Thanks for sharing this! It's something I've been confused by the absence of, for years. This seems exceedingly worthy. It will be very interesting to see them make progress with the fuel and distance limitations. I hope they are more than successful.
Well, perhaps, though running several jet turbines... aside from the amazingly loud noise, that seems a lot of maintenance and fuel? EZ-fly's 5 engines, 280 lb payload, and 12 minutes duration, suggests something vaguely like JetCat P400-PRO 89 lb thrust engines. So say $3/min fuel. Running near max, so maybe low/mid-order 100hrs for minor/major teardowns? A $10k engine. So about the same cost/min for maintenance? Swap out an engine each shift. So several hundred dollars per hour operating cost? So like a light helicopter? But louder.
I confess, I'm waiting for an Xjet/WASP III. Can't help it. I do agree that there is room for improvement, notably with efficiency. Do you have any estimate of the decibel level of the WASP?
Any estimate? Well... WASP was apparently a turbofan, and thus likely quieter than these small turbines - less high-frequency noise from shear. Quick googling turns up [1], which has a CJR900 small airliner as 78 SEL dBA @ 400 ft @ low 1k lb taxi thrust. So perhaps take that as a low bound. And [2] suggests an upper bound of 120 db at 9 ft for one of those small turbines. So...?
I was going to say "No idea, sorry", but when encouraging estimation and rough quantitative reasoning, I argue that one should never say "no idea", because its almost always untrue - one can almost always get some bounds. And surprisingly often, they are satisficingly narrow. Though perhaps not these.
One notable thought from [2] was the high-frequency noise attenuates rapidly with distance.
[1] https://www.youtube.com/watch?v=3UbOG0ERCwM [2] https://www.youtube.com/watch?v=ExAY2kYvkpQ [3] https://www.youtube.com/watch?v=Qjvm5kO6ILA