Insitu and Sonex team up to switch UAV from gasoline
Insitu has teamed with Sonex Research to develop a heavy-fuel engine for the ScanEagle unmanned air vehicle as it prepares to compete to keep its contracts to provide UAV services to the US Marine Corps and Navy in south-west Asia.
The US military wants to use heavy fuels instead of gasoline in its UAVs for safety and logistics reasons, and Insitu has licensed technology from combustion system specialist Sonex to covert the ScanEagle's 2.5hp (2kW) single-cylinder, two-stroke 3W-28 gasoline engine to burn jet fuel.
Insitu has completed 300h of ground tests with a modified engine and is "encouraged" by the results, says president and chief executive Stephen Sliwa, adding: "We are just weeks away from a first flight." The company plans to begin delivering heavy-fuel engines next year, he says.
Sliwa says the HFE-powered ScanEagle will fly in a "totally safe configuration", able to operate over the full altitude and temperature range, but will incur a "25-30%" endurance penalty initially because of the modified engine's higher fuel consumption.
"Over the coming months we hope to regain some of the performance deficit," he says, but points to the 22h endurance exceeded by the latest Block D ScanEagle. "We have some excess endurance, and can back off 25% and still get better than 12h."
Ground testing is being done using JP5 fuel. "That's the toughest one," says Sliwa. "JP8 is easier and diesel halfway between." Tests have included full-power runs with the UAV mounted on a car to simulate flight conditions, and a "zip test" to ensure the engine runs during a 12g catapult launch.
Teamed with Boeing, Insitu has sole-source contracts to provide UAV services for the US Marine Corps in Iraq and the US Navy in the Gulf. These are to be opened to competition, Sliwa says, as a bridge to the USN/USMC small tactical unmanned air system, development of which will begin in 2010.
Insitu has licensed the Sonex technology for exclusive use in UAVs up to a certain weight. "By combining their technology with our own ideas, we can offer an HFE for our class of UAV," says Sliwa.
Source: Flight International
