Tuesday, June 9, 2015

Techy Tuesday - Reusable Booster Rockets With a Twist

SpaceX has been making headlines with its attempts to land a booster on a barge at sea, completely autonomously, and completely unsuccessfully to date, but they're not alone. The European Space Agency's contractor, Airbus has unveiled their version of a reusable booster called Adeline, the Advanced Expendable Launcher with Innovative engine Economy.  What makes Adeline innovative is it has wings and propellers that allow the engines to follow a ballistic trajectory, and then fly like an airplane back to a runway.
SpaceX and Airbus have very different methods of return, too. Falcon 9 keeps some fuel in reserve, which is used to slow the first stage's descent. Adeline detaches from the fuel tank, continues on a ballistic path, and then eventually uses winglets and propellers to land horizontally on a runway, a bit like a UAV. The main benefit of this method, at least as Airbus tells it, is that it requires much less fuel than SpaceX's method.
 Airbus' Adeline
It's no big secret that launching payloads into space is still horrifically expensive.  Rocket engines are the main problem.  They're the most expensive part of a disposable expendable vehicle.   Orbital Sciences Corporation (OSC) paid around $1 billion to the Russian company Roscosmos for 20 RD-180 rocket engines.  These are the engines OSC used on the ISS supply mission that ended in a catastrophic explosion within seconds of igniting.  They're actually old engines, dating back to the Soviet Union, and after the explosive ending to that mission, OSC says they're not going to use them.  The current flight mode of jettisoning and throwing away these multimillion dollar engines after they've run for two to three minutes is one of the barriers to space flight.  
All current space launch systems—SpaceX's Falcon 9, Airbus' Ariane 5, Russia's Soyuz, etc.—are expendable.  During every single rocket launch, the rocket engines and fuel tanks fall back to Earth, usually into the ocean, never to be used again.
This is why companies like SpaceX, and now Airbus, are developing technologies that can bring the rocket engines back to the launchpad, so that they can be reused. SpaceX, which is currently leading the charge in this area, says that it wants to reuse rocket engines and fuel tanks within "single-digit hours" of their return. Depending on who you talk to, and the configuration of the rocket, current space launch prices are somewhere around $250-500 million; with reusable components, SpaceX wants to get that price down below $100 million.
Airbus includes the almost-mandatory computer generated animation of their design concept.

Cool?  Sure.  Interesting design idea.  I hope they succeed in lowering the costs like they say.  There were reports going around the area that the reusable boosters from the Space Shuttle program didn't really save appreciable amounts of money; they never really reduced launch costs.  Whether that was due to the incredible documentation and reliability requirements on manned space flight, or something else, I don't know.  


  1. Sea Launch was doing ~$100 million launches with throw-away rockets until fairly recently.

    Unfortunately, it's doubtful they'll ever launch again.

    And I've heard the "We'llhave lauch costs down to $xxx per pound!" so many times that I tend to be a bit skeptical.

    The Airbus proposal almost looks like one of the old Von Braun/Willy Ley ideas for a reusable booster!


  2. Refurbishing a used solid casing is probably damn near as expensive as making one from scratch. All the fancy steerable nozzles and hydraulics probably get totaled by immersion so all you've got is a big steel pipe to start with, possibly with heat damage, and coated with corrosive salts from the burned fuel.

  3. boy, I dunno. I respect Elon Musk and what he has done/is doing, and I'm sure he has calculated the cost/benefit analysis. And from a practical standpoint, re-using an engine seems attractive.

    But let me pose this design question:

    which would you think would be cheaper to design and build from the engineers standpoint ?

    1. an engine that needs to be durable enough to survive multiple launches/recoveries and can be easily rebuilt for a minimum of cost?


    2. A throwaway engine that only needs to live 10 minutes at full power?

    If you look at it that way, the throwaway looks awfully attractive.

    I'm reasonably sure that with enough careful design work, the extra work and weight to make the engine fully re-usable, and the additional cost and weight associated with the recovery apparatus might tip the scale.

    But as an engineer, option 2 looks very nice......

  4. The current technology for leaving this gravity well is simply too costly and inefficient to allow humans to leave earth and travel, explore and exploit space in any meaningful volume. It would be akin to using the Nina, Pinta and Santa Marie to deliver ONLY Columbus by his lonely self to the new world. Not economical or efficient. We only travel to space because governments take money by taxing to do so. The handful of private platforms rely on philanthropy and venture capital....with no payback in sight. It currently costs about $10K per pound to put both material and people up to orbit and that doesn't include actually leaving orbit. Till we cut that by 99% space travel will remain the purview of tax supported governments and will only happen for reasons that suit politicians. Without profits private space travel will be very limited and usually be partnered with government projects.

  5. That Airbus thingy needs a couple of Pratt R-4360's.
    I watch YouTube videos of them starting just for fun. And have been known to drive 100 miles to see one run in real life.
    Real aviation, round motors, sticks and rags. :-)

  6. Terry, Airbus wouldn't put a pair of Pratt radials on their rocket. One of those engines has more balls than the entire Airbus corporation. They couldn't stand to be around it.

    They'll put some whiny little "green" motor on it.

  7. Anon 12:43, I don't know, but I'd bet any engine that could survive 10 minutes of launch stress could be cleaned and refurb'ed. Although dunking the engine in the ocean might complicate things.

    The shuttle main engines were the kind of complexity we're talking about, not the solid rocket thrust vectored engines. They never got dunked in saltwater, but while they were thought of as really scary when the program started, they had a flawless record by the time the Shuttle program ended.

  8. For Old Surfer:
    Cleaning and refurbing the casings from the solids was nowhere near as expensive as making them from scratch. And the nozzle and hydraulics packs were routinely refurbished far less expensively than making them from scratch as well.

    For Graybeard:
    A significant portion of the cost of shuttle operations was thermal protection. If you can't use ablative insulation, you are stuck with tiles and such. Ablative is not a good choice for reusable, since you have to get the old stuff off and the new stuff on between flights. Which takes time and costs a buncha bucks. And tiles and such were still state-of-the-art at the last review I participated in. That was several years ago before I retired, but there has been no significant testing of any new options since then.

    Airbus' proposed concept makes about as much sense as Roton. Look it up.

    Hopefully SpaceX has either hired some of the people who worked DC-X, or at least had a serious discussion with them of "lessons learned" from that project. They successfully proved how to launch, transition, and land, although their project was effectively the equivalent of an unmanned helicopter with limited range and no payload capability. Unfortunately, their "save money" concept crashed the vehicle when the landing gear was not configured properly before launch. Letting a lone tech or engineer do something as complex as advanced rocketry is a good way to end up with a smoking hole in the ground. On complex tasks, people develop tunnel vision and fail to see what they're doing to things they aren't intentionally working on. If you have to make an important presentation, do you do your own proofreading? Or do you get someone else knowledgeable to check it for you? Same issue with orbital rockets. But that is usually the first thing that gets cut.

  9. Now SpaceX DOES have a more complex problem that what DC-X faced. That project launched and landed from a concrete pad in the desert. No pitching. No rolling. And when you add in what would seem to be a higher CG than that of DC-X, the problem gets even worse. Now long term, SpaceX plans to fly back to land, since the salt spray from landing under thrust on a barge and towing back to shore will cause major problems with the engines. But the Air Force Eastern Test Range is not likely to approve that until SpaceX successfully demonstrates at least one successful barge landing. And the USAF ETR has safety responsibility for all launches from the Eastern Test Range.

    Dunking a pump-fed engine like that of the Shuttle or SpaceX into the ocean causes sufficient problems to make it cheaper and faster to build a new one than to recertify one that went through such an event for flight. Big Dumb Booster, which was a blow-down concept that had no pumps for the propellant MIGHT have survived, but like many other concepts there seems to be no way to get useful payload to orbit with such a design.

    You might also want to look at VentureStar, which was a LockMart proposal to build a single-stage-to-orbit (SSTO) vehicle. Unfortunately, once they got into the detailed design, they realized the payload capability of the vehicle was -5000 lbs. And yes, that IS a negative sign.

    This actually IS "rocket science".