After reading the Technische Universität Dresden (TUD) report and realizing that the on/off power cycle for the California State University, Fullerton (CSUF) thrust devices (MEGA) were not responding according to predictions (Blog 5), I decided to look for switching transients on my DIY Mach Effect Device (DMED). I should also mention that the MEGA on/off power cycles were behaving according to predictions at CSUF as reported in the NASA document. Dr. Woodward stated,“This follows immediately from the dP/dt term in the mass fluctuation equation (Equation 8).” After shifting 90 degrees TUD reported switching transient thrust in the orthogonal direction which does not agree with CSFU results. Just as a reminder, that failed test at TUD appears to have passed with DMED since my stack always swings in a fashion representing unidirectional force and nothing appears in the orthogonal direction. But there is much more to this switching transient story. Is it possible that I’m only seeing on/off drive forces and seeing nothing during the steady state drive portion? I don’t have a torsion balance machine to measure forces directly during the drive cycle. So, I have to determine thrust forces indirectly by measuring the resulting motion on my hanging stack. This next test will vary the drive pulse duration to see how that effects the stack motion.

To determine how much thrust was applied to the stack, I measured the range of motion under varying drive durations. A large “power on” impulse would be more obvious for short drive times unless the “power off” sequence erased the effect because it would be opposite in polarity. That positive “power on”, negative “power off” effect was evident in CSUF and TUD data. The first plot, Figure 13, shows the effect of increasing the drive length from 25 to 100 ms in 25 ms steps. The resulting negative motion at 1.9 s increases normally. (As always in my data, drive is toward the large mass.) The motion at different drive durations appears also to be approximately linear with no constant offset. (within +/- 1 sigma). Therefore, there was no large impulse. This same result would also be evident if the “turn off” sequence erased the “turn on” sequence. In order to eliminate that possibility I looked at longer drive cycles that ended before and after the hanging stack starts back to zero, sometimes called the “turnaround “ point.

Figure 13. Four DMED tests at 616 kHz showing the ten point average response, varying the drive durations from 25 to 100 ms. Error bars represent +/- sigma for two of the larger variances. All drives start at 1.7 s. The stack has negative polarity on the large mass end, which is facing north and measured on the north end with laser pointing west.

In the next two tests shown in Figure 14, the “power off” points bracket the turnaround point which is ~470 ms after “power on”. The before turnaround “power off” test is at 430 ms and the after turnaround “power off” test is at 530 ms. If there is a significant “power off” thrust and it is opposite to the “power on” thrust, it would provide opposing movement force before turnaround and aid movement force after turnaround. In that case there would be a large difference in the positive extent of the stack on the before and after tests. An can be seen around 2.4 s, there is very little difference in the before and after turnaround tests; therefore, there is little or no “power off” impulse. The last point to nail this issue is the fact that the stack response increased so dramatically from Figure 13 to Figure 14 by simply increasing the drive time regardless of any supposed switching transient.

Figure 14. Two DMED test at 616 kHz showing the 50 point average response while powering down before and after the normal turnaround point. This illustrates no “power off” impulse. The sigmas are around 2 mV. The stack has negative polarity on the large mass end, which is facing north and measured on the north end with laser pointing west.

So, there is no measurable switching transient in DMED, but why not, if CSUF always measures this force. CSUF has a much lower drive frequency (35 kHz) than DMED (616 kHz) and I’m fairly sure their power on/off sequence is much faster than my device produces. That could generate a significant change in power (dP/dt in Dr. Woodward’s equation). I was unable to find a good way to switch the signal generator so I merely switch the amplifier power on/off with a solid state relay. This is a fairly slow process compared to my 616 kHz frequency transitions; therefore, there should be very little change in power .

DMED continues to agree with the Mach Effect equations and I will continue to look for ways that disagree. So far my tests agree but I haven’t tried everything. Later I’ll show that the force is toward the small mass when the device can operate close to the PzC resonance. As before  let me know other error modes, questions or suggestions that come to mind. Until next time, thanks for viewing. – Larry