Dragon 2 conducts Pad Abort leap in key SpaceX test
SpaceX’s Dragon 2 test vehicle has conducted her maiden flight on Wednesday, leaping off a Cape Canaveral truss structure under the power of eight SuperDraco engines at 9am local time. Known as the Pad Abort test, the objectives of the flight involved the gathering of key test data to help graduate the vehicle to be ready to carry NASA astronauts to the International Space Station (ISS).
Dragon 2 Pad Abort Test:
With the CRS-6 Dragon currently berthed to the ISS and the CRS-7 Dragon preparing for launch next month, SpaceX is now an established name in the orbital outpost’s contact list.
However, the company’s aspirations have always been focused on launching “biological payloads” of the human variety, an ambition that is set to be realized via an evolution of its trusted Dragon spacecraft.
As revealed by SpaceX supremo Elon Musk last year, the Dragon V2 (or Dragon 2 as its now commonly known) honors the heritage of her cargo hauling sibling, while sporting a change to the Outer Mold Line (OML) and the addition of solar arrays and fins around the circumference of the trunk.
With an interior that is both functional and beautiful, the Dragon 2 promises to be an executive jet ride into space for astronauts fortunate enough to ride onboard her.
However, as with all spacecraft, safety is the overriding priority.
Under the guidance of NASA’s strict rules, the Commercial Crew partners have to negotiate the proving grounds of safety-driven milestones, with SpaceX ready to take the next leap forward via the Pad Abort Test objectives.
Lasting just one minute and 39 seconds – slightly less than predicted, potentially due to a noted “under performance” on the loop, the flight involved an abundance of data gathering goals that can only be achieved by flying the vehicle.
As noted by Dragon 2 Program Lead – and former Shuttle astronaut – Dr. Garrett Reisman, the Dragon 2 test vehicle is “a very flight-like propulsion system per what goes into the abort, including the avionics, which will be identical to the avionics were are planning for the flight vehicle.
“That test will prove if we have enough total impulse, thrust and controllability (to conduct a safe pad abort).”
Providing the power were Dragon’s SuperDraco thrusters, lofting the capsule off a truss structure located at SpaceX’s SLC-40 Pad at Cape Canaveral.
Eight liquid SuperDraco engines, built into the side walls of the Dragon spacecraft, will be capable of producing up to 120,000 pounds of axial thrust to drive the Dragon and crew safely away from a failing launch vehicle.
Following the Static Fire that took place on Tuesday, the Dragon 2 test vehicle targeted launch within a large – and recently altered – window that opened at 09:00 local time and closed at 16:00.
The weather was favorable for the test with winds the main item of concern. However, the launch went ahead at 9am local time without requiring the remainder of the window.
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The test began with the ignition of the SuperDracos, reaching maximum thrust within approximately 100 milliseconds of the ignition command, propelling the spacecraft off the truss structure.
After half a second of vertical flight, the Dragon pitched toward the ocean and continued its controlled burn around five seconds into the test.
The SuperDraco engines throttled to control the trajectory based on real-time measurements from the vehicle’s onboard sensors.
The liquid thrusters are capable of a series of throttling ranges, in turn allowing for redundancy, with SpaceX claiming Dragon could lose one of the eight abort engines and still recover the vehicle and crew successfully.
The engines can also be restarted multiple times.
The abort burn was terminated once all the propellant had been consumed, resulting in the Dragon coasting for just over 15 seconds to its highest point about 1500 meters (.93 mi) above the launch pad.
At around 21 seconds into the test, the trunk was jettisoned and the spacecraft began a slow rotation with its heat shield pointed toward the ground again.
The pressure vessel is based on the cargo Dragon vehicle, albeit with the smaller hatch.
There are no actual windows in the capsule, with gold mirrors mimicking the outer windows of the operational Dragon 2.
The abort vehicle was outfitted with seven seats, one of which was occupied by a human-size test dummy, embedded with a suite of sensors.
It was initially noted that the dummy was called “Buster” – but SpaceX later revealed it opted against naming the test pilot.
“There will be a dummy on board the spacecraft, but despite popular belief, his name is not Buster,” SpaceX said. “Buster the Dummy already works for a great show you may have heard of called MythBusters. Our dummy prefers to remain anonymous for the time being.”
The dummy was placed in a “black composite flight article” seat, whereas the other seats were constructed from an aluminum metal frame with white steel plates bolted to them to simulate crew weight. The interior is surrounded by bare isogrid walls, accompanied by a few black boxes.
Parachutes were involved with the safe splashdown of the Dragon, with the drogue chutes deployed during a 4 to 6 second window following trunk separation.
At around T+35 seconds, the three main parachutes deployed and further slowed the spacecraft before splashdown, which concluded the test. This mark was predicted to occur at T+107 seconds.
Per the actual test, the splashdown was marked at T+99 seconds and appeared to be closer to the shore than expected.
Parachute assisted landings will be used until the SuperDracos are employed during propulsive landings, which will come after testing of the technology via the Dragonfly test vehicle.
Dragon splashed down at a point downrange of the launch pad, and is now being recovered by the ship that will return the capsule to port.
The test vehicle will then head to Vandenberg for the next Commercial Crew Program test, namely the In Flight Abort test flight that will involve the spacecraft riding on a Falcon 9 booster sporting just three Merlin 1D engines.
The booster – which mirrors the configuration of the F-9R Dev-1 test vehicle that was housed the SpaceX’s McGregor test center – was recently put through a tanking test at its SLC-4E launch site at Vandenberg and is currently back in its hanger awaiting Dragon’s arrival.
This test will involve an abort scenario occurring at “Max Drag” in the transonic region.
Passing both of these abort tests will be a major step towards the historic event of a crew riding on a Dragon 2 to the International Space Station, which may come as early as April 2017.
The mission, called “SpX-DM2” – will be the second flight of the Dragon 2 spacecraft to the orbital outpost, following on from the December 2016 “SpX-DM1” flight, which is set to be an uncrewed demonstration mission.
SpaceX is working with NASA through the Commercial Crew Transportation Capability (CCtCap) contract milestones, with the goal – alongside Boeing and the CST-100 spacecraft – of regaining American crew launch independence, removing the reliance on the Russian Soyuz that has been a stranglehold on NASA since the retirement of the Shuttle fleet.
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