Revisions Merlin (rocket engine family)

1 revisions

1.1 merlin 1a
1.2 merlin 1b
1.3 merlin 1c
1.4 merlin vacuum (1c)
1.5 merlin 1d
1.6 merlin 1d vacuum

revisions
merlin 1a

spacex merlin 1a

the initial version, merlin 1a, used inexpensive, expendable, ablatively cooled carbon-fiber-reinforced polymer composite nozzle, , produced 340 kn (77,000 lbf) of thrust. merlin 1a flew twice: first on march 24, 2006, when caught fire , failed due fuel leak shortly after launch, , second time on march 21, 2007, when performed successfully. both times merlin 1a mounted on falcon 1 first stage.

the spacex turbopump entirely new, clean sheet design contracted barber-nichols, inc. in 2002 performed design, engineering analysis, , construction; company had worked on turbopumps rs-88 (bantam) , nasa fastrac engine programs. merlin 1a turbopump used unique friction-welded main shaft, inconel 718 ends , integral aluminum rp-1 impeller in middle. turbopump housing constructed using investment castings, inconel @ turbine end, aluminum in center, , 300-series stainless steel @ lox end. turbine partial-admission impulse design , turned @ 20,000 rpm, total weight of 150 lb.

merlin 1b

the merlin 1b rocket engine upgraded version of merlin 1a engine. turbopump upgrades handled barber-nichols, inc. spacex. intended falcon 1 launch vehicles, capable of producing 380 kn (85,000 lbf) of thrust @ sea level, , 420 kn (95,000 lbf) in vacuum, , performing specific impulse of 261 seconds @ sea level , 303 seconds in vacuum. merlin 1b enhanced on 1a turbine upgrade, increasing power output 1,500 kw (2,000 hp) 1,900 kw (2,500 hp). turbine upgrade accomplished adding additional nozzles, turning partial-admission design full admission. enlarged impellers both rp-1 , lox part of upgrade. model turned @ faster 22,000 rpm , developed higher discharge pressures. turbopump weight unchanged @ 150 lb. notable change on 1a move tea-teb (pyrophoric) ignition on torch ignition.

initial use of merlin 1b on falcon 9 launch vehicle, on first stage there have been cluster of 9 of these engines. due experience falcon 1 s first flight, spacex moved merlin development merlin 1c, regeneratively cooled. therefore, merlin 1b never used on launch vehicle.

merlin 1c

three versions of merlin 1c engine produced. merlin engine falcon 1 had movable turbopump exhaust assembly used provide roll control vectoring exhaust. merlin 1c engine falcon 9 first stage identical variant used falcon 1, although turbopump exhaust assembly not movable. finally, merlin 1c vacuum variant used on falcon 9 second stage. engine differs falcon 9 first stage variant in uses larger exhaust nozzle optimized vacuum operation , can throttled between 60 , 100 percent.

the merlin 1c uses regeneratively cooled nozzle , combustion chamber. turbopump used merlin 1b model slight alterations. fired full mission duty firing of 170 seconds in november 2007, first flew on mission in august 2008, powered first privately-developed liquid-fueled rocket reach orbit , falcon 1 flight 4, in september 2008, , powered falcon 9 on maiden flight in june 2010.

as configured use on falcon 1 vehicles, merlin 1c had sea level thrust of 350 kn (78,000 lbf), vacuum thrust of 400 kn (90,000 lbf) , vacuum specific impulse of 304 seconds. in configuration, engine consumed 140 kg (300 lb) of propellant per second. tests have been conducted single merlin 1c engine running total of 27 minutes (counting duration of various tests), equals ten complete falcon 1 flights. merlin 1c chamber , nozzle cooled regeneratively 45 kilograms (100 lb) per second of kerosene flow , able absorb 10 megawatts (13,000 hp) of thermal heat energy.

a merlin 1c first used part of unsuccessful third attempt launch falcon 1. in discussing failure, elon musk noted, flight of our first stage, new merlin 1c engine used in falcon 9, picture perfect. merlin 1c used in successful fourth flight of falcon 1 on september 28, 2008.

on october 7, 2012, merlin 1c (engine no. 1) of crs-1 mission experienced anomaly @ t+00:01:20 appears on crs-1 launch video flash. failure occurred vehicle achieved max-q (maximum aerodynamic pressure). spacex s internal review found engine shut down after sudden pressure loss , aerodynamic shell destroyed, generating debris seen in video; engine did not explode, spacex ground control continued receive data throughout flight. primary mission unaffected anomaly due nominal operation of remaining 8 engines , onboard readjustment of flight trajectory, secondary mission payload failed achieve orbit due safety protocols in place prevent collisions iss.

spacex planning develop 560 kn version of merlin 1c used in falcon 9 block ii , falcon 1e boosters. engine , these booster models dropped in favor of more advanced merlin 1d engine , longer falcon 9 v1.1 booster.

merlin vacuum (1c)

merlin 1c vacuum engine @ hawthorne factory in 2008

on march 10, 2009, spacex press release announced successful testing of merlin vacuum engine. variant of 1c engine, merlin vacuum features larger exhaust section , larger expansion nozzle maximize engine s efficiency in vacuum of space. combustion chamber regeneratively cooled, while 2.7 metres (9 ft)-long niobium alloy expansion nozzle radiatively cooled. engine delivers vacuum thrust of 411 kn (92,500 lbf) , vacuum specific impulse of 342 seconds. first production merlin vacuum engine underwent full duration orbital insertion firing (329 seconds) of integrated falcon 9 second stage on january 2, 2010. flown on second stage inaugural falcon 9 flight on june 4, 2010. @ full power, merlin vacuum engine operates greatest efficiency ever american-made hydrocarbon rocket engine.

an unplanned test of modified merlin vacuum engine made in december 2010. shortly before scheduled second flight of falcon 9, 2 cracks discovered in 2.7 metres (9 ft)-long niobium-alloy-sheet nozzle of merlin vacuum engine. engineering solution cut off lower 1.2 metres (4 ft) of nozzle , launch 2 days later, performance have been gained longer nozzle not necessary meet objectives of mission. shortened nozzle, engine placed second-stage orbit of 11,000 kilometres (6,800 mi) altitude.

merlin 1d

the merlin 1d engine developed spacex in 2011–2012, first flight in 2013. merlin 1d (april 2011) designed sea level thrust of 620 kn (140,000 lbf). in 2011, revealed engine have vacuum thrust of 690 kn (155,000 lbf), vacuum specific impulse (isp) of 310 s, increased expansion ratio of 16 (as opposed previous 14.5 of merlin 1c) , chamber pressure in sweet spot of 9.7 mpa (1,410 psi). new feature engine ability throttle 100% 70%. later refinements of merlin 1d have been operated down 40% of full thrust.

the design goals new engine included increased reliability (increased fatigue life , increased chamber , nozzle thermal margins), improved performance (thrust design objective 140,000 pounds-force (620 kn) , 70-100 percent throttle capability), , improved manufacturability (lower parts count , fewer labor hours).

when engine testing completed in june 2012, spacex stated engine had completed full mission duration test firing of 185 seconds delivering 650 kn (147,000 lbf) of thrust , confirming expected thrust-to-weight ratio exceeded 150. of november 2012 merlin section of falcon 9 page describes engine having sea level thrust of 650 kn (147,000 lbf), vacuum thrust of 720 kn (161,000 lbf), sea level specific impulse (isp) of 282 s , vacuum specific impulse (isp) of 311 s. engine has highest specific impulse ever achieved gas-generator cycle kerosene rocket engine.

on march 20, 2013, spacex announced merlin 1d engine had achieved flight qualification. in june 2013, first orbital flight vehicle use merlin 1d, falcon 9 1.1 first stage, completed development testing.

the first flight of falcon 9 merlin 1d engines launched cassiope satellite canadian space agency. cassiope, 360 kg (800 lb) weather research , communications satellite, launched near-polar low earth orbit (leo). second flight geosynchronous transfer orbit (gto) launch of ses-8.

the basic merlin fuel/oxidizer mixture ratio controlled sizing of propellant supply tubes each engine, small amount of total flow trimmed out servo-motor-controlled butterfly valve provide fine control of mixture ratio.

on november 24, 2013, during joint teleconference of ses , spacex regarding ses-8 launch, elon musk stated engine operating @ 85% of potential, , anticipated able increase sea level thrust 730 kn (165,000 lbf). in june 2015 tom mueller answered question merlin 1d thrust-weight ratios on quora. specified merlin 1d has mass of 470 kg (1,030 lb) including thrust actuators, current vacuum thrust of 723 kn (162,500 lbf), , uprated vacuum thrust of 825 kn (185,500 lbf), without increased mass. these figures provide current thrust-weight ratio of ≈158 , uprated thrust-weight ratio of ≈180. uprated engines used on falcon 9 full thrust, iteration of falcon 9 launch vehicle multiple other changes. vehicle launched first on flight 20 eleven orbcomm og2 satellites.

in may 2016, spacex announced plans further upgrade merlin 1d increasing vacuum thrust 914 kn , sea-level thrust 845 kn; according spacex, additional thrust increase falcon 9 leo payload capability 22 metric tons on expendable mission. spacex noted unlike previous full thrust iteration of falcon 9 vehicle, increase in performance solely due uprated engines , no other significant changes vehicle publicly planned.

merlin 1d vacuum

a vacuum version of merlin 1d engine developed falcon 9 v1.1 , falcon heavy second stage.

in late 2012, elon musk tweeted image of merlin 1d vacuum firing on test stand , stated: test firing our advanced engine, merlin 1d vacuum, @ 80 tons of thrust. official spacex s falcon 9 product page lists thrust of merlin vacuum on second stage of launcher @ 934 kn (210,000 lbf) , specific impulse of 348 seconds in vacuum conditions. increase due greater expansion ratio afforded operating in vacuum, 165:1 using updated nozzle extension.

according spacex-released payload user s guide, merlin 1d vacuum can throttle down 39% of maximum thrust, or 360 kn (81,000 lbf).