SpaceX Lights Up Its Raptor Engine For The First Time

First Fire
Credit Elon Musk, SpaceX

SpaceX has announced the first test firing of its next generation Raptor engine. Word came, as it so often does, via Elon Musk’s Twitter account:

SpaceX propulsion just achieved first firing of the Raptor interplanetary transport engine pic.twitter.com/vRleyJvBkx

— Elon Musk (@elonmusk) September 26, 2016

A series of follow up tweets provided a bit more detail, while promising fuller disclosure during Musk’s presentation tomorrow afternoon at the International Astronautical Congress in Guadalajara, Mexico.

Chamber pressure is almost 3X Merlin, so engine is about the same size for a given area ratio

— Elon Musk (@elonmusk) September 26, 2016

The numbers cited refer to the overall performance capability of the engine at Mars ambient pressure, and imply a truly huge exhaust nozzle with a diameter of nearly 14 feet. On the other side of the supply line Musk hopes to establish between Earth and Mars, the sea level version of the methane/oxygen Raptor will have a considerably smaller exhaust nozzle, while still operating at the extremely high chamber pressure SpaceX is attempting to achieve with its staged combustion design.

At 300 bar pressure being generated in its combustion chamber, the Raptor will be operating at approximately 4,350 lbs per square inch. By comparison, the Russian built RD-180 engine which is widely considered to be the world’s premier rocket engine operates at a chamber pressure of 3,870 PSI.

If successful, the Raptor will constitute an enormous leap in launch technology for SpaceX, which has built it business thus far around the relatively simple, open cycle design of the Merlin 1-D engine which powers both stages of the Falcon 9. Its operating pressure is 1,410 PSI.

Much more to come.