While probably better known for its engineering solutions for ground vehicles, Ricardo announced in late May that it is developing a new purpose-built family of UAV engines for both civilian and military applications.
As the Pentagon's investment in UAVs has more than doubled to $4 billion since 2006, U.S. military UAV operations have grown from about 165,000 hours in 2006 to more than 550,000 hours annually currently, according to the U.S. DOD. In fact, Ricardo cites statistics that today the U.S. Air Force actually trains more unmanned than manned aircraft pilots. That said, there has also been a very steep increase in the use of UAVs for more nonmilitarized applications, such as border protection, drug interdiction, firefighting, etc.
An interesting observation from Dr. Ron Storm, Ricardo's Director, Military Market Development, is that while smaller UAVs routinely carry multimillion-dollar systems of cameras, sensors, and other electronics, they are typically powered by gasoline engines originally designed for lawn and garden equipment or model planes.
"Today, the engine is the weak link in the UAV system, especially in these smaller aircraft," said Storm. "The military and aircraft integrators worked with off-the-shelf engines and adapted them for UAVs so they could deploy the technology to war fighters rapidly. However, the engines weren't designed as part of a complete system around the needs of soldiers in the field, so failures have been unacceptably high."
To understand the specific needs of UAV customers and pilots, Ricardo worked with military and civilian experts, including Rick Scudder, Director of the University of Dayton Research Institute's Center for UAV Exploitation, and Larrell Walters, Director of the UoD-led Institute for Development and Commercialization of Advanced Sensors Technology.
"This program has been an exciting collaboration," said Stephen Cakebread, Ricardo Project Director, Unmanned Systems, and architect of the Wolverine 3. "As we learned more from people with hands-on UAV development and in-field experience, we realized that an engine that isn't purpose-built for aviation is going to be inherently compromised from the standpoint of performance, weight, package efficiency, and durability."
In particular, relying on gasoline creates logistical and reliability problems in the field, Ricardo learned.
"Most military vehicles and stationary power sources use heavy fuels, so gasoline is often shipped in at enormous expense or sourced locally, which means that octane and purity levels can vary widely," said Ricardo's Tom Howell, Chief Engineer. "It's not uncommon for engines to fail after only a few hours of service, and poor fuel quality is often the culprit. Our heavy-fuel design will help reduce these costly failures that put lives at risk."
The first engine in the family, designated Ricardo Wolverine 3, will power lightweight aircraft and use military-spec heavy fuels. It is a 3.1-hp, two-cylinder, two-stroke, air-cooled engine with spark ignition, direct fuel injection, and 500 W of onboard power, thanks to an integrated starter-generator. Ricardo is studying plans to develop Wolverine engines to power UAVs with heavier payload and greater range and endurance requirements.
Ricardo says the engineers at its Detroit Technology Campus took the Wolverine 3 from concept to production readiness in six months, and they successfully completed the engine's first fire on a dynamometer test stand in early May.
Next, the engine will be installed in a small tactical UAV in preparation for its first flight, which is scheduled for this summer at the Nevada test site. Ricardo is currently in talks with over a dozen UAV integrators about putting the engine into series production.