Span: 7.4676m / 25ft
Length: 5.81558m / 19ft
Height: 1.72822m / 6ft
Wing Area: 8.7326m² / 94ft²
Short Title: Stephens Akro
Empty Weight: 385.56kg / 850lbs
Gross Weight: 544.32kg / 1,200lbs
Maximum Speed: 362.025km/h
Cruise Speed: 233.305km/h / 145mph
Power Plant: One modified Lycoming 210 h.p. engine
Range: 563.15km / 350miles
Serial Number: 434
Clayton Stephens designed the Akro specifically for homebuilders who want a plane for competitive aerobatics. The late Margaret Ritchie, 1966 U.S. Women's Aerobatic Champion, flew the prototype. The Akro's wooden wings and fabric-covered steel tube fuselage might seem flimsy, but it's rated to +12 g and -11 g -- meaning the plane can withstand the violent stresses of aerobatic maneuvers. The Akro design is the basis for the development of many modified mid-wing aerobatic planes, such as the Lasers, Ravens, and Extras seen on the air show circuit today.
The Museum's example was built by Gerry Zimmerman with a modified Lycoming 210-horsepower engine and became the first amateur-built Akro to fly in 1971. Purchased by Joann Osterud in 1976, the plane is a veteran of hundreds of aerobatic performances. Osterud donated the Akro in 1994.
Joann Osterud learned to fly here at Boeing Field and now performs magnificent maneuvers like hammerhead turns, tail-slides, and lomcevaks (tumbling end over end) on the air show circuit. Osterud also has a second aviation career -- she was the first woman pilot hired by Alaska Airlines.