RS-68

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The Rocketdyne RS-68 (Rocket System 68) is a liquid hydrogen / liquid oxygen rocket engine from Rocketdyne . It is used Template: future / in 4 yearsin the first stage of the Delta IV rocket .

properties

The engine generates 2.9 meganewtons of thrust near the ground and 3.3 meganewtons in a vacuum. It is in the first stage and the boosters of the rocket Delta IV used and should in the Ares V can be used. The RS-68 was created with the aim of considerably simplifying the engine compared to the SSME space shuttle main engine in order to be able to manufacture it more cheaply. In return, the efficiency of the engine was largely foregone. So were z. B. cheaper manufacturing methods were used and ablative cooling of the exhaust nozzle was used. These measures increased the mass of the engine, but the manufacturing costs fell significantly. The engine has a mass of 6696 kg, has a specific momentum of 3580 Ns / kg or 365 s (in a vacuum 4022 Ns / kg or 410 s) and develops a thrust of 2,891 kN (in a vacuum 3312 kN) when taking off ), making it the second most powerful LOX / LH2 engine worldwide. It is only surpassed by the successor version RS-68A. The power of the engine can be regulated from a minimum of 60% to a maximum of 102% of the nominal thrust. An RS-68 will cost about 14 million US dollars . The engine is the first new development of a large rocket engine in the USA since the SSME over 20 years ago.

The further developed version RS-68A had its first run on September 25, 2008. As with the previous version, its thrust can be throttled. The RS-68A has a specific impulse of 3570 Ns / kg on the ground and 4072 Ns / kg in a vacuum. The thrust is 3065 kN when lifted and 3496 kN in a vacuum. The RS-68A was first used on June 29, 2012. All three CBCs of a Delta IV Heavy are Template: future / in 4 yearsequipped with it.

Technical specifications

version RS-68
height 5.20 m
diameter 2.43 m
Dimensions 6696 kg
Fuels Liquid oxygen (LOX) and hydrogen (LH2) in a ratio of 6: 1
Thrust / weight ratio 51.2

Performance data

RS-68 performance at 100% 60%
Vacuum thrust 3314 kN 1957 kN
Ground thrust 2891 kN 1535 kN
Mixing ratio 6.0
Specific impulse in a vacuum 4022 Ns / kg (410 s)
Specific impulse on the ground 3581 Ns / kg (365 s)
Combustion chamber pressure 97 bar (9.7 MPa; 1410 psia) 58 bar (5.8 MPa; 836 psia)
Expansion Ratio (E) 21.5

Web links

Individual evidence

  1. Space.com: NASA Eyes alternative to Shuttle Main Engine for Heavy Lift . March 2006
  2. ^ Norbert Brügge: Engines Delta IV , accessed on July 2, 2012
  3. RS-68 ( Memento April 18, 2008 in the Internet Archive ) from Pratt & Whitney Rocketdyne