Multiple ,Three color, Triangular objects at high altitude and high speed I have seen twice 30 yrs apart.

Back when I was a kid around 10PM ,august, 1975 I saw a dozen or more objects I could not identify that were flitting around the sky at extreme altitude. They were  elongated, triangular and three dimensional. They were utterly silent. The objects did not seem to have any orientation bias in their flight. They tumbled or flew in  any direction  as they tumbled on all axis’s. They seemed to have mass and were subject to momentum because turns appeared to be rounded  arcs instead of right angles. Starts and stops were linier and fluid. I had no way to judge scale but speeds were fast. Perhaps 5000 mph and I assume since there was no sonic booms, they were out of atmosphere.  They gave me the impression of water bugs  skating on the surface tension of water. They all shared the same colors of red, yellow and green and appeared as though they were backlit in some way. They flew back and forth in a small part of the sky  appearing to be separated into two groups and flying through each other’s positions almost like dog fighting but without any fire. Looked like they were playing.  The sighting lasted for about an hour. I never really thought much about it over the years but about 2 years ago, I saw one of the same craft spinning across the sky. Same altitude, same colors. This time it came over one horizon and disappeared over the other in a straight line. It was very fast and very high. I can’t seem to get it out of my head. I keep thinking about it every day and I am getting mildly obsessive about it .
Witness indicates that the date of the incident is approximate.  PD