CLAREMORE — This cold metal tube almost single-handedly crippled the Nazi war machine in a blaze of all-American glory.

Pieced together by rivets, bolts and old-fashioned Boeing craftsmanship, the U.S. military rode its knack for decimating German factories straight into Berlin.

Gundy’s Airport resident Bill Harrison shudders when he says only 15 B-17 Flying Fortresses are in flying shape today. But that’s the surviving tally for the 12,732 built before and during World War II.

Harrison, who donated his B-17 “Aluminum Overcast” to the Experimental Aircraft Association in 1983, has watched organization volunteers keep the 1940s behemoth alive with nationwide public flying tours since 1994 — the year they completed a decade-long restoration.

The Aluminum Overcast has now finished its 2010 nationwide tour. It took paying passengers on 30-minute flights from Jenks’ Riverside Airport through Sunday before heading back to Oshkosk, Wis., for winter maintenance.

“When you look at this plane sitting on the ground, it’s like a pretty picture,” Harrison said. “But when you’re flying in it, you just get goose bumps because you’re flying in a piece of living history.”

The interior is barely tall enough for stand up, and its walkways are only as wide as the curving, tube-like design allows. And yet one B-17 variant could carry more than 60 troops.

In its normal configuration, it holds about 10 passengers.

Harrison’s 1945 G model was the last in the B-17 line. It was also among the last B-17s Boeing ever produced, as Adolph Hitler surrendered before it could be used — at least, during that particular war. It helped make aerial maps of Southeast Asia during the Vietnam War and found rest as a crop duster back home, accumulating over 1 million miles of flight.

Harrison bought it 1981, hoping to restore the plane to its former glory and fly it around the world. When money got tight and he looked to donate, the Experimental Aircraft Association took up the restoration job. That took 10 years.

Now, its clean silver finish, working bomb bay doors and 14 authentic World War II machine guns bring back the look and feel of its heyday. Theoretically, it could still bomb a small city into submission.

Not that it would compare to today’s bombers.

During the war, only a metal frame stood between crew members and temperatures well below zero, thousands of feet above the German countryside. In some missions, its four propeller engines were responsible for hundreds of miles of flight.

Nearly 40 percent of the B-17s built were lost during combat missions.

“I don’t think we can really appreciate what (crew members) went through,” Harrison said.

He bought the plane in 1978 with a group of investors hoping to show off exactly what plane operators endured. They never succeeded, but Harrison hoped the Experimental Aircraft Association could take the reigns.

For about $400, passengers can take a 30-minute flight through history at tour stops each year.

Harrison thinks it’s worth it.

“We can’t duplicate it but we can take a step back in time,” he said. “This was the most important airplane in the European theater during World War II.”

As an Army doctor, Harrison never flew a B-17 in wartime. Flying is just a hobby.

He often flies his personal plane over his Gundy’s Airport flying community.

“I love aviation. I love the people in aviation,” he said. “It’s fun living at Gundy’s. It’s really nice to take your plane out on a sunny day.”

For more information on the “Aluminum Overcast” or to book a flight, visit www.b17.org. The Experimental Aircraft Association is taking reservations for its 2011 tour.