The book describes them as long and thin. These concepts are all before the movie came out, and I was surprised by the solar powered "wings" the craft had that resembled plucked dragon fly wings glued to these enormous ships. In the book they are mysteriously, if conveniently, powered by "the Ninth Ray"which seemed to be the levitational power in these tanks with propellers providing forward thrust.
Very cool! It looks like a cross between the speeder bikes of Return of the Jedi and the ornithopters of Frank Herbert's Dune. I always wondered what the one-seaters would look like according to artists who love Edgar Rice Burroughs. Oh, and I have an artbook by Joe Jusko that features his work on Edgar Rice Burroughs and his myriad books. It's old, and it was hard to find, but it was worth it!