Satnews Daily
February 25th, 2013

SpaceX...A Dragon Performs In A Dress Rehearsal... For Two Seconds (Launch)

[SatNews] With a vacuum specific impulse of 311s, this is the highest performance gas generator cycle kerosene engine ever built, exceeding the Boeing Delta II main engine, the Lockheed Atlas II main engine and the Saturn V F-1.





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. Like Falcon 1, the interstage, which connects the upper and lower stage for Falcon 9, is a carbon fiber aluminum core composite structure. The separation system is a larger version of the pneumatic pushers used on Falcon 1.

Nine SpaceX Merlin engines power the Falcon 9 first stage with 147,000 lbs-f sea level thrust per engine for a total thrust on liftoff of just over 1.3 Million lbs-f. After engine start, Falcon is held down until all vehicle systems are verified to be functioning normally before release for liftoff.


A single Merlin engine powers the Falcon 9 upper stage 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).

The main engine, called Merlin, was developed internally at SpaceX, but draws upon a long heritage of space proven engines. The pintle style injector at the heart of Merlin was first used in the Apollo Moon program for the lunar module landing engine, one of the most critical phases of the mission.


Combining the above three functions into one device that we know is functioning before the vehicle is allowed to lift off means a significant improvement in system level reliability.

Sea Level Thrust : 147,000 lbf
Vacuum Thrust: 161,000 lbf
Sea Level Isp: 282s
Vacuum Isp: 311s

With a vacuum specific impulse of 311s, Merlin is the highest performance gas generator cycle kerosene engine ever built, exceeding the Boeing Delta II main engine, the Lockheed Atlas II main engine and the Saturn V F-1.