What is "jumbos"

Usage examples of "jumbos".

A compressed gas bomb sloughed into the earth a thousand feet ahead, exploded, tilting the Jumbos of the third wave, toppling three onto their backs where they lay spinning tread like helpless turtles.

The Setessins had attacked the Romaghin home planet, landing with their Jumbos in the Hellfire Desert.

Seven Jumbos had been pulverized by direct hits, and one more had been crushed when caught between two blasts.