And, once again, it's time for another clue since there were no guesses:
Everyone is familiar with the V-12 powered aircraft of WWII but what was the first V-12 powered aircraft to see combat and who built it's engine?
1) It was an unsolicited product designed as an upgrade to a proven combat aircraft
2) It was used by several nations for over a decade after the end of hostilities(this was yesterday's clue)
3) It was used as a multi-role aircraft
4) It was a two seater with an innovative design feature
5) It was a two-bay biplane