On 23 May 1922 Army contract #7388 was awarded to the Lawrence Sperry Aircraft Vo for three special Army Sir Service R-3 racing aircraft. The price was set at $25,000 per aircraft without powerplant. The special Wright H-3 High Compression engines were to be furnished by the Air Service, but installation was to be done by the builder. Serial numbers 22-326, 22-327 and 22-328 were assigned to the three racers. Three propellers were shipped from McCook Field to the Sperry plant in Farmingdale, Long Island, but these were never used. They were but the first of a long series of props designed to get the most out of the special Wright engines.
The Air Service contract with Wright Aeronautical called for modification of three engines originally designed for the MB-3, at $750 engine each. After the 1922 race, they were to be returned to Wright, re-modelled and re-consigned to Boeing Aircraft Co.
Alfred Verville had the R-3 design finalised, the work got underway at the Sperry plant. Things progressed normally except for a few items. There were no 200mph airspeed indicators. But Pioneer Instrument Company built enough for the planes entered in the Pulitzer race.
New birch propellers were ordered from the Hartzell Walnut Propeller outfit on 18 August. It was decided that several different props would afford a better test range, so two of the new props were 99 inch in diameter, 100 inc pitch, the other two 96 inch in diameter with 104.5 inch pitch. Whirl tests were to be conducted on all, and if they did not turn 2000 rpm, they would be trimmed until they did. Trhee props were delivered to Sperry on 15 September. But just three days before that, the Engineering Division at McCook Field notified the contractor that they had designed four different type of props and were building them at McCook Field.
The first was refitted with a 500hp Curtiss D-12 in 1923 and won the Pulitzer Trophy in 1924 at 216.5 mph.
Engine: 400hp Wright H-3
Wingspan: 29’3″
Length: 22’5″
Speed: 191 mph
Seats: 1
All Aero 