Well done Nick. Just some thoughts, your jet being somewhat "symmetrical", it would be interesting to see how the intake/snorkel would work from the other end. Probably it would not be as good but something similar might run, having a mirror image look if cut in half in the middle.
I can relate to your first video, that's all I have ever done with propane, pop, pop, bang, bang. And my neighbor gently reminds me of how loud it is. Glad to see you back and your recent success and enjoyable movies.
Foa comes to mind, he said something about two engines, one having good aspiration, the other good mixing or something, my memory is off. I think there is a sketch of two engines in his book illustrating a kind of trade-off. Does anyone remember that reference in Foa's, "Elements of Flight Propulsion." ?
Presentation is Everything