The sound is so distinct it's almost foreign, but to a dwindling population, it represents far more.

Seven decades ago, the sound was common over the skies of France, Belgium, Germany and Holland. Today, the sound is rare, but still draws the attention of those on the ground, curious to see the B-17 that to many still represents America's aerial power and industrial resolve during World War II.

Bob Hill, of Nashville, who flies the Madras Maiden around the country for tours, said there are far fewer baby boomers who turn out to see one of just eight flying B-17s remaining in the world.

He said in areas he visits like Nashville, it's easy to find a memorial or Civil War battlefield to tour and become immersed in the history. With aerial battles, though, they're as fleeting as the clouds.

"The closest you can get is to visit something like this — a flying museum," Hill said.

The plane experienced a mechanical problem on its way to Smyrna on Monday, preventing 94-year-old WWII veteran Bob Boggild from taking a ride in it.

He has never been on a B-17 before, even through his work on Corsair aircraft during the war and tour through southeast Asia. He wasn't in it for much, just to "look out and feel the vibration," he said.

This week, the Liberty Foundation's 2017 Salute to Veterans tour will bring the Madras Maiden to Smyrna Airport to celebrate the aircraft's history and its contributions to the largest ground war ever fought. On Sunday, it will move to Memphis.

The Madras Maiden has been restored from WWII-era glory, when it was known as Chuckie. Some 12,000 B-17s were produced and used throughout World War II, Korea and Vietnam, and the fleet dropped more than 600,000 tons of bombs in Europe alone. Around 4,100 were shot down during WWII, making it one of the most dangerous assignments during the war.

Many Tennesseans are familiar with the Memphis Belle as one of the most famed B-17 bombers and crew. Last year, the legislature voted to make the plane the official state airplane.

More:Memphis Belle is the new state airplane

The visit of the Madras Maiden comes with a purpose, however: It's touring the country as part of an effort to raise money to preserve it and other decades-old aircraft for future generations.

"It is only through your efforts and the public’s support that we can continue to keep the B-17 on tour and from being permanently silenced to sit in a museum," a release said.

The plane will be open to the public for tours and flights Saturday.

Jake Lowary covers veterans and military affairs for the USA TODAY Network. Reach him at 931-237-1583 or follow him on Twitter @JakeLowary.

If you go

What: Liberty Foundations 2017 Salute to Veterans tour

When: Saturday, Oct. 14, at Smyrna Airport; and Sunday, Oct. 15, Olive Branch Airport, Olive Branch, MS

Where: Smyrna Airport, 278 Doug Warpoole Road; Olive Branch Airport, Metro Aviation Services FBO, 8000 Terminal Drive, Olive Branch, MS 38654

Cost: $450 per passenger, which supports the foundation. Tours of the aircraft are free.

More: libertyfoundation.org