Russian strap-on boosters

On 4/13/2011 4:30 PM, Brian Thorn wrote:
On Wed, 13 Apr 2011 08:20:43 -0700 (PDT), Frogwatch
wrote:

The Russian rockets such as the ones used for the Soyuz have the strap
on boosters oriented so their axes angle into the core rocket whereas
US rockets have the strap ons axis parallel to the axis of the core.
Why is this?
Do the engines of the Russian strap ons orient straight up and down or
are they aligned with the axis of the strap-on?

The fire through the vehicle's center of mass, as do the US strap-ons,
through gimbaled engine nozzles.

No, they fire straight down; look at the plans of the vehicle I linked
to, or video of a launch.
And the four man chambers of the RD-107 engines used in the strap-ons do
not gimbal. Pitch, roll, and yaw control of the vehicle are handled by
two smaller engine chambers on each of the strap-ons, and they only
swivel back-and-forth in one plane of motion, rather than gimbaling:
http://www.ninfinger.org/models/vault2007/R-7/Rd107.jpg

Pat