R&D organization Battelle has completed preliminary design of an improved icing spray system to replace equipment now used by the U.S. Army to perform icing certification on military and civil helicopters and smaller fixed-wing aircraft.

Under a $13 million contract awarded in June 2011, Columbus, Ohio,-based Battelle is developing the Objective Helicopter Icing Spray System (Ohiss) to replace a modified Boeing CH-47D Chinook that has been used for decades.

The Army-operated helicopter spray system is used by military and civil aircraft manufacturers as an alternative to seeking out natural icing conditions, a process that can often lead to delays in testing required for certification.

With the current system, the modified Chinook sprays water and air through a bar that produces an artificial cloud. An aircraft flies behind the helicopter to measure the cloud’s water content and droplet size as the spray is adjusted until the desired test conditions are met, when it is replaced by the helicopter of aircraft being tested.

The Ohiss will be a kit that can be installed on any CH-47F-model Chinook within three days. The kit includes a spray array that can produce a larger cloud with a wider range of water content and droplet sizes, says program manager John Moorehead.

Attached to the helicopter’s belly and fed with air and water via the center cargo-hook “hellhole,” the array will extend out to 60 ft. wide and hang 40-50 ft. below the helicopter , moving the cloud out of the rotor wash so that it remains intact.

The larger spray array will speed certification , he says, as the system is capable of producing one cloud configuration to test a complete rotor or wing, and another to test a fuselage or engine inlet.

Battelle will fly a prototype spray boom early next year, and 125 hr. of flight tests are planned before the Ohiss becomes operational in January 2016, during the 2015-16 icing season, Moorehead says.