roy@phri.nyu.edu (Roy Smith) (01/10/90)
Watching the 30-second video on the news of yesterday's shuttle
launch, I noticed that the SRBs were still burning when they separated, and
kept doing so for at least a few seconds (i.e. as long as they showed
them). To me, this means they waste some significant fraction of the SRB
thrust after separation. Is that really true?
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
{att,philabs,cmcl2,rutgers,hombre}!phri!roy -or- roy@alanine.phri.nyu.edu
"The connector is the network"dkrause@orion.oac.uci.edu (Doug Krause) (01/10/90)
In article <1990Jan10.142852.23804@phri.nyu.edu> roy@phri.nyu.edu (Roy Smith) writes:
#
# Watching the 30-second video on the news of yesterday's shuttle
#launch, I noticed that the SRBs were still burning when they separated, and
#kept doing so for at least a few seconds (i.e. as long as they showed
#them). To me, this means they waste some significant fraction of the SRB
#thrust after separation. Is that really true?
It's probably better to separate while they are still burning, before
they become dead weight.
Douglas Krause One yuppie can ruin your whole day.
----------------------------------------------------------------------
University of California, Irvine Internet: dkrause@orion.oac.uci.edu
Welcome to Irvine, Yuppieland USA BITNET: DJKrause@ucivmsaKDA101@PSUVM.BITNET (KeithPetto Alexander) (01/11/90)
In article <4109@orion.cf.uci.edu>, dkrause@orion.oac.uci.edu (Doug Krause) says: > >In article <1990Jan10.142852.23804@phri.nyu.edu> roy@phri.nyu.edu (Roy Smith) >writes: ># Watching the 30-second video on the news of yesterday's shuttle >#launch, I noticed that the SRBs were still burning when they separated, and >#kept doing so for at least a few seconds (i.e. as long as they showed >#them). To me, this means they waste some significant fraction of the SRB >#thrust after separation. Is that really true? > >It's probably better to separate while they are still burning, before >they become dead weight. Yes, they also have been known to cause problems (explosions and such) so I would think it would be a good idea to jetison them as soon as they are no longer needed. Less variables, less to go wrong, we hope. ------- Petto :-> "The opinions expressed above may or may not be my own." kda101@psuvm.bitnet
mac@idacrd.UUCP (Robert McGwier) (01/11/90)
From article <1990Jan10.142852.23804@phri.nyu.edu>, by roy@phri.nyu.edu (Roy Smith): > launch, I noticed that the SRBs were still burning when they separated, and > them). To me, this means they waste some significant fraction of the SRB At the end of burn the thrust decreases rapidly. When the acceleration provided by this decreasing thrust falls BELOW that which would be achieved by dropping them, they are let go. (Remember F=MA?). The mass in F=MA falls further than F when they are dropped at the instant chosen so that A actually gets bigger. Bob -- ____________________________________________________________________________ My opinions are my own no matter | Robert W. McGwier, N4HY who I work for! ;-) | CCR, AMSAT, etc. ----------------------------------------------------------------------------
henry@utzoo.uucp (Henry Spencer) (01/11/90)
In article <1990Jan10.142852.23804@phri.nyu.edu> roy@phri.nyu.edu (Roy Smith) writes: >... I noticed that the SRBs were still burning when they separated, and >kept doing so for at least a few seconds (i.e. as long as they showed >them). To me, this means they waste some significant fraction of the SRB >thrust after separation. Is that really true? SRB burnout is a gradual process. Separation occurs after thrust has dropped to something fairly insignificant -- it is not possible to do the separation while the SRBs are at full blast -- but they do go on putting out a little bit of exhaust for some seconds. -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
moe@nuchat.UUCP (Norman C. Kluksdahl) (01/11/90)
In article <1990Jan10.142852.23804@phri.nyu.edu> roy@phri.nyu.edu (Roy Smith) writes: > >I noticed that the SRBs were still burning when they separated, and >kept doing so for at least a few seconds (i.e. as long as they showed >them). To me, this means they waste some significant fraction of the SRB >thrust after separation. Is that really true? The SRBs may still be burning when they are jettisoned, but they may not be producing USEFUL thrust. If the thrust from an SRB is less than its combined mass and contribution to atmospheric drag, it is dead weight, and actually detracts from the useful payload, since the SSMEs must carry the difference. ===================================================================== Norman Kluksdahl ...!nuchat!moe