Large, black, "boomerang" shaped object gliding silently overhead.

My financee and 2 friends were at a local drive-in theater. We were all college students at the time. I happened to look up outside the car window and noticed a huge black "boomerang" shaped object slowly gliding across the sky. It was directly overhead. It had several lights spaced out along its leading edge. There was no sound from the object at all. I would estimate that it's height above ground was about 1000 feet. I excitedly pointed out this observance to my friends in the car and they also saw it. It was headed in a general direction from west to east. The drive-in was located about 7-8 miles east of the Albany International Airport, about 2 miles south of the U.S. Army's Watervliet Arsenal, and 1 mile north of Albany. 
This incident happened 35 years ago so the exact date is not known. I know however that it was in the fall of 1971.
Witness indicates that the date of the event is approximate.  PD