Sierra Nevada Corporation (SNC) is quietly, but steadily, moving forward swiftly with the development of their reusable Dream Chaser orbital spacecraft, and this week the company announced the successful completion of yet another critical milestone in the SNC’s efforts to develop their Dream Chaser to restore U.S. crew capability to low-Earth orbit. With the completion of Milestone 8 Wind Tunnel Testing under SNC’s Commercial Crew Integrated Capability (CCiCap) agreement with NASA SNC has now received over 80 percent of the total award value under the CCiCap agreement, and the company is on track to complete the program by the end of 2014.
The latest series of wind tunnel tests, which were conducted at NASA’s Ames Research Center in CA, CALSPAN Transonic Wind Tunnel in New York, and at NASA’s Langley Research Center Unitary Plan Wind Tunnel in Virginia, has helped SNC advance the overall design of the Dream Chaser by analyzing the forces and flight dynamic characteristics that it will experience during orbital ascent and re-entry—two of the most dangerous events in any spaceflight. The testing has, according to SNC, significantly advanced the path to orbital flight of the Dream Chaser spacecraft and the Dream Chaser Atlas-V integrated launch system.
“The aerodynamic data collected during these tests has further proven and validated Dream Chaser’s integrated spacecraft and launch vehicle system design. It also has shown that Dream Chaser’s expected performance is greater than initially predicted,” said Mark Sirangelo, corporate vice president and head of SNC’s Space Systems. “Our program continues to fully complete each of our CCiCap agreement milestones assisted through our strong collaboration efforts with our integrated ‘Dream Team’ of industry, university and government strategic partners. We are on schedule to launch our first orbital flight in November of 2016, which will mark the beginning of the restoration of U.S. crew capability to low-Earth orbit.”
With all the controversy lately over ULA’s use of Russian RD-180 engines on their Atlas-V rockets AmericaSpace reached out to SNC for comment on the company’s other launch options, but the company declined to comment on the issue at this time.
In the latest series of tests SNC subjected several scale model Dream Chasers to a variety of different wind tunnel tests in various configurations, including the spacecraft and Atlas-V integrated launcher. The company received the full award value of $20 million for the passage of CCiCap Milestone 8 from NASA, but they also fully self-funded an additional wind tunnel test that will accelerate the Dream Chaser development schedule and path to completion of the Critical Design Review.
“The NASA-SNC effort makes for a solid, complementary relationship,” said Andrew Roberts, SNC aerodynamics test lead. “It is a natural fit. NASA facilities and the extensive work they’ve done with the Dream Chaser predecessor, HL-20, combined with SNC’s engineering, is synergistic and provides great results.”
In the tests at Langley SNC spent six weeks observing how turbulent flow affects the Dream Chaser model at different angles and positions, using over 250 individually placed grains of sand glued to the Dream Chaser model to create turbulent flow along the vehicle and simulate what the actual spacecraft will experience during flight. Engineers also outfitted the Dream Chaser model with hundreds of sensors to gather every detail about air flow around the vehicle to confirm their expectations, with the resulting data being used to make any modifications to the spacecraft and adjust their computer models accordingly.
The data acquired from the Milestone-8 wind tunnel tests has validated what existing computer models predicted the Dream Chaser would do, paving the way for the next series of tests as the company aims for Dream Chaser’s first launch from Cape Canaveral Air Force Station Space Launch Complex-41 in the fall of 2016 atop the proven workhorse United Launch Alliance (ULA) Atlas-V 402 rocket, with the first crewed mission to launch in the third quarter of 2017. SNC intends on operating a fleet of Dream Chasers out of NASA’s Kennedy Space Center, using the space agency’s famed Operations and Checkout Building (known as the O&C) for pre-flight and post-flight Dream Chaser processing, as well as utilizing the three-mile-long shuttle landing facility (SLF) as the spacecraft’s runway of choice when returning home.
It was just a couple months ago that SNC successfully completed a “flight-profile data review” milestone for Dream Chaser to validate the aerodynamic performance of the Dream Chaser and “significantly matured its aerodynamic database in the subsonic region of flight,” according to SNC. Dream Chaser’s autonomous ALT-1 flight last October flew perfectly until it came time to land. Only two of its three gear deployed, causing the engineering test vehicle to skid off the runway at Edwards Air Force Base in California and sustain minor structural damage after touchdown. The problem, although still not officially identified publicly yet by SNC, is suspected to have been a mechanical issue with the specific landing gear in question, rather than something related to bad software (none of the primary systems that gave the commands that control the flight failed or had any problems).
That minor mechanical issue with the landing did nothing to stall the vehicle’s development. Dream Chaser has proven it can fly autonomously, and fly well—at least at sub-sonic speeds—and the Dream Chaser team was able to authenticate that over 40 aerodynamic predictions, from extensive analysis, matched within the limits of the actual vehicle performance. The ALT-1 post-flight analysis was also reviewed by NASA and the space agency agreed that the Dream Chaser met or exceeded everyone’s expectations in the flight.
The Dream Chaser’s potential as a reusable lifting-body (winged glider) spacecraft is unique—no other company is developing anything similar, nor have those other companies announced any target launch date(s) for their first crewed orbital spaceflights. Dream Chaser will have no abort blackout zones and a 3.5-day free-flight capability—with the added benefit of deorbiting at any time (since Dream Chaser can land on any conventional runway, not just the SLF). The spacecraft will also be able to stay at the International Space Station (ISS) for up to seven months at a time, if needed, before having to return to Earth, and an expected 1.5 G nominal reentry will provide ideal conditions for returning fragile cargo and science experiments, in addition to making the return to gravity easier on the crew (SNC expects immediate access to crew and cargo upon landing). A quick turnaround and an almost entirely reusable vehicle put Dream Chaser in a class all its own.
A second autonomous free-flight test, known as ALT-2, is planned to take place at Edwards AFB again later this year before the company conducts its first piloted Dream Chaser free flight test. No specific date(s) have been announced by SNC for those flights, and we likely will not hear about it until after the flights are conducted (if history is any indication).