In regard to centrifugal fans for creating thrust - www.entecho.com.au --turn this 90 degrees and Voila! ( the designer was principal engineer with the Orbital engine company which was a 'non revolutionary' engine from the early 70s (it didn't revolve but 'orbitted' -irrotational circular motion of the rotor ) that didn't pan out but led to superior fuel injection technology for two stroke and other engines . I proposed and did a preliminary design report for the Orbital firm in 1981 for an "orbital" aircraft (project Boomerang, --send it off to the East and it returns from the West.... --a flight right around Earth in one go ergo orbit, and submitted the design and drawings via the bloke who had involved the Broken Hill corporation (BHP-Australia's biggest company) with the engine inventor and whom I knew through gliding. I met Kim Schlunke at the 2009 Avalon airshow where their VTOL using the centrifugal fan was doing demo flights IN the booth (and looking just like a jellyfish or one of those 'flying jellyfish' from Avatar --bumping into people and the walls harmlessly --almost see through semi transparent and quiet.) My orbital proposal was considered either 'impossible' or something but of course the Voyager went on to show that it was doable (with almost identical parameters --my design three view was published in a model aircraft magazine and at least referred to in print in 1982 so can be verified pre Voyager ) SCALED built the GM Ultralight concept car to showcase the Orbital engine --it occasionally turns up in futuristic SCI FI films as a prop .