Christensen Zipper
The Christensen Zipper is an air racer that was built to compete in the Goodyear midget air races. Design and development. The Christensen Zipper was developed by Harvey Christensen and was patterned after Steve Wittman's Bonzo and Buster midget racers. The Zipper is a single-place, mid-winged aircraft with conventional landing gear. The fuselage was constructed from welded steel tubing with fabric covering. The wing used two wooden spars with strut wire bracing and fabric covering. Operational history. During the 1948 National Air Races the aircraft was disqualified due to a spar structure inspection. In the  1949 National Air Races the Zipper flew with the race number 59, sponsored by Rich-O-Root Beer with a qualifying run of . Christensen flew to third place, but landed one lap early after seeing the checkered flag for a competitor who had lapped him. The Zipper fell to tenth place for landing early.