# SpaceX Kestrel > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/SpaceX_Kestrel > Markdown URL: https://mediated.wiki/source/SpaceX_Kestrel.md > Source: https://en.wikipedia.org/wiki/SpaceX_Kestrel > Source revision: 1336638351 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) The **SpaceX Kestrel** was an [LOX](/source/Liquid_oxygen)/[RP-1](/source/RP-1) [pressure-fed](/source/Pressure-fed_engine) [rocket engine](/source/Rocket_engine). The Kestrel engine was developed in the 2000s by [SpaceX](/source/SpaceX) for upper stage use on the [Falcon 1](/source/Falcon_1) rocket. Kestrel is no longer being manufactured; the last flight of Falcon 1 was in 2009. Kestrel was built around the same [pintle](/source/Pintle_injector) architecture as the [SpaceX Merlin](/source/SpaceX_Merlin) engine but does not have a [turbopump](/source/Turbopump) and is fed only by tank pressure. Kestrel was [ablatively](/source/Ablation) cooled in the chamber and throat and [radiatively cooled](/source/Radiative_cooling) in the nozzle, which was fabricated from a high strength [niobium](/source/Niobium) alloy. As a metal, niobium is highly resistant to cracking compared to [carbon-carbon](/source/Reinforced_carbon%E2%80%93carbon). According to SpaceX, an impact from orbital debris or during stage separation might dent the metal but have no meaningful effect on engine performance.[4] [Helium](/source/Helium) pressurant efficiency is substantially increased via a titanium [heat exchanger](/source/Heat_exchanger) on the ablative/niobium boundary.[5] Thrust vector control is provided by electro-mechanical actuators on the engine dome for pitch and yaw. Roll control (and attitude control during [coast phases](/source/Coast_phase)) is provided by helium [cold gas thrusters](/source/Cold_gas_thruster). A [TEA](/source/Triethylaluminium)-[TEB](/source/Triethylborane) pyrophoric [ignition](/source/Rocket_ignition) system is used to provide restart capability on the upper stage and simplify design.[6] In a multi-manifested mission, this design would allow for drop off at different altitudes and inclinations. ## Kestrel 2 Enhancements to the design of the original Kestrel engine were planned, called the **Kestrel 2**.[7] The engine design was still [pressure-fed](/source/Pressure-fed_engine_(rocket)), and was supposed to fly on a newly designed second stage that used [Aluminium-lithium alloy](/source/Aluminium-lithium_alloy) [2195](/source/2195_aluminum_alloy), rather than the [2014 Aluminum](/source/2014_aluminum_alloy) used in the Falcon 1 second stage.[7] Engine changes were to include tighter tolerances to improve consistency, higher [Isp](/source/Specific_impulse), and lighter weight.[8] The Kestrel 2 did not remain in active development after the Falcon 1 was replaced by the much larger [Falcon 9 v1.0](/source/Falcon_9_v1.0) which used an improved [Merlin 1C](/source/Merlin_1C) for its upper stage. ## See also - [SpaceX Draco](/source/SpaceX_Draco) - [SpaceX Merlin](/source/SpaceX_Merlin) - [SpaceX Raptor](/source/SpaceX_Raptor) ## References 1. ["Falcon 1 Users Guide"](https://web.archive.org/web/20081001161902/http://www.spacex.com/Falcon1UsersGuide.pdf). SpaceX. 2008-09-28. Archived from [the original](http://www.spacex.com/Falcon1UsersGuide.pdf) on October 1, 2008. 1. ["SpaceX Falcon Data Sheet"](https://web.archive.org/web/20150119203838/http://www.spacelaunchreport.com/falcon.html). 2015-01-19. Archived from [the original](http://www.spacelaunchreport.com/falcon.html) on 19 January 2015. Retrieved 2024-12-27. 1. Wade, Mark. ["Kestrel"](http://www.astronautix.com/k/kestrel.html). *[Encyclopedia Astronautica](/source/Encyclopedia_Astronautica)*. [Archived](https://web.archive.org/web/20250527002905/http://www.astronautix.com/k/kestrel.html) 2025-05-27 at the Wayback Machine. Retrieved 2026-02-04. 1. Greg Zsidisin (23 March 2007). ["SpaceX Confirms Stage Bump On Demoflight 2"](http://www.spacedaily.com/reports/SpaceX_Confirms_Stage_Bump_On_Demoflight_2_999.html). Space Daily. Retrieved 2008-09-30. 1. ["Falcon 1 Flight Three Press Kit"](https://web.archive.org/web/20081001161901/http://www.spacex.com/SpaceX_F1-003_PressKit.pdf). SpaceX. Archived from [the original](http://www.spacex.com/SpaceX_F1-003_PressKit.pdf) on 2008-10-01. Retrieved 2008-09-30. 1. ["Space Exploration Technologies Corporation - Updates Archive"](https://web.archive.org/web/20071105080852/http://spacex.com/updates_archive.php?page=0205-0505). *SpaceX*. Archived from [the original](http://spacex.com/updates_archive.php?page=0205-0505) on 2007-11-05. Retrieved 2024-09-13. 1. Bjelde, Brian; Max Vozoff; Gwynne Shotwell (August 2007). ["The Falcon 1 Launch Vehicle: Demonstration Flights, Status, Manifest, and Upgrade Path"](http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1456&context=smallsat). *21st Annual AIAA/USU Conference on Small Satellites*. '***(SSC07 - III - 6). Retrieved 2013-12-06.*** 1. Bergin, Chris & Braddock Gaskill (2007-09-24). ["Elon Musk Q and A - Updates SpaceX status on Falcon and Dragon"](https://web.archive.org/web/20080529015150/http://www.nasaspaceflight.com/content/?cid=5237). NASAspaceflight.com. Archived from [the original](http://www.nasaspaceflight.com/content/?cid=5237) on 2008-05-29. Retrieved 2008-06-16. ## External links - [SpaceX Falcon engines page](https://web.archive.org/web/20110103230037/http://www.spacex.com/falcon1.php) --- Adapted from the Wikipedia article [SpaceX Kestrel](https://en.wikipedia.org/wiki/SpaceX_Kestrel) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/SpaceX_Kestrel?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.