SpaceX, Orbital ATK, and Sierra Nevada awarded contracts to ISS

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The competition heats up: NASA has decided to award contracts to all three competitors, Orbital ATK, SpaceX, and Sierra Nevada, in the second round of cargo contracts to ISS.

Or as Yogi Berra once said, “When you come to a fork, take it.”

The main winners appear to be Orbital and SpaceX, with Sierra Nevada coming in later. Details at this moment remain vague, so stay tuned.


  • Cotour

    Related, because it flys:

    I am going to to have to get one of these.

  • Cotour

    Also related because it fly’s: Questions for an aerospace engineer / designer about this Osprey design.

    While I love the Osprey’s concept and design, although those big props spinning and changing their angle along with the inability to auto rotate makes me nervous, why don’t they just put properly sized turbo fans at the ends of those wings ?

    Looks to me like it would result in a net reduction in weight and potential mechanical complications. Thinking about it for a moment I suppose the concentrated downward thrust in landing mode might create substantially more concentrated dust problems, but there is already a significant amount of dust and crap flying around anyway.

  • Matt in AZ

    I’m not an aerospace engineer, but I’m guessing the heat output and directed thrust from turbofans would be an issue for where it could land, and where personnel would be safe around it, not to mention increased wear from foreign objects blown towards neighboring aircraft, vehicles, and equipment. I’m not sure if it would or wouldn’t make a difference in IR signature.

  • Cotour

    Good points, but check this out, the VJ101.

    Two old tech pure jet engines mounted on a fighter frame, imagine two modern turbofan pods with 80 percent bypass mounted on the Osprey.

    Something like this (properly sized) is essentially a self driven high power ducted fan system. It seems more workable to me with less weight and less hardware and would probably have a much higher horizontal / forward cruising speed.

    I suppose the blades give it a bit of auto rotation safety capability but I believe they are actually too small to be fully effective.

  • Edward

    At the risk of continuing to divert the topic away from rocket engines, and although I did not work on the Osprey, I have two cents to put in:
    Another advantage to the propellers on the Osprey is ease of running a shaft between the engines to assure that both propellers remain powered in the case that one engine fails. The lower speed on this shaft is less stressful on its bearings and the rest of the structure. Notice the Transmission Interconnect Shaft through the wing in this sketch:

    There are always trade-offs in engineering, and I suspect that the likelihood that an Osprey’s engine will eventually be shot out of action made the safety of having the shaft more desirable than the (probable) weight savings.

    The vertical take-off and landing versatility is more like a helicopter than the F-22 or the F-35 (which can land vertically, but only has short take-off capability rather than vertical take-off). As Matt suggested, it certainly can land more places than the jets, making it more versatile.

    Matt, the photograph in Cotour’s link* shows that the exhaust from the turboprop engine would still be directed downward. Although it would not be a blast of hot air blowing foreign objects (good call on the FOD concern) toward neighboring aircraft (or nearby personnel), it would still be hot as an IR target, and it may not be safe on areas of dry grass or brush.

    * The article was about the collision of two Sikorsky CH-53E Super Stallion helicopters. Yet another case of a journalist (two, actually) not paying attention to detail, running the wrong photo with their story.

  • Cotour

    Just to flesh this out a bit more, the setup would basically be the same two shaft interconnected turbines where one could drive the other if necessary, only a new propulsion system designed around specialized composite fan blades in a composite ducted fan type configuration.

    I understand the trade offs that occur when choosing systems, is there an advantage to the helicopter type blades other than their auto rotation potential, limited as it might be? Stability? Controlability?

  • Cotour

    Thinking further about it in this application the lift, controllability, stability and foldability provided by the over head blade configuration IS more desirable to just brute force thrust.

    And your correct I did not read the article I just saw the picture and it brought up my natural uncomfortability with the Osprey configuration. Its a fantastic machine, but it makes me uneasy. My uncomfortability comes from before I understood that the two power units were connected and one could drive the other if absolutely necessary, I just thought it an unbalanced proposition. The Osprey also appears to provide little chance for productive gliding or auto rotation in an emergency situation.

  • Edward

    Perhaps this will be considered, should there be a similar design for a next generation, but the V-22 is a quarter century old, and turbofans were not so common, as the high-bypass turbine engine was popular on airliners until about the time the V-22 started production. Turboprops were a well understood engine, at the time, having been used on aircraft such as the C-130 and P-3 for three or so decades.

    I do not know much about helicopter blades, auto gyros, or auto rotation, but the V-22 propellers look to me like a cross between helicopter blades and propellers, perhaps with a little more emphasis on propeller.

    I am a bit surprised to have read that the V-22 had a composite propeller, however. I once worked with an engineer who had tested composite rotary wings for helicopters. They believed that there were advantages* in addition to the lighter weight. However, the composites they tested did not do well when damaged, such as from bullets or other projectiles. He told me that the idea was dropped because metals survived small damages better, but damaged composites tended to crack, split, and fly apart too easily.

    Airliners, on the other hand, are not expected to take enemy fire, so they are a great place to gain experience on technologies that may not do well under fire.

    If you are interested in the topic and have an hour to spare, the following is a video about how Rolls Royce builds one of their turbofan engines for jumbo jets. However, the fan blades are metal rather than composite. (1 hour)

    * I took a couple of composite courses in the 1990s, and composites are a fascinating topic. One of the things that my friend said was that they designed the helicopter blade layup to twist a little bit as the blade went faster — a homogeneous material, such as metal, won’t do this, but there can be better cross-coupling characteristics in composites than in metals. As I recall his explanation, they used this characteristic so that at higher rotation speeds the pull from the ends of the blades caused a small twist in the composite that changed the angle of attack at and near the tips so that the blades could rotate faster without airflow separation spoiling the lift.

  • Edward

    In pondering the unexpected contract award to three companies instead of two, I have reminded myself of a thought from some time back: NASA may be encouraging the Dream Chaser but acknowledges that the two existing resupply vessels are a logical fallback in case Sierra Nevada is unable to make Dream Chaser work in a timely manner. With a relatively easy modification to the contract, the other two companies can easily fill any gaps created, should delays arise at Sierra Nevada.

    Technical difficulties exist in any development program, and they have been known to kill several programs. All of the Single Stage To Orbit projects of the 1990s come to mind. There once was great hope that Virgin Galactic would be flying passengers before the beginning of this decade, but after technical difficulty with their intended rocket engine, we now just hope that they will be able to fly passengers someday.

    Dream Chaser has shown that it is flight-worthy, with its successful approach and almost successful landing, so I think that the only real challenges are to show that it is space-worthy and reentry-worthy. Since it uses an Atlas V rocket for launch, Sierra Nevada avoids the major propulsion problems that currently plague Virgin Galactic.

    I have high hopes that Dream Chaser will demonstrate — as we had hoped the Space Shuttle would do — the inexpensive reusability of a lifting-body spacecraft and a runway landing, and that Sierra Nevada will raise the bar of competition so that this style of craft becomes common.

    I am glad that Orbital ATK will get to continue to build and improve its Cygnus spacecraft, as they may be intending to modify it into a space habitat for living space on deep space missions, such as cis-lunar space or Mars.

    I have not heard much about what SpaceX intends to do with Dragon after they have the manned version operational, but I hope that they are developing something that gets us closer to Mars or to the Moon.

  • Cotour

    All good points about the blades and the age of the technology, thanks for your comments. I am certain we will begin to see some new and interesting applications of composites as they are better understood.

    And I had watched that R Royce video a while ago (fantastic), along with most other videos about turbine engine manufacturing, blades, composites and all aspects of machining, anything CNC etc, etc.

    Its what I watch instead of Dancing With The Stars and State Of The Union speeches (for the last 7 years anyway).

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