Does anyone know how to calculate the KG per second of RP-1 and LOX from the 9 Merlin 1D engines?

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as can be seen from the title, I have been through at least 1,000 chrome tabs in the last few hours trying to find some form of definitive answer, but I've found absolutely nothing. Could anyone help me with a calculation from its 7,607kn to Fuel consumption KG/s







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    up vote
    6
    down vote

    favorite












    as can be seen from the title, I have been through at least 1,000 chrome tabs in the last few hours trying to find some form of definitive answer, but I've found absolutely nothing. Could anyone help me with a calculation from its 7,607kn to Fuel consumption KG/s







    share|improve this question







    New contributor




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




















      up vote
      6
      down vote

      favorite









      up vote
      6
      down vote

      favorite











      as can be seen from the title, I have been through at least 1,000 chrome tabs in the last few hours trying to find some form of definitive answer, but I've found absolutely nothing. Could anyone help me with a calculation from its 7,607kn to Fuel consumption KG/s







      share|improve this question







      New contributor




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










      as can be seen from the title, I have been through at least 1,000 chrome tabs in the last few hours trying to find some form of definitive answer, but I've found absolutely nothing. Could anyone help me with a calculation from its 7,607kn to Fuel consumption KG/s









      share|improve this question







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









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      asked Sep 6 at 11:21









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          2 Answers
          2






          active

          oldest

          votes

















          up vote
          11
          down vote



          accepted










          As @RussellBorogove points out in his excellent answer, Isp or "mass-specific impulse" is the number that expresses the relationship between thrust and mass flow rate.



          Mass specific impulse with units would be Newtons per kg/sec. While that has units of m/s, and may be identical or at least quite close to the average velocity of the exhaust (which will have a distribution), the derivation below is a handy way to either remember how things are related, and/or to get the units to work out.




          Force can be equated to change in momentum per unit time.



          $$F = fracdpdt$$



          Momentum is mass times velocity:



          $$p = mv$$



          So



          $$F = v fracdmdt = v dotm$$



          where $dotm$ is the mass rate.



          The specific impulse of a Falcon 9 Merlin 1D is about 262 seconds in the atmosphere. Multiply that by standard gravity of about 9.81 m/s^2 to get an exhaust velocity of about 2570 m/s.



          $$ 7,607,000 = 2570 dotm$$



          Solve for $dotm$.



          $$ dotm = frac7,607,0002570 $$



          That's one way how to calculate the kg/sec of RP-1 and LOX. If you want to know each one separately, find the the ratio between the two. Search this site for oxidizer fuel ratio or similar terms if you can't find it on the internet.






          share|improve this answer






















          • That assumes 100% efficiency and ignores the fuel required for the turbopump, though.
            – Hobbes
            Sep 6 at 11:41






          • 2




            I think uhoh's answer is in the ballpark. Here's another (less precise) approach: First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel [1] Let's assume oxygen density as 1,1417 [2] and RP-1 density as 0,915 (average of 0.81 and 1.02 in [3]). So we have 280424 Kg of Oxygen and 133608 Kg of RP-1. First stage burn time is 162s [4]. So (280424+133608)/162 = 2555 Kg/s. [1] en.wikipedia.org/wiki/Falcon_9#cite_note-falcon9-2015-3 [2] uigi.com/o2_conv.html [3] en.wikipedia.org/wiki/RP-1 [4] spacex.com/falcon9
            – BlueCoder
            Sep 6 at 12:19






          • 2




            Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers, I think uhoh's answer is correct at the very least in the order of magnitude. By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.
            – BlueCoder
            Sep 6 at 12:20






          • 1




            BlueCoder's approach is the one I had in mind as well, but couldn't find the numbers for on short notice.
            – Hobbes
            Sep 6 at 12:40






          • 1




            @2012rcampion Since (at)BlueCoder's answer chooses to do the numbers, the've already reported a value for this there, so it's not necessary to do here. And while we don't have a specific homework policy as some sites do, I feel that there's a certain comradely cordiality to not over-answering a question that specifically asks only for how to do something rather than "tell me what the answer is."
            – uhoh
            Sep 7 at 0:43


















          up vote
          8
          down vote













          I think uhoh's answer (7607000/2570=2959 Kg/s) is in the ballpark.



          Here's another (less precise) approach:



          First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel (1)



          Let's assume oxygen density as 1,1417 (2) and RP-1 density as 0,915 (average of 0.81 and 1.02 in (3)).



          So we have 245620*1,1417 = 280424 Kg of Oxygen and 146020*0,915 = 133608 Kg of RP-1.



          First stage burn time is 162s (4).



          So (280424+133608)/162 = 2555 Kg/s.



          Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers*, I think uhoh's answer is correct at the very least in the order of magnitude.



          By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.



          • I just took as good the first sources I found around. To make a better estimate, I would at least verify more carfully the actual RP-1 density and also have a look at the thrust level during the whole 162 seconds.
            Also note that some of the first stage fuel is kept for landing.





          share|improve this answer






















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            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            11
            down vote



            accepted










            As @RussellBorogove points out in his excellent answer, Isp or "mass-specific impulse" is the number that expresses the relationship between thrust and mass flow rate.



            Mass specific impulse with units would be Newtons per kg/sec. While that has units of m/s, and may be identical or at least quite close to the average velocity of the exhaust (which will have a distribution), the derivation below is a handy way to either remember how things are related, and/or to get the units to work out.




            Force can be equated to change in momentum per unit time.



            $$F = fracdpdt$$



            Momentum is mass times velocity:



            $$p = mv$$



            So



            $$F = v fracdmdt = v dotm$$



            where $dotm$ is the mass rate.



            The specific impulse of a Falcon 9 Merlin 1D is about 262 seconds in the atmosphere. Multiply that by standard gravity of about 9.81 m/s^2 to get an exhaust velocity of about 2570 m/s.



            $$ 7,607,000 = 2570 dotm$$



            Solve for $dotm$.



            $$ dotm = frac7,607,0002570 $$



            That's one way how to calculate the kg/sec of RP-1 and LOX. If you want to know each one separately, find the the ratio between the two. Search this site for oxidizer fuel ratio or similar terms if you can't find it on the internet.






            share|improve this answer






















            • That assumes 100% efficiency and ignores the fuel required for the turbopump, though.
              – Hobbes
              Sep 6 at 11:41






            • 2




              I think uhoh's answer is in the ballpark. Here's another (less precise) approach: First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel [1] Let's assume oxygen density as 1,1417 [2] and RP-1 density as 0,915 (average of 0.81 and 1.02 in [3]). So we have 280424 Kg of Oxygen and 133608 Kg of RP-1. First stage burn time is 162s [4]. So (280424+133608)/162 = 2555 Kg/s. [1] en.wikipedia.org/wiki/Falcon_9#cite_note-falcon9-2015-3 [2] uigi.com/o2_conv.html [3] en.wikipedia.org/wiki/RP-1 [4] spacex.com/falcon9
              – BlueCoder
              Sep 6 at 12:19






            • 2




              Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers, I think uhoh's answer is correct at the very least in the order of magnitude. By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.
              – BlueCoder
              Sep 6 at 12:20






            • 1




              BlueCoder's approach is the one I had in mind as well, but couldn't find the numbers for on short notice.
              – Hobbes
              Sep 6 at 12:40






            • 1




              @2012rcampion Since (at)BlueCoder's answer chooses to do the numbers, the've already reported a value for this there, so it's not necessary to do here. And while we don't have a specific homework policy as some sites do, I feel that there's a certain comradely cordiality to not over-answering a question that specifically asks only for how to do something rather than "tell me what the answer is."
              – uhoh
              Sep 7 at 0:43















            up vote
            11
            down vote



            accepted










            As @RussellBorogove points out in his excellent answer, Isp or "mass-specific impulse" is the number that expresses the relationship between thrust and mass flow rate.



            Mass specific impulse with units would be Newtons per kg/sec. While that has units of m/s, and may be identical or at least quite close to the average velocity of the exhaust (which will have a distribution), the derivation below is a handy way to either remember how things are related, and/or to get the units to work out.




            Force can be equated to change in momentum per unit time.



            $$F = fracdpdt$$



            Momentum is mass times velocity:



            $$p = mv$$



            So



            $$F = v fracdmdt = v dotm$$



            where $dotm$ is the mass rate.



            The specific impulse of a Falcon 9 Merlin 1D is about 262 seconds in the atmosphere. Multiply that by standard gravity of about 9.81 m/s^2 to get an exhaust velocity of about 2570 m/s.



            $$ 7,607,000 = 2570 dotm$$



            Solve for $dotm$.



            $$ dotm = frac7,607,0002570 $$



            That's one way how to calculate the kg/sec of RP-1 and LOX. If you want to know each one separately, find the the ratio between the two. Search this site for oxidizer fuel ratio or similar terms if you can't find it on the internet.






            share|improve this answer






















            • That assumes 100% efficiency and ignores the fuel required for the turbopump, though.
              – Hobbes
              Sep 6 at 11:41






            • 2




              I think uhoh's answer is in the ballpark. Here's another (less precise) approach: First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel [1] Let's assume oxygen density as 1,1417 [2] and RP-1 density as 0,915 (average of 0.81 and 1.02 in [3]). So we have 280424 Kg of Oxygen and 133608 Kg of RP-1. First stage burn time is 162s [4]. So (280424+133608)/162 = 2555 Kg/s. [1] en.wikipedia.org/wiki/Falcon_9#cite_note-falcon9-2015-3 [2] uigi.com/o2_conv.html [3] en.wikipedia.org/wiki/RP-1 [4] spacex.com/falcon9
              – BlueCoder
              Sep 6 at 12:19






            • 2




              Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers, I think uhoh's answer is correct at the very least in the order of magnitude. By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.
              – BlueCoder
              Sep 6 at 12:20






            • 1




              BlueCoder's approach is the one I had in mind as well, but couldn't find the numbers for on short notice.
              – Hobbes
              Sep 6 at 12:40






            • 1




              @2012rcampion Since (at)BlueCoder's answer chooses to do the numbers, the've already reported a value for this there, so it's not necessary to do here. And while we don't have a specific homework policy as some sites do, I feel that there's a certain comradely cordiality to not over-answering a question that specifically asks only for how to do something rather than "tell me what the answer is."
              – uhoh
              Sep 7 at 0:43













            up vote
            11
            down vote



            accepted







            up vote
            11
            down vote



            accepted






            As @RussellBorogove points out in his excellent answer, Isp or "mass-specific impulse" is the number that expresses the relationship between thrust and mass flow rate.



            Mass specific impulse with units would be Newtons per kg/sec. While that has units of m/s, and may be identical or at least quite close to the average velocity of the exhaust (which will have a distribution), the derivation below is a handy way to either remember how things are related, and/or to get the units to work out.




            Force can be equated to change in momentum per unit time.



            $$F = fracdpdt$$



            Momentum is mass times velocity:



            $$p = mv$$



            So



            $$F = v fracdmdt = v dotm$$



            where $dotm$ is the mass rate.



            The specific impulse of a Falcon 9 Merlin 1D is about 262 seconds in the atmosphere. Multiply that by standard gravity of about 9.81 m/s^2 to get an exhaust velocity of about 2570 m/s.



            $$ 7,607,000 = 2570 dotm$$



            Solve for $dotm$.



            $$ dotm = frac7,607,0002570 $$



            That's one way how to calculate the kg/sec of RP-1 and LOX. If you want to know each one separately, find the the ratio between the two. Search this site for oxidizer fuel ratio or similar terms if you can't find it on the internet.






            share|improve this answer














            As @RussellBorogove points out in his excellent answer, Isp or "mass-specific impulse" is the number that expresses the relationship between thrust and mass flow rate.



            Mass specific impulse with units would be Newtons per kg/sec. While that has units of m/s, and may be identical or at least quite close to the average velocity of the exhaust (which will have a distribution), the derivation below is a handy way to either remember how things are related, and/or to get the units to work out.




            Force can be equated to change in momentum per unit time.



            $$F = fracdpdt$$



            Momentum is mass times velocity:



            $$p = mv$$



            So



            $$F = v fracdmdt = v dotm$$



            where $dotm$ is the mass rate.



            The specific impulse of a Falcon 9 Merlin 1D is about 262 seconds in the atmosphere. Multiply that by standard gravity of about 9.81 m/s^2 to get an exhaust velocity of about 2570 m/s.



            $$ 7,607,000 = 2570 dotm$$



            Solve for $dotm$.



            $$ dotm = frac7,607,0002570 $$



            That's one way how to calculate the kg/sec of RP-1 and LOX. If you want to know each one separately, find the the ratio between the two. Search this site for oxidizer fuel ratio or similar terms if you can't find it on the internet.







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Sep 7 at 1:24









            2012rcampion

            1,603618




            1,603618










            answered Sep 6 at 11:39









            uhoh

            27.9k1288344




            27.9k1288344











            • That assumes 100% efficiency and ignores the fuel required for the turbopump, though.
              – Hobbes
              Sep 6 at 11:41






            • 2




              I think uhoh's answer is in the ballpark. Here's another (less precise) approach: First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel [1] Let's assume oxygen density as 1,1417 [2] and RP-1 density as 0,915 (average of 0.81 and 1.02 in [3]). So we have 280424 Kg of Oxygen and 133608 Kg of RP-1. First stage burn time is 162s [4]. So (280424+133608)/162 = 2555 Kg/s. [1] en.wikipedia.org/wiki/Falcon_9#cite_note-falcon9-2015-3 [2] uigi.com/o2_conv.html [3] en.wikipedia.org/wiki/RP-1 [4] spacex.com/falcon9
              – BlueCoder
              Sep 6 at 12:19






            • 2




              Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers, I think uhoh's answer is correct at the very least in the order of magnitude. By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.
              – BlueCoder
              Sep 6 at 12:20






            • 1




              BlueCoder's approach is the one I had in mind as well, but couldn't find the numbers for on short notice.
              – Hobbes
              Sep 6 at 12:40






            • 1




              @2012rcampion Since (at)BlueCoder's answer chooses to do the numbers, the've already reported a value for this there, so it's not necessary to do here. And while we don't have a specific homework policy as some sites do, I feel that there's a certain comradely cordiality to not over-answering a question that specifically asks only for how to do something rather than "tell me what the answer is."
              – uhoh
              Sep 7 at 0:43

















            • That assumes 100% efficiency and ignores the fuel required for the turbopump, though.
              – Hobbes
              Sep 6 at 11:41






            • 2




              I think uhoh's answer is in the ballpark. Here's another (less precise) approach: First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel [1] Let's assume oxygen density as 1,1417 [2] and RP-1 density as 0,915 (average of 0.81 and 1.02 in [3]). So we have 280424 Kg of Oxygen and 133608 Kg of RP-1. First stage burn time is 162s [4]. So (280424+133608)/162 = 2555 Kg/s. [1] en.wikipedia.org/wiki/Falcon_9#cite_note-falcon9-2015-3 [2] uigi.com/o2_conv.html [3] en.wikipedia.org/wiki/RP-1 [4] spacex.com/falcon9
              – BlueCoder
              Sep 6 at 12:19






            • 2




              Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers, I think uhoh's answer is correct at the very least in the order of magnitude. By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.
              – BlueCoder
              Sep 6 at 12:20






            • 1




              BlueCoder's approach is the one I had in mind as well, but couldn't find the numbers for on short notice.
              – Hobbes
              Sep 6 at 12:40






            • 1




              @2012rcampion Since (at)BlueCoder's answer chooses to do the numbers, the've already reported a value for this there, so it's not necessary to do here. And while we don't have a specific homework policy as some sites do, I feel that there's a certain comradely cordiality to not over-answering a question that specifically asks only for how to do something rather than "tell me what the answer is."
              – uhoh
              Sep 7 at 0:43
















            That assumes 100% efficiency and ignores the fuel required for the turbopump, though.
            – Hobbes
            Sep 6 at 11:41




            That assumes 100% efficiency and ignores the fuel required for the turbopump, though.
            – Hobbes
            Sep 6 at 11:41




            2




            2




            I think uhoh's answer is in the ballpark. Here's another (less precise) approach: First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel [1] Let's assume oxygen density as 1,1417 [2] and RP-1 density as 0,915 (average of 0.81 and 1.02 in [3]). So we have 280424 Kg of Oxygen and 133608 Kg of RP-1. First stage burn time is 162s [4]. So (280424+133608)/162 = 2555 Kg/s. [1] en.wikipedia.org/wiki/Falcon_9#cite_note-falcon9-2015-3 [2] uigi.com/o2_conv.html [3] en.wikipedia.org/wiki/RP-1 [4] spacex.com/falcon9
            – BlueCoder
            Sep 6 at 12:19




            I think uhoh's answer is in the ballpark. Here's another (less precise) approach: First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel [1] Let's assume oxygen density as 1,1417 [2] and RP-1 density as 0,915 (average of 0.81 and 1.02 in [3]). So we have 280424 Kg of Oxygen and 133608 Kg of RP-1. First stage burn time is 162s [4]. So (280424+133608)/162 = 2555 Kg/s. [1] en.wikipedia.org/wiki/Falcon_9#cite_note-falcon9-2015-3 [2] uigi.com/o2_conv.html [3] en.wikipedia.org/wiki/RP-1 [4] spacex.com/falcon9
            – BlueCoder
            Sep 6 at 12:19




            2




            2




            Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers, I think uhoh's answer is correct at the very least in the order of magnitude. By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.
            – BlueCoder
            Sep 6 at 12:20




            Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers, I think uhoh's answer is correct at the very least in the order of magnitude. By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.
            – BlueCoder
            Sep 6 at 12:20




            1




            1




            BlueCoder's approach is the one I had in mind as well, but couldn't find the numbers for on short notice.
            – Hobbes
            Sep 6 at 12:40




            BlueCoder's approach is the one I had in mind as well, but couldn't find the numbers for on short notice.
            – Hobbes
            Sep 6 at 12:40




            1




            1




            @2012rcampion Since (at)BlueCoder's answer chooses to do the numbers, the've already reported a value for this there, so it's not necessary to do here. And while we don't have a specific homework policy as some sites do, I feel that there's a certain comradely cordiality to not over-answering a question that specifically asks only for how to do something rather than "tell me what the answer is."
            – uhoh
            Sep 7 at 0:43





            @2012rcampion Since (at)BlueCoder's answer chooses to do the numbers, the've already reported a value for this there, so it's not necessary to do here. And while we don't have a specific homework policy as some sites do, I feel that there's a certain comradely cordiality to not over-answering a question that specifically asks only for how to do something rather than "tell me what the answer is."
            – uhoh
            Sep 7 at 0:43











            up vote
            8
            down vote













            I think uhoh's answer (7607000/2570=2959 Kg/s) is in the ballpark.



            Here's another (less precise) approach:



            First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel (1)



            Let's assume oxygen density as 1,1417 (2) and RP-1 density as 0,915 (average of 0.81 and 1.02 in (3)).



            So we have 245620*1,1417 = 280424 Kg of Oxygen and 146020*0,915 = 133608 Kg of RP-1.



            First stage burn time is 162s (4).



            So (280424+133608)/162 = 2555 Kg/s.



            Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers*, I think uhoh's answer is correct at the very least in the order of magnitude.



            By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.



            • I just took as good the first sources I found around. To make a better estimate, I would at least verify more carfully the actual RP-1 density and also have a look at the thrust level during the whole 162 seconds.
              Also note that some of the first stage fuel is kept for landing.





            share|improve this answer


























              up vote
              8
              down vote













              I think uhoh's answer (7607000/2570=2959 Kg/s) is in the ballpark.



              Here's another (less precise) approach:



              First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel (1)



              Let's assume oxygen density as 1,1417 (2) and RP-1 density as 0,915 (average of 0.81 and 1.02 in (3)).



              So we have 245620*1,1417 = 280424 Kg of Oxygen and 146020*0,915 = 133608 Kg of RP-1.



              First stage burn time is 162s (4).



              So (280424+133608)/162 = 2555 Kg/s.



              Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers*, I think uhoh's answer is correct at the very least in the order of magnitude.



              By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.



              • I just took as good the first sources I found around. To make a better estimate, I would at least verify more carfully the actual RP-1 density and also have a look at the thrust level during the whole 162 seconds.
                Also note that some of the first stage fuel is kept for landing.





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                I think uhoh's answer (7607000/2570=2959 Kg/s) is in the ballpark.



                Here's another (less precise) approach:



                First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel (1)



                Let's assume oxygen density as 1,1417 (2) and RP-1 density as 0,915 (average of 0.81 and 1.02 in (3)).



                So we have 245620*1,1417 = 280424 Kg of Oxygen and 146020*0,915 = 133608 Kg of RP-1.



                First stage burn time is 162s (4).



                So (280424+133608)/162 = 2555 Kg/s.



                Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers*, I think uhoh's answer is correct at the very least in the order of magnitude.



                By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.



                • I just took as good the first sources I found around. To make a better estimate, I would at least verify more carfully the actual RP-1 density and also have a look at the thrust level during the whole 162 seconds.
                  Also note that some of the first stage fuel is kept for landing.





                share|improve this answer














                I think uhoh's answer (7607000/2570=2959 Kg/s) is in the ballpark.



                Here's another (less precise) approach:



                First stage has 245,620 L of liquid oxygen and 146,020 L of RP-1 fuel (1)



                Let's assume oxygen density as 1,1417 (2) and RP-1 density as 0,915 (average of 0.81 and 1.02 in (3)).



                So we have 245620*1,1417 = 280424 Kg of Oxygen and 146020*0,915 = 133608 Kg of RP-1.



                First stage burn time is 162s (4).



                So (280424+133608)/162 = 2555 Kg/s.



                Considering that the engines won't be at their maximum thrust for the whole 162 period (they slow down at least during Max-Q I think) and the uncertainties on these numbers*, I think uhoh's answer is correct at the very least in the order of magnitude.



                By the way, using this calculation we get 1731 Kg/s for the Oxygen and 824 Kg/s for RP-1.



                • I just took as good the first sources I found around. To make a better estimate, I would at least verify more carfully the actual RP-1 density and also have a look at the thrust level during the whole 162 seconds.
                  Also note that some of the first stage fuel is kept for landing.






                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Sep 6 at 13:10

























                answered Sep 6 at 12:26









                BlueCoder

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