OK, I've run the geometry through my acoustic models, too. First, I have to unfold the motor,
to analyze the open pipe properties, then consider the closed pipe contribution. I can then determine the (virtual point) combustion locus that gets a match for intake length and throat location. The open pipe combustion locus is bracketed by 22 and 25% of the unfolded length. Graham, I'm curious what your locus estimate is in Nudis; for your reference, converted to closed pipe percentages that would make sense to you, I estimate your zero crossing point as bracketed by 13 and 16% of the closed pipe. Is this close?
I have two models, and both are satisfied with the intake length and throat location within .1%.
Otherwise, as with M.'s model, I can make no sense of the tail. I'm still working on a more accurate model, so this is not conclusive, nor will it be as accurate as M's, nor do I yet consider volumetrics or areas. That being said, when M.'s model says it's good, so does mine, generally, and when his says it's schizophrenic, so does mine, for what that's worth
What this motor does have in common with my pocket jet is that intake and throat satisfy both of my models, but the pocket jet has no tail features to make sense of, being a straight pipe. Satisfying both of my models is a rare thing across the many motors I have geometry for.