A black, noiseless, lightless, fast, triangular shaped object flew over our heads in NJ in 83'/84'.

When I was a child, my friends and I were playing war around the block until dusk. Everyone left to go home except my friend from next door and myself. We were sitting on the sidewalk in between our homes talking when we both saw movement above our heads and looked up. The triangular shaped object, about 18-20' long seemed to be following the direction of the road (North) then it physically turned (not banked) left. I say it turned because at the speed it was traveling (about 60-70 MPH), it any plane would have needed to bank. It flew right above the tree tops (approx. 40-50 feet), made no sound (but a slight whoosh), had no lights, was completely black, didn't shake the trees, and had no flame from behind (like the flame from a jet). We sat there looking in the sky for about another hour hoping it would come back, completely dumbfounded. We thought it was strange that we would see such a thing in our neighborhood (very busy suburb of Philadelphia) and we were only 12 miles from the Philadelphia International Airport. I would have thought that the airport would have seen it on radar. I can't be sure of the date, but I know it was summer and we were 13, or 14 (either 1983 or 1984). The closest movie type space craft I could relateit to was a star fighter from Battlestar Galactica. It seemed to be a triangular shaped pyramid.
 The funny thing is, my brother-in-law saw the same thing on the same street approximately 10 years later. My sister told me he saw it and he said he would tell no one.
Date may be approximate, although the witness does not indicate that fact.  PD