Boeing Starliner aerodynamics

In article ,
says...

Saw picture sof the Boeing Starliner mouted on rocket at pad ready for
launch on Dec 20th.

It is wider than the rocket body.

Yes, it's a fairly short hammer head shape.

Out of curiousity, shouldn't the fairing below the starliner gently
narrow from starliner diametre to that of the rocket for aerodynamic flow?

No. There is an atmospheric skirt below the capsule which makes sure
that the shock wave produced by the capsule doesn't impinge on the
Centaur upper stage. Cite:

Boeing's Starliner Atlas V Rocket Ride Is Wearing a 'Skirt' for Launch.
Here's Why. By Mike Wall
https://www.space.com/boeing-starlin...ket-aeroskirt-
explained.html

On a "normal" Atlas V launch, the payload fairing is much longer, so
this simply isn't an issue.

Seems rather odd to see it abruptly end with what seems to be empty
space below it. Is there any explanation for this design decision?

See above.

Jeff
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In article ,
says...

On 2019-12-22 12:28, Jeff Findley wrote:
https://www.space.com/boeing-starlin...ket-aeroskirt-
explained.html

Thanks. So this un-aerodynamic looking skirt changed the airflow to
resolve a shockwave at the bottom of rocket.

It still hits the first stage/interstage. They needed to prevent it
from hitting the Centaur *upper* stage.

Would such a skirt (compared to a smooth fairing) end up generating drag
that is noticeable in performance or is the difference with normal
fairing small enough that it is not an issue?

I realise the skirt is the best solution for airflow further down, but
that doesn't mean it doesn'kt come at a cost. Just curios if this is
significant drag or not.

Not sure. I'm not privy to the results of the supersonic CFD
simulations that prompted the skirt.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.