STS-1: Orbital Maneuvering System (OMS) burns

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Author	Topic: STS-1: Orbital Maneuvering System (OMS) burns
Lunar Module 5 Member Posts: 370 From: Wales, UK Registered: Dec 2004	posted 04-26-2014 04:48 PM According to the mission audio, STS-1's orbital maneuvering system (OMS)-3 burn was completed by using the right side OMS engine only. Does anyone know if OMS4 was done with both or single OMS engines?
Robert Pearlman Editor Posts: 42988 From: Houston, TX Registered: Nov 1999	posted 05-02-2014 02:53 PM Courtesy Dennis Jenkins: OMS-1 - Both - 87 seconds OMS-2 - Both - 75 seconds OMS-3 - Left - 29 seconds OMS-4 - Right - 33 seconds Deorbit - Both - 155 seconds
Lunar Module 5 Member Posts: 370 From: Wales, UK Registered: Dec 2004	posted 05-03-2014 01:15 PM Thanks for the info Robert. In the STS-1 audio, Crippen refers to OMS3 as using the right hand engine and that's confirmed by Capcom Hartsfield... perhaps they were looking at them the wrong way. For the full mission video, because I didn't know any better, I showed the right engine firing for OMS3 and both for OMS4 - apologies to the purists.
Robert Pearlman Editor Posts: 42988 From: Houston, TX Registered: Nov 1999	posted 05-04-2014 10:39 AM Dennis discovered the reason for the disparity between reports: the mission report was wrong. The times are correct (depending on how one rounds to a full second) but the engines were reversed. He suspects this might have been because the OMS-3 and -4 burns were conducted as cross-feed tests where the opposite set of tanks fed the engine (so OMS-3 used propellant from the left tanks to feed the right engine). This may have led to some confusion when whomever transcribed the verbal report to the written report. According to the mission events list (MEL) it was: OMS-1 - Both - 87 seconds OMS-2 - Both - 75 seconds OMS-3 - Right - 29 seconds OMS-4 - Left - 33 seconds Deorbit - Both - 155 seconds
Lunar Module 5 Member Posts: 370 From: Wales, UK Registered: Dec 2004	posted 05-04-2014 04:02 PM Thanks Robert - that makes more sense now.

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