For SpaceX and its founder Elon Musk, 2019 has been shaping up to be an interesting year.
After completing work on the miniaturized version of the Starship Alpha or "Starship
hopper", over the holidays, SpaceX moved ahead with the test-firing of its new Raptor
engine in late January and early February.
In accordance with Musk's vision, these engines will give the Starship the necessary
thrust to reach the Moon and Mars.
The test-firing took place at SpaceX Rocket Development and Test Facility, located just
outside of McGregor, Texas.
As Musk recently tweeted, the tests went very well, achieving the thrust necessary for both
the Starship and its first-stage booster, the Super-Heavy.
Musk also claimed that the engine broke the previous record for combustion chamber pressure,
which was established by the Russian, RD-180.
Keeping that in mind, in this video, Engineering Today will discuss about combustion chamber pressure
of SpaceX Raptor engine as well as Russian, RD-180. Why Elon Musk think, Raptor can truly
outperform the RD-180 in near future?
So, Let's get into details.
The Raptor engine has
shattered a previously-held record that's been untouched for almost 20 years.
SpaceX began full-scale tests of its Raptor, a week ago and it's already showing promise.
Its eventual goal?
Sending Starship 33,926,870 miles it needs to travel to reach Mars.
Musk tweeted that it has already reached an all-time high level of chamber pressure, which
affects how much thrust it's able to generate compared to its size, and how efficient it
is with fuel.
The RD-180 was the product of the Soviet-era, Energia rocket program, which sought to create
a super-heavy launch vehicle, that would take the reusable Buran spacecraft, which is a
Russia's version of the Space Shuttle, into orbit.
While the program was discontinued, the engine survived and was even imported to the US,
where it became part of Lockheed Martin's Atlas III rocket.
The Russian engine also has been put to consistent use, flying on the United Launch Alliance's
Atlas V rocket since 2000, proving time and again that it can replicate its history-making
chamber pressure in the field.
Raptor only started full-scale testing on February 4, so it has to be mounted on a launch
vessel before it dethrones RD-180.
For decades, the RD-180 and its predecessor (the RD-170) held the record for combustion
chamber pressure, ranking in at 26.7 MPa or 3,870 psi, and 24.52 MPa or 3556 psi respectively.
However, three days after Musk initially tweeted about the Raptor's performance results,
he declared that the chamber pressure had "reached 268.9 bar" – which works out
to 26.89 MPa (3,900 psi), thus establishing a new record by about a 1% margin.
That means SpaceX engine can reach forces equivalent to having one male hippopotamus
crammed, in every square inch of Raptor's combustion chamber, the small area the precedes
its cone-shaped nozzle.
This is an early sign that SpaceX creation has the potential to surpass the RD-180,
but there's still work to be done.
Musk was asked, if this performance had anything to do with SpaceX decision, to use a combination
of cryogenically-supercooled liquid methane and liquid oxygen, in short LOX, to power
the engines, which will reportedly be able to give them a 10-20% boost over conventional
engines.
To this, Musk replied in the negative, stating that the methane and liquid oxygen fuel were
barely kept below liquid temperature, for the test-firing.
When kept at cryogenic temperature, Musk anticipates that the engine will be able to achieve its
target chamber pressure of 300 bar or 4350 psi, but went on to state that "only 250
bar is needed for nominal operation of Starship and Super Heavy."
If this proves to be true, the Raptor will have exceeded the previous performance record
by a margin of 11%.
Granted, these results are all preliminary, and the Raptor has yet to perform as part
of an integrated system.
And with almost 20 years of experience under its belt, reaching chamber pressures of up
to ~257.5 bar or 3735 psi, regularly aboard the Atlas V rocket, the RD-180 still has the
edge.
However, with test flights of the Starship Alpha expected to begin next year, we won't
have to wait long to see if the Raptor can truly outperform the RD-180.
In the longer run, its higher chamber pressure means that Raptor should be able to do more
with less real-estate.
Though it's physically only marginally larger than SpaceX Merlin engines — which power
Falcon 9 and Falcon Heavy — it should someday be capable of more than triple the thrust.
If these levels are maintained during the Starship's hop tests, the Raptor engine
will be posed to revolutionize space travel.
SpaceX has already constructed a "hopper" prototype of the Starship that will undergo
a series of suborbital "hop tests" during the first half of 2019.
The final Starship will be comprised of two segments.
The second stage will look like the hopper, Musk has shown off on Twitter, and will carry
passengers.
The first stage has been dubbed Super Heavy and will be made up of 31 Raptor engines,
allowing the entire vessel to lift "100 metric tons" from Earth, to the surface
of Mars.
The uncrewed maiden voyage of Starship is scheduled for 2022.
Now that Raptor has shown itself capable of generating record-breaking force, SpaceX has
inched closer towards meeting that window.
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