David Lesher wrote:
"Jorge R. Frank" writes:

I know it saved the bacon when lighting hit the launching stack, but
for example, how did it navigate? I see it had its own radar; I'm
guessing it interrogated ground transponders that let it calculate its
position to compare with the INS. Correct?
Not correct. It had an inertial platform (ST-124) and used inertial
navigation. There was no "external" source of position; the LVDC
computed position and velocity by integrating the acceleration from the
ST-124.

I'll add (of course) that the ground did perform tracking of the S-V and
could uplink a new state vector to the IU if the inertial navigation
system got too far off.

So what did it use the radar for?

Depends on what you mean by "it". The Saturn V did not have radar. The
LM did (both a rendezvous radar and a landing radar), but of course
these could not be used during launch since the LM was stowed in the SLA
and powered down.