Flying Fortress facts

* Paid flights or free on-ground inspections of the Memphis Belle B-17 Flying Fortress are available Saturday and Sunday at Northeast Philadelphia Airport, 9800 Ashton Road.

Half-hour, $450 flights are offered from 10 a.m. to 2 p.m. every hour on the hour. Free ground tours will be conducted from 2:30 to 6:30 p.m.

The cost is high because it costs $4,500 an hour to keep the plane in the air.

* The original Memphis Belle was one of the first B-17s to survive 25 missions - with its crew intact - in the early, dark days of World War II. The original can't fly and is being renovated by a museum. More than 12,000 B-17s were produced during the war and only a dozen are still airworthy.

* The B-17 here was used in the 1990 "Memphis Belle" movie, starring Matthew Modine. Other movies have featured the plane.

* Crews loved the war plane because of its ability to absorb punishment and get them back to their base. Aviation fans love its distinctive silhouette and unique sound.

* Philadelphia radio talk-show host Irv Homer, who died in 2009, was a B-17 pilot over Italy.