). It is not dependent on the type of thruster.Now if one wanted to apply this to a CubeSat with a little bitty EM Drive, here is how the numbers might stack up:Typical CubeSat available power: 0.5 Whttp://www.diyspaceexploration.com/power-system-budget-analysis/Typical CubeSat mass: 1.3 kghttp://en.wikipedia.org/wiki/CubeSatNow, choose your assumed EM Drive efficiency and compute acceleration. For example if you want to assume 0.1 N/kW, your acceleration would be (0.1 N/kW)*(0.5 W)*(0.001 kW/W)/(1.3 kg)/(9.81 m/s2/g) = around 4 micro-gs.You can then look at the chart, find the 4 micro-g line and see the altitude gain as a function of thruster on-time. You can decide for yourself if you want it to have constant thrust at constant power or if you want compute the time you think the universe will let the thruster operate and see how high it will get.
Quote from: deltaMass on 06/08/2015 05:44 pmRe. the recent flyby reference to the Aachen group's Baby EmDrive and CubeSats, I'm reminded that their team leader has already flown a couple of amateur space missions with an outfit called PoqetQub (from memory). This is a NASA forum, so presumably packed to the brim with orbital mechanics specialists!! So... what value of k (N/W) is needed to get EmDrive up from LEO, O Experts?ETA: On reflection that's a dumb question Any positive k value will do.You would have to determine what constitutes an orbit change that is outside the natural decay forces. Cubesats don't have much power, so they may not get much thrust. Would a retardation of orbital decay convince anyone? That is a tricky deal, because orbit decay is sensitive to upper atmosphere expansion/contraction, which is affected by solar activity, etc.If the thrust was significantly greater than the decay forces, you can use something like the Edelbaum approximation to determine the altitude change you should see with constant, tangential acceleration. If there is interest, I'll run some quick parametrics to see what that might be.
Re. the recent flyby reference to the Aachen group's Baby EmDrive and CubeSats, I'm reminded that their team leader has already flown a couple of amateur space missions with an outfit called PoqetQub (from memory). This is a NASA forum, so presumably packed to the brim with orbital mechanics specialists!! So... what value of k (N/W) is needed to get EmDrive up from LEO, O Experts?ETA: On reflection that's a dumb question Any positive k value will do.
Height of the International Space Station vs time, look at the effect of air drag at 416 to 398 km(hat tip to TMEubanks )
19 hours after posting their YouTube video, they still donīt know (or haven't reported) if there is thrust yet...
Quote from: SeeShells on 06/10/2015 03:10 pmWhy not just launch 2 in tandem? One without an EM thruster and get real baseline data comparing the two orbits? Eliminate a lot of unknowns in your test.ShellBecause as Marshall said, " (If drag is large, then you will never be able to model it well enough to say that <thrust - drag> is actually meaningful.)" the atmospheric drag force at a particular location is too difficult to model and the thrust force of the EM Drive is too small to differentiate.Similar situation we are facing now with the tests on the ground, as the skeptics, for very good scientific reasons point out that the experimental uncertainty overwhelms what is being claimed as having been measured.Even with all the "do it yourself" experiments coming up, we will face pretty soon a situation similar to "cold fusion" which persists to this date with some claiming success and others not.What is needed is to have scientific measurements that are repeatable and where the level of uncertainty is much lower than what is being claimed to be measured.
Quote from: TMEubanks on 06/10/2015 01:23 pmQuote from: Prunesquallor on 06/09/2015 06:51 pmQuote from: Prunesquallor on 06/08/2015 07:58 pmQuote from: deltaMass on 06/08/2015 05:44 pmRe. the recent flyby reference to the Aachen group's Baby EmDrive and CubeSats, I'm reminded that their team leader has already flown a couple of amateur space missions with an outfit called PoqetQub (from memory). This is a NASA forum, so presumably packed to the brim with orbital mechanics specialists!! So... what value of k (N/W) is needed to get EmDrive up from LEO, O Experts?ETA: On reflection that's a dumb question Any positive k value will do.You would have to determine what constitutes an orbit change that is outside the natural decay forces. Cubesats don't have much power, so they may not get much thrust. Would a retardation of orbital decay convince anyone? That is a tricky deal, because orbit decay is sensitive to upper atmosphere expansion/contraction, which is affected by solar activity, etc.If the thrust was significantly greater than the decay forces, you can use something like the Edelbaum approximation to determine the altitude change you should see with constant, tangential acceleration. If there is interest, I'll run some quick parametrics to see what that might be.Here's some analysis of what kind of orbital raising one could expect given constant, tangential, in-plane orbit thrust acceleration starting from a 600 km circular orbit (an average CubeSat altitude). It is not dependent on the type of thruster.Now if one wanted to apply this to a CubeSat with a little bitty EM Drive, here is how the numbers might stack up:Typical CubeSat available power: 0.5 Whttp://www.diyspaceexploration.com/power-system-budget-analysis/Typical CubeSat mass: 1.3 kghttp://en.wikipedia.org/wiki/CubeSatNow, choose your assumed EM Drive efficiency and compute acceleration. For example if you want to assume 0.1 N/kW, your acceleration would be (0.1 N/kW)*(0.5 W)*(0.001 kW/W)/(1.3 kg)/(9.81 m/s2/g) = around 4 micro-gs.You can then look at the chart, find the 4 micro-g line and see the altitude gain as a function of thruster on-time. You can decide for yourself if you want it to have constant thrust at constant power or if you want compute the time you think the universe will let the thruster operate and see how high it will get.The chart posted above does NOT seem to include atmospheric drag (which dramatically changes orbital lifetimes etc. at low altitudes). Note that most cubesat launches are at 300 - 400 km - the ISS is 330 km, and that is probably the easiest platform to launch from. A cubesat is 0.1x0.1 meter (1U), so its area is 10^-2 m^2. Its mass will be ~ 1 kg. Assume 0.1 N/kW or 10^-4 N/W or ~ 5 x 10^-5 N for a 0.5 W drive. That means we want forcing to be(ideally) << 5 x 10^-3 N/m^2 to be sure a thrust observed is actually from the thruster. (If drag is large, then you will never be able to model it well enough to say that <thrust - drag> is actually meaningful.)Solar radiation pressure is 4.5 (absorption) to 9 (reflection) micro N / m^2, so radiation force will be < 10^-7 N, which is fine and can be ignored. (For LEO, the radiation pressure from the Earth is also substantial, and hard to model as it depends on cloud albedo, but it will be < solar and so also can be ignored). Drag at altitude depends heavily on the solar activity, and thus the solar cycle (which brought Skylab down). We are near peak right now, which is bad, but in 2 or 3 years or so things could be a lot better. See this prediction:http://en.wikipedia.org/wiki/Solar_cycle_24#/media/File:Solar_cycle_24_sunspot_number_progression_and_prediction.gifLooking at the old Harris-Preister model atmosphere (see Figure 2 of http://stk.com/downloads/support/productSupport/literature/pdfs/whitePapers/A%20Critical%20Assessment%20of%20Satellite%20Drag%20.pdf ) we would want the altitude to be > 300 km. At 400 km, Harris-Preister drag prediction is 3 x 10^-4 N/m^2, which might be OK, but is a little too close for comfort for me. That says to me that a CASIS launch of a test from Station would not be adequate, but a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials. (For various reasons, get-away specials basically never seem to be available for launches to GEO and higher.)Also note that a 600 km circular orbit is about as high as you can go with a reasonable expectation of a 25 year post mission lifetime for a cubesat, which is needed to meet IADC guidelines on limiting space debris :http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2011/8_Leveque_Orbital_Decay.pdfYou are absolutely correct - there are no other forces accounted for in that plot other than spacecraft thrust acceleration. As I mentioned in the above quote, I think you need to be clearly above the region where predicted drag deceleration is within an order of magnitude of your expected thrust acceleration. As time permits, I was going to try to do some calculations and include them as a "keep out zone" in that plot.I am actually NOT a big fan of a space test, especially CubeSat. I think the prospect of introducing error sources is much higher than in the lab. Drag is one, but for example most CubeSats do NOT have active attitude control - they just tumble. You have no ability, really to shield thruster electronics from spacecraft electronic and vice versa - you just don't have the space or mass available.Somewhere I saw that the AVERAGE CubeSat deployment altitude was 600 km, which is why I used it in that example, but the analysis was just to answer the question of what kind of altitude change you could expect as a function of predicted thruster performance. I still maintain that an early CubeSat test at this stage that returns a null results tells us nothing.
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Quote from: OttO on 06/10/2015 02:39 pmQuote from: SeeShells on 06/10/2015 02:03 pmNo, no toaster elements allowed.Allowing the device to move freely permits any unanticipated force to remain unmeasured and produce unpredictable accelerations.By placing one of my tests in water, any and all abnormalities can show up and I'm looking to address any of them. Things you'll not see on a bench strapped down to a air bearing or simply pushing on a force gauge or hanging in free air with a wire. Being submerged with the device water cooled I can reduce the issues with the thermal expansion coefficients of the case. See any unknown effects and log them, measuring in real time the EmDrive to move freely in XYZ & T. It's all about the data and getting data in 3D is better than in 2D.Shell
Quote from: SeeShells on 06/10/2015 02:03 pmNo, no toaster elements allowed.Allowing the device to move freely permits any unanticipated force to remain unmeasured and produce unpredictable accelerations.
By placing one of my tests in water, any and all abnormalities can show up and I'm looking to address any of them. Things you'll not see on a bench strapped down to a air bearing or simply pushing on a force gauge or hanging in free air with a wire. Being submerged with the device water cooled I can reduce the issues with the thermal expansion coefficients of the case. See any unknown effects and log them, measuring in real time the EmDrive to move freely in XYZ & T. It's all about the data and getting data in 3D is better than in 2D.Shell