Path: utzoo!attcan!uunet!samsung!brutus.cs.uiuc.edu!rpi!crdgw1!ge-dab!peora!tarpit!libcmp!mamab!f49.n363.z1.FIDONET.ORG!Mike.Pompura From: Mike.Pompura@f49.n363.z1.FIDONET.ORG (Mike Pompura) Newsgroups: sci.space.shuttle Subject: Re: Shuttle roll maneuver Message-ID: <575.25527AA8@mamab.FIDONET.ORG> Date: 3 Nov 89 18:17:00 GMT Sender: ufgate@mamab.FIDONET.ORG (newsout1.26) Organization: FidoNet node 1:363/49 - NASA Aerospace Inf, Orlando FL Lines: 62 Perhaps I may be of assistance in this discussion over the Saturn V. Reprint taken from: SATURN V FLIGHT MANUAL SA-508 Section II - Performance Launch And Boost To Earth Parking Orbit --------------------------------------- The vehicle rises nearly vertically from the pad, for approx 450 feet, to clear the tower. During this period, a yaw maneuver is executed to provide tower clearance in the event of adverse wind conditions, deviation from nominal flight and/or engine failure. After clearing the tower, a tilt and roll maneuver is initiated to achieve the flight attitude and proper orientation for the selected flight azimuth. Launch azimuth is 90 degrees; flight azimuth may vary between 72 and 96 degrees. The actual flight azimuth within this range is computed is computed just prior to launch from a launch-day-dependent polynomial of launch azimuth as a function of launch time. From the end of the tilt maneuver to tilt-arrest, the pitch program provides a near-zero-lift trajectory that satisifies vehicle performance, heating, and loads requirements. Tilt-arrest freezes the pitch attitude to dampen out pitch rates prior to S-IC/S-II seperation. The pitch attitude remains constant until initiation of the Iterative Guidance Mode which occurs during the S-II stage flight. Mach 1 is achieved approx 1 minute 8 seconds after first motion. Max dynamic pressure is encountered at approx 1 minute 25 seconds after first motion. S-IC center engine cutoff is commanded at 2 minutes 15 seconds after first motion, to limit the vehicle acceleration to a nominal 3.98g. The S-IC outboard engines are cut off by propellant-depletion sensors. A time interval of 4.4 seconds elapses between S-IC cutoff and the time the J-2 engines of the S-II stage reach mainstage . During this period, ullage rockets are fired to seat the S-II propellant, the S-IC/S-II seperation occurs and the retrorockets back the S-IC stage away from the flight vehicle. Threshold for engine status light OFF is 65% thrust. The S-II aft interstage is jettisoned 30.7 seconds after S-IC cutoff, and the LET is jettisoned by crew action approx 6 seconds later, after assurnace that S-II ignition and thrust buildup have occured. IGM is initiated about 39 seconds after S-II ignition. An early S-II center engine cutoff is programmed for Time Base 3 + 299 seconds. This early cutoff is designed to preclude the vehicle longitudinal oscillations which have occurred late in the S-II burn in previous missions. The outboard engines are cut off simultaneously when any 2 of 5 cutoff sensors in either tank are activated. An interval of 6.5 seconds elapses between S-II cutoff and the time the S-IVB J-2 engine attains mainstage. During this coast period, the S-IVB ullage rockets are fired to seat the stage propellant, the S-II/S-IVB seperation occurs, and the retrorockets back the S-II stage away from the flight vehicle. Threshold for engine status light OFF is 65% thrust. The S-IVB first burn inserts the vehicle into a 100 nautical mile altitude circular parking orbit. If there is anything else that anyone wishes to know about the SATURN V launch vehicle , post your questions here, and I will attempt to find the answers. -- Fidonet: Mike Pompura via 1:363/9 Internet: Mike.Pompura@f49.n363.z1.FIDONET.ORG UUCP: uunet!sceard!tarpit!libcmp!mamab!49!Mike.Pompura