Space Exploration Technologies Corporation better known as SpaceX was founded just 15 years ago by Elon Musk, the world famous entrepreneur and genius behind other notable ventures such as Tesla Motors, Solar City and others. The aerospace manufacturer and space transport company was started with modest goals such as reducing space transportation cost and enabling the colonization of Mars.
SpaceX has developed the Falcon launch vehicle family and the Dragon spacecraft family. Using these vehicles SpaceX has achieved things which just twenty years ago most people would not have thought possible for a private company. The Falcon launch vehicles are propelled by Merlin rocket engines which is a family of engines developed by SpaceX. The Merlin engine uses RP-1 and liquid oxygen as rocket propellants in a gas-generator cycle.
RP-1 which is also known either as Rocket Propellant-1, or Refined Petroleum-1, is a form of highly refined kerosene which bears a strong similarity to jet fuel. RP-1 has a lower specific impulse than liquid hydrogen but is cheaper to produce, far more stable at room temperature, and far denser which makes it significantly more powerful by volume than liquid hydrogen. RP-1 is most commonly burned using liquid oxygen as an oxidizer.
RP-1 was first formulated by rocket designers in the mid-1950s as a replacement for the alcohol based fuels which were previously the most commonly used liquid rocket fuels. Since its advent by fuel chemists it has been the primary fuel used for rocket propulsion by the United States. The lack of light hydrocarbons in RP-1 give it a very high flash point and make it less of a fire hazard than common gasoline, many forms of diesel fuel, or even some jet fuels. Rocket-grade kerosene gases made by Russia and previously by the Soviet Union are very similar in structure and are commonly designated T-1 and RG-1.
Liquid oxygen was first produced in 1883 and must be kept extremely cold and has a freezing point of -361.82 ºF and a boiling point of -297.33 ºF. The extreme temperatures which it must be kept at causes materials it comes in contact with to become extremely brittle. It acts as an extremely powerful oxidizing agent when brought in contact with organic matter and is commonly used as rocket fuel because it creates a very high specific impulse.
The Merlin engine was originally designed by SpaceX for sea recovery and reuse. The injector at the center the Merlin is a pintle type which was first used during the Apollo program. The original version of the Merlin was the Merlin 1A which was used twice in 2006 and 2007 on a Falcon 1 first stage. The Merlin 1B was an upgraded version of the Merlin 1A, but was discarded by SpaceX due to its experience from the Falcon 1.
The Merlin 1C was used from 2008-2012 on the Falcon 1 and the Falcon 9 before being dropped in favor of the Merlin 1D. The Merlin 1D was used on its first flight in 2013 and is the current model in production for SpaceX. It is able to produce more than twice the thrust of the Merlin 1A at sea level. SpaceX indicates that it needs to produce hundreds of engines per year in order to support its current rocket production plans.
