Merlin is a family of rocket engines developed by SpaceX for use on Falcon 1, Falcon 9 and Falcon Heavy launch vehicles. The Merlin machine uses RP-1 and liquid oxygen as a rocket propellant in the gas-generator power cycle. The Merlin engine was originally designed for the recovery and reuse of the sea.
Injector at the heart of Merlin is the kind of pintle first used in the Apollo program for moon module landing (LMDE).
The propellant is fed through a single shaft, double impeller turbopump. Turbugs also provide high pressure fluids for hydraulic actuators, which then recycle into low-pressure inlets. This eliminates the need for separate hydraulic drive systems and means the failure of thrust vector control with hydraulic fluid runs is not possible.
Video Merlin (rocket engine family)
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Merlin 1A
The initial version, Merlin 1A , uses a carbon fiber reinforced polymer nozzle that is reinforced, removed, ablative, and produces 340 dB (76,000 lbf) thrust. Merlin 1A only flew twice: First on March 24, 2006, when it burned and failed due to a fuel leak shortly after launch, and the second time on March 21, 2007, when it was successful. Both times Merlin 1A is installed in the first phase of Falcon 1.
Turbochar SpaceX is a completely new and clean sheet design contracted by Barber-Nichols, Inc. in 2002 which undertakes all design, engineering, analysis and construction; the company has previously worked on turbopumps for the RS-88 (Bantam) machine program and the NASA Fastrac program. The Merlin 1A turbopump uses a unique main axle welded friction, with an Inconel 718 ending and an integral aluminum RP-1 impeller in the middle. Turbopump housing is built using investment castings, with Inconel at the end of turbine, aluminum in the center, and 300-series stainless steel at the end of LOX. The turbine is a partially impulse design and is turned on up to 20,000 rpm, with a total weight of 150 lb.
Merlin 1B
The rocket engine Merlin 1B is the latest version of the Merlin 1A engine. The turbopump upgrade is handled by Barber-Nichols, Inc. for SpaceX. It was intended for the Falcon 1 launch vehicle, capable of generating 380 kN (85,000 lbf) thrust at sea level, and 420 kN (95,000 lbf) in a vacuum, and performing with specific impulses 261 seconds at sea level and 303 seconds in a vacuum. The Merlin 1B is improved through 1A with turbine upgrades, increasing power output from 1,500 kW (2,000 hp) to 1,900 kW (2,500 hp). The turbine upgrade is done by adding additional nozzles, changing the previous partial reception design to full admission. The slightly enlarged impeller for RP-1 and LOX is part of the upgrade. This model is changing faster 22,000 rpm and develops higher discharge pressure. The heavy turbopump is unchanged at 150 pounds. Another important change over 1A is the displacement to the TEA-TEB (pyrophoric) ignition over the ignition of the torch.
The initial use of Merlin 1B is to be in the Falcon 9 launch vehicle, which in the first stage there will be a group of nine of these machines. Due to the experience of Falcon 1's first flight, SpaceX shifted Merlin's development to Merlin 1C, which is regeneratively cooled. Therefore, Merlin 1B was never used on a launch vehicle.
Merlin 1C
Three machine versions Merlin 1C are produced. The Merlin engine for Falcon 1 has an actuated turbopump exhaust assembly that is used to provide roll control with a vector exhaust. The 1C Merlin 1C engine for the first 9 Falcon stages is almost identical to the variant used for Falcon 1, although the turbopump exhaust assembly can not be moved. Finally, the Merlin 1C vacuum variant is used in the second phase of Falcon 9. This machine is different from the first phase variant of the Falcon 9 because it uses a larger exhaust nozzle that is optimized for vacuum operation and can be banned between 60 and 100 percent.
The Merlin 1C uses a nozzle and regenerated coolant regeneration chamber. Turbo used is Merlin 1B model with little change. Fired with a full-fledged mission mission of shooting 170 seconds in November 2007, first flew on a mission in August 2008, powered "the first privately-fueled liquid rocket developed to successfully achieve orbit", Falcon 1 Flight 4, in September 2008, and supported Falcon 9 on its maiden flight in June 2010.
As configured for use on Falcon 1 vehicles, Merlin 1C has a thermal stroke of 350 kN (78,000 lbf), 400 kN (90,000 lbf) vacuum impulse and a vacuum-specific impulse of 304 seconds. In this configuration, the machine consumes 140 kg kg (300 lb) of propellant per second. The test has been performed with a single Merlin 1C engine successfully running a total of 27 minutes (counting together the duration of various tests), which equals ten complete Falcon 1 flights. The Merlin 1C space and nozzle are regeneratively cooled with 45 kilograms (100 pounds) per second of kerosene flow and are capable of absorbing 10 megawatts (13,000 hp) of thermal heat energy.
Merlin 1C was first used as part of a third attempt that failed to launch Falcon 1. In discussing failure, Elon Musk noted, "Our first-stage flight, with the new Merlin 1C engine to be used at Falcon 9, is a picture perfect." Merlin 1C was used in the fourth flight Falcon 1 on September 28, 2008.
On October 7, 2012, Merlin 1C (Engine No. 1) of the CRS-1 mission underwent an anomaly at T 00: 01:20 which appeared on the CRS-1 launch video as flash. Failure occurs when the vehicle reaches max-Q (maximum aerodynamic pressure). The internal review of SpaceX found that the engine was shut down after abrupt pressure loss and only aerodynamic shell was destroyed, resulting in the debris seen in the video; the engine does not explode, because the land control of SpaceX continues to receive data from all flights. The main mission is unaffected by the anomalies due to nominal operations of the remaining eight engines and the onboard reconfiguring of the flight path, but secondary mission loads fail to reach its orbital targets because of on-site safety protocols to prevent collisions with the ISS. This protocol prevents the second firing of the upper stage for secondary charges.
SpaceX plans to develop 560 kN (130,000 lbf) Merlin 1C version for use in Falcon 9 Block II and Falcon 1E boosters. This engine and this reinforcing model is derived for the more advanced Merlin 1D engine and again Falcon 9 v1.1 amplifier.
Merlin Vacuum (1C)
On March 10, 2009, the press release SpaceX announced the successful test of the Merlin Vacuum machine. The 1C engine variant, Merlin Vacuum has a larger exhaust section and a much larger expansion nozzle to maximize engine efficiency in a vacuum. The combustion chamber is cooled regeneratively, while the 2.7 meter (9Ã, ft) -long niobium alloy expansion nozzle is radiologically cooled. The engine provides a 411 kN (92,500 lbf) vacuum boost and a 342 second vacuum special impulse. The first production of the Merlin Vacuum engine underwent an insertion of full orbital duration (329 seconds) from the second integrated Falcon 9 stage on January 2, 2010. The aircraft was flown in the second phase for the inaugural Falcon 9 flight on June 4, 2010. At full power, the Merlin Vacuum engine operates with the greatest efficiency for American-made hydrocarbon rocket engines.
An unplanned test of the modified Merlin Vacuum engine was made in December 2010. Shortly before the scheduled second Falcon 9 flight, two cracks were found at 2.7 meters (9Ã, ft) -long niobium-alloy-sheet nozzle from the Merlin Vacuum machine. The engineering solution is to cut the lower 1.2 meters (4 feet) from the nozzle and launch two days later, because the extra performance that will be gained from the longer nozzle is not required to meet mission objectives. Even with the shortened nozzle, the engine puts the second stage into an orbit of 11,000 kilometers (6,800Ã, mi).
Merlin 1D
The 1D Merlin engine was developed by SpaceX in 2011-2012, with the first flight in 2013. Merlin 1D originally (April 2011) is designed to thrust sea surface 620 kN (140,000 lbf). In 2011, it was revealed that the engine would have a 690 kN (155,000 lbf) vacuum thrust, a special vacuum impulse (I sp ) of 310 s, an expansion expansion ratio of 16 (as opposed to the previous 14.5 of Merlin 1C) and room pressure in the "sweet spot" of 9.7 MPa (1,410 psi). New features for the machine is the ability to bark from 100% to 70%. Then Merlin 1D improvements have been operated up to 40% of full thrust.
Design goals for new engines include increased reliability (increased fatigue life and increased space and nozzle heat margins), performance improvements (thrust 140,000 pound-force (620 kN) design goals and 70-100 percent throttle capability), and improved manufacturability (number of parts down and fewer work hours).
When engine testing is completed in June 2012, SpaceX states that the machine has completed the full test of the 185 second firing test duration giving 650 dB (147,000 lbf) thrust and also confirming the expected thrust-to-weight ratio exceeding 150. In November 2012, Merlin of the Falcon 9 page describes the engine having a sea level thrust of 650 kN (147,000 lbf), a vacuum pressure of 720 kN (161,000 lbf), a special impulse at sea level (I sp ) of 282 and a special vacuum impulse ( I sp ) of 311 s. The machine has the highest specific impulse ever achieved for a gas cycle cycle-gas cycle generator cycle.
On March 20, 2013, SpaceX announced the 1D Merlin engine has reached flight qualification. In June 2013, the first orbital flight vehicle using Merlin 1D, Falcon 9 1.1 first stage, completed development testing.
The first Falcon 9 flight with the 1D Merlin engine launched the CASSIOPE satellite for the Canadian Space Agency. CASSIOPE, a satellite research and communication satellite weighing 360 kg (800bb), was launched into a low Earth orbit near the pole (LEO). The second flight is the launch of geosynchronous orbit orbit (GTO) orbit from SES-8.
The fuel/oxidation ratio of the fuel mixture base is controlled by the size of the propellant supply tube to each machine, with only a small amount of the total stream being trimmed by the "servo-controlled butterfly valve" to provide good control over the mix ratio.
On November 24, 2013, during a joint SES and SpaceX joint teleconference on the launch of SES-8, Elon Musk stated that the engine actually operates at 85% of its potential, and they anticipate to be able to increase the sea surface thrust to around 730 kN (165,000 lbf). In June 2015, Tom Mueller answered the question of the weight ratio of the weight of Merlin 1D weight in Quora. He mentioned that Merlin 1D has a mass of 470 kg (1,030 Ib) including actuator thrust, current vacuum pressure of 723 kN (162,500 lbf), and an increased vacuum pressure of 825 kN (185,500 lbf), with no increase in mass. These numbers provide for the current thrust-weight ratio? 158 and the weight ratio elevated thrust 180? The upgraded engine is currently used on full thrust Falcon 9, a repetition of the Falcon 9 launch vehicle with some other changes. The vehicle was first launched on Flight 20 with eleven Orbcomm OG2 satellites.
In May 2016, SpaceX announced plans to further increase Merlin 1D by increasing vacuum pressure to 914 kN (205,000 lbf) and thrusting up to 845 kN (190,000 lbf); according to SpaceX, additional thrust will increase Falcon 9 LEO payload capability to about 22 metric tons on a fully removable mission. SpaceX also notes that unlike the previous Full Thrust iteration of the Falcon 9 vehicles, performance improvements are solely due to improved engines and no other significant changes to publicly planned vehicles.
In May 2018, just before the launch of Bangabandhu-1, Elon Musk announced that the 190,000 pound goal had been achieved. Merlin 1D is close to the sea level drive of a retired Rocketdyne H-1/RS-27 engine used on Saturn I, Saturn IB, and Delta II.
Merlin 1D Vacuum
The vacuum version of the 1D Merlin engine was developed for Falcon 9 v1.1 and Falcon Heavy in the second stage.
At the end of 2012, Elon Musk tweeted a picture of Merlin 1D Vacuum shooting up the test stand and stated: "Now test firing our most advanced engine, Merlin 1D Vacuum, at 80 tons of thrust." In 2018, the SpaceX's Falcon 9 product page contains the Vacuum Merlin thrust at the second stage of the launcher at 934 kN (210,000 lbf) and a 348-second specific impulse in vacuum. This increase is due to the greater expansion ratio provided by the operation in a vacuum, now 165: 1 using the updated nozzle extension.
According to the PayX User Guide released by SpaceX, Merlin 1D Vacuum can reduce up to 39% of its maximum thrust, or 360 kN (81,000 lbf).
Maps Merlin (rocket engine family)
Design
Machine control
SpaceX uses dual-redundant design on the Merlin aviation computer. The system uses three computers in each processing unit, each constantly checking the other, to instantiate the design of fault tolerance. One processing unit is part of each of the ten Merlin engines (nine in the first stage, one in the second stage) used on the Falcon 9 launch vehicle.
Turbopump
The Turbochar Merlin LOX/RP-1 used on the Merlin 1A-1C engine is designed and developed by Barber-Nichols.
Production
In August 2011, SpaceX produced a Merlin machine at a rate of eight per month, the final plan to increase production to about 33 machines per month (or 400 per year). In September 2013, SpaceX's total space production has risen to nearly 93,000 square meters (1,000,000 sq. Ft.) And the plant has been configured to achieve maximum production levels of up to 40 rocket cores per year, enough to use the 400 machines yearly estimated by the engine plan previous. In October 2014, SpaceX announced it has produced the 1D Merlin engine to-100 and the machine is now produced at a rate of 4 per week, soon to be increased to 5.
In June 2015, SpaceX produces the Merlin engine at a rate of four Merlin 1D engines per week, with total production capacity at the plant a maximum of five per week.
In February 2016, SpaceX indicated that the company would need to build hundreds of machines per year to support Falcon 9/Falcon Heavy build levels of 30 rocket cores per year by the end of 2016.
See also
- Draco (rocket engine) - Thruster SpaceX RCS.
- Kestrel (rocket engine) - SpaceX small top-level machine for Falcon 1.
- Falcon (rocket family) - SpaceX rockets exclusively use LOX/RP-1 launch vehicle engine.
- Raptor (family of rocket machines) - various SpaceX methane/LOX machines for the Interplanetary Transport System
- Comparison of orbital rocket engines
- Rocket engine
- Pintle injector
- TR-106 - Low Cost Pintle Machine (LCPE) using LOX/LH2 developed by TRW in 2000.
- TR-107 - The RP1 engine is developed under SLI for future reusable launch vehicles.
- RS-27A - The RP-1 machine used in the US Delta II launcher; Legacy Saturn 1B H-1.
- Rocketdyne F-1 - LOX/RP-1 main engine from the Saturn V rocket.
References
- Notes
External links
- Space Exploration Technologies Corporation
Source of the article : Wikipedia
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