SpaceX completes qualification test of 3D-printed SuperDraco thruster
By David Szondy
May 28, 2014
SpaceX’s Dragon spacecraft is set for an upgrade with the company announcing the successful qualification testing of its SuperDraco rocket engine. Designed to replace the Draco engines used for attitude control on the Dragon orbital spacecraft, the SuperDraco will act as the Dragon’s launch emergency escape system, as well as giving it the ability to make a powered landing on Earth and other worlds.
The SuperDraco differs from most rocket engines in that its combustion chamber is 3D printed by direct metal laser sintering (DMLS), where complex metal structures are printed by using a laser to build the object out of metal powders one thin layer at a time. The regeneratively-cooled combustion chamber is made of inconel; a family of nickel-chromium alloy that’s notable for its high strength and toughness, and is also used in the Falcon 9’s Merlin engine.
“Through 3D printing, robust and high-performing engine parts can be created at a fraction of the cost and time of traditional manufacturing methods,” says Elon Musk, Chief Designer and CEO at SpaceX. “SpaceX is pushing the boundaries of what additive manufacturing can do in the 21st century, ultimately making our vehicles more efficient, reliable and robust than ever before.”
The propellant is a pair of non-cryogenic liquids; monomethyl hydrazine for the fuel and nitrogen tetroxide for the oxidizer, which is the same as for the Draco engine. These are hypergolic. That is, they ignite on contact with one another, which helps the SuperDraco to restart multiple times. It’s also built to be deep throttled, and can go from ignition to full throttle in 100 ms. But what sets the SuperDraco apart is that is has 200 times the power of the Draco engine, which works out to 16,400 lb of thrust.
The SuperDraco’s main purpose is to provide attitude control for the Dragon capsule in orbit and during reentry. It also acts as the craft’s launch escape system. Unlike previous US manned space capsules of the 1960s and ‘70s, the next version of the Dragon won’t use a tower equipped with rocket motors to carry the capsule away in case of a launch accident. The SuperDraco can be used at any point in the launch from pad to orbit, not just during the first minutes of launch, as the towers were. Eight engines firing for five seconds are enough to carry the capsule safely away from the booster with 120,000 lb of axial thrust. In addition, the eight engines also provide a high degree of redundancy should one or more engines fail.
But what’s really ambitious about the SuperDraco is that, like the Falcon 9 booster, the Dragon is designed to ultimately return to its spaceport under its own power and land with the precision of a helicopter, and it’s the power and control of the SuperDraco that makes this possible. SpaceX is even looking beyond that by planning to use the SuperDraco engine for its Red Dragon Mars lander; an unmanned modification of the Dragon designed for exploring the Red Planet.
According to SpaceX, the test firings were completed last month at its Rocket Development Facility in McGregor, Texas and included prolonged firings, multiple restarts, and operating under extreme conditions. The SuperDraco will make its first flight on a pad abort test later this year as part of NASA’s Commercial Crew Integrated Capabilities (CCiCap) initiative.
The video below shows a SuperDraco test firing.