{{Short description|Proposed spaceflight launch system}} {{refimprove|date=June 2025}} {{Infobox rocket |name = Falcon X |image = |caption = |function = Re-usable orbital launch vehicle |manufacturer =SpaceX |country-origin = United States |cpl = |height = {{convert|55|m|ft|abbr=on}} |diameter = {{convert|6.0|m|ft|abbr=on}} |mass = |stages = 2 |LEO-payload = '''Normal:''' {{convert|38,000|kg|lb|abbr=on}} '''Heavy:'''{{convert|125,000|kg|lb|abbr=on}} |payload-location = |payload = |status = Proposed |sites = |launches = |success = <!-- Note these are labeled LAUNCH Successes, not mission successes. --> |fail = <!-- LAUNCH failures only to match label in Infobox. --> |boosters = 2 |diff = Falcon X Heavy |boosterengines = 3 x Merlin 2 |boosterthrust = {{convert|3,600,000|lb-f|kN|lk=on|abbr=on}}(sl) <ref name="commercialspace.pbworks.com">http://commercialspace.pbworks.com/f/SpaceX_Overview_TEM%20small.pptx{{Dead link | date=June 2025 | fix-attempted=yes}}</ref> |boosterSI ='''Sea level:''' 285 sec (- kN/kg)<br>'''Vacuum:''' 321 sec (- kN/kg)<ref name="ReferenceA">http://commercialspace.pbworks.com/f/Markusic%20-%20SpaceX%20Propulsion%20small.pptx{{Dead link | date=June 2025 | fix-attempted=yes}}</ref> |boostertime = Unknown |boosterfuel =LOX/RP-1 |stage1engines = 3 x Merlin 2 |stage1thrust = {{convert|3,600,000|lb-f|kN|lk=on|abbr=on}}(sl)<ref name="commercialspace.pbworks.com"/> |stage1SI = |stage1time = |stage1fuel = LOX/RP-1 |stage2engines = 1 Raptor |stage2thrust = {{convert|150,000|lb-f|kN|lk=on|abbr=on}} <ref name="ReferenceA"/> |stage2SI = '''Vacuum:''' 470.1 sec (- kN/kg)<ref name="NSFF"/> |stage2time = 345 seconds{{Citation needed|date=August 2010}} |stage2fuel = LOX/LH2 }} '''Falcon X''' was a proposed spaceflight launch system that uses rockets designed and manufactured by SpaceX. Like the Falcon 1 and Falcon 9 the first stage of this two-stage-to-orbit vehicle would have used liquid oxygen (LOX) and rocket-grade kerosene (RP-1) propellants and was intended to be reusable.<ref name=nsf20090112>[http://www.nasaspaceflight.com/2009/01/musk-ambition-spacex-aim-for-fully-reusable-falcon-9/ Musk ambition: SpaceX aim for fully reusable Falcon 9], ''NASAspaceflight.com'', 2009-01-12, accessed 2010-06-03. E. Musk Quotation: ''"By flight six we think it’s highly likely we’ll recover the first stage, and when we get it back we’ll see what survived through re-entry, and what got fried, and carry on with the process. ... That's just to make the first stage reusable, it'll be even harder with the second stage – which has got to have a full heatshield, it'll have to have deorbit propulsion and communication."''</ref> The second stage would use liquid oxygen (LOX) and liquid hydrogen (LH2) and be powered by the Raptor engine.
Multiple variants were planned with payloads to low Earth orbit of up to {{convert|38000|kg}} for the basic version and up to {{convert|125000|kg}} for the 3 core heavy, placing the Falcon X design in the heavy-lift to super heavy-lift range of launch systems.<ref name=NSFF>{{cite web|title=July 28 SpaceX presentations: Merlin 2, Falcon HLVs, Raptor, methane Merlin, etc|url=http://forum.nasaspaceflight.com/index.php?topic=22395.0|publisher=NASA Space Flight|accessdate=30 July 2010}}</ref>
== Design == The proposed base Falcon X would have been a two stage, LOX/RP-1, LOX/LH2, fueled launch vehicle. Its first stage would be powered by 3 SpaceX Merlin 2 rocket engines with 5.3 MN (1.2M lbf) sea-level thrust per engine for a total thrust on liftoff of approximately 16 MN (3.6 million lbf).<ref name="Falcon9Overview">{{cite news |url=http://www.spacex.com/falcon9.php |title=Falcon 9 Overview |date=8 May 2010 |publisher=SpaceX |archive-date=1 May 2013 |access-date=7 August 2010 |archive-url=https://web.archive.org/web/20130501002858/http://www.spacex.com/falcon9.php |url-status=dead }}</ref> The Falcon X first stage would likely of used a pyrophoric mixture of triethylaluminum-triethylborane (TEA-TEB) as a first-stage ignitor, as does the Falcon 9.<ref name=sfn20100602> [http://www.spaceflightnow.com/falcon9/001/status.html Mission Status Center, June 2, 2010, 1905 GMT], ''SpaceflightNow'', accessed 2010-06-02, Quotation: ''"The flanges will link the rocket with ground storage tanks containing liquid oxygen, kerosene fuel, helium, gaserous nitrogen and the first stage ignitor source called triethylaluminum-triethylborane, better known as TEA-TAB."''</ref>
The cancelled Falcon X Heavy configuration consists of a standard Falcon X with two additional Falcon X first stages acting as liquid strap-on boosters,<ref name=NSFF/> which is conceptually similar to EELV launchers such as the Delta IV Heavy and the future Atlas V HLV, and also to the Russian Angara carrier rocket.
The upper stage would be powered by a single Raptor engine which would use LOX/LH2, with an expansion ratio of 250:1 and throttle range of 50-100%. For added reliability of restart, the engine has dual redundant pyrophoric igniters (TEA-TEB).<ref name="Falcon9Overview"/> SpaceX had expressed hopes that both stages will eventually be reusable.<ref name=nsf20090112/>
The interstage, which would of connected the upper and lower stage for Falcon X, would be a carbon fiber aluminum core composite structure, scaling up designes used for the Falcon 1 and Falcon 9. Stage separation would occur via reusable separation collets and a pneumatic pusher system.{{Citation needed|date=August 2010}} The Falcon X tank walls and domes would be made from aluminum lithium alloy. SpaceX uses an all friction stir welded tank, the highest strength and most reliable welding technique available. The second stage tank of Falcon X is simply a shorter version of the first stage tank and uses most of the same tooling, material and manufacturing techniques, however using a different engine. This results in significant cost savings in vehicle production.
As with the company's smaller Falcon 1 and Falcon 9, the Falcon X launch sequence would of included a hold-down feature that allows full engine ignition and systems check before liftoff.{{Citation needed|date=August 2010}} After first stage engine start, the launcher would be held down and not released for flight until all propulsion and vehicle systems are confirmed to be operating normally.{{Citation needed|date=August 2010}} An automatic safe shut-down and unloading of propellant occurs if any abnormal conditions are detected.{{Citation needed|date=August 2010}}
Falcon X will have triple redundant flight computers and inertial navigation, with a GPS overlay for additional orbit insertion accuracy.
== Launch sites == Musk has expressed the opinion that NASA would be advised to retain SLC-39 for use by vehicles such as this.{{Citation needed|date=August 2010}}
== Launcher versions == {| class="wikitable" |- ! Version ! Falcon X ! Falcon X Heavy |- | '''Stage 0''' | align="right"| — | align="right"| 2 boosters with 3 × Merlin 2 each |- | '''Stage 1''' | align="right"| 3 × Merlin 2 | align="right"| 3 × Merlin 2 |- | '''Stage 2''' | align="right"| 1 × Raptor | align="right"| 1 × Raptor |- | '''Height'''<br/>(max; m) |align="right"| ~55 (large fairing) |align="right"| ~55 (large fairing) |- | '''Diameter'''<br/>(m) |align="right"| 8 |align="right"| 8 (large fairing) |- | '''Initial thrust'''<br/>(lb-f) |align="right"| 3.6M |align="right"| 10.8M |- | '''Takeoff weight'''<br/>(tonnes) |align="right"| 325 |align="right"| 885 |- | '''Fairing diameter'''<br/>(Inner; m) |align="right"| 6 |align="right"| 6 |- | '''Payload'''<br/>(LEO; lb) |align="right"| 38,000 |align="right"| 125,000 |- | '''Success ratio'''<br/>(successful/total) |align="right"| - |align="right"| - |}
== Initial descriptions == At an appearance in May 2004 before the U.S. Senate Committee on Commerce, Science and Transportation, Elon Musk testified, "Long term plans call for development of a heavy lift product and even a super-heavy, if there is customer demand. [...] Ultimately, I believe $500 per pound [of payload delivered to orbit] or less is very achievable."<ref>{{cite web |url=http://www.spaceref.com/news/viewsr.html?pid=12774 |date=May 5, 2004 |title=Space Shuttle and the Future of Space Launch Vehicles |author=Testimony of Elon Musk |publisher=U.S. Senate}}</ref>
SpaceX formally announced the Falcon X on 2010-07-28. A Falcon X medium was described as being capable of launching approximately {{convert|38000|lb|abbr=on}} to low Earth orbit.
== See also == *Kestrel *Merlin *Raptor *Falcon 1 *Falcon 5 *Falcon 9 *Falcon XX
== References == {{Reflist}}
{{SpaceX}}
Category:Cancelled space launch vehicles Category:Spacecraft design Category:SpaceX launch vehicles