Povel,You and Monomorphic are not using the word "Thrust" in the same sense. You are arguing the thrust is in the direction of movement. Monomorphic's diagram is indicating the thrust is out the back and its movement is in the opposite direction.
I'd argue it is actually opposite. Using the notation of the scheme device you posted, the displacement you highlighted is in the positive x verse, while the thrust expected is in the negative x verse.
You and Monomorphic are not using the word "Thrust" in the same sense. You are arguing the thrust is in the direction of movement. Monomorphic's diagram is indicating the thrust is out the back and its movement is in the opposite direction.
Sorry, I think you are right and I have my labels for PZT and rubber backwards. This image is probably more accurate than the first.
Quote from: Povel on 12/02/2017 06:43 pmI'd argue it is actually opposite. Using the notation of the scheme device you posted, the displacement you highlighted is in the positive x verse, while the thrust expected is in the negative x verse.Sorry, I think you are right and I have my labels for PZT and rubber backwards. This image is probably more accurate than the first.
I don't think you had rubber and PZT backwards. Your other diagram was correct. The rubber is a thin sheet, between the brass mass and the mounting bracket. The aluminum on the left is the mounting bracket, not the end cap. The aluminum on the right is the end cap, and the Thrust is toward that side.
Povel,In the latest experiments and per Dr. Rodal's exact solution, the thrust is toward the aluminium end cap at the light-mass end of the stack.
As the first fundamental frequency due to piezoelectricity is approached from lower or higher frequencies thatare more than the (dimensionless) damping ratio (the ratio of the actual damping to the critical value ofdamping) away from the resonant frequency peak, the Mach effect force response is directed towards thetail (brass) big mass, in agreement with the experiments of Woodward and Fearn. Inside a bandwidthenveloped by the damping ratio, the Mach effect force response changes direction and is instead directed inthe opposite direction, towards the front (aluminum) small mass, reaching a peak value at the piezoelectricnatural frequency that is seven times greater than the peak value reached in the direction towards the tailmass
So correct me if I'm wrong, but to mimic a (presumably on average zero) thrust signal this simulation shows that you basically need a quite thick rubber pad with very low damping.
In the latest experiments and per Dr. Rodal's exact solution, the thrust is toward the aluminium end cap at the light-mass end of the stack.
Quote from: WarpTech on 12/02/2017 07:36 pmIn the latest experiments and per Dr. Rodal's exact solution, the thrust is toward the aluminium end cap at the light-mass end of the stack.The thrust is dependent on the phase relationship of the mechanical vibrations and imposed voltages. By moving them through 180 degrees, it can be nullified and reversed. Of course none of it means anything until tested in a vacuum, and with the other tests in Woodward's protocol......Also many orders of magnitude more difficult to detect any signal produced by 250Hz, the effect is frequency dependent.
Quote from: tdperk on 12/03/2017 12:27 pmQuote from: WarpTech on 12/02/2017 07:36 pmIn the latest experiments and per Dr. Rodal's exact solution, the thrust is toward the aluminium end cap at the light-mass end of the stack.The thrust is dependent on the phase relationship of the mechanical vibrations and imposed voltages. By moving them through 180 degrees, it can be nullified and reversed. Of course none of it means anything until tested in a vacuum, and with the other tests in Woodward's protocol......Also many orders of magnitude more difficult to detect any signal produced by 250Hz, the effect is frequency dependent.So as I have said, the best way for a skeptic to test Woodward's experiments might be to grab their devices, seal them in a box, and hang the box on the torsion balance. Otherwise what ever the skeptic could have done, people would point out their differences from Woodward's experiments and do not take them seriously.
You realize not operating the devices on something like a torsion balance while in a vacuum does fail to exclude confounding false positives or negatives from reaction with the air, right?
Quote from: PotomacNeuron on 12/04/2017 03:02 pmQuote from: tdperk on 12/03/2017 12:27 pmQuote from: WarpTech on 12/02/2017 07:36 pmIn the latest experiments and per Dr. Rodal's exact solution, the thrust is toward the aluminium end cap at the light-mass end of the stack.The thrust is dependent on the phase relationship of the mechanical vibrations and imposed voltages. By moving them through 180 degrees, it can be nullified and reversed. Of course none of it means anything until tested in a vacuum, and with the other tests in Woodward's protocol......Also many orders of magnitude more difficult to detect any signal produced by 250Hz, the effect is frequency dependent.So as I have said, the best way for a skeptic to test Woodward's experiments might be to grab their devices, seal them in a box, and hang the box on the torsion balance. Otherwise what ever the skeptic could have done, people would point out their differences from Woodward's experiments and do not take them seriously.You realize not operating the devices on something like a torsion balance while in a vacuum does fail to exclude confounding false positives or negatives from reaction with the air, right?
Quote from: tdperk on 12/04/2017 05:58 pmQuote from: PotomacNeuron on 12/04/2017 03:02 pmQuote from: tdperk on 12/03/2017 12:27 pmQuote from: WarpTech on 12/02/2017 07:36 pmIn the latest experiments and per Dr. Rodal's exact solution, the thrust is toward the aluminium end cap at the light-mass end of the stack.The thrust is dependent on the phase relationship of the mechanical vibrations and imposed voltages. By moving them through 180 degrees, it can be nullified and reversed. Of course none of it means anything until tested in a vacuum, and with the other tests in Woodward's protocol......Also many orders of magnitude more difficult to detect any signal produced by 250Hz, the effect is frequency dependent.So as I have said, the best way for a skeptic to test Woodward's experiments might be to grab their devices, seal them in a box, and hang the box on the torsion balance. Otherwise what ever the skeptic could have done, people would point out their differences from Woodward's experiments and do not take them seriously.You realize not operating the devices on something like a torsion balance while in a vacuum does fail to exclude confounding false positives or negatives from reaction with the air, right?Air might be a confounding factor if there is movement/"thrust". However, it is not a confounding factor if there is no movement. So no, for my proposed experiment, it is not. That is the beauty of the experiment. Now the question is whether "they" are willing to lend their devices out.
Uhuh. Why can't you build you own per their specs? Like the other people replicating their work did? For that matter, what is the difference between operating the device in an evacuated box on a torsion balance, and putting the whole thing in the vacuum?
Quote from: tdperk on 12/05/2017 12:18 amUhuh. Why can't you build you own per their specs? Like the other people replicating their work did? For that matter, what is the difference between operating the device in an evacuated box on a torsion balance, and putting the whole thing in the vacuum?Because I expect to see no thrust if I correctly control for the Bull's effect. Then you will say that's because my build is different and it can not be used to invalidate Woodward's experiment. That's why.
Quote from: PotomacNeuron on 12/05/2017 02:15 amQuote from: tdperk on 12/05/2017 12:18 amUhuh. Why can't you build you own per their specs? Like the other people replicating their work did? For that matter, what is the difference between operating the device in an evacuated box on a torsion balance, and putting the whole thing in the vacuum?Because I expect to see no thrust if I correctly control for the Bull's effect. Then you will say that's because my build is different and it can not be used to invalidate Woodward's experiment. That's why.That critique is only valid if your build deviate from the specs. If it doesnt then the critique is invalid. As a supporter of the work without the resources to do such a test myself I would love to see someone else do the test if they have the ability and resources. As long as they are going to be open about their build and willing to answer questions. I think if you did do a perfect build and got negative results I would want to know if the PZT stack is good.
Agree. I was talking about if it were me how I would do it. I will not do the experiment for reasons presented on page 55. I'd like to see somebody to do the experiment. Monomorphic's experiment, however, as expected, drew critiques of being different.
Quote from: PotomacNeuron on 12/05/2017 03:26 amAgree. I was talking about if it were me how I would do it. I will not do the experiment for reasons presented on page 55. I'd like to see somebody to do the experiment. Monomorphic's experiment, however, as expected, drew critiques of being different.My prediction is Woodward's MET wouldn't work as well on my torsional pendulum due to the mechanical differences between the two systems. Mine is much longer to accommodate a laser displacement sensor (LDS) with 3um resolution vs Woodward's 0.25um. A shorter stroke, as what is produced by the PZT, would be harder for me to detect. It may even fall below the resolution of my laser displacement sensors. The most economical way for me to proceed is to complete this last series of physical tests with the asymmetric shaker, but then concentrate on producing a more accurate physics-based simulation. If the same effect can be produced with simple known physics via simulation, then there shouldn't be the need for anything else.
Was this done in a vaccum chamber?
I would be willing to wager that Woodward's device "works" in air due to the large mass of the brass end-cap, but a vacuum is used so that the experiment is taken to be more rigorous.