You know what would probably work?
So the TF-X and other VTOL designs do seem quite unrealistic. And the Transition as it stands isn't really a flying car as such, though it is a car which can fly, if you happen to be a pilot and there's an airstrip handy.
But there is a realistic way forward even so. Quiet, affordable VTOL without destructive downwash is probably just a dream: but a quiet short-takeoff winged craft might not be. Highly reliable robotic takeoff, landing, cruise flight and traffic control certainly isn't a dream - the problems are actually easier than robotic ground cars, and they have pretty much been solved already.
Once you had a working Transition, you would surely not bother trying for VTOL. The next step would surely be to improve it's STOL performance - perhaps using electric hybridisation, if this genuinely seemed to help - and add a robot autopilot (major parts of which are already on offer).
Such a machine could set down or depart making no more noise than a lorry from the sort of small strip you could fit into a supermarket car park, or tack onto an existing road or street with no more difficulty than adding a layby. Such mini-strips could be scattered across a city, and associated multiply redundant automated traffic-control infrastructure added, for tiny fractions of what it costs to build a new railway line or freeway through such terrain. Out in the suburbs or the countryside the cost would be even less.
You might let fully-licenced pilots fly on manual control, but probably not above urban areas (indeed private pilots are already mostly barred above big cities today). The robots would do a much better and safer job.
And there you'd have it: access to the third dimension for relatively ordinary people. Needless to say there would be a few aircars suffering mechanical failures every once in a while and descending on parachutes (the Transition is so equipped already). The occupants would be fine, as these aren't normal light aircraft: they have much better crash protection. There'd be some damage to buildings, or perhaps even unlucky bystanders, on some occasions, which would lead the usual witless Luddites to call for a ban - but they would not be listened to by sensible folk, any more than sensible folk would countenance a ban on trucks or buses just because they (frequently) smash into buildings or run people over.
It would also be possible to make the broken-down aircars come down in safe places most of the time: robot-guided parachutes capable of quite accurate into-wind landings are already available.
NASA once had a plan to push this more realistic kind of flying car, which it referred to as a Personal Air Vehicle (PAV). The agency had intended to build an affordable (car engined) light STOL aircraft, which would be very quiet as it was propelled by a ducted tail fan rather than a normal propellor (a bit like the TF-X). Sadly that project was axed in 2005.
But, in your correspondent's opinion if nobody else's, that seems a more realistic route than VTOL for flying car enthusiasts once roadability is achieved. Terrafugia might like to consider that as and when it gets the basic Transition working, and leave the electric-tiltrotor idea for the stage after that. ®
Lewis Page holds a UK private pilot's licence, though changes in his disposable income in recent years have meant he's no longer current.
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