Silvery, football-shaped object rotates then accelerates upward until out of sight.

It was early summer in 1966, mid-afternoon. Clear, cloudless sky. I was installing a television antenna on a rooftop in Odessa, Texas. While looking upward to align the antenna, I saw a motionless silvery-metallic, football shaped object in the sky, straight above. It was smooth and shiny without any surface features that I could see. However, the metallic nature of the surface was very apparent against the blue sky with sunlight reflecting off of it.. As I watched, it began to turn slowly end-over-end, accelerated vertically at a great speed, and then disappeared. The entire duration of the event was approximately 10 seconds. It was not possible to guage the size or the altitude of the object, since I had nothing to reference it to. My subjective impression is that it was about the size of an automobile, a couple thousand feet up. From the time I first noticed it, the object stayed motionless for about 5 seconds. It then rotated in a "wobbly" end-over-end manner  3 or 4 times and began to accelerate upward very fast. The total time from when it began to accelerate until was out of sight was less than a couple of seconds.
Date is approximate.  PD