I don't think you would have seen Goldorak unless you lived in France or Belgium - there's also an arabic version.

Goldorak was a redubbed version of Grendizer from Japan - it proved so popular in France that at one time it was the top rated show for its time slot (around 7 PM if memory serves).

There was a similar series of shows that appeared on US TV called Force 5 - this show featured smaller (edited) segments of Japanese dubbed TV cartoons for Mazinger Z, Gaiking, Grandizer, Danguard Ace, and Spaceketeers. Danguard Ace had two doors on his chest and could shoot a huge missile - this sounds like the robo that you remember. He had red wings on his back and could fly.

-- Best, John