The aircar rocketed them at speeds in excess of R17 through the steel tunnels that lead out onto the appalling surface of the planet which was now in the grip of yet another drear morning twilight. Ghastly grey lights congealed on the land.
R is a velocity measure, defined as a reasonable speed of travel that is consistent with health, mental wellbeing and not being more than say five minutes late. It is therefore clearly an almost infinitely variable figure according to circumstances, since the first two factors vary not only with speed taken as an absolute, but also with awareness of the third factor. Unless handled with tranquility this equation can result in considerable stress, ulcers and even death.
R17 is not a fixed velocity, but it is clearly far too fast.
The aircar flung itself through the air at R17 and above, deposited them next to the Heart of Gold which stood starkly on the frozen ground like a bleached bone, and then precipitately hurled itself back in the direction whence they had come, presumably on important business of its own.
Shivering, the four of them stood and looked at the ship.
Beside it stood another one.