The United States Navy is getting all the credit for its recent investment in the technology (and perking up the news cycle), but the rotating detonation engine has actually been in the works for a few decades, at this point. The patent for the engine was filed in 1982 and granted in 1988 to a Rockville, Md.-based inventor named Shmuel Eidelman. (The patent is actually called the "rotary detonation engine," rather than "rotating" -- it's unclear when the moniker changed.)
Shmuel Eidelman has been a busy man. He has been awarded 14 patents since 1982, focusing on aeronautics, propulsion and chemicals through his work with scientific corporations and military organizations [source: PatentBuddy]. So when the patent was filed, it seemed like the Navy had pushed the gas-turbine as far as it could go, and it was time to start thinking fresh.
The U.S. Navy was initially interested in pulse detonation engines (as described earlier), and invested in research to develop these fuel-saving systems. The Navy's researchers say that maximizing the potential of this type of engine relies on understanding its complex physics [source: U.S. Naval Research Laboratory]. The rotating detonation engine is still a gas-turbine engine, like the engines currently powering the Navy's fleet of ships and aircraft, but tweaking and refining the cycle unlocks a lot of additional power. Navy researchers believe that rotating detonation engines have the potential to reduce fuel consumption in new equipment by 25 percent, which would be an annual savings of about $300 to $400 million [source: Quick]. Another benefit of the system is that it could be configured to power up an electric motor, which would, in theory, allow military fleets to start transitioning to (potentially) cleaner, cheaper and more efficient electric drivetrains.
Rotating detonation engines aren't ready to go just yet, so simulations are the best predictor of their efficiency -- yet they're still promising enough that the Navy is pushing forward with development. There's no publicly-known ETA for completion or implementation, but the rotating detonation engine is likely to arrive -- someday, anyway -- at a naval base near you.
Author's Note: How the Rotating Detonation Engine Works
It doesn't appear anyone's suggested (not yet, anyway) that the rotating detonation engine might actually have potential to be used in cars or trucks. It was invented by a guy who specialized in military technology and is being pushed into development by the U.S. Navy. The actual size of the engine model in development hasn't been mentioned anywhere, so this is all speculation. But we do know this: It's obviously big enough to power ships and planes, and that's way more power than a car needs. Where would the efficiency be in that?
But years of writing about cars and transportation technology has shown me that a lot of the stuff we use every day was originally developed for completely different purposes -- and race cars and military vehicles are two common sources. Even though fuel-efficient cars are currently going in a different direction (hybrids, electrics and biofuels), it's not incomprehensible to say that someday, someone could find a way to scale down a super-efficient gas-turbine engine and stuff it under the hood of a car.
- Google Patents. "Patent US4741154 -- Rotary detonation engine." (Feb. 17, 2013) http://www.google.com/patents/US4741154
- Green Car Congress. "Navy researchers project Rotating Detonation-Wave Engines could yield 10 percent power gain, 25 percent reduction in fuel burn over gas turbines." Nov. 2, 2012. (Feb. 13, 2013) http://www.greencarcongress.com/2012/11/rdwe-20121102.html
- PatentBuddy. "Eidelman, Shmuel." 2013. (Feb. 17, 2013) http://www.patentbuddy.com/Inventor/Eidelman-Shmuel/11310789
- Physics Today. "US Navy developing rotating detonation engine." Nov. 6, 2012. (Feb. 13, 2013) http://blogs.physicstoday.org/newspicks/2012/11/us-navy-developing-rotating-detonation-engine/
- Quick, Darren. "U.S. Navy investigates use of fuel-saving Rotating Detonation Engines." Gizmag.com. Nov. 4, 2012. (Feb. 13, 2013) http://www.gizmag.com/us-navy-nrl-rotating-detonation-engine/24862/
- U.S. Naval Research Laboratory. "Navy Researchers Look to Rotating Detonation Engines to Power the Future." Nov. 2, 2012. (Feb. 13, 2013) http://www.nrl.navy.mil/media/news-releases/2012/Navy-Researchers-Look-to-Rotating-Detonation-Engines-to-Power-the-Future