NavList:

Alexandre Eremenko wrote:

>>
Greg,
> After the third rocket motor has separated,
> the warhead carrier takes a star-sighting to confirm position and
> manoeuvres to the point at which the warheads can be released to

The word "maneuvres" implies that that there is still some engine
"after the third rocket motor" has separated.

The earlier missiles, about which I read, had their last engine separated
shortly after launch. The reason of this is simple: they try to use
as much of the payload which goes to the space as possible for the
warheard(s). Everything else (as much as possible) they want to separate
on the early stages.
>>

Greg has it right. Prior to launch, the missile guidance platform is aligned to point at the predicted location of the target star. During boost, the guidance system's gyros are used to maintain this exact orientation in inertial space. After the solid rocket boost stage, the star is sighted with the stellar sensor. Any errors are used to back compute the actual trajectory. The remaining payload has thrusters which provide final corrective maneuvering until the warhead(s) is/are released.

Don Seltzer
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