Falcon 9 v1.0

The Falcon 9 v1.0 first stage was used on the first five Falcon 9 launches, and powered by nine SpaceX Merlin 1C rocket engines arranged in a 3x3 pattern. Each of these engines had a sea-level thrust of 556 kN (125,000 pounds-force) for a total thrust on liftoff of about 5,000 kN (1,100,000 pounds-force).[3]

The Falcon 9 tank walls and domes were made from aluminum lithium alloy. SpaceX uses an all-friction stir welded tank, the highest strength and most reliable welding technique available.[3]

The Falcon 9 v1.0 first stage used a pyrophoric mixture of triethylaluminum-triethylborane (TEA-TEB) as a first-stage ignitor.[7]

The upper stage was powered by a single Merlin 1C 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).[3] 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 saves money during vehicle production.[3]

The Falcon 9 v1.0 interstage, which connects the upper and lower stage for Falcon 9, is a carbon fiber aluminum core composite structure. Reusable separation collets and a pneumatic pusher system separate the stages. The stage separation system had twelve attachment points (later reduced to just three in the v1.1 launcher).[8]

SpaceX uses multiple redundant flight computers in a fault-tolerant design. Each Merlin engine is controlled by three voting computers, each of which has two physical processors that constantly check each other. The software runs on Linux and is written in C++. For flexibility, commercial off-the-shelf parts and system-wide "radiation-tolerant" design are used instead of radiation-hardened parts.[9]

Four Draco thrusters were to be used for at least the second revision of the Falcon 9 v1.0 rocket second-stage as a reaction control system.[10] It is unknown whether Falcon 9 ever flew with these thrusters; the second revision of Falcon 9 v1.0 was replaced with the Falcon 9 v1.1, which used nitrogen cold gas thrusters.[11] The thrusters were used to hold a stable attitude for payload separation or, as a non-standard service, were also designed to be used to spin up the stage and payload to a maximum of 5 rotations per minute (RPM),[10] although none of the five flown missions had a payload requirement for this service.

While SpaceX spent its own money to develop its first launch vehicle, the Falcon 1, the development of the Falcon 9 was accelerated by the purchase of several demonstration flights by NASA. This started with seed money from the Commercial Orbital Transportation Services (COTS) program in 2006.[12] SpaceX was selected from more than twenty companies that submitted COTS proposals.[13] Without the NASA money, development would have taken longer, Musk said.[2]

The development costs for Falcon 9 v1.0 were approximately US$300 million, and NASA verified those costs. If some of the Falcon 1 development costs were included, since F1 development did contribute to Falcon 9 to some extent, then the total might be considered as high as US$390 million.[14][2]

NASA also evaluated Falcon 9 development costs using the NASA‐Air Force Cost Model (NAFCOM)—a traditional cost-plus contract approach for US civilian and military space procurement—at US$3.6 billion based on a NASA environment/culture, or US$1.6 billion using a more commercial approach.[15][14]

Falcon 9 booster tank at the SpaceX factory, 2008

In December 2010, the SpaceX production line was manufacturing one new Falcon 9 (and Dragon spacecraft) every three months, with a plan to double the production rate to one every six weeks in 2012.[16]