markp@tekmdp.UUCP (Mark Paulin) (10/07/83)
Can someone speak with the voice of authority and compare the G-forces experienced by the shuttle astronauts with those felt by the Apollo astronauts? Did the Saturn-V have a much bigger "kick"? Isn't the shuttle lift-off assembly a lot lighter than the Saturn-V and thus maybe accelerates faster? Mark Paulin ...tektronix!tekmdp!markp
henry@utzoo.UUCP (Henry Spencer) (10/12/83)
The Shuttle boosts much more gently than the Saturn V. Saturn V
accelerations just before staging were 7-8 G. The Shuttle gives
a maximum of 3 G. This is quite deliberate, to make life easier
for both people and payloads. I believe the shuttle throttles its
engines back at times to stay under the 3-G line. The Saturn V's
engines basically had one throttle setting: wide open.
It is somewhat more efficient to boost at high acceleration, because
you finish acceleration sooner and hence use less fuel fighting gravity
during boost. (In case this isn't obvious, consider an extreme case:
if you boost at just slightly more than 1 G, you go up very slowly
and spend most of your fuel just keeping yourself from falling.)
But high-G boost is much harder on payloads and their support structures,
and one specific intent of the shuttle was to make payloads cheaper by
providing a less severe environment during boost. It also complicates
crew selection; it is reasonable to assume that any healthy adult can
take 3 G, but 7 G is nastier.
--
Henry Spencer @ U of Toronto Zoology
{allegra,ihnp4,linus,decvax}!utzoo!henry