Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!cs.utexas.edu!asuvax!noao!ncar!mephisto!mcnc!rinne From: rinne@mcnc.org (Glenn A. Rinne) Newsgroups: sci.space.shuttle Subject: Re: Liftoff Question Message-ID: <7082@alvin.mcnc.org> Date: 15 Sep 90 01:28:53 GMT References: <52900004@uxa.cso.uiuc.edu> <36104@eerie.acsu.Buffalo.EDU> Reply-To: rinne@mcnc.org.UUCP (Glenn A. Rinne) Organization: MCNC; RTP, NC Lines: 30 In article shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes: > In article <52900004@uxa.cso.uiuc.edu>, sfn20715@uxa.cso.uiuc.edu writes... > > > >When the shuttle lifts off, what is used to make it turn and roll? > >(roll/pitch? turn/yaw? you know what I mean...) > >The whole shuttle is an aerodynamic surface producing lift (your force >opposite in direction to the external tank) out the top of the shuttle >(can you say "lifting body"?) which is a better way of referring to it >than as opposite the external tank. This lift isn't dependent on the >location of the external tank, so it's confusing to phrase it this >way. Did you mean control surfaces (ailerons, rudder, and body flap) >were used in the roll? The lift would, at most, produce a pitching >moment, not a rolling moment. > The original question referred to the need for the roll just after liftoff. Looking at the Shuttle stack, wouldn't the center of thrust (given the SRB's large thrust) be on the orbiter side of the stack? If so, the 180 degree roll may facilitate using the SMEs to control the trajectory. Since the SMEs can vector (gimbal) thrust more effectively, they may be more effective in a _pitch-up_ mode rather than a _pitch-down_ mode, given the ballistic tendency of stack. >-- > "A MiG at your six is better than no MiG at all"--Unknown US fighter pilot My brother (a United co-pilot) and I love your .sig Glenn Rinne MCNC Center for Microelectronics RTP, NC, 27709-2889 rinne@mcnc.org.UUNET