It's an aeroplane! It's a submarine!
It's a floor wax! It's a dessert topping! There's nothing
that spells progress in large, friendly letters like trying to combine
two totally incompatible technologies.
Submarines are supposed to be thick hulled to keep
out pressure and aeroplanes are supposed to be thin hulled to make
them light enough to fly, so let's make one machine that splits the
difference and does the job of both-- badly.
It's the greatest idea since the armour-plated