Engineers and machinists have built war helicopters in Delaware County since vertical-lift pioneer Frank Piasecki opened his shop in Sharon Hill, after making a Navy prototype in World War II.

Will successor Boeing Corp.'s helicopter plant in Ridley Township - the Philadelphia area's top remaining industrial employer - keep its place as a leading military contractor, as drones and robotic warfare start to replace human fighters?

Nearly 5,000 Boeing employees will build 50 $30 million Chinook helicopters for the U.S. and foreign armies, and 21 fuselages for $70 million-plus Ospreys for the U.S. Marines this year.

That's fewer than the "Chinook a day" that Boeing built here during the Vietnam War, when the company employed up to 13,000 locals, and antiwar activists from nearby Swarthmore College lined the gates to protest, recalls Boeing veteran Doug Williamson.

His father worked at Piasecki's former plant in Morton, he worked for Boeing at Ridley, and his daughters still work there.

"The Chinook has been our mainstay here for more than 50 years. It's got another 50 years, the Army says. It's a great platform," even more enduring than Boeing's long-running B-52 bomber line, Gary Baker, Philadelphia production center leader for Boeing military aircraft, told me. We spoke at the American Helicopter Society's Friday ceremony to honor Piasecki at his former plant in Morton.

"This industry defines our region," Rep. Patrick Meehan (R., Pa.) told the crowd outside the repurposed Morton plant, now home to a BJ's Wholesale Club, Keystone-Crozer offices, and repair shops.

The Ridley complex endured the recession, supplying the U.S. wars in Afghanistan and Iraq. But the federal budget sequestration agreement designed to limit government spending has trimmed military orders, Meehan told me. He credits pro-helicopter congressional allies such as Reps. Rodney Frelinghuysen (R., N.J.) and Mike Conaway (R., Texas) with supporting multiyear funding arrangements that helped restore three Ospreys the Obama administration wanted to cut this year.

Meehan maintained that the Osprey, which faced criticism in its early development after fatal test crashes, is now the Marines' aircraft of choice for delivering troops without risking improvised-explosives road attacks. The military also uses the ships for emergency relief, is developing them for refueling operations, and maybe for new weapons. He's hopeful the Air Force will start buying Ospreys.

Meehan's support for Boeing has boosted his local popularity against right-wing challengers. "Helicopter people" stop work to watch ships fly; they have a special dedication, Frank Piasecki's son, John, told the crowd. He is president of Piasecki Aircraft Corp., now a 40-person design and consulting firm based in Essington.

Is dedication enough, as war technology pivots? Local Congress members from both parties are looking at unmanned-aerial vehicle prospects, Meehan says: "We can't allow this thing to quit."

215-854-5194@PhillyJoeD