Carter proposed the C-130-based Heliplane for the US Army's Joint Heavy Lift concept design study, but did not get a contract. Since then it has shifted its attention to more modest designs - the two- and four-seat "personal air vehicles" seen below.
But a check of the website - http://www.cartercopters.com/ - shows that its ambition to build a bigger aircraft is not dead. There is a new "CH-150 Heliplane" image, attributed to a Czech artist Milan Soukup, who is described as a "fan". Looks substantially different, but still looks like wishful thinking.
There are also several engineering images here:
http://www.cartercopters.com/heliplane_iso.html
DARPA, meanwhile, has a programme called Heliplane under which Groen Brothers is developing a high-speed gyroplane demonstrator...