The Sprain Motor, in the context of the so-called "Magnetic Wankel" brings up a salient point which was never adequately addressed during the previous episode of Takahishi a decade ago.
That is the potential advantage of using modern electronics to provide what (for lack of a better term) can be called the 'selective application of torque'. This is a subset of a putative 'low-duty anomaly' which is arguably present in a number of physical systems, for which there is also no real proof - but some tantalizing hints. And when one is operating on-the-fringe, and following the jagged cutting-edge, then one often pays some attention to tantalizing hints - as unproven as they may be. The logic (or at least the nice-sounding argument) is this. IF an electric pulse can be translated into torque at high efficiency (say 95%+) then - when you compare two situations: 1) the uniform application of torque over a complete revolution of an axle through a 360 degree cycle - compared with: 2) the uneven and pulsed application of much more torque to only a few degrees of rotation, with the assumption that in both cases the net energy expended is equal... Then, in situation #2, compared with situation #1 - and all else being equal - there 'could be' a net advantage (due to a combination of factors including leverage, momentum, the Aspden effect, better utilization of back EMf, etc.) I will agree that none of these, standing alone, makes much sense (other than the Aspden effect, which might involve the "circular polarization" of some kind of 'aether friction' but that is not a terribly robust effect, even if it is valid.) There are also some possible hints of anomalous energy phenomena in low-duty cycles of electrical discharge which may involve higher effective voltage from the same net energy. The assumption being that uniform discharges can inhibit the high end of a Maxwellian distribution. We often think of this kind of selective torque being most evident in the the child's swing - where the energy expended to keep moving ever higher is most valuable only in a very short segment of each cycle. For another more relevant example - let's consider the situation of a bicyclist who wants to get the most possible boost out of lightweight battery which he/she is using for auxiliary power. In that case, pulsing the same amount of net energy over only the few degrees of the cranking cycle, when the cyclist can also best use his own physical exertion for leverage (at about 3 O'clock and 9 O'clock of the cranking cycle) ... this selective application of torque also makes some sense, compared to a constant input. Both the bicyclist and the child are using leverage, of course, and we normally do not think of that as being applicable to a constant rotation situation- but in the case of the cyclist - we can see how it can possibly be an advantage. Also in the sense of the Aspden-effect being non-linear, such that a very short boost over a very small slice of that 360 degrees, makes even more sense if the curve of non-linearity is very steep at the start... well, you can see where this is going. "Selective torque" would not favor the Sprain implementation (any more than the previous Takahishi version) - on the surface at least. Terry mentioned some advantage to attraction vs. repulsion, but I have heard the opposite argument as well. The great difference now, over the situation a decade ago, is the advances which have been made in fast electronics - which can now (conceivably) make any slight effect more interesting. Lets say that the Takahishi motor used a pulse over 5% of the cycle (or 18 degrees). Lets say Sprain has advanced this so that now he can apply the same power to just 6 degrees of the cycle. This is interesting in an anecdotal sense in that in two cases which I have been involved in, there is evidence that the putative "low-duty" advantage kicks in at 5% and is maximized at around 2%. Admittedly, this is anecdotal and the evidence is light - but still, I find this fascinating - especially in the context to the Aspen effect (the magnetic and the non-magnetic versions of that effect). At any rate, there are some ways to maximize this selective torque effect in the both Aspden and the fully leveraged contexts - which are being neglected by Sprain, and were missed by Takahishi as well. Perhaps that is where he is going with the next generation. Jones
