Minuteman Stage I nozzles - why four?

I used to be in a MM III wing, but I can't remember this. On Stage 1,
why four nozzles for one engine? They were swileveled for control, but
why whould that mandate four? Other solids (like MM III second
stage) achieve controllability with a single nozzle. Isn't there a
weight/complexity penalty? I've never quite made sense of it.

On Sat, 8 Oct 2011 13:19:43 -0700 (PDT), Matt
wrote:

I used to be in a MM III wing, but I can't remember this. On Stage 1,
why four nozzles for one engine? They were swileveled for control, but
why whould that mandate four? Other solids (like MM III second
stage) achieve controllability with a single nozzle. Isn't there a
weight/complexity penalty? I've never quite made sense of it.

You can't control roll with a single nozzle, so Stage 2 and above
probably used some sort of independent roll control system, which may
not have had enough control authority in the thick lower atmosphere,
mandating additional roll control through gimbaled nozzles on Stage 1.
Why four instead of two, I don't know. Base heating, perhaps (less
exposed area at the base of the stage with four nozzles burning than
with two.) Maybe just increased thrust through four nozzles versus
two.

Brian

In message
Matt wrote:

I used to be in a MM III wing, but I can't remember this. On Stage 1,
why four nozzles for one engine? They were swileveled for control, but
why whould that mandate four? Other solids (like MM III second
stage) achieve controllability with a single nozzle. Isn't there a
weight/complexity penalty? I've never quite made sense of it.

With more than one nozzle you can do roll control as well as pitch and
yaw. Using four means each nozzle only has to be capable of movement in
one plane rather than gimbal in all directions.

Anthony