Putting a new twist on the notion of fighting fire with fire, Boeing has patented a plan for packing howitzer shells with retardant chemicals and lobbing them into the path of a forest fire.

With wildfires raging across the West again this summer, another tactic might be welcome. Talk about a hot market.

But there’s no sign Boeing has even tested its thinking on this idea — no working prototypes are required to win a patent.

The patent, on which a half dozen Puget Sound Boeing employees are credited as the inventors, claims the approach could be more efficient and flexible than dropping the retardant from airplanes or helicopters.

It notes that aircraft can’t fly at night or during bad weather, and “deliver fire-retarding material at a low rate which often makes them inadequate to control forest fires.”

With artillery, the patent asserts, retardant could be delivered in a variety of patterns — “a concentration barrage, a creeping barrage, a rolling barrage, or a block barrage” — without regard to light or weather conditions and with reduced risk to firefighters.

Boeing envisions non-explosive shells opening at preset heights to rain down retardant at 1 to 6 gallons per 100 square feet, according to the patent. With the right gun, delivery could be accurate to within 15 feet over 15 miles, it says.

But not everyone is fired up about the idea.

Tim Ingalsbee, executive director of Firefighters United for Safety, Ethics, and Ecology, an advocacy group for progressive approaches to wildfire management, questioned whether artillery could provide the unbroken coverage of retardant necessary to keep a fire from spreading.

“It sounds ridiculous because it’s a matter of scale — how many rounds do they have to pound out to lay out a good retardant line?” he asked.

Aircraft “are often grounded by extreme conditions, heavy smoke,” Ingalsbee acknowledged, but when able to fly they can deliver retardants “in remote areas, steep canyons.” Maneuvering artillery pieces to get a shot at such areas would not be easy, either, he speculated.

Ingalsbee also said he’s not keen about adapting another weapon of war to the wildfire problem. People should regard wildfires as a natural phenomenon to be managed, rather than an enemy to be fought and defeated.

A federal wildfire official was more neutral about Boeing’s idea.

“Wildland fire agencies are always interested in exploring new technologies that have the potential to enhance the effectiveness and efficiency of wildland fire management and wildfire suppression,” said Randy Eardley, chief of external affairs with the Bureau of Land Management’s National Fire and Aviation program. “However, there are rigorous processes in place to test new technologies to determine whether it is feasible and appropriate to incorporate them or not. Until a product is fully tested, we cannot speculate on their potential applicability or future uses.”

Boeing spokesman Brett Jensen said in an email that the company gets hundreds of patents annually and “the awarding of a patent does not necessarily mean that Boeing will be developing that concept or design in the near future.”

Boeing’s patent application does offer some additional details, though they seem more “concept” than “design.”

It says the shells should be made of material that degrades in anywhere from 1 month to 10 years — “but at no time before, during or after its degradation shall it be toxic to the environment.”

Also, the application suggests some likely delivery systems: the M777 medium field howitzer or M109 Paladin self-propelled howitzer built by BAE Systems; the Haubits Fh77 howitzer by Bofors; or a variant of the 2A65 howitzer developed in the former Soviet Union.

Boeing included spreadsheets demonstrating the superiority of its artillery system over aircraft delivery of retardant — though it labeled the figures as “simulation results.”

A fire that begins at 28 acres could be contained with a helicopter delivering 6,469 gallons of retardant over 7.6 hours, and during that time the fire would have spread to 100 acres, Boeing says, citing a government guide to forest fire response.

By contrast, bombarding the fire with 3-gallon artillery shells, it could be contained in 2.6 hours using just 4,990 gallons of retardant and containing the damage to just 39 acres, Boeing asserts.