Why did the S-IV-B refer to “jettison”ing its ullage?

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This is based on a recent question about S-IV-B ullage motor shutoff timing, specifically something found in the Technical Information Summary AS-501, page 15:




Ullage Jettison ~ 532.




But why "JETTISON" (not "ullage engines on or off")? What does it mean?










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    up vote
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    down vote

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    This is based on a recent question about S-IV-B ullage motor shutoff timing, specifically something found in the Technical Information Summary AS-501, page 15:




    Ullage Jettison ~ 532.




    But why "JETTISON" (not "ullage engines on or off")? What does it mean?










    share|improve this question









    New contributor




    A. P. Heiler is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.





















      up vote
      2
      down vote

      favorite









      up vote
      2
      down vote

      favorite











      This is based on a recent question about S-IV-B ullage motor shutoff timing, specifically something found in the Technical Information Summary AS-501, page 15:




      Ullage Jettison ~ 532.




      But why "JETTISON" (not "ullage engines on or off")? What does it mean?










      share|improve this question









      New contributor




      A. P. Heiler is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      This is based on a recent question about S-IV-B ullage motor shutoff timing, specifically something found in the Technical Information Summary AS-501, page 15:




      Ullage Jettison ~ 532.




      But why "JETTISON" (not "ullage engines on or off")? What does it mean?







      apollo-program terminology ullage






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      A. P. Heiler is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question









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      edited 4 hours ago









      Nathan Tuggy

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          1 Answer
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          There are two separate systems for ullage on the S-IVB (500 series only). The first one is used for the first start of the S-IVB during launch. Some information can be found in the AS-503 Saturn V Flight Manual, pages 6-31 and 6-32:




          ULLAGE ROCKET SYSTEM



          To provide propellant settling and thus ensure stable flow of lox and LH2 during J-2 engine start, the S-IVB stage requires a small acceleration. This acceleration is provided by two ullage rockets.



          Each ullage rocket has a single grain, five point star configuration, internal burning, polymerized solid propellant that is case bonded in a 4134 steel case. The propellant weighs approximately 58.8 pounds and burns for 3.8 seconds, developing a thrust of 3390 pounds (175,000 feet, 70 degrees F).



          ULLAGE ROCKET JETTISON SYSTEM



          To reduce weight, the ullage rockets and their fairings are jettisoned after J-2 engine start.




          For ullage thrust after orbital insertion and before TLI the S-IVB uses two ullage thrusters that are part of the Auxiliary Propulsion System. These thrusters are not jettisoned and they draw propellant from the same source as the attitude control thrusters. From pages 6-21 and 6-22 of the document linked above:




          AUXILIARY PROPULSION SYSTEM



          The S-IVB auxiliary propulsion system provides three axis stage attitude control and main stage propellant control during coast flight.



          Nitrogen tetroxide (N2O4) is used as an oxidizer and monomethylhydrazine (MMH) is used as fuel for these engines. The 150-pound thrust engines utilize eight control vales (four for fuel, four for oxidize) in a fail safe series parallel arrangement. The 70-pound ullage engine uses only single valves on both the fuel and oxidizer lines.



          APS Operation



          Two of the three 150-pound thrust engines in each module control roll and yaw, while one controls pitch. The 70-pound thrust engine in each module is used to settle the propellants in the propellant tanks. Just prior to J-2 engine restart, propellant control is accomplished by firing the 70-pound thrust engines.







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            1 Answer
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            active

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            1 Answer
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            active

            oldest

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            active

            oldest

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            up vote
            3
            down vote













            There are two separate systems for ullage on the S-IVB (500 series only). The first one is used for the first start of the S-IVB during launch. Some information can be found in the AS-503 Saturn V Flight Manual, pages 6-31 and 6-32:




            ULLAGE ROCKET SYSTEM



            To provide propellant settling and thus ensure stable flow of lox and LH2 during J-2 engine start, the S-IVB stage requires a small acceleration. This acceleration is provided by two ullage rockets.



            Each ullage rocket has a single grain, five point star configuration, internal burning, polymerized solid propellant that is case bonded in a 4134 steel case. The propellant weighs approximately 58.8 pounds and burns for 3.8 seconds, developing a thrust of 3390 pounds (175,000 feet, 70 degrees F).



            ULLAGE ROCKET JETTISON SYSTEM



            To reduce weight, the ullage rockets and their fairings are jettisoned after J-2 engine start.




            For ullage thrust after orbital insertion and before TLI the S-IVB uses two ullage thrusters that are part of the Auxiliary Propulsion System. These thrusters are not jettisoned and they draw propellant from the same source as the attitude control thrusters. From pages 6-21 and 6-22 of the document linked above:




            AUXILIARY PROPULSION SYSTEM



            The S-IVB auxiliary propulsion system provides three axis stage attitude control and main stage propellant control during coast flight.



            Nitrogen tetroxide (N2O4) is used as an oxidizer and monomethylhydrazine (MMH) is used as fuel for these engines. The 150-pound thrust engines utilize eight control vales (four for fuel, four for oxidize) in a fail safe series parallel arrangement. The 70-pound ullage engine uses only single valves on both the fuel and oxidizer lines.



            APS Operation



            Two of the three 150-pound thrust engines in each module control roll and yaw, while one controls pitch. The 70-pound thrust engine in each module is used to settle the propellants in the propellant tanks. Just prior to J-2 engine restart, propellant control is accomplished by firing the 70-pound thrust engines.







            share|improve this answer
























              up vote
              3
              down vote













              There are two separate systems for ullage on the S-IVB (500 series only). The first one is used for the first start of the S-IVB during launch. Some information can be found in the AS-503 Saturn V Flight Manual, pages 6-31 and 6-32:




              ULLAGE ROCKET SYSTEM



              To provide propellant settling and thus ensure stable flow of lox and LH2 during J-2 engine start, the S-IVB stage requires a small acceleration. This acceleration is provided by two ullage rockets.



              Each ullage rocket has a single grain, five point star configuration, internal burning, polymerized solid propellant that is case bonded in a 4134 steel case. The propellant weighs approximately 58.8 pounds and burns for 3.8 seconds, developing a thrust of 3390 pounds (175,000 feet, 70 degrees F).



              ULLAGE ROCKET JETTISON SYSTEM



              To reduce weight, the ullage rockets and their fairings are jettisoned after J-2 engine start.




              For ullage thrust after orbital insertion and before TLI the S-IVB uses two ullage thrusters that are part of the Auxiliary Propulsion System. These thrusters are not jettisoned and they draw propellant from the same source as the attitude control thrusters. From pages 6-21 and 6-22 of the document linked above:




              AUXILIARY PROPULSION SYSTEM



              The S-IVB auxiliary propulsion system provides three axis stage attitude control and main stage propellant control during coast flight.



              Nitrogen tetroxide (N2O4) is used as an oxidizer and monomethylhydrazine (MMH) is used as fuel for these engines. The 150-pound thrust engines utilize eight control vales (four for fuel, four for oxidize) in a fail safe series parallel arrangement. The 70-pound ullage engine uses only single valves on both the fuel and oxidizer lines.



              APS Operation



              Two of the three 150-pound thrust engines in each module control roll and yaw, while one controls pitch. The 70-pound thrust engine in each module is used to settle the propellants in the propellant tanks. Just prior to J-2 engine restart, propellant control is accomplished by firing the 70-pound thrust engines.







              share|improve this answer






















                up vote
                3
                down vote










                up vote
                3
                down vote









                There are two separate systems for ullage on the S-IVB (500 series only). The first one is used for the first start of the S-IVB during launch. Some information can be found in the AS-503 Saturn V Flight Manual, pages 6-31 and 6-32:




                ULLAGE ROCKET SYSTEM



                To provide propellant settling and thus ensure stable flow of lox and LH2 during J-2 engine start, the S-IVB stage requires a small acceleration. This acceleration is provided by two ullage rockets.



                Each ullage rocket has a single grain, five point star configuration, internal burning, polymerized solid propellant that is case bonded in a 4134 steel case. The propellant weighs approximately 58.8 pounds and burns for 3.8 seconds, developing a thrust of 3390 pounds (175,000 feet, 70 degrees F).



                ULLAGE ROCKET JETTISON SYSTEM



                To reduce weight, the ullage rockets and their fairings are jettisoned after J-2 engine start.




                For ullage thrust after orbital insertion and before TLI the S-IVB uses two ullage thrusters that are part of the Auxiliary Propulsion System. These thrusters are not jettisoned and they draw propellant from the same source as the attitude control thrusters. From pages 6-21 and 6-22 of the document linked above:




                AUXILIARY PROPULSION SYSTEM



                The S-IVB auxiliary propulsion system provides three axis stage attitude control and main stage propellant control during coast flight.



                Nitrogen tetroxide (N2O4) is used as an oxidizer and monomethylhydrazine (MMH) is used as fuel for these engines. The 150-pound thrust engines utilize eight control vales (four for fuel, four for oxidize) in a fail safe series parallel arrangement. The 70-pound ullage engine uses only single valves on both the fuel and oxidizer lines.



                APS Operation



                Two of the three 150-pound thrust engines in each module control roll and yaw, while one controls pitch. The 70-pound thrust engine in each module is used to settle the propellants in the propellant tanks. Just prior to J-2 engine restart, propellant control is accomplished by firing the 70-pound thrust engines.







                share|improve this answer












                There are two separate systems for ullage on the S-IVB (500 series only). The first one is used for the first start of the S-IVB during launch. Some information can be found in the AS-503 Saturn V Flight Manual, pages 6-31 and 6-32:




                ULLAGE ROCKET SYSTEM



                To provide propellant settling and thus ensure stable flow of lox and LH2 during J-2 engine start, the S-IVB stage requires a small acceleration. This acceleration is provided by two ullage rockets.



                Each ullage rocket has a single grain, five point star configuration, internal burning, polymerized solid propellant that is case bonded in a 4134 steel case. The propellant weighs approximately 58.8 pounds and burns for 3.8 seconds, developing a thrust of 3390 pounds (175,000 feet, 70 degrees F).



                ULLAGE ROCKET JETTISON SYSTEM



                To reduce weight, the ullage rockets and their fairings are jettisoned after J-2 engine start.




                For ullage thrust after orbital insertion and before TLI the S-IVB uses two ullage thrusters that are part of the Auxiliary Propulsion System. These thrusters are not jettisoned and they draw propellant from the same source as the attitude control thrusters. From pages 6-21 and 6-22 of the document linked above:




                AUXILIARY PROPULSION SYSTEM



                The S-IVB auxiliary propulsion system provides three axis stage attitude control and main stage propellant control during coast flight.



                Nitrogen tetroxide (N2O4) is used as an oxidizer and monomethylhydrazine (MMH) is used as fuel for these engines. The 150-pound thrust engines utilize eight control vales (four for fuel, four for oxidize) in a fail safe series parallel arrangement. The 70-pound ullage engine uses only single valves on both the fuel and oxidizer lines.



                APS Operation



                Two of the three 150-pound thrust engines in each module control roll and yaw, while one controls pitch. The 70-pound thrust engine in each module is used to settle the propellants in the propellant tanks. Just prior to J-2 engine restart, propellant control is accomplished by firing the 70-pound thrust engines.








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                answered 4 hours ago









                indy91

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