New Rocket Motor Takes Flight in Mojave Desert

EL SEGUNDO, Calif. (Aerospace Corporation PR) — Solid, liquid, or gas? That might sound like a question on your high school physics test, but it’s an important consideration when powering a rocket into space.

A team from Aerospace successfully tested a new type of 3-D printed rocket motor that could potentially lead to less expensive and more efficient rocket propellants.

“The Aerospace Corporation created and has led the field of 3-D printed propellant from its beginning, but we’ve never flown any of the technologies we created in this area,” said Jerry Fuller, who came up with the idea in the first place. “This test was the first flight of a novel liquid motor.”

Propulsion Options

Traditionally, there are several types of rocket propulsion systems. Liquid propellants are the most capable, but also the most expensive. Solid propellants are simple, inexpensive, and common. Hybrid propellants (combining solid fuel with a liquid or gas oxidizer) are reasonably inexpensive, but are rarely used since they don’t perform very well.

“The truth is hybrids don’t burn fast enough and are not as efficient as they should be,” Fuller said.

A 3-D printed fuel grain ready to be filled with liquid fuel.

Fuller has been investigating ways to 3-D print hybrid motors, and has come up with helical shapes that enable the liquid or gas oxidizer to interact with the solid fuel more effectively and dramatically improve performance.

Not satisfied to stop there, he is now looking at what he calls “Port Injected Liquid” motors. Normally, liquid motors require expensive turbopumps to deliver the fuel and oxidizer. Fuller rearranged the traditional structure of a liquid motor, where the fuel and oxidizer are pumped from low pressure tanks into a thrust chamber, to look more like that of a hybrid rocket, where liquid oxidizer flows through a chamber that contains solid fuel. Here, a printed “liquid fuel grain” stores a liquid fuel and meters the flow of fuel as the oxidizer passes through it. This arrangement can eliminate much or all of the plumbing and turbomachinery typically seen in liquid motors. It also allows liquid motors to be very small and simple and inexpensive.

Fuller and systems engineer John McVey cooked up the idea to test these motors, and they pulled in propulsion science engineer Andrew Cortopassi and amateur high-power rocketry wonk Chris Kobel to complete the task. With Cortopassi’s expertise, the team first tested the motors in Aerospace’s Propulsion Research Facility, and then decided it was time for the motors to, quite literally, take flight.

They packed up their gear and took a field trip to California’s Mojave Desert, where they launched four of their liquid motors and one hybrid motor on high-power hobby rockets. They expected to reach an altitude of 1,000-4,000 feet, but one of the liquid motors exceeded their expectations, reaching a maximum altitude of a little over 5,000 feet, with a maximum velocity of almost 600 mph. These results bode well for the future.

Looking Forward

Fuller emphasizes that the research thus far has been for small motors, like the ones just tested in the Mojave Desert. Larger motors would need to be tested, but with current 3-D printers, creating a fuel grain for a sounding rocket or a small CubeSat launch vehicle is not out of the realm of possibility.

More research is needed, but the potential for a less-expensive, high-performance motor is attractive. As Fuller puts it:

“A simple liquid motor is something that doesn’t really exist at the moment, and if we can find ways, probably through 3-D printing, to manage the delivery of liquid fuel, then we will have made a significant advance in rocket motor technology,” he said. “At the moment it looks like we have found at least one of these ways.”

  • SamuelRoman13

    Some interesting rocket engine news. I just ran into some old news while looking for the price of a RL-10 in 2011. https://www.darmatechnology.com/chase-10.html
    Doug said in a 2011 article that Chase-10 is a replacement for the RL-10 at 3million $ Vs 38 million for RL-10. It is a methane engine of 22,000lb thrust. The website says call for price. A year to deliver. I wonder if OmegA had heard of this engine. Seems to be a small company though. I never found the current price of a RL-10 engine. 38 million? Does not sound correct.

  • Enrique Moreno

    Very, very interesting

  • voronwae

    What the heck is a “liquid fuel grain”?

  • Michael Halpern

    from my understanding, instead of using turbopumps, its filling a helical structure with liquid fuel, using surface tension, inertia and oxidizer flow to force the fuel into the combustion chamber, basically treating liquid fuel as you would solid fuel.

  • Ignacio Rockwill

    I think these “gimmicks” to get rid of Turbomachinery are relics of the disposable launcher era of spaceflight. Nobody complains about the cost or complexity of aircraft gas turbines. And those machines are lauded for their reliability (the recent tragic accident being decidedly rare)

  • Michael Halpern

    Depends on the application of the rocket in question, in small launch due to mass constraints it can make sense even if you intend to reuse it somehow, turbo pumps are heavy after all, in a weapon your not going to reuse the rocket and if SRM industry starts to buckle from the launch industry abandoning solid rocket motors, the military will want a solution be it subsidizing SRMs or finding an alternative

  • Ignacio Rockwill

    I think weapons will stick to SRM’s for the foreseeable future.

  • Michael Halpern

    depends on economics, if stopping use of srbs in launch vehicles causes SRMs to be too expensive, and a viable alternative exists or is in significant development there really wont be much of a choice, being able to afford your ammo is a very important part of any weapon system

  • Michael Halpern

    advanced weapons systems have been cancelled simply because the ammo was too expensive, the new stealth destroyers dont have a main gun right now because of this. think about that. I am not talking soon but in say 10-15 years, the need to replace SRMs can be a very real possibility

  • Michael Vaicaitis

    The concept of “small launch” is a “relic of the disposable launcher era”. With the imminent advent of reusable launch architectures, the concept of small or medium or heavy launch will disappear, to be replaced by only “cost of launch”.

  • Michael Halpern

    No it’s not because the goal isn’t to lower costs, its to give small sats a dedicated ride

  • Michael Halpern

    The various lift classes will not go away, just like we have trucks, trains and frieghters of various sizes for different needs, same will apply to launch vehicles

  • Michael Halpern

    Launch is a transportation industry, like air, water, road and rail it will have various niches, they break down into a few concerns, cost of transportation method, how much it can carry for that cost, how available it is, how quickly it can get what you are transporting to its destination, quality of service and a few others. Let’s look at cost per launch right now and just with American rockets at $5m usd the lowest cost launch is Rocket Lab’s Electron. Cost per kg at 95m usd is Falcon Heavy with the center core expended, however most of SpaceX’s customers don’t need that kind of lift so reusable f9 at 62m usd or fully reusable FH at 90m usd are better options most of the time

  • Vladislaw

    it will be cost per pound.. if launch vehicles have a 150 ton capacity it will have few single cargo customers.

  • Vladislaw

    and pretty much without exception they charge by weight . cost per pound or cost per ton … with cargo launch vehicles able to 150 tons.. it will be more like a container ship or a railroad.. multiple cargoes and mulitple customers…

  • Michael Halpern

    True but expedited service is a premium as is quality service

  • Michael Vaicaitis

    dude, shouldn’t that be cost per kg, and 150 tonne 🙂

  • Vladislaw

    true … thanks for the heads up ..

  • windbourne

    If they get it working, hopefully, they will build model rocketry engine with it and sell these to fund their company. Seriously, if they have better performance than Este they could use this re-develop the model industry and bring it back.

  • Michael Halpern

    Better preformance, lower cost possible limited reuse, and so on, if its somewhat throttlable, you get the drone crowd involved with people trying to small scale f9

  • windbourne