Hi, DCB! I don't have a running model at the moment, anymore, but yes, indeed, when I get a proto worthy of the name going ( one that produces significant power output), testing to failure will certainly be part of the protocol.
The present design is to run at around 2000 RPM at a pulsed torque value of 160 inch-lbs, which works out to something around 1.25HP given a 25% pulse duty cycle. Enough to run a reasonable lawn mower, I think.
I'll be clutching the engine to the blade with a magnetic clutch, and the drive shaft will be plain old 5/8" CR. I'm being frugal, as 5/8" SS is way expensive. The mag clutch is non-contact with the blade drive running inside a helical spring so if anything dead-stops the blade suddenly, it won't just automatically self-destruct the engine as has happened in the past. That's a Really Bad Thing to have happen. I was mowing a field with a Ford tractor running a 48" brush mower once, and ran into a (believe it or not) buried engine block that had somehow "floated up" in the clay/aggregate soil. Stopped the Ford cold and sheared a key in the mower, but fortunately did no major damage to anything but my temper, with me grousing about idiots who would bury something like that! Not as bad as running over a discarded roll of electric fence wire and having to untangle a half-mile or so, but bad enough!
Actually, a 1.25 HP motor is way enough to run a motorbike, but I need a mower more, and don't want to be designing bike drives until my grass is cut! LOL
So you know, the plan is to run against a dynamometer at about 50% output, fully instrumented so we can observe both low and high vibration frequencies and record same to the compy. As much time and effort as this critter has been, it'd be just plain stupid of me to not test absolutely everything to the limits of our instrumentation.
We are using good, precision, heavy-duty components, so we don't anticipate it will be easy to shut it down under normal loads. But things do have a way of proving Murphy. I guess we'll see!
Before I go, I want to ask you, particularly, whether you found the text description of "how it works" at all enlightening. I tried to write to make Michael happy, but I tend to be more verbally visual, according to him, and he didn't like it. However, from your earlier correspondence, I "got" that you would be able to decipher it. If you need anything at all clarified, please feel free to
write me directly and I'll do my best to cast light on whatever you need!
All the best, thanks for the great question!
God Bless and guide us all, and let's hope for a "petroleum-free" future!
Bill Whedon