Rocket Lab Unveils First Battery Powered Motor

Rutherford motor (Credit: Rocket Lab)
Rutherford motor (Credit: Rocket Lab)

COLORADO SPRINGS, Colo. (Rocket Lab PR) — Rocket Lab, the rapidly growing aerospace company, today unveiled the Rutherford engine, revealing that the Electron launch system is the world’s first battery-powered rocket.

Electron is a small orbital launch vehicle, designed to transform the global space industry with affordable, high-frequency launches of small satellites.

“Historically, the time and expense to launch small satellites have been prohibitive, costing many millions of dollars and requiring endless patience and flexibility waiting for months to ‘hitch a ride’ to space,” said Peter Beck, CEO of Rocket Lab. “With Electron, companies can launch whenever they would like, at a substantially more affordable cost. This monumental advancement in space technology gives satellite-reliant businesses the freedom they have been waiting for, which will lead to vast improvements in how we use satellite technology in space.”

Electron features announced today:

  • Electric Rutherford engine. Unlike traditional propulsion cycles based on complex and expensive gas generators, the 4,600 lbf Rutherford adopts an entirely new electric propulsion cycle, making use of high-performance brushless DC electric motors and lithium-polymer batteries to drive its turbopumps.
  • 3D-printed primary components. Rutherford is the first oxygen/hydrocarbon engine to use 3D printing for all primary components including its engine chamber, injector, pumps and main propellant valves. Using this process, Rocket Lab’s engineers have created complex, yet lightweight, structures previously unattainable through traditional techniques, reducing the build time from months to days and increasing affordability.
  • Payload integration. Electron’s upper stage is designed with the capability to disconnect the payload integration from the main booster assembly. Sealed integrated payloads can then be transported back to Rocket Lab where integration with the main booster can occur in a matter of hours. This approach eliminates the risk of cascading delays and allows customers to regain control of the integration process, using their own preferred facilities and personnel.

“Although the privatization of the space industry has promised an easier path to commercial launches, space has remained an incredibly difficult and expensive place to reach,” said Beck. “Electron makes it possible for us to continue to execute on our vision to enable easier access to space. As more small satellite companies are able to quickly reach orbit, we will see immense advancements in communication and imaging technologies, which has the potential to drastically change our world – from improved traffic reporting to crop planning to even mitigating the life-threatening damages of natural disasters.”

About Electron

Electron is an entirely carbon-composite vehicle that uses Rocket Lab’s Rutherford engines for its main propulsion system. Electron is 20 m in length, 1 m diameter and has a lift-off mass of 10,500 kg. The vehicle is capable of delivering payloads of up to 100 kg to a 500 km sun-synchronous orbit, which is the target range for the high growth constellation-satellite market.

The carbon-composite Electron creates increased access to space by giving customers the ability to launch satellites more frequently and affordably with a dedicated launch priced at $4.9 million. In a process that used to take years, Rocket Lab has reduced the lead-time from load to launch to weeks through vertical integration with Rocket Lab’s private launch facility.

About Rocket Lab

Rocket Lab’s mission is to remove commercial barriers to space. The company was founded on the belief that small payloads require dedicated launch vehicles and a flexibility not currently offered by traditional launch systems. Rocket Lab is a privately funded company with its major investors including Khosla Ventures, K1W1, Bessemer Venture Partners and Lockheed Martin. Founded in 2008, Rocket Lab is headquartered in Los Angeles with operations and a launch site in New Zealand.

  • GreenShrike

    “high-performance brushless DC electric motors and lithium-polymer batteries to drive its turbopumps”

    Why bother with the turbine? Why not drive the pumps directly from the electric motors?

    Unless it’s the typist’s muscle-memory that actually pre-pended the “turbo” onto the pump, and not Rocket Lab’s tech. 😉

    More seriously, my fingers are crossed for them. Between Electron and Firefly, I hope small-sat launch become a vibrant industry. And with Electron’s electric pumps and Firefly’s aerospike setup, the the companies do seem to be actively innovating.

    Now they just need to actually fly. 🙂

  • Larry J

    Aviation Week used similar language in their article. I think it’s incorrect to say that this rocket battery powered turbo machinery. Instead, it uses electric pumps to move the propellant. Pretty clever! Perhaps if the market isn’t large enough to support both Electron and Firefly, they could combine their technologies. For example, they might be able to use the electric propellant pumps with the aerospike engines on Firefly’s composite casings.

  • Hug Doug

    the correct terminology is indeed “turbopump,” because a turbine is used to move the fuel / oxidizer at very high speeds. they are just using an electric motor to turn it rather than using fuel or oxidizer (or burning the two) to do so, as done in other rocket engines. there’s no other pumps involved here, and it’s still called a turbopump.

  • Larry J

    I don’t think that’s correct. In turbochargers, jet engines, and turbopumps, the turbine drives the compressor/fuel pumps. Combustion gases are what spin the turbine. In this new case, the pumps are being driven by powerful yet lightweight electric motors.

    If it works as advertised, this is a significant development. Developing reliable turbopumps is probably the most difficult and expensive part of most rocket engine development. It probably doesn’t scale well to larger engines because those turbopumps develop thousands of horsepower, but for a small engine and with the electric motors’ higher efficiency, this can be a viable solution.

  • Hug Doug

    Ah. In that case, I’m uncertain of the correct terminology. Electro-pumps maybe? 🙂

  • stoffer

    Electro-turbine pumps?

  • Doug Weathers

    The scaling problem would likely be the batteries rather than the electric motor. The energy density of batteries is very poor compared to, say, kerosene.

  • Doug Weathers

    I’m not sure I agree that “turbines” have to be driven by burning fuel. Power plant generators are spun by turbines that are driven by steam.

    I’d call them “electric turbopumps”, myself, or if this is too provoking, “electric pumps”.

  • Larry J

    Agreed. There’s one thing that you can’t get around and that one horsepower equals 746 watts. That’s a physical constant and not subject to debate or wishful thinking. When it comes to those pumps, the situation is actually worse due to the inescapable friction and resistance losses. As a rule of thumb, you can figure on about 900-1000 watts per horsepower. It takes a lot of power to move propellants at the flow rates and pressures required for a large rocket engine. An engine the size of a Merlin D can easily require well over 1000 horsepower for the turbopumps. Even with the higher efficiency of these electric pumps, you’re probably looking at electrical loads of 500k to one megawatt per engine for 150 seconds or more. That’s a tall order for batteries. Turbopumps are engineering marvels, but they’re difficult and expensive to develop and build.

  • Hug Doug

    I meant that in most rocket engines, the turbines are driven by either burning fuel or the fuel or oxidizer pressure as it goes through to the engine.

  • stoffer

    The Rutherford is much smaller than Merlin. The batteries are pretty good these days. Li-Ion batteries have energy density of one fourth of hydrogen peroxide (used to drive pumps in Soyuz). Given that electrical engines have above 95% efficiency, compared to 20% of turbines, I would say batteries are interesting. Of course, you get rid of HTP as you ascend, but the high pressure HTP tanks still weight something, and they probably have a lighter structure (CRFP) than say Soyuz, so it may work for them. Not to mention, that startups will be much easier with electric pumps. Also, most people don’t mind batteries in their pockets, but would feel very uneasy about powering their cellphones with HTP :). Perceived safety may be also an advantage, at least for the insurers.

  • Larry J

    I think turbopumps are closer to 50% efficient but the point stands that electric pumps are much more efficient. Still, the issue of whether this technology scales well is that large engines would require excessively high discharge rates (perhaps thousands of amps). The article said that each of these electric motors produces 50 HP. That’s over 37 kilowatts at 100% efficiency per pump. If the electric motors and power supply system were 90% efficient (doubtful it’s that high), then you’ll need over 41 kilowatts of electricity per pump. Even at 500 volts, that’s almost 83 amps of current. It’s certainly doable for pumps of this size but it’d be much more difficult for large engines.

    If this works as advertised, they’ve come up with a very cleaver, novel, and cost effective engineering solution. Kudos to them. I hope it works.

  • stoffer

    A high temperature high pressure ratio turbine can be 50% efficient, but HTP driven turbines have lower pressures and lower temperatures. I think that a gas generator or an expander cycle will always be better in performance than a battery driven pump, but electrics may have an edge over HTP driven pumps and they definitely have an edge over a pressure fed launcher, especially on the first stage high pressure is needed to get any reasonable Isp. If I were to bet on Firefly or Electron, I would bet on Electron. Currents and power density are still challenging and I think that is is not an accident that we see this kind of cycle on a small launch vehicle.

  • Saturn13

    XCOR has done this using a piston pump.

  • Larry J

    I’d love to see a combination of their technologies – Firefly’s aerospike engines made using Electron’s 3D printing and electric propellant pumps, attached to a high efficient composite structure.

  • GreenShrike

    Great, now I had to go and actually look up stuff to cover my wiseass-ery. 😉

    A “turbine” is a “is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work”. So, no, your explanation is wrong. A device which imparts energy into a fluid flow using rotational mechanical energy is not a turbine — such a device is a compressor.

    However, compressors are a type of turbomachinery, as are centrifugal pumps. *If* Electron’s pumps are of centrifugal design — which I think likely, as I believe XCOR are the only ones trying out piston pumps in the aerospace field — then even though the pump isn’t being driven by an actual turbine, it could be argued that “turbopump” is an appropriate term.

    Not, however, by me. 😉

  • Hug Doug

    Having to look stuff up is half the fun xD

  • kentercat

    As for nomenclature, I suspect it’s just habit becoming terminology that a rocket fuel pump is a turbine/turbopump. We now have cars with “electric turbochargers” and we call it that because people know, functionally, what a “turbocharger” is for.
    As for the technology, I would like to see this considered for Mars Sample Return, It looks perfect for that, especially if you make your own fuel on board.
    A piston one was proposed around a decade ago by a guy at Laurence Livermore Labs specifically for Mars sample return, because it fits in that range below a conventional pump. Sounds like XCOR took up that project.

  • savuporo

    Late to the party but .. but the motors used here are probably pretty much lifted straight from the bigger electric RC aircraft motor designs, that have been previously scaled up to powered paragliders and light electric aircraft. The specific power these things pack on the motor side is insane, limited really only by sufficient cooling.
    Also, i’d be surprised if these guys are not using primary batteries with very high discharge rates, which again give much higher specific energy per Kg than rechargeable lithium batteries for instance.

  • Jsashcroft

    Couple of things I didn’t appreciate
    1. The power these brushless ac motors can produce for the weight.. 200kw from a motor weighing less than 20kg .. Yes “insane”
    2. The power density and high discharge rate of the poly lithium ion batteries.

    This is combination sounds bizzare but really looks like a significant way forwards for rocket engines.

    Just surprised Elon Musk didn’t think of it!