SNC: Yeah, We Lit that Candle and it Worked, Baby!

SpaceShipTwo in its first powered flight over Mojave.
SpaceShipTwo in its first powered flight over Mojave.

Sparks, NV, April 29, 2013 (SNC PR) – Sierra Nevada Corporation’s (SNC) Space Systems is proud to announce that its Hybrid Rocket Motor propelled Virgin Galactic’s SpaceShipTwo (SS2) sub-orbital vehicle on its first ever powered flight. SNC’s hybrid propulsion system is the largest hybrid ever used for space vehicle propulsion.

SNC manufactures two major subsystems on the SpaceShipTwo vehicle including the main oxidizer valve and the hybrid rocket motor, plus nitrous oxide dump system and nitrous oxide pressurization system control valves.

Upon reaching 47,000 feet altitude and approximately 45 minutes into the flight, SS2 was released from the WhiteKnightTwo carrier plane. After cross-checking data and verifying stable control, the pilots triggered ignition of the rocket motor, causing the main oxidizer valve to open and igniters to fire within the fuel case. At this point, SS2 was propelled forward and upward to a maximum altitude of 55,000 feet. The entire engine burn lasted 16 seconds, as planned. During this time, SS2 went supersonic, achieving Mach 1.2.

“The rocket motor ignition went as planned, with the expected burn duration, good engine performance and solid vehicle handling qualities throughout,” said Virgin Galactic president and CEO George Whitesides. “The successful outcome of this test marks a pivotal point for our program. We will now embark on a handful of similar powered flight tests, and then make our first test flight to space.”

SNC’s hybrid rocket systems offer a safe, high performing, and non-toxic alternative to solid and hydrazine liquid propulsion systems. As the rocket motor fuel is industrial rubber, there are no special handling or transportation requirements, thereby greatly reducing the lifecycle cost to our customers.

“I am enormously proud of our team and motor, thrilled to be part of space history, thankful to be in a country where such entrepreneurship is possible and humbled to be part of the dawn of the next era of flight,” said Mark Sirangelo, head of SNC’s Space Systems.

“This first powered flight test marks a historic day on the path to commercial passenger space flight. SNC’s Space Systems is proud to be a part of that success and proves that SNC’s safe, non-toxic hybrid propulsion systems can be scaled to meet the needs of many applications,” said Michael Borck, SNC’s director of programs.

The hybrid rocket motor and the oxidizer valve system are produced in SNC’s high rate manufacturing facility located in Poway, Calif., in conjunction with Scaled Composites of Mojave, Cali. This location is currently producing motors for both SpaceShipTwo and SNC’s own Dream Chaser orbital crew vehicle.

For more information about Virgin Galactic’s SpaceShipTwo program visit

About Sierra Nevada Corporation’s Space Systems

Sierra Nevada Corporation’s Space Systems business area headquartered in Louisville, Colo., designs and manufactures advanced spacecraft, space vehicles, rocket motors and spacecraft subsystems and components for the US Government, commercial customers as well as for the international market. SNC’s Space Systems has more than 25 years of space heritage in space and has participated in over 400 successful space missions through the delivery of over 4,000 systems, subsystems and components. During its history, SNC’s Space Systems has concluded over 70 programs for NASA and over 50 other clients. For more information about SS visit

About Sierra Nevada Corporation

Sierra Nevada Corporation (SNC), headquartered in Sparks, Nev., is one of America’s fastest growing private companies based on its significant expansion and reputation for rapid, innovative, and agile technology solutions in electronics, aerospace, avionics, space, propulsion, micro-satellite, aircraft, communications systems and solar energy. Under the leadership of CEO Fatih Ozmen and President Eren Ozmen, SNC employs over 2,500 people in 30 locations in 16 states. SNC’s six unique business areas are dedicated to providing leading-edge solutions to SNC’s dynamic customer base.

SNC is also the Top Woman-Owned Federal Contractor in the United States. Over the last 30 years under the Ozmen’s leadership, SNC has remained focused on providing its customers the very best in diversified technologies to meet their needs and has a strong and proven track record of success. The company continues to focus its growth on the commercial sector through internal advancements and outside acquisitions, including the emerging markets of renewable energy, telemedicine, nanotechnology, cyber and net-centric operations. For more information on SNC visit

  • Carolyne

    I have considerable experience in the design, testing and application of Nitrous Oxide Hybrid Rocket motors and I have previously expressed grave concerns regarding the motor being employed in Spaceship Two.

    I have reviewed the footage released by Virgin Galactic on the Youtube website:

    My first observation is that the rocket motor came perilously close to a catastrophic explosion. The obvious failure to ignite reliably is of the gravest concern. The
    consequences of a ‘hard start’ in such motors are well known. Very often the result is the explosive destruction of the rocket motor casing. The mechanism involved relates to the compression-shocking of un-burned N2O gas, next to a hot fuel grain as further high volumes of liquid N2O enter a motor that has failed to ignite promptly.

    I have photographic evidence of the consequences of such an event. It is most possible that, had the motor failed to light for a few fractions of a second longer, the aircraft would have been destroyed.

    I have further concerns regarding the fuel-grain being used. It is obvious from the close up of the ejector and the long shots of the tail plume and dark smoke trail,that a large quantity of un-burned fuel is exiting the motor. This indicates that the motor is running very fuel rich. Hybrids with pure HTPB fuel grains never run rich. In fact, they always run too lean.

    In this footage, the grain carries on burning several seconds after the oxidiser flow is cut off. This indicates that the builders may have added an oxidiser or other agent to the fuel grain, in an attempt to overcome the problems of hard ignition in such large HTPB motors. This is, in itself, a very dangerous practice. They may have turned the ‘stable and benign’ fuel grain into a mild explosive.

    I find it hard to believe that such sooty smoke trails would be found environmentally acceptable in a vessel designed to fly on a regular basis. It is highly polluting.

    Before this device is certified for passenger flight, the FAA must obtain all information relating to the motor systems design and construction and all
    data-traces from flight testing. This information must be reviewed by parties with expertise in the field who have no business relationship with Virgin Galactic or any of its contractors.
    I predict that the chamber-pressure trace will show a pressure spike on start-up and a much bigger (potentially dangerous one) as the motor resumed burning after the flame-out.

    Remember three people have already died as a result of the shortcomings of this technology. If more people die, as they probably will, there will be hard questions to answer by all concerned.

  • In this footage, the grain carries on burning several seconds after the
    oxidiser flow is cut off. This indicates that the builders may have
    added an oxidiser or other agent to the fuel grain
    B.S. It indicates nothing of the sort. The hot grain will continue to out gas until it cools sufficiently. This small mass flow of fuel will mix with the air in the base region of the vehicle where there is a large separation (now that the motor is no longer on). In other engines we call these sorts of recirculation zones “flame holders”. As the video shows, once the grain cools fuel stops being added and the flame goes out.

    Care to share any links to your photographic evidence or any other sort of supporting analysis? Your comment strikes me as baseless Fear, Uncertainty and Doubt (FUD).

  • Mark

    The burning grain comment in the initial post was based on several factors observed in the video. In addition at 55000 ft any out gassing will be oxygen starved and will not flare, flame holder comments not with standing.
    Picking one small part of the first post and then dissing the entire comentary as FUD is a shabby way to treat the concerns raised.

    Concerns expressed as bullet points
    The motor is running very rich. High stiffness grains ie HTPB do not run this way unless modified.
    Chuffing at ignition is a VERY bad thing.

    This is not about trying to stop progress etc it is about legitimate concerns that ignored will have a horrific effect on space tourism

  • Your summary of Carolyn’s points missed the part where she stated that the burning after the oxidizer was cut off indicated that Sierra Nevada’s hybrid had been turned into a stick of dynamite. This is a ridiculous leap.

    It also seems incoherent to claim that adding oxidizer would make the rocket run rich, or that this modified grain with all the extra oxidizer (“mild explosive”!) is so hard to light (“catastrophic explosion”!). Smells like FUD.

  • Nickolai

    “Hybrids with pure HTPB fuel grains never run rich. In fact, they always run too lean.”

    Wouldn’t it depend on the amount of oxidizer being pumped in?

  • Mark

    “It also seems incoherent to claim that adding oxidizer would make the
    rocket run rich, or that this modified grain with all the extra oxidizer
    (“mild explosive”!) is so hard to light (“catastrophic explosion”!)”
    Unfortunately while you may think it “inchoherent” the chemistry is on Carolynnes side. As motor has gone from as heated N2O oxidizer after the disaster that killed staff at the test site to a helium presure feed chilled N2O flow it is now much harder to light off the rocket. In the large hybrid world the dirty little secret is to “modify” the fuel grain with a touch of solid oxidizer. The video ex Virgin Galatic appears to show that. If the N2O soaks into the fuel grain it indeed is now some where between a road flare and a large blasting stick. Yes it may not happen straight away the combination comes up. But over 100’s of flights?

  • Nickolai

    Why does N2O soaking into the fuel grain lead to this ‘explosive’ property? Wouldn’t it just continue to burn slowly until all the N2O is used up?

  • More gish-gallop. Adding some solid oxidizer to the grain so that you have some non-zero NEW is different than some magical N20 diffusion process. You still haven’t explained how either of those processes might make the motor run fuel rich (a “dirty” trick as opposed to “pure” tar, ha!). Care to describe even a merely plausible mechanism for that?

  • Mark

    N2O is a solvent and can be absorbed into plastics etc. The explosive properties are the same as the liquid oxgen soaked charges used extensively in the 1930’s. If shocked ie from a hard start it can explode. Pluis there is a critical point for N2O based on temeprature where it can by itself explode. It only needs a few grams to detonate rather than burn and that will be a disaster.

  • That’s neat Mark, but how does that make the motor run fuel rich?

  • I was interested in finding the environmental statements provided by VG to the EPA but purely for technical reasons. They usually give the amounts of propellant to be carried. For instance the ones provided by SpaceX on the Falcon 9 had this info.
    I was interested in finding the specs on the Spaceshiptwo.

    Bob Clark

  • The Scaled Composites accident shows that hybrids are not necessarily safer than liquid fueled rockets. There is also the fact that the combustion chamber has to be replaced after every flight with the SS2 hybrid engine, reducing reusability savings.
    This maybe why VG plans to replace the SS2 hybrids with liquid fueled rockets:

    Virgin Reveals LauncherOne Plan.
    By Guy Norris
    July 11, 2012
    “LauncherOne will be powered by a two-stage, liquid-fueled rocket, now in initial development by Virgin Galactic. The same rocket also is intended to ultimately replace the non-reusable RM2 hybrid motor that will power the SS2 to suborbit, Virgin says.”

    Liquid fueled rockets are also of higher efficiency. In fact studies have shown by using a hydrogen fueled engine SS2 could *alone* fly all the way from the ground to suborbital altitude without the need for WK2:

    SpaceShipTwo could be single stage to suborbit says ESA firm.
    By Rob Coppinger on April 29, 2010 4:24 PM |

    Bob Clark

  • Carolyne’s group managed to get CalOSHA to release its investigation report into the 2–7 explosion as well as an analysis. They make for sobering reading.