The original calculations for the flight were that in early summer, including twilight, 20 hours of daylight were available for a westbound flight. By averaging an hour, the distance of from New York to San Francisco could be covered in 16 hours 40 minutes. Mitchell had struck a deal with Curtiss Aircraft to purchase 25 new PW-8 fighters, patterned after the R-6 Racer, if Curtiss would help modify one of the prototypes for use in the project. The D-12 engine on the PW-8 produced and Mitchell's intended modifications were to enable it to make the flight at full throttle power setting. If the armament and unnecessary equipment were also removed from the XPW-8, additional fuel capacity could be installed to extend its range, and larger oil tanks for engine cooling. The flight plan calculated four stops of 30 minutes each for refueling. McCook Field, Ohio; Saint Joseph, Missouri; Cheyenne, Wyoming; and remote Salduro Siding, Utah, were selected as refueling points, following a recently established mail route.