SpaceX’s Commercial Crew contender, the Dragon V2, will initially return to terra firma under parachutes, assisted by a SuperDraco soft touchdown firing, according to Dragon V2 Program Lead Dr. Garrett Reisman. Eventually, the impressive spacecraft will employ pinpoint propulsive landings, once the technology has been matured via the DragonFly test program.
SpaceX’s crew version of the Dragon spacecraft is one of three main contenders aiming to win back domestic crew transportation independence for the United States.
SNC’s Dream Chaser, Boeing’s CST-100 and SpaceX’s Dragon are all vying for continued NASA funding via NASA’s Commercial Crew Program, as the agency prepares to announce the Commercial Crew Transportation Capability (CCtCap) contract awards.
With an announcement now expected in September, a likely scenario would see two spacecraft winning through to the CCtCAP stage.
The contact award process is secretive, due to competition rules. However, SpaceX’s Dragon V2 – and SNC’s Dream Chaser spaceplane – appear to have the groundswell of support within the space flight community.
One key advantage for Dragon is her continuing role as a cargo vehicle under the Commercial Resupply Services (CRS) contract, having already racked up numerous successful trips to the International Space Station (ISS).
With mission experience – ranging from manufacture and processing, to launch and mission operations – already proven, the transition to the Dragon V2 will mainly focus on the spacecraft’s increased capabilities.
The V2 is a major leap forward from her cargo lofting cousin. While her appearance is stunning – with a sporty Outer Mold Line (OML) and a Trunk with fins, along with an interior that makes some sci fi spacecraft seem dated – it’s her capabilities that provide most of her charms.
One such capability will be the employment of propulsive landings, something no other spacecraft is capable of doing.
As revealed by SpaceX CEO Elon Musk at the end of May, the Spacecraft will return under the protection of a third generation PICA-X heat shield, prior to turning on her set of SuperDraco thrusters, slowing her down for a guided touchdown at a designated landing site.
“That is how a 21st Century spaceship should land,” Mr. Musk noted.
It was also confirmed that the system will have a traditional form of redundancy, via the use of the parachute system that will still ride with the Dragon V2.
“Dragon V2 still retains the parachutes of Dragon V1,” Mr. Musk explained at the event. “When Dragon reaches a particular altitude, a few miles before landing, it will test and verify all the engines are working and then proceed to a propulsive landing (or else revert to chutes).”
However, as was expected – and prudent – the Dragon V2 will not rush into utilizing propulsive landings.
First up with be tests of the propulsive landing technology at SpaceX’s McGregor test site in Texas, involving the DragonFly test vehicle, which will look very similar to the Dragon V2.
The DragonFly testing regime will allow for engineers to fine-tune the technology, prior to the first propulsive landing for a Dragon V2.
As has now been revealed by Dr. Reisman, Dragon V2 will initially conclude missions under her parachutes, prior to a later switch to a fully propulsive landing.
This will allow of an incremental approach to transitioning the V2 toward the eventual goal of landing exclusively under SuperDraco power. However, the new thrusters will still find a use during the final few seconds of landing.
“We land on land under parachutes and then use the SuperDraco launch abort system to provide cushioning for the final touchdown,” noted the former Shuttle astronaut to Future In-Space Operations (FISO) Working Group this week.
“Then we have landing legs that are designed to take up any residual load and allow us to land on a variety of different surface hardnesses.
“The propulsive assist is really just in the final descent and landing really within the last few seconds otherwise it’s parachute all the way down.”
Crew safety is still the obvious priority, regardless of the landing method, with Dr. Reisman noting that the Dragon V2 can abort to water, but also to land, even without any propulsive assist for a soft touchdown.
“The whole landing system is designed so that it’s survivable if there’s no propulsive assist at all. So if you come down chutes only with the landing legs, we anticipate no crew injury. It’ll be kind of like landing in the Soyuz.”
While the current Dragon returns from her CRS mission under parachute assist – for an ocean splashdown – the Dragon V2 will employ an improved version of the chutes.
This is, in part, required for the additional strains of an abort scenario, something that is not required during cargo missions.
Testing the new parachutes has already taken place, with a drop test conducted under the Commercial Crew Integrated Capability (CCiCap) milestones.
The successful test was conducted at Morro Bay, in California, demonstrating how the parachute system would function in the event of an emergency on the launch pad or during ascent.
“The parachutes had to be completely redesigned from the cargo version, because they have to be able to work in a pad abort case,” Dr. Reisman said at the FISO. “You have to be able to open them up at very low altitude.”
The test requirements for the Dragon V2 will involve a pad abort and an in-flight abort test.
The pad abort test is scheduled to take place in November, two months prior to the in-flight abort test.
“Soon we will be left with the two big ticket items, which are the abort tests,” Dr. Reisman continued.
“The pad abort test is going to be a very flight-like Dragon and Trunk, but it’s going to depart from a truss structure rather than sitting atop of a Falcon 9.”
This test will involve a passenger, although his name remains a secret.
“We’ll do it at the Cape (SLC-40) and we’re going to have a crash test dummy inside in a prototype seat, so we’ll get data from that for the crew seat.
“We’ll have 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 all goes to plan with the pad abort, the next test, set for January, will utilize a Falcon 9 that will provide a real life test of an in-flight abort.
“The greatest challenge is the in-flight abort test that will occur not quite at Max-Q, but at Max Drag, which is in the transonic region,” added Dr. Reisman.
“We plan to fly a modified Falcon 9 as the launch vehicle and then have Dragon punch out right when we hit that criteria.”
These tests will satisfy the milestones in SpaceX’s agreement with NASA under the CCiCAP contract.
However, by that time, engineers and technicians at the Californian company will hope they’ll be busy working through their CCtCap requirements, another step on the path to removing America’s reliance on the Russian Soyuz for its crew transportation needs.
(Images via SpaceX, Boeing, SNC, NASA and L2).
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