were actually balanced and steered by vanes in the blasts of their jets,
and they combined the absolute maximum of sheer thrust with the
irreducible minimum of flyability.

Crane-trucks went out to pick them up. Joe said anxiously, "We'd better
check our flight plan again. We have to know it absolutely!"

He headed across the floor to the flight data board. He passed the hull
of another ship like his own, which was near completion, and the bare
skeletons of two others which needed a lot of work yet. They'd been
begun at distant plants and then hauled here on monstrous trailers for
completion. The wooden mockup of the design for all the ships--in which
every possible arrangement of instruments and machinery had been tested
out--lay neglected by the Shed wall.

The four stood before the flight data board. It listed the readings
every instrument should show during every instant of the flight. The
readings had been calculated with infinite care, and Joe and the others
needed to know them rather better than they knew their multiplication
tables. Once they started out, they wouldn't have time to wonder if
everything was right for the time and place. They needed to know.

They stood there, soaking up the information the board contained,
forming mental pictures of it, making as sure as possible that any one
of them would spot anything wrong the instant it showed up, and would
instantly know what had to be done about it.

A gigantic crane-truck came in through the wide doorway. It dangled a
pushpot. It rolled over to the launching cage in which the spaceship lay
and set the unwieldy metal object against that cage. There was a _clank_