Henry Spencer wrote:
In article .com,
wrote:
Also, it's conceivable the roll to wings-level might have an effect.
This puts the oxygen lines on the top, where they will have slightly
less pressure...

Not unless there's an attempt being made to exploit aerodynamic lift,
which is unlikely. The rocket is in free fall except for its engine
thrust, so the roll angle doesn't change the pressure in the oxygen
lines.

That makes perfect sense, except Av Week stated:

"Roll maneuver. At 2 min. 33 sec., the vehicle began a 50-sec. "roll to
wings level" maneuver, which if viewed as an airplane, put the liquid
strap-ons parallel to the flight path angle. This was done to place the
large oxygen feed lines on the exterior of the vehicle out of the
high-velocity airflow."

So if one side of the vehicle is in the aerodynamic shadow, and the
roll affects this, then it seems to me it must be flying at some
non-zero angle of attack. This is also indicated by the fact that the
roll "puts the strap-ons parallel to the flight path angle". (If the
flight path angle was identical to the vehicle angle, roll would have
no effect). This means there must be aerodynamic forces, and some
pressure gradient across the rocket. This is probably not a very big
effect since the deviation from the velocity vector could only be a few
degrees at most, and the rocket is not very wide, but every little bit
helps (or hurts).

Lou Scheffer