Month: September 2021

I just reviewed an interesting paper from the exceptional laboratory at the Institute of Aerospace Engineering, Technische Universität Dresden (TUD), where the authors completed a thorough analysis of the Woodward’s MEGA Drive and reported negative results. I am grateful one of the authors, Prof. Dr. Martin Tajmar, forwarded a copy via ResearchGate. (FYI ResearchGate is a great way to add cred to your “citizen scientist” status.) Aside from a large switching transient, the only tiny force they observed (~0.4 uN) with a very sensitive torsion balance using the MEGA Drive in a vacuum chamber was clearly not due to the Mach Effect. Moreover, neither the small steady state nor the switching transient force changed when the MEGA stack was rotated 90 degrees. Quoting from the paper, ” Hence, the effects observed by Woodward using the MEGA drive on a torsion balance can be explained by thermal and vibrational artefacts using Newtonian mechanics.”

On the positive results side, I keep testing my DIY Mach Effect device (DMED) every way I can imagine and continue to get consistent results although not always agreeing with the Woodward equations. I get good agreement using different drive voltages, large/small mass ratios, orientations, directions, polarity and changing devices but I don’t think frequency responds as predicted. DMED works best near the anti-resonant frequency and not much otherwise. I’ve independently measured the stack action at different frequencies and that’s where the action is located so it should be most effective at anti-resonance. I’ll do some runs at different frequencies later and report them, but for now, I want to show a recent result correcting the cross talk problem mentioned in my third blog.

I’m calling this one Build 3.1 since I added a MCP6001 buffer to the Channel 1 signal to the PicoLab and switched back to the Forward Power for channel 2. The higher drive voltage used before on Channel 2 was causing most of the cross talk and the buffer matches the PicoLab input impedance which has helped reduce noise sigma. This test again uses a stack with large mass having negative polarity as in Figure 10 (Blog 4) except now the internal polarity of the piezoelectric chip (PzC) is reversed by simply gluing the large mass onto the other face of the PzC. I have been assured by ThorLabs that all PA2JEW chips are laid up and marked identically so it is easy to identify the left face from the right face. Figure 12 shows the results for this example, measuring on the east end with laser pointing north. Response, in blue, is the average of 50 runs and the drive power (~2 watts) is in red. With Build 3.1 and this ~ 2.0 g stack the 16 mV response, I’m guessing, represents about 1.5 uN and notice that the sigmas are better. Later I’ll show that the force is toward the small mass when the device can operate close to the PzC resonance.

The negative result from TUD don’t necessarily condemn the Mach Effect or the MEGA Device. The MEGA Stack is assembled by hand, it contains piezoelectric material that can degrade, the torsion balance has it own issues and measuring uNs is always difficult. My positive results are also not conclusive but they continue to suggest that the Mach Effect is actually driving the stack or there is some other unknown something causing the stack to swing in a Mach Effect fashion. As before  let me know other error modes or suggestions that come to mind. Until next time, thanks for viewing. – Larry

Testing for false positives on my DIY Mach Effect device (DMED) is important because it is possible there is some other phenomenon causing this apparent Mach Effect force. By reversing all the configuration constraints it will become obvious because the force will switch with the problem should it exist. The plots in the previous blog used a stack with the large mass having positive polarity. To eliminate polarity and direction, I switched to a stack with negative polarity on the large mass end and rotated the stack 180 degrees. (Later I’ll show the result of doing only the rotation.)

Figure 10 shows the results for this example, still measuring on the west end with laser pointing north. Response, in blue, is the average of 50 runs and the drive voltage is in red. As before, when first energized, the response drops, this time to -40 mV. This is not thrust, it is mainly caused by crosstalk in the PicoScope which is now corrected.(This effect is confirmed in Figure 11). When the PzC expands the stack center of mass shifts very slightly toward the PzC causing the stack to rebalance very slightly toward the large mass end. Since I’m now measuring on the large mass end, that causes the photo detector output to drop very slightly. That effect is true but the major portion of the change was due the crosstalk. The opposite happens when the power is turned off and the PzC collapses to its original dimension. The crosstalk does not minimize what happened between those two events when the stack is vibrating at 616 kHz. The response went down from -40mV to -58 mV between 1.4 s and 2.0 s. That -18 mV toward the large mass is real thrust because the stack immediately begins oscillating. The thrust is less than in Figure 8 and the sigma’s are larger. There is considerable variation from one test to next and each stack has a different response curve; however, the forces always remain consistent regardless of the change. One of my goals for the future is to reduce this variation.

In order to confirm that the PzC expansion does not cause thrust, the previous test was run again with the signal generator de-energized. Figure 11 is the averaged result of 50 runs showing the -40 mV change for the duration of the drive with DC voltage only. After the drive de-energizes the stack is barely moving for the remaining ~4.0 seconds. The oscillation is now less than 1.0 mV p-p and when compared with the 27 mV p-p oscillation of Figure 10, the crosstalk problem, the PzC expansion and collapse is not causing significant thrust (With the crosstalk corrected these tests will be rerun later.) Later I’ll show that the force is toward the small mass when the device can operate close to the PzC resonance.

This continues to suggesting that the Mach Effect is actually driving the stack or there is some other unknown something causing the stack to swing so consistently. As before  let me know other error modes or suggestions that come to mind. Until next time, thanks for viewing. – Larry

The reversible stack worked very well however, the power and support wires were effected by the heat generated in the piezoelectric chip (PzC). I was powering the stack for 5 s and heat would travel from the PzC to the first brass mass, then to the nickel bronze guitar string attached to that mass. The same would happen to the second brass mass later. The first string would expand faster than the second string causing a bias that would look like thrust toward the large mass. Even worse, when the stack was reversed everything would reverse and still the thrust appeared toward the large mass. The big clue was that the thrust did not release immediately when the power was cut, but slowly diminished. The problem was easy to verify. I just pinched the first string with wire cutters pliers just above the stack. Rerunning the test showed none of the original thrust. Having power and support with the same wires was a great idea that didn’t work. Their still appeared to be thrust so I went next to Build 3.0 (See Figure 7)

I wanted to reduce the dampening the the stiff guitar strings caused so I switched to 4 lb test nylon fishing line. It’s really like thread but, also being nylon conducts heat very slowly. I also increased the string length to 25 cm to reduce the gravitational force on the stack. Now called the DIY Mach Effect Device (DMED), Figure 7 shows the other significant change which was attaching 30 awg stranded copper wires directly to the top of each support screw. I also separated the strands ~ 3 cm to allow the stack to vibrate freely while simultaneously providing power.

I started running data with a very short 0.5 s, 4 watt power cycle to reduce the PzC heating. I got great results as you can see in Figure 8. When first energized the response drops to -53 mV but this is not thrust. (That was confirmed later by turning off the signal generator and driving the stack with 13 VDC causing no stack oscillation.) When the power hits the PzC it immediately expands  ~0.3 um (according to Thorlabs). Since I’m measuring on the PzC end that slight expansion causes the photo detector output to drop slightly. That’s not what happened here as I later found. The lions portion was due to crosstalk in the PicoScope which is now corrected. I will redo those runs in a later blog. That problem does not minimize what happened during the period when the stack is vibrating at 616 kHz. The response went from up from -53 mV to -26 mV between 0.9 s and 1.25 s. That 27 mV toward the large mass is real thrust because the stack immediately begins oscillating. The period is easy to calculate in Figure 8 at ~.9 s.

With that result I decided to try multiple drive cycles at the natural stack period .9s. Figure 9 shows the result of 5 drive cycles where the stack is driven to 230 mV p-p. The obvious next step was to drive for 30 cycles and video the motion (The problem with the PicoScope is not a factor here since it’s not in the circuit). I placed an led in the frame so you can see when the stack is energized.  It weighs about 2 g and is moving about 1 mm p-p after 20 drive cycles which means it is responding to about 2 uN force on each drive cycle. If you look carefully you can see the thrust is always toward the large mass. If confirmed by Dr. Woodward and others, the Mach Effect will be a new force in physics or maybe a new gravitational force since they are using Einstein’s field equations.

In order to eliminate false positives, I tried different orientations of the stack: reversing, changing polarity, different compass directions and using a different stack. All caused thrust toward the large mass. Later I’ll show that the force is toward the small mass when the device can operate close to the PzC resonance. I also ran another video with just the PzC and no large mass to show there was no drive thrust.

This is all suggesting that the Mach Effect is actually driving the stack or there is some other unknown something causing the stack to swing so consistently. As before  let me know other error modes or suggestions that come to mind. Until next time, thanks for viewing. – Larry