Quote from: Davidthefat on 07/29/2013 02:34 amQuote from: justineet on 07/29/2013 02:26 amQuote from: Davidthefat on 07/28/2013 09:25 pmI'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rRThe reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators. The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.edit: unless they shortened it dramatically.Well, I'll be... It does seem they have shortened it significantly from the last revision.Can compare it with the 1C in the picture below...quite shorter..overall I think more compact and smaller..http://www.popularmechanics.com/cm/popularmechanics/images/WZ/spacex-factory-06-0112-lgn-87860333.jpg
Quote from: justineet on 07/29/2013 02:26 amQuote from: Davidthefat on 07/28/2013 09:25 pmI'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rRThe reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators. The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.edit: unless they shortened it dramatically.Well, I'll be... It does seem they have shortened it significantly from the last revision.
Quote from: Davidthefat on 07/28/2013 09:25 pmI'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rRThe reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators. The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rRThe reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.
Quote from: justineet on 07/29/2013 10:06 pmQuote from: Davidthefat on 07/29/2013 02:34 amQuote from: justineet on 07/29/2013 02:26 amQuote from: Davidthefat on 07/28/2013 09:25 pmI'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rRThe reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators. The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.edit: unless they shortened it dramatically.Well, I'll be... It does seem they have shortened it significantly from the last revision.Can compare it with the 1C in the picture below...quite shorter..overall I think more compact and smaller..http://www.popularmechanics.com/cm/popularmechanics/images/WZ/spacex-factory-06-0112-lgn-87860333.jpgThis picture shows the M1Ds ready for static testing, with its shorter exhaust. http://i.imgur.com/lj9zTrL.jpg
From the new spaceX website "SpaceX's Merlin vacuum engine has the highest vaccum specific impulse (isp)--a measure of engine efficiency--of any American liquid oxygen/kerosene engine with a vaccum isp of 340 seconds"
Interesting, wikipedia, sourcing a spacex press release, claims the M1c Vac had an ISP of 342 seconds.
(801 kN/716 kN)*311 s = 348 s(801 kN/654 kN)*282 s = 345 s
Quote from: Arthree on 07/31/2013 04:43 am(801 kN/716 kN)*311 s = 348 s(801 kN/654 kN)*282 s = 345 sI believe the vac thrust of Merlin 1D is ~741 kN, from spacex.com; 1500000 lbf / 9 ~ 166.5 klbf ~ 741 kN. Instead of 311s for Vac ISP for Merlin 1D (non Vac), we use 320; Merlin 1D Vac ISP: 1500000/1323000 * 282 = 319.73 (total Vac/SL thrust, from spacex.com)This would also make the calculation match better; (801 kN/741 kN)*319.73 s = 345.6 s(801 kN/654 kN)*282 s = 345.4 sDifference probably due to rounding.
I would guess that the numbers posted on the F9/FH pages (1,500,000 lbs/6672 kN per core) are either rounding errors or wishful thinking on SpaceX's part.Or they somehow managed 9 more seconds of vacuum Isp without affecting SL performance.
Doesn't it depend on the stage? AFAIK, the 2nd stage Merlin 1D is optimized for vacuum, with larger nozzle.
the 2nd stage merlin is optimized for vacuum and its isp = 340 ssource: http://www.spacex.com/falcon9 - you can see the info, when you click the "inside the interstage" blue text
If we assume the 340s number is correct (which some say would be lower than the Merlin 1C, hence unreliable), the 1DVac thrust should be 177 klbf, which in itself is not unreasonable to round to 180 klbf.