09/30/2008. Remarks by Johan Visschedijk: "Designed by William T. Thomas, the single-seat MB-3 was heavily influenced by the French SPAD designs, and four prototypes were ordered in 1918. First flown on February 21, 1919, the type had its teething problems, but by June 1920 the USAAS was sufficiently impressed and ordered fifty aircraft.
After competitive bidding, an order for an additional 200 improved MB-3As was won by Boeing. This model differed mainly by a revised cooling system, with radiators on each fuselage side (as visible above, in this photo and the 3-view), instead of in the upper wing on the MB-3. The first MB-3A flew on June 7, 1922, and by December 27, 1922, all 200 had been delivered."