It looked just like a helicopter, but was flying at jet speed and sounded like a jet, not a helicopter.  It was going so fast you couldn't tell if it had helicopter blades.  It had a big belly like a helicopter and a long skinny tail like a helicopter, but was just going faster than any helicopter I've ever seen and had that real loud jet noise.   I watched for approximately 45 seconds zoom by.  By the way, the sky was crystal clear blue in every direction and it was in the mid-morning.

Any ideas what that was?