A Look at Stratolaunch’s New Rocket Engine

Air-launched boosters (Credit: Stratolaunch)

Aviation Week has a photo gallery detailing the PGA engine developed to power the rockets that will air launched from Stratolaunch’s massive carrier aircraft. The engine’s details include:

  • fuel-rich, staged-combustion liquid oxygen and hydrogen engine capable of generating 200,000 lb. of thrust
  • three cores with single PGA engine each will power medium launch vehicle
  • fully reusable Black Ice space plane powered by three PGAs; and,
  • engine testing to begin at NASA Stennis in October.

  • duheagle

    Testing at Stennis next month, eh? Having decided to build their own engines and air-launch vehicles early this year, Stratolaunch doesn’t seem to have let any grass grow under its feet. I eagerly await further news.

    More potential bad news for AJR? If Stratolaunch proves out this engine, it could offer it, with a sea-level bell, to other builders of smallsat launchers. If the price point is low enough, a cluster of three or four of these – even allowing for the crummy hydrolox sea-level Isp – could compete with a single AR-1 as a booster stage powerplant and, as a bonus, make reusability a lot easier to implement.

  • Kirk

    “three cores with single PGA engine each will power medium launch vehicle”

    That should be “medium launch vehicle-heavy” (per slide 7). The plain MLV uses a single PGA.

    What an awkward phrase, akin to “extra medium”!

  • Flechette

    The Mach 10 vehicle in the slides appears to be a copy of DynaSoar.

  • Andrew Tubbiolo

    Space X, Blue, Stratolaunch, and Rocketlab have the full spectrum of space launch ‘for the masses’ pretty much closed up assuming they stick with it. What’s really needed now are more applications startups along the lines of Planet Labs. Now we need some real reasons to fly.

  • Larry J

    I like your scenario of Stratolaunch offering their engines to others. Whether they would be suitable for reuse would depend on their throttleability. We know nothing about that potential aspect of their engines. It could be that with additive manufacturing, the costs are low enough that reuse wouldn’t gain you very much.

  • voronwae

    Actually, much more like an HL-20 evolved for modern materials. The DynaSoar resemblance is there, but Dynasoar used an aluminum heat-sink design and this thing uses a scow nose and most likely CMC and carbon materials. Excellent to see someone finally taking advantage of what’s become available, if that turns out to be the case.

  • Flechette

    The rear of the vehicle appears more DynaSoar-ish, but I agree with you on the nose.

  • duheagle

    There are already dozens of such and we hear about new ones almost daily. The next 24 months or so will, I hope, see the meeting of launch providers, new and old, and new space applications companies getting a bunch of stuff on-orbit and generating revenue.

  • duheagle

    Or the ever-popular “jumbo shrimp.”

  • duheagle

    Most liquid propellant engines are at least somewhat throttleable. The Raptor certainly is and Stratolaunch’s propulsion chief worked on that engine when he was at SpaceX.

    For launch-from-surface vehicles, engine throttleability is useful for limiting G-forces during Max-Q in the lower atmosphere.

    For air-launched vehicles, that is a much less important consideration, but throttleability is still desirable to limit G-forces on payloads during the latter stages of flight as propellant burns off.

    Throttleability,as you correctly point out, is also very useful for reuseability implemented via vertical landing.

    I don’t know if any of Stratolaunch’s vehicles are going to be designed to be reusable – except perhaps the manned and hypersonic ones. Air launches done well out over the ocean tend to complicate reuse unless one is looking to do as SpaceX has done and land on a ship.

    Stratolaunch’s announced engine seems to fit a thrust and – most likely – price point that could be very attractive to other vehicle designers. Perhaps some of those other vehicle designers would even plan to use the Stratolaunch Roc to carry their vehicles up for air-launch. Blue Origin just struck a big deal to supply engines to an incumbent competitor. Stratolaunch could well find it beneficial to do the same. Additional production volume and/or additional flight ops for the Roc would both benefit Stratolaunch’s bottom line. It would be nice if Stratolaunch booked enough business in fairly short order to justify the construction of a second Roc.

    Additive manufacturing has many charms, especially for complex, low-volume parts. But it is not the same as getting parts for free. Given that essentially every new smallsat launcher company will be making use of 3-D printed parts, there is no obvious competitive advantage accruing to any individual firm merely from such use. A resuable stage with 3-D printed parts will still be more economical, over time, than an expendable stage built using the same technology. SpaceX already uses a lot of 3-D printed metal in its Merlin 1-D’s and will use even more in its Raptors. But the plan is still to reuse the engines for as long as possible. Ditto Blue Origin’s engines and vehicles. The builders of smallsat launchers will be forced to embrace reuseability to stay competitive with early adopters in this market who go that route.

  • redneck

    Air launches well out over the ocean could target the landing zone on the coast for recovery. Launch off the west coast for recovery at a precise location on the coast. Fly forward recovery as Jon Goff calls it.