This is one of six categories of aircraft that participate in the Reno Air Races, in Reno, NV.
All Formula One Aircraft are strictly controlled as to powerplant, wing area and weight; other than that, it is up to the designer.
The engine is a 100hp Continental O-200. The same 200 cubic inch, horizontally opposed engine used in the Cessna 150. The weights and sizes of each major part within the engine must be within stock limits. The cam profile and carburetor are strictly controlled as well. Aircraft participating in this race must have a wing area of at least 66 square feet and weigh at least 500 pounds empty. They also must have fixed landing gear and a fixed pitch propeller.
This category of aircraft was introduced after WWII. Air races preceding WWII were largely tests of airframe design and engineering. After WWII, the surplus of military aircraft took over these races, thus eliminating the need to create new designs. In order to restore the creativity of original design and its subsequent benefits to the aviation community, the Formula 1 category was introduced. The improvements in aerodynamic finesse and engine refinement finally had a home again.