Serious question, would nuclear powered planes be viable? As far as energy density goes it seems pretty hard to beat!
They also experimented with nuclear powered drones. https://www.popularmechanics.com/military/research/a33565112...
And Russia now claims to have a nuclear engine that can make a cruise missile fly for days. https://en.wikipedia.org/wiki/9M730_Burevestnik
edit: Sigh.. disregard, cf. https://web.archive.org/web/20080109011832/http://www.nuclea...