When you hear "hybrid engine" you probably think of an automobile, right? There's actually another kind of hybrid: rocket engines. While there are environmental advantages to these special engines, critical challenges to adoption remain. A new approach patented this month could change everything.

Admittedly, I didn't know much about hybrid rocket engines until reading Christopher Mims' Technology Review post about the new invention. With all the alt vehicles at the LA Auto Show, I've had automobiles on the brain more than aircraft. However, from what I gather, "hybrid" rocket engines use both solid and liquid or gas propellants. The advantages to these engines include better control, less risk of explosion and the ability to use nontoxic oxidizers to get everything going.

Mims explains that hybrid rocket engines do exist, notably in Virgin Galactic's SpaceShipOne spacecraft, but there are several sticking points for widespread adoption. The major hitch is getting the two states of matter to combine consistently and effectively over the course of the burn. A recently filed patent presents a possible way to overcome this hybrid hurdle. Prepare for your brain to explode.

To achieve the right mixture of propellant, the patent presents a hybrid rocket motor that would use 3-D stereolithography to essentially print the fuel. Yes, print it. The technique would produce thin layers of fuel. "The method provides greater control over the burn profile," the patent reads. "The hybrid rocket motor could be built to almost any size."

Jerome K. Fuller is listed as the inventor on the patent, and the legal team is from the Aerospace Corporation in El Segundo, California. From what I could find out online, Fuller is a mechanical designer with a background in laser tech. Hopefully this invention goes into production soon.

I'm no space cowgirl, but I do recognize that humans love to fly. If we can go to space with improved hybrid rocket engines on half the fuel used now, that would be a giant step.

Photo: Virgin Galactic's SpaceShipOne might not be the rare hybrid rocket engine for long. Credit: Ron Dantowitz.