note: This question is about the aerodynamics of boomerang flight and how it differs in microgravity environments. Some background information available here in Aviation SE: Are frisbees and boomerangs technically gliders? and in Space SE: How does one throw a boomerang in space? Does it return?
The Space-Toys.com article says:
Finally, on March 18 2008, Japanese astronaut Takao Doi took a three bladed boomerang (supplied by Yasuhiro Togai) aboard the Space Shuttle Endeavor on a mission to install equipment on the International Space Station. The boomerang that he threw was the only space boomerang that was specifically designed for space flight. The photo of the boomerang that Maurizio supplied to me show that the blades are recessed to the rear, as you would find in a Fast Catch boomerang. This is the optimal design for a space boomerang because when the blades are shifted to the rear, the secondary precessional forces that cause a boomerang to lay over in flight are retarded. The Japanese team of Yasuhiro Togai and Takao Doi deserve credit for making and throwing the first [multibladed] boomerang that was optimized for use in microgravity conditions.
What exactly are the "secondary precessional forces" referred to in the article?
Takao Doi in a space three-point stance throwing a returning boomerang aboard the ISS: