Monday, November 30, 2009

Atlas? 5

I was surfing for the X37B and landed on the Atlas 5 which
is going to be the X37's launch vehicle soon. I didn't know
much about the Atlas 5 and admittedly, I still don't know
enough.  Research will continue though.  I have a few
points to make in this post, more may arise in the future.

As near as I can tell, this is practically a new vehicle, it
bears so little commonality with the Atlas that I know,
it hardly deserves the name. Atlas always had  3 liquid
rocket motors in a stage and a half arrangement. It took
off on 3 motors, then later drops the outer pair,
continueing on the center motor alone. A sweet solution.
This new bird has only 2 liquid motors.
More important than the name, L-M adds the older Atlas
launch success rate in with the new one, claiming over 600
successful launches. Most of those flights were made by
the original Convair later renamed General Dynamics.
Marketing hype that doesn't fool anybody who cares.

The pics above are from the recent launch of the Intelsat
14 satelite. Reading about the flight, I found that it used
3 strap-on motors. Scrolling through the roll-out pics,  I
was struck by the sight of 2 of the strap-ons side by side.
Typically 3 strap-ons would be attached equidistant around
the booster. Further through the pics I find the third strap-
on on the other side next to an empty mounting pad for a
fourth. The Atlas 5 is outfitted for only 4 strap-ons mounted
in 2 opposite pairs. I would've designed the booster with 6
mounting pads, which would allow any balanced combo of
2,3,4, or 6.  It's a pure guess on my part that they didn't
want to rebuild the launch pad. The umbilical tower is a
bit too close to allow strap-ons on that side.

These days, strap-on motors are about as likely to have
inward canted nose cones as traditional concentric cones.
The Atlas 5 strap-ons have a cone style I've never seen
before. They are canted inward but the tip is full width
and flattened next to the main booster.
Wonder what they call it?


  1. Hello,

    just for your info - The Atlas-5 can feature any number from 0 to 5 strap ons - and none of those is balanced.

    Photos of the different versions:

    X-37 will be launched by a version without strap ons and a large fairing. It will look like this:

    best regards,
    Gunter Krebs

  2. Gunter,
    Thanks for the info. I should've thought to check Wiki at the time.
    So, up to 5 strap-ons in odd combo?
    Stranger still.

    I currently get no notification of posted comments. Gotta find them the old fashioned way.