Falcon 9

Decision Points

Falcon 9 is a spaceflight launch system that uses rocket engines designed and manufactured by SpaceX. Both stages of the two-stage-to-orbit vehicles use liquid oxygen (LOX) and rocket-grade kerosene (RP-1) propellants. Multiple variants are planned with payloads of 10,450–26,610 kilograms (23,000–58,700 lb) to low Earth orbit, and 4,450–15,010 kilograms (9,800–33,100 lb) to geostationary transfer orbit, which will place the Falcon 9 design in the medium-lift to heavy-lift range of launch systems.

The first Falcon 9 flight was successfully launched from Cape Canaveral Air Force Station on June 4, 2010 14:45 EDT (19:45 UTC) with a successful orbital insertion, after several delays.

The Falcon 9 will be the launch vehicle for the SpaceX Dragon spacecraft. The Falcon 9 and Dragon combination won a Commercial Resupply Services (CRS) contract from NASA to resupply the International Space Station under the Commercial Orbital Transportation Services (COTS) program. The second Falcon 9 launch, and the first launch of the Dragon spacecraft, occurred at 10:43 EST (15:43 UTC) on December 8, 2010 from Cape Canaveral. The launch was successful, with the Dragon spacecraft completing two orbits before splashing down in the Pacific Ocean.

Bigelow Aerospace is also considering the Falcon 9 for their Orion Lite manned spacecraft.

The base Falcon 9 is a two stage, LOX/RP-1 powered launch vehicle. Its first stage is powered by nine SpaceX Merlin 1C rocket engines with 556 kN (125,000 lbf) sea-level thrust per engine for a total thrust on liftoff of approximately 5.0 MN (1.1 million lbf). The Falcon 9 first stage uses a pyrophoric mixture of triethylaluminum-triethylborane (TEA-TEB) as a first-stage ignitor.

The proposed Falcon 9 Heavy configuration consists of a standard Falcon 9 with two additional Falcon 9 first stages acting as liquid strap-on boosters, which is conceptually similar to EELV launchers Delta IV Heavy and the future Atlas V HLV, and also to the Russian Angara carrier rocket.

The upper stage is powered by a single Merlin engine modified for vacuum operation, with an expansion ratio of 117:1 and a nominal burn time of 345 seconds. For added reliability of restart, the engine has dual redundant pyrophoric igniters (TEA-TEB). SpaceX has expressed hopes that both stages will eventually be reusable.

The interstage, which connects the upper and lower stage for Falcon 9, is a carbon fiber aluminum core composite structure. Stage separation occurs via reusable separation collets and a pneumatic pusher system. The Falcon 9 tank walls and domes are 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 9 is simply a shorter version of the first stage tank and uses most of the same tooling, material and manufacturing techniques. This results in significant cost savings in vehicle production.

As with the company's smaller Falcon 1 vehicle, Falcon 9's launch sequence includes a hold-down feature that allows full engine ignition and systems check before liftoff. After first stage engine start, the launcher is held down and not released for flight until all propulsion and vehicle systems are confirmed to be operating normally. Similar hold-down systems have been used on other launch vehicles such as the Saturn V and Space Shuttle. An automatic safe shut-down and unloading of propellant occurs if any abnormal conditions are detected.

Falcon 9 will have triple redundant flight computers and inertial navigation, with a GPS overlay for additional orbit insertion accuracy. 

Source:wikipedia