Others saw the planes flying low here today. Here's more:

Jack LaGue

Richard Gagne said that he had seen them before and checked them out and it was the Connecticut Air Guard doing exercises flying below the radar.  He had read that their deck for the exercises is 300ft.

I was interested in what these things are actually classed as - a plane or a helicopter. I looked it up and here's what I found:
 The V-22 Osprey is a joint service multirole combat aircraft utilizing tiltrotor technology to combine the vertical performance of a helicopter with the speed and range of a fixed-wing aircraft. With its rotors in vertical position, it can take off, land and hover like a helicopter.

Maybe it should be called a heliplane.