There's a good article in Flight Global today about the rise of "optionally-piloted vehicles" (OPVs), which are plane that can fly either with or without a pilot, such as the L-3 Mobius shown above. Why would anyone want that? A few reasons:
--You can fly them in domestic airspace, where there is not currently a workable approval process for commercial UAVs
--You can use a pilot to fly them over civilian areas to get to a military theater, without having to transport them in another vehicle, as is currently the case for for all military UAVs.
--Much better field of vision with a pilot onboard, when that is required
From the article:
There are at least 26 models of OPV flying today, most of which are still in testing, and many of which are technology demonstrators or testbeds.
OPVs fill a niche role; they must be large enough to haul a pilot and a useful payload while piloted, but provide the endurance expected of a similarly-sized UAV when unmanned. Most similar UAVs are medium-altitude long-endurance (MALE) models - and so too are the OPVs.
I've seen Blackbird helicopters converted to OPVs, and indeed these seems to the way they're all going. From the article:
The US army is planning to convert almost all of its massive helicopter fleet to OPV control schemes. "Over the next 25 years, the [US] Army aviation shifts from being almost entirely manned to consisting of mostly unmanned and OPV," states the army's aviation planning document - the so-called roadmap.