SpaceX Falcon қозғыштары: Merlin двигательдері

Rocket engine in SpaceX Falcon launch vehicles
the line of rocket engines developed by SpaceX
Merlin is a family of rocket engines developed by SpaceX for use on its Falcon 1, Falcon 9 and Falcon Heavy launch vehicles. Merlin engines use RP 1 and liquid oxygen as rocket propellants in a gas generator power cycle. The Merlin engine was originally designed for sea recovery and reuse, but since 2016 the entire Falcon 9 booster is recovered for reuse by landing vertically on a landing pad using one of its nine Merlin engines. The injector at the heart of Merlin is of the pintle type that was first used in the Apollo Lunar Module landing engine (LMDE). Propellants are fed by a single shaft, dual impeller turbopump. The turbopump also provides high pressure fluid for the hydraulic actuators, which then recycles into the low pressure inlet. This eliminates the need for a separate hydraulic drive system and means that thrust vectoring control failure by running out of hydraulic fluid is not possible.

The initial version, the Merlin 1A, used an inexpensive, expendable, ablatively cooled carbon fiber reinforced polymer composite nozzle and produced of thrust. The Merlin 1A flew only twice: first on March 24, 2006, when it caught fire and failed due to a fuel leak shortly after launch, and the second time on March 21, 2007, when it performed successfully. Both times the Merlin 1A was mounted on a Falcon 1 first stage. The SpaceX turbopump was an entirely new, clean sheet design contracted to Barber Nichols, Inc. in 2002, who performed all design, engineering analysis, and construction; the company had previously worked on turbopumps for the RS 88 (Bantam) and NASA Fastrac engine programs. The Merlin 1A turbopump used a unique friction welded main shaft, with Inconel 718 ends and an integral aluminum RP 1 impeller in the middle. The turbopump housing was constructed using investment castings, with Inconel at the turbine end, aluminum in the center, and 300 series stainless steel at the LOX end. The turbine was a partial admission (i. e., working fluid is only admitted through part of the rotation of the turbine; an arc, not the whole circumference) impulse design and turned at up to 20,000 rpm, with a total weight of .

On March 10, 2009, a SpaceX press release announced successful testing of the Merlin Vacuum engine. A variant of the 1C engine, Merlin Vacuum features a larger exhaust section and a significantly larger expansion nozzle to maximize the engine's efficiency in the vacuum of space. Its combustion chamber is regeneratively cooled, while the 9 feet (3 m) The first production Merlin Vacuum engine underwent a full duration orbital insertion firing (329 seconds) of the integrated Falcon 9 second stage on January 2, 2010. It was flown on the second stage for the inaugural Falcon 9 flight on June 4, 2010. At full power and as of March 10, 2009, the Merlin Vacuum engine operates with the greatest efficiency of any American made hydrocarbon fueled rocket engine. An unplanned test of a modified Merlin Vacuum engine was made in December 2010. Shortly before the scheduled second flight of the Falcon 9, two cracks were discovered in the 9 feet (3 m) niobium alloy sheet nozzle of the Merlin Vacuum engine. The engineering solution was to cut off the lower 1.22 m of the nozzle and launch two days later, as the extra performance that would have been gained from the longer nozzle was not necessary to meet the objectives of the mission. The modified engine successfully placed the second stage into an orbit of altitude.

The Merlin 1D engine was developed by SpaceX between 2011 and 2012, with first flight in 2013. The design goals for the new engine included increased reliability, improved performance, and improved manufacturability. In 2011, performance goals for the engine were a vacuum thrust of , a vacuum specific impulse (Isp) of , an expansion ratio of 16 (as opposed to the previous 14.5 of the Merlin 1C) and chamber pressure in the "sweet spot" of Merlin 1D was originally designed to throttle between 100% and 70% of maximal thrust; however, further refinements since 2013 now allow the engine to throttle to 40%. The basic Merlin fuel/oxidizer mixture ratio is controlled by the sizing of the propellant supply tubes to each engine, with only a small amount of the total flow trimmed out by a "servo motor controlled butterfly valve" to provide fine control of the mixture ratio. On November 24, 2013, Elon Musk stated that the engine was actually operating at 85% of its potential, and they anticipated to be able to increase the sea level thrust to about and a thrust to weight ratio of 180. This version of the Merlin 1D was used on Falcon 9 Full Thrust and first flew on Flight 20. In May 2016, SpaceX announced plans to further upgrade the Merlin 1D by increasing vacuum thrust to and sea level thrust to ; according to SpaceX, the additional thrust will increase the Falcon 9 LEO payload capability to about 22 metric tons on a fully expendable mission. SpaceX also noted that unlike the previous Full Thrust iteration of the Falcon 9 vehicle, the increase in performance is solely due to upgraded engines, and no other significant changes to the vehicle are publicly planned. In May 2018, ahead of the first flight of Falcon 9 Block 5, SpaceX announced that the goal had been achieved. The Merlin 1D is now close to the sea level thrust of the retired Rocketdyne H 1 / RS 27 engines used on Saturn I, Saturn IB, and Delta II. On 23 February 2024, one of the nine Merlin engines powering that launch flew its 22nd mission, which was at the time the flight leading engine. It is already the most flown rocket engine to date, surpassing Space Shuttle Main Engine no. 2019's record of 19 flights.

The March 18, 2020, launch of Starlink satellites on board a Falcon 9 experienced an early engine shutdown on ascent. The shutdown occurred 2 minutes 22 seconds into the flight and was accompanied with an "event" seen on camera. The rest of the Falcon 9 engines burned longer and did deliver the payload to orbit. However, the first stage was not successfully recovered. In a subsequent investigation SpaceX found that isopropyl alcohol, used as cleaning fluid, was trapped and ignited, causing the engine to be shut down. To address the issue, in a following launch SpaceX indicated that the cleaning process was not done. On October 2, 2020, the launch of a GPS III satellite was aborted at T 2 seconds due to a detected early startup on 2 of the 9 engines on the first stage. The engines were removed for further testing and it was found that a port in the gas generator was blocked. After removing the blockage the engines started as intended. After this, SpaceX inspected other engines across its fleet and found that two of the engines on the Falcon 9 rocket intended for the Crew 1 launch also had this problem. Those engines were replaced with new M1D engines. On February 16, 2021, on Falcon 9 flight 108 launching Starlink satellites, an engine shut down early due to hot exhaust gasses passing through a damaged heat shielding cover. The mission was a success, but the booster could not be recovered.

A vacuum version of the Merlin 1D engine was developed for the Falcon 9 v1.1 and the Falcon Heavy second stage. As of 2020, the thrust of the Merlin 1D Vacuum is with a specific impulse of 348 seconds, the highest specific impulse ever for a U. S. hydrocarbon rocket engine. The increase is due to the greater expansion ratio afforded by operating in vacuum, now 165:1 using an updated nozzle extension. The engine can throttle down to 39% of its maximum thrust, or Based on mission requirements, they are Medium Coast & Long Coast kits, i. e., depending on the number of helium bottles for pressurization, added batteries for power and other hardware to make sure that the fuel and stages systems operate as long as needed. Transporter 7 mission launch debuted a new MVac nozzle extension design or variant aimed at increasing cadence and reducing costs. This new nozzle extension is shorter and, as a result, decreases both performance and material usage. This nozzle is only used on lower performance missions, as with this nozzle, the MVac engine produces 10% less thrust in space. The nozzle decreases the amount of material needed by 75%; this means that SpaceX can launch over three times as many missions with the same amount of rare niobium metal as with the longer design.

The Merlin LOX/RP 1 turbopump used on Merlin engines 1A–1C was designed and developed by Barber Nichols. It spins at 36,000 revolutions per minute, delivering .

The LOX/RP 1 turbopump on each Merlin engine is powered by a fuel rich open cycle gas generator similar to that used in the Apollo era Rocketdyne F 1 engine.

as of 2011, SpaceX was producing Merlin engines at the rate of eight per month, planning eventually to raise production to about 33 engines per month (or 400 per year). By October 2014, SpaceX announced that it had manufactured the 100th Merlin 1D engine and that engines were now being produced at a rate of four per week, soon to be increased to five. In February 2016, SpaceX indicated that the company will need to build hundreds of engines a year in order to support a Falcon 9/Falcon Heavy build rate of 30 rocket cores per year by the end of 2016. Each Falcon 9 booster uses nine Merlin engines, and the second stage uses one Merlin vacuum engine. The second stage is expended, so each launch consumes one Merlin Vacuum engine. SpaceX designed the booster with its engines to be recovered for reuse by propulsive landing, and the first recovered booster was reused in March 2017. By 2020, only five of the 26 Falcon 9 launched that year used new boosters. By 2021, only two of the 31 Falcon 9 launches used new boosters.

At the American Institute of Aeronautics and Astronautics Joint Propulsion conference on July 30, 2010, SpaceX McGregor rocket development facility director Tom Markusic shared some information from the initial stages of planning for a new engine. SpaceX’s Merlin 2 LOX/RP 1 fueled engine on a gas generator cycle, capable of a projected of thrust at sea level and in a vacuum and would provide the power for conceptual super heavy lift launch vehicles from SpaceX, which Markusic dubbed Falcon X and Falcon XX. Such a capability, if built, would have resulted in an engine with more thrust than the F 1 engines used on the Saturn V.

Conceived to be potentially used on more capable variants of the Falcon 9 Heavy, Markusic indicated that the Merlin 2 "could be qualified in three years for $1 billion". By mid August, SpaceX CEO Elon Musk clarified that while the Merlin 2 engine architecture was a key element of any effort SpaceX would make toward their objective of "super heavy lift" launch vehicles—and that SpaceX did indeed want to "move toward super heavy lift"—the specific potential design configurations of the particular launch vehicles shown by Markusic at the propulsion conference were merely conceptual "brainstorming ideas", just a "bunch of ideas for discussion." Since the original discussion, no work on any "Merlin 2" kerolox engine has been pursued and made public. At the 2011 Joint Propulsion Conference, Elon Musk stated that SpaceX were instead working towards a potential staged cycle engine. In October 2012, SpaceX publicly announced concept work on a rocket engine that would be "several times as powerful as the Merlin 1 series of engines, and won't use Merlin's RP 1 fuel". They indicated that the large engine was intended for a new SpaceX rocket, using multiple of these large engines could notionally launch payload masses of the order of to low Earth orbit. The forthcoming engine currently under development by SpaceX has been named "Raptor". Raptor will use liquid methane as a fuel, and was stated as having a sea level thrust of Since the initial announcement of Raptor, Musk has updated the specification to approximately —about one third the original published figure—based on the results of optimizing for thrust to weight ratio.