EASTON, United States - With a steady hand, pilot John Bode pushes the big red throttles forward. Four radial engines roar in unison, and a living piece of World War II history takes flight.
Of the 12,732 iconic B-17 Flying Fortress heavy bombers built in the 10 years through 1945, only about a dozen are still flying, and Aluminum Overcast is one of them.
Restored and maintained by the Experimental Aircraft Association, it criss-crosses the nation, offering aerial tours that provide a unique glimpse into military aviation's distant past.
"I've flown over 1,600 hours in this airplane, and I've never seen anybody come off ... without a smile on their face," pilot George Daubner told AFP.
"People love this plane. They love the sights, the sounds, the smells of the B-17, the vibrations - that's something very special." It's hard not to be charmed, as Bode and Daubner took Aluminum Overcast - its silver fuselage and wings glistening in the sun - aloft for a 20-minute run at 1,200 feet (375 metres) over rural Maryland on a crisp autumn day.
The panoramic view out the Plexiglass bombardier's nose cone is spectacular, even if the 100-pound bombs are fake and the 13 .50-caliber machine guns inoperative.
But as Bode stressed in a pre-flight briefing, in wartime, on daytime bombing raids over Nazi Germany and occupied Europe, the B-17 was no joyride for its 10-man crew, typically in their late teens and early 20s.
"Think about what was going through their heads," he told a group of passengers on the tarmac at Easton airport, a two-hour drive east of Washington, one recent afternoon.
Herbert Meeker, a 20-year-old when he flew 30 missions over Germany as a B-17 navigator, needed no reminders as he took a seat in Aluminum Overcast alongside his grand-daughter.
"The missions were very long, about eight hours," wrote Meeker in a note to his fellow passengers, as he is too frail to speak, let alone crawl up front to the navigator's seat as he had wished.
"It was late 1944 and early 1945, so therefore it was very cold at 30,000 feet. That was the hardest part of the entire tour for me, trying to keep warm if and when my heated suit failed."
Enemy fighters loom
To interrupt the cold and boredom, "every once in a while, the bad guys would come up and try to shoot you," Bode added, referring to Luftwaffe fighters.
"These were 21-, 22-, 23-year-old kids," added Daubner, "and they went out there every single day, knowing there was a 30 per cent chance on any given day that they were not going to come home." Some 4,735 B-17s were lost in combat; others were wrecked in flying mishaps. Of those that came out of the war, many were sold for a few hundred dollars for scrap metal.
One survivor, Memphis Belle, became the first B-17 to complete 25 missions over Europe with its entire crew alive and safe, before returning stateside to promote the sale of war bonds.
It is currently undergoing restoration at the US Air Force museum in Ohio, leaving another B-17 in Memphis Belle markings - one that appeared in an eponymous 1990 movie - to travel the country.
At more than US$400 (S$500) a shot, B-17 rides don't come cheap; ground tours at US$10 are a far more economical option, but there's enough interest all around for Aluminum Overcast to make about 350 flights a year.
And the funds are welcome to help preserve an aircraft that guzzles 200 gallons of fuel an hour, with 1,200-horsepower engines that need 37 gallons of oil each, and parts not always easy to source.
"More now than ever, it's expensive to operate these planes," said Hunter Chaney of the Collings Foundation, a non-profit with a stable of vintage warbirds - including a B-17 christened Nine-O-Nine - out on tour.
"But they really are living machines. The more they fly, the better they are," he told AFP.