The third transportation vehicle for NASA’s Commercial Resupply Services 2 contracts for resupply efforts of the International Space Station has passed a major test milestone at Edwards Air Force Base, California. Sierra Nevada Corporation’s Dream Chaser mini-spaceplane conducted the first of a series of Captive Carry flight tests suspended underneath a 234-UT lifting commercial helicopter.
Dream Chaser’s history:
After its initial reveal earlier this decade, Dream Chaser’s long-term prospects were relatively grim following NASA’s decision to pass on the spaceplane as part of the 2014 Commercial Crew Transportation Capabilities contracts for the International Space Station (ISS).
Despite that setback, Sierra Nevada Corporation pushed forward with development of Dream Chaser on its own and secured an unfunded Space Act Agreement (SSA) with NASA to continue cooperative development of Dream Chaser.
This SSA worked significantly to Sierra Nevada’s favor when NASA solicited bids for its Commercial Resupply Services 2 (CRS-2) contracts.
For CRS-2, Sierra Nevada submitted a proposal to use Dream Chaser in its uncrewed, cargo-only configuration.
Initially, NASA was expected to award only two CRS-2 contracts; however, the agency formally announced in January 2016 that three companies would be awarded contracts – including Sierra Nevada for Dream Chaser alongside current CRS-1 contract holders SpaceX and Orbital ATK.
With CRS-2 contract flights scheduled to begin No Earlier Than 2019, Sierra Nevada is proceeding with a final testing sequence of Dream Chaser – capitalizing on previously conducted tests of the Engineering Test Article (ETA) of the spaceplane.
The series of ongoing tests at Edwards Air Force Base, CA, mark the second time the Dream Chaser ETA has been present for testing at the desert facility.
Back in 2013, the Dream Chaser ETA went through a very similar series of tests at Edwards, culminating in the craft’s first free-flight test on 26 October 2013.
That October 2013 test saw Dream Chaser hoisted to altitude underneath a helicopter before being released for an autonomous flight to the runway.
The test was designed to verify and validate Dream Chaser’s low-atmosphere aerodynamics, flight control surfaces, flight characteristics for approach, flare and landing, and landing systems.
During this to date only free flight, the space plane flew itself toward the ground and runway for a landing approximately one minute after release.
However, as it approached the runway and landing gear deployment was commanded, the left landing gear failed to deploy fully, resulting in the vehicle skidding off runway 22L at Edwards.
Post-test recovery of Dream Chaser showed that while the craft suffered minor damage, the crew compartment was intact and all of its systems were still operational.
Unintentionally, the landing gear failure accidentally demonstrated Dream Chaser’s ability to safely protect its crew/cargo and survive a landing gear out scenario at landing.
New milestones and upcoming tests:
While the 2013 tests of Dream Chaser were deemed a success by both Sierra Nevada and NASA (despite sliding off the runway), Dream Chaser’s teams have elected to repeat the craft’s ground and flight tests in an effort to gather more data and fly Dream Chaser in a more robust flight environment.
Since arriving at Edwards earlier this year, Dream Chaser’s refurbished ETA has been used to validate numerous ground processing activities on the vehicle and has recently completed a major milestone test.
That test saw Sierra Nevada engineers hook Dream Chaser up to a separable towing mechanism to allow the team to gather data on stresses and responses on the vehicle to various towing speeds as well as its final landing elements (i.e., how it decelerates in its final moments of landing).
During the test earlier this month, a pickup truck towed Dream Chaser’s ETA to a total speed of 60 mph (96.5 k/h), performing several s-curve ground turns before initiating a release of the tow mechanism to allow Dream Chaser to slow to a stop on its skid strip and tires.
Now, teams are conducting a series of two Captive Carry tests ahead of the free flight Approach and Landing Test 2 (ALT-2) for Dream Chaser.
While teams continue to work off “open issues and perform regression testing of flight components and software in preparation for ALT-2”, according to an update on L2, Sierra Nevada’s teams are understood to be targeting late-September for the ALT-2.
Moreover, the helicopter that will be used for both Captive Carry tests and for ALT-2, arrived at Edwards Air Force Base in mid-August and is very different from the one used in 2013.
That helicopter was an ERICKSON S-64F. The new copter is a 234-UT lifting helicopter – the civilian version of the CH-47 Chinook.
The 234-UT is capable of lifting 11,793 kg (26,000 lb) and of attaining a cruise speed of 120 kts (222 k/h – 138 mph) – something that will aide Sierra Nevada in their desire to use ALT-2 to send Dream Chaser through a more robust flight environment on her short, one minute flight from altitude to the runway.
But before ALT-2, the 234-UT will lift Dream Chaser to altitude, performing two Captive Carry test.
According to updates available in L2, “Two ETA Captive Carry tests in work, no specific dates at this time.” However, this week SNC noted the first test will be conducted on Wednesday.
During the Captive Carry tests, Dream Chaser is suspended below the 234-UT while the helicopter flies a pattern at various altitudes within the perimeter of Edwards Air Force Base.
The first test was successfully completed in the morning of Wednesday.
“We are very pleased with results from the Captive Carry test, and everything we have seen points to a successful test with useful data for the next round of testing,” said Lee “Bru” Archambault, SNC’s director of flight operations for the Dream Chaser program.
“One of the primary objectives of the first Captive Carry test is to verify and validate the performance of the ETA Guidance Navigation and Control systems and to exercise operations of the ETA under the control of the flight control team while in an actual flight-like operational environment,” notes the L2 update.
If those two Captive Carry test are successful, Sierra Nevada will move on to ALT-2 at the end of September.
Currently, if funding levels and schedules hold, Sierra Nevada anticipates the first cargo Dream Chaser flight to the ISS in 2020.
The current CRS-2 contracts grant Sierra Nevada, SpaceX, and Orbital ATK six flights each for resupply services to and from the Station – for a total of 18 commercial cargo runs between 2019 and 2024.
Under the CRS-2 contract, Dream Chaser will provide a total cargo uplift capability on each flight of 5,000 kg (11,000 lb) of pressurized cargo and 500 kg (1,100 lb) of unpressurized cargo – with a recoverable downmass cargo capability of 1,750 kg (3,860 lbs) and a disposable cargo capability of 3,250 kg (7,170 lb).
Moreover, Dream Chaser has been selected by the United Nations to fly uncrewed microgravity science missions for nations that don’t have domestic access to space (the first of which is expected No Earlier Than 2021), and the Trump Administration in the United States is understood to be studying a proposal set forth by Sierra Nevada to use of Dream Chaser for a crewed servicing mission to the Hubble Space Telescope in the 2020s.
(Images: Sierra Nevada, NASA, and L2 artist Nathan Koga – The full gallery of Nathan’s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*)