مرلن (طراز محركات صواريخ)

Merlin 1C
	Merlin 1C under construction at SpaceX factory
بلد الأصل	الولايات المتحدة
الصانع	SpaceX
الاستخدام	Main stage engine, Upper stage engine
مركبة الإطلاق المقترنة	Falcon 9
محرك وقود سائل
الدافع	LOX / RP-1 (rocket grade kerosene)
الدورة	Gas-generator
الأداء
الدفع (فراغ)	480 kن (110,000 رطلق)
الدفع (SL)	420 kن (94,000 رطلق)
نسبة الدفع إلى الوزن	96
ضغط التجويف	6.77 Mبا (982 psi)
(فراغ)	304.8 s (3.0 km/s)
(SL)	275 s (2.6 km/s)
الأبعاد
الطول	2,920 mم (9.58 قدم)
الوزن الجاف	1,380 رطلs (630 kغ)

Merlin 1D
	Test firing at SpaceX McGregor's test stand of the Merlin 1D
بلد الأصل	الولايات المتحدة
الصانع	SpaceX
الاستخدام	Main stage engine, Upper stage engine
مركبة الإطلاق المقترنة	Falcon 9, Falcon Heavy
محرك وقود سائل
الدافع	LOX / RP-1 (rocket grade kerosene)
الدورة	gas-generator
الأداء
الدفع (فراغ)	914 kن (205,000 رطلق)
الدفع (SL)	845 kن (190,000 رطلق)
نسبة الدفع إلى الوزن	180.1
ضغط التجويف	9.7 Mبا (1,410 psi)
(فراغ)	311 seconds
(SL)	282 s (2.73 km/s)
الأبعاد
الوزن الجاف	1,030 رطلs (470 kغ)
المراجع
المراجع

Merlin is a family of rocket engines developed by SpaceX for use on its Falcon 1 and Falconتسعة launch vehicles. SpaceX also plans to use Merlin engines on its Falcon Heavy. 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.

The injector at the heart of Merlin is of the pintle type that was first used in the Apollo program for the lunar module landing engine (LMDE).

Propellants are fed via a single shaft, dual impeller turbopump. The turbo-pump 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.

Variants

Three versions of the Merlin 1C engine have been produced. The Merlin engine for Falcon 1 had a movable turbo-pump exhaust assembly which was used to provide roll control by vectoring the exhaust. The Merlin 1C engine for the Falconتسعة first stage is nearly identical to the variant used for the Falcon 1 except that the turbo-pump exhaust assembly is not movable. Finally, a Merlin 1C vacuum variant is used on the Falconتسعة second stage. This engine differs from the Falconتسعة first stage variant in that it uses a larger exhaust nozzle optimized for vacuum operation and can be throttled between 60 and 100 percent.

Revisions

Merlin 1A

SpaceX Merlin 1A

The initial version, the Merlin 1A, used an inexpensive, expendable, ablatively cooled carbon-fiber-reinforced polymer composite nozzle, and produced 340 kN (77,000 lbf) 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.

مرلن 1C

The Merlin 1C uses a regeneratively cooled nozzle and combustion chamber. The turbopump used is a Merlin 1B model with only slight alterations. It was fired with a full mission duty firing of 170 seconds in November 2007, first flew on a mission in August 2008, powered the "first [[private spaceflight|privately- [ك‍]developed]] liquid-fueled rocket to successfully reach orbit", Falcon 1 Flight 4, in September 2008, and powered the Falconتسعة on its maiden flight in June 2010.

Merlin Vacuum (1C)

Merlin 1C Vacuum engine at Hawthorne factory in 2008

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 2.7 مترs (9 قدم)-longniobium alloy expansion nozzle is radiatively cooled. The engine delivers a vacuum thrust of 411 kن (92,500 رطل_ق) and a vacuum specific impulse of 342 seconds. The first production Merlin Vacuum engine underwent a full duration orbital insertion firing (329 seconds) of the integrated Falconتسعة second stage on January 2, 2010. It was flown on the second stage for the inaugural Falconتسعة flight on June 4, 2010. At full power the Merlin Vacuum engine operates with the greatest efficiency ever for an American-made hydrocarbon rocket engine.

Merlin 1D

The Merlin 1D engine was developed by SpaceX in 2011–2012, with first flight in 2013. The Merlin 1D was originally (April 2011) designed for a sea level thrust of 620 kن (140,000 رطل_ق). In 2011, it was revealed that the engine would have a vacuum thrust of 690 kن (155,000 رطل_ق), a vacuum specific impulse (I_sp) of 310 s, an increased expansion ratio of 16 (as opposed to the previous 14.5 of the Merlin 1C) and chamber pressure in the "sweet spot" of 9.7 Mبا (1,410 psi). A new feature for the engine is the ability to throttle from 100% to 70%. Later refinements of the Merlin 1D have been operated down to 40% of full thrust.

Merlin 1D Vacuum

A vacuum version of the Merlin 1D engine was developed for the Falconتسعة v1.1 and the Falcon Heavy second stage.

Design

Engine control

SpaceX uses a dual-redundant design in the Merlin flight computers. The system uses three computers in each processing unit, each constantly checking on the others, to instantiate a fault-tolerant design. One processing unit is part of each of the ten Merlin engines (nine on first stage, one on second stage) used on a Falconتسعة launch.

Turbopump

The Merlin LOX/RP-1 turbopump used on Merlin engines 1A–1C was designed and developed by Barber-Nichols.

Production

اعتبارا من أغسطس 2011^[تحديث], 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 September 2013, SpaceX total manufacturing space had increased to nearly 93,000 متر مربعs (1,000,000 قدم²) and the factory had been configured to achieve a maximum production rate of up to 40 rocket cores per year, enough to use the 400 annual engines envisioned by the earlier engine plan. By October 2014, SpaceX announced it had manufactured the 100th Merlin 1D engine and that engines were now being produced at a rate of أربعة per week, soon to be increased to 5.

References

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^ Clark, Stephen (September 28, 2008). "Sweet Success at Last for Falcon 1 Rocket". Spaceflight Now. Retrieved April 6, 2011. the first privately- [ك‍]developed liquid-fueled rocket to successfully reach orbit.
^ Boyle, Alan (June 4, 2010). "Shuttle successor succeeds in first test flight". MSNBC. Retrieved June 5, 2010.
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^ SpaceX (March 10, 2009). "SpaceX Falcon 9 upper stage engine successfully completes full mission duration firing.". Press release. Archived from the original. You must specify the date the archive was made using the |archivedate= parameter. http://www.spacex.com/press/2012/12/19/spacex-falcon-9-upper-stage-engine-successfully-completes-full-mission-duration. Retrieved on March 12, 2009.
^ . SpaceX. January 2, 2010.
^ "SpaceX Falconتسعة Upper Stage Engine Successfully Completes Full Mission Duration Firing". SpaceX. March 10, 2009. Retrieved May 31, 2016.
^ Harwood, William (April 5, 2011). "World's biggest private space rocket planned". CBS. Retrieved April 5, 2011.
^ Lindsey, Clark S. (August 1, 2011). "SpaceX Merlin 1D". Archived from the original on October 11, 2012. Retrieved August 6, 2011.
^ https://twitter.com/elonmusk/status/728753234811060224
^ "SpaceX Falconتسعة product page". Retrieved November 1, 2015.
^ Svitak, Amy (November 18, 2012). "Dragon's "Radiation-Tolerant" Design". Aviation Week. Archived from the original on 2013-12-03. Retrieved November 6, 2013. "We've got computers in the Falcon 9, we've got three computers in one unit on each engine in the Falcon 9, so that's 30 computers right there."
^ "Merlin LOX/RP-1 Turbopump". website "Products" page: Rocket Engine Turbopumps. Barber-Nichols. Retrieved November 22, 2012.
^ "Production at SpaceX". SpaceX. September 24, 2013. Archived from the original on 2016-04-03. Retrieved September 30, 2013.
^ "SpaceX Completes 100th Merlin 1D Engine". SpaceX. October 22, 2014. Archived from the original on 2016-04-04. Retrieved October 16, 2014.