Originally Posted by perttime

The Walrus is a great guess, but I have something a little different in mind.

What aircraft?

1) it was at the cutting edge of technology when introduced - but didn't stay there long.
2) it was used by 7 nations
3) the chief design engineer used to make part of his living performing at a circus
4) the design was derived from a 3 seat amphibian airplane
5) same lineage can be seen in a more famous fighter design that the company produced - later, after changing company name.

6) a few of these were used for racing, and with some success too.