Raptor (rocket engine)

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Raptor on the first test
Approach for landing of the originally planned Interplanetary Transport System launcher with 42 Raptor engines

The Raptor is a development project by the private space company SpaceX for a liquid rocket engine . It should enable two-stage, refuelable and propulsively landable large rockets with both stages, with which the founder and CEO of the company, Elon Musk , wants to pave the way for a Mars colonization .

Initially, the engine was intended as part of the Interplanetary Transport System (ITS) concept. According to these plans, the launch vehicle should have been carried into space by 42 engines. As a second stage, the spaceship itself was supposed to fly to Mars with nine of these engines, land there and finally fly back to Earth from the Martian surface.

In September 2017, Elon Musk presented a modified and slightly reduced (about 9 instead of 12 meter diameter) missile concept with the provisional code name BFR , the first stage of which is now to propel the second stage, the spaceship, into space with the help of 31 Raptor engines. The name was renamed Starship and Super Heavy in 2018.

Technical specifications

Potential sources of methane (CH 4 ) on Mars

In the conception phase, liquid hydrogen and liquid oxygen (LOX) were initially considered as a fuel mixture. After that, SpaceX settled on liquid methane and liquid oxygen. Methane can be obtained on Mars by the Sabatier process and used as fuel for the return journey, so it does not have to be carried on the outward journey. The Sabatier process is to use carbon dioxide, which is the main component of the Martian atmosphere, and water, namely the water ice deposits found on Mars. The energy for the process is to be obtained using solar panels. So far, SpaceX has used RP-1 rocket kerosene and liquid oxygen for its main engines ( Merlin and Kestrel ) .

Tom Mueller , formerly SpaceX Vice President for Engine Development, announced on February 19, 2014 that the Raptor engine had been designed for a thrust of 4500  kN . In comparison, the current Merlin 1D engine has a thrust of 689 kN. The specific momentum should be 321 s and 363 s in a vacuum at sea level .

In September 2016 Elon Musk presented the ITS project with 42 Raptor engines. The thrust was given as 3500 kN at sea level.

On September 29, 2017, Elon Musk presented a smaller space system similar to the ITS at the International Astronautical Congress (IAC) in Adelaide, which was temporarily called the BFR (Big Falcon Rocket).

The launch rocket is said to have 31 Raptor engines. Together, these should generate a thrust of 5400 tons for the BFR, which weighs a maximum of 4400 tons. As with the Falcon 9, some of these engines should therefore also function as landing engines of the first stage.

The spaceship, the second stage of the BFR rocket, should have two different Raptor engines: Two landing engines with a diameter of 1.3 m and a thrust of 1700 kN each at sea level. The specific impulse should be 330 s at sea level and 356 s in a vacuum. The four vacuum engines should have a thrust of 1900 kN each. Specific impulse: 375 s. The diameter of the outlet nozzle would have been 2.4 m.

In the second half of 2018, the design of the spaceship was changed and the engine was " radically redesigned ". Initially, only one Raptor variant with 2000 kN thrust is to be used for the entire BFR. Later, the thrust of the first stage engines is to be increased to 2500 kN, while a vacuum variant with a specific impulse of at least 380s is to be used in the spaceship.

Proving Ground

On April 21, 2014, SpaceX President Gwynne Shotwell , the governor of the US state of Mississippi , Phil Bryant , and Senator Thad Cochran, together with the director of the John C. Stennis Space Center, ceremoniously opened the test stand E-2 on the SpaceX das Raptor engine will be tested in collaboration with NASA .

Testing

Until 29 September 2017 42 tests were performed with a reduced prototype of the engine on the grounds of the Stennis Space Center of NASA in Hancock County (Mississippi) performed. The engines burned together for more than 1200 seconds during several tests. The maximum burning time per test was limited to 100 s due to the size of the tanks on the test stand. The test engines worked with a combustion chamber pressure of up to 200 bar.

The first tests with a full-size prototype (serial number SN1) took place in February 2019 at the SpaceX test center in McGregor, Texas. The engine reached the combustion chamber pressure of 250 bar required for Starship and Super Heavy and was damaged by even higher pressures.

A second engine (SN2) was tested at the SpaceX South Texas Launch Site in early April 2019 . It is mounted in a vehicle called the “ Starhopper ”, which, like the Falcon 9 Grasshopper, is intended for flight tests at low altitude. Tests with Raptor SN3 took place in McGregor in April; a burning time of up to 40 seconds was achieved. Several other engines broke there during test runs before the first short Starhopper flight with SN6 was successful on July 25, 2019.

According to Elon Musk, in August 2020 a prototype reached a combustion chamber pressure of 330 bar, more than any other liquid rocket engine ever tested.

Individual evidence

  1. ^ Alejandro G. Belluscio: SpaceX advances drive for Mars rocket via Raptor power. nasaspaceflight.com, March 7, 2014, accessed December 13, 2014 .
  2. ↑ a b Elon Musk: Making Life Multiplanetary | SpaceX. Accessed October 1, 2017 .
  3. ↑ Eric Ralph: SpaceX CEO Elon Musk reveals photos of Starship's first completed Raptor engine. In: Teslarati. January 31, 2019, accessed February 2, 2019 .
  4. ↑ Rebecca Strecker: NASA, SpaceX Cut Ribbon To Launch Testing Partnership. NASA, April 21, 2014, accessed December 13, 2014 .
  5. ↑ SpaceX's Starship engine breaks Russian rocketry record held for two decades. In: Teslarati. February 10, 2019, accessed February 11, 2019 .
  6. ↑ Twitter message from Elon Musk , February 21, 2019.
  7. ↑ Chris Gebhardt: Starhopper conducts Raptor Static Fire test. In: Nasaspaceflight.com. April 4, 2019, accessed April 4, 2019 .
  8. ↑ Eric Ralph: SpaceX wants to unleash Starhopper but longer Raptor test fires come first. In: Teslarati. April 29, 2019. Retrieved April 29, 2019 .
  9. ↑ Eric Ralph: SpaceX CEO Elon Musk says major Starship engine bug is fixed as Raptor testing continues. In: Teslarati. July 7, 2019, accessed on July 13, 2018 ( several have been destroyed so completely that they could barely be used to inform design optimization work ).
  10. ^ Thomas Burghardt: Starhopper successfully conducts debut Boca Chica Hop . In: Nasaspaceflight.com , July 25, 2019 (local time), accessed July 26, 2019.
  11. ↑ https://twitter.com/elonmusk/status/1295495834998513664. Retrieved August 17, 2020 .