Well, the vandar isn't piloting the floater, but he might as well have been - it has conveniently slipped its moorings and drifted on the air currents to exactly the right place. Why didn't it just float off into the sky?, you may well be asking. Well, Mr Carter has a scientific explanation all ready for you.
Although totally weightless, the ship could not rise above a certain level unless propelled higher by its rotors. The mysterious urlium metal had a "negative" weight, and fell up - but the urlium was only a thin sheath over a strong frame of steel ribs, held together by en even heavier keel. The steel frame, then, had a "positive" weight, and pulled down at precisely the correct weight to balance the upward pull of the magic metal.
The floater still has the rope attached that Thongor had used to tie it down with, so he leaps from his saddle and climbs up to grab the controls; Ald Turmis follows him up. They begin to make their plans to rescue the princess, and laugh about what great heroes they are.
"you will soon become acustomed to hurtling through the sky like the hero Phondath astride his winged dragon in the myths," Thongor chuckled.
Ald Turmis grimaced. "I was thinking more along the likes of of the Nuld," he said, referring to the legended and mysterious Winged Men of Zand, beyond the Mountains of Mommur. "But your analogy is just as apt."
They eat some food, then fly over to Thurdis, where the city seems strangely empty. Ald Turmis spots the huge column of soldiers in the distance - well, actually, he just spotted some smoke, and it took Thongor's keen barbarian eyesight to see what was actually going on. He can even make out the designs on the banners, and so works out that his princess is among the soldiers!
But just then another crisis occurs. For some reason, the floater begins to move of its own accord, away from the army, and there is nothing Thongor can do to stop it. It's now hurtling southwest, away from any known civilisation! Failing to make it stop, Thongor decides to go to sleep instead.
His keen barbarian senses wake him up as soon as the floater starts to slow down, and he finds it descending towards a lost city, deep within the uncharted jungles of the Chush. The city is mostly in ruins, but he spots the odd glimmer of light from one or two windows.
Suddenly a mysterious force grabs him and throws him against the wall, pinning him there! There he remains, until pale zombie-like people climb up to the floater, tie him up, then take off his harness (?) which releases him from the mysterious force. Now, this is the first time we've heard about his harness, I think; last time we saw Thongor's clothing, he just had a loincloth and a cloak on, but now his harness is off and he's apparently completely naked (apart from his boots). It looks like this force is supposed to be some kind of super magnet, as the harness remains stuck to the steel bars of the wall, as does Thongor's sword - oh yes, and the chapter is called The Magnetic Ray. Thongor figures this out and grins, cos even though they've been captured, he now knows that it was a giant magnet that pulled the floater across half the continent...