The path to green flight is paved with money. In our transactional world, good ideas are sometimes rewarded with filthy lucre, even if those ideas are intended to clean up a besmirched world. Several examples of clean aviation attracting solid investments follow, along with some stumbling on unexpected obstacles. Jetson ONE For a flying machine lighter than most of its prospective pilots, the Jetson ONE has attracted a host of followers, including the host of a late-night chat show. Besides receiving 3,000 purchase requests in two months the firm has sold its initial production runs for 2022 and 2023. At $92,000 a unit, 100 craft in the first year would net $9.2 million, enough to finance the simple assembly and fabrication of the machines. A $22,000 deposit would discourage idle gawkers, although Internet views exceed 14 million. Keeping it simple allows reasonable progress to the next level. Opener Blackfly Opener claims over 36,000 flight hours in 5,000 operations for …