Circumpolar! is a novel by Richard A. Lupoff published in 1984.
Circumpolar! is a novel in which an alternative history is depicted with alternate geography, involving a Great Air Race with von Richthofens vs Charles Lindbergh and Howard Hughes. [1]
Dave Langford reviewed Circumpolar! for White Dwarf #70, and stated that "It goes on a bit long and it grossly libels the Red Baron, but it's amusing." [1]
In his Science Fact and Science Fiction: An Encyclopedia, Brian M. Stableford cited the book as one of the relatively rare examples of science fiction dealing with the Flat Earth concept. [2]