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Broadly speaking, most rocket systems appear to have at least 3 or 4 fold radial symmetry about their long axis (if you don't consider internals or smaller features not obvious from a distance). A notable exception is the Space Shuttle, which (broadly) displays only bilateral symmetry.

Descriptions of launch profiles often include roll and pitch maneuvers. For the shuttle, it's quite obvious what is going on. Not so much for a vehicle like Apollo.

Presumably, for vehicles such as Apollo, Gemini, and Mercury, pitch, roll, and yaw axes were consistent with the crew's seated positions (or vice versa) - "pitch down" equated to the crew experiencing a "forward" rotation.

When sitting on the pad, in which directions were Apollo's pitch and yaw axes oriented relative to the launch tower? What visual cues did the vehicle have purposely or incidentally that one could use once the vehicle was in flight to discern its orientation about the roll axis relative to the viewer?

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  • $\begingroup$ Here's Saturn V Markings overview. Astronauts also use the right-hand rule to determine the z-axis (along the line that the thumb is pointing, if you hold your right hand directly in front of you, as seated, fingers in "thumbs up" position). Here's vehicle coordinate system graphic for orientation (source). $\endgroup$ – TildalWave Jul 19 '14 at 4:40
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    $\begingroup$ Not sure your links are helping. If viewing video footage of an Apollo launch, what cues (if any) are visible at such resolution to ascertain the vehicle's roll orientation relative to the camera position i.e. which direction would correspond to a pitch change and which would correspond to a yaw change? The markings described in your links are either too small to be visible on "public consumption" launch footage or aren't described with reference to the vehicle's "co-ordinate space". $\endgroup$ – Anthony X Jul 19 '14 at 13:53
  • $\begingroup$ I'm afraid that's all the markings that Saturn V had, and even then, as you can see, they were not same for all missions. They were sufficient for launch tracking, I guess they didn't think that general public will want to know its coordinate system axes. Knowing the position of astronauts during launch relative to these markings, together with the right-hand rule, gives you all three axes and their signs for all six directions. It would take a bit of work for Saturn V launch vehicles, but some newer ones might have easier to follow on-body visual orientation cues. $\endgroup$ – TildalWave Jul 19 '14 at 21:56
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Broadly speaking, most rocket systems appear to have at least 3 or 4 fold radial symmetry about their long axis.

That's not quite true. There are little things that make every vehicle not quite symmetric. Many of those little things were important. Plumbing, electrical connections, communication equipment, navigation sensors, computers, and the crew compartments were not symmetrically laid out in Saturn V / Apollo rocket. The umbilical tower was a rather important part of the Saturn V / Apollo rocket system, and that umbilical tower gave a marked asymmetry to the system. The rocket proper had its x-axis (roll axis) pointing upward when the rocket was on the pad, the +y axis toward the umbilical tower, and the +z axis completing a right hand coordinate system.

When sitting on the pad, in which directions were Apollo's pitch and yaw axes oriented relative to the launch tower?

From How Apollo Flew to the Moon by W. David Woods, page 73,

At this point, it is worth outlining the vehicle's coordinate system. The Saturn V's plus-x axis ran along the length of the rocket and out through the top of the escape tower. Its plus-y axis ran through the vehicle towards the umbilical tower and therefore was pointed north. The plus-z axis ran through the vehicle to the west. As the crew lay on the couches, their heads aimed east and therefore towards the minus-z axis.

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