The XP-15 (Model 202) and the F5B-1 (Model 205) were monoplane fighters based on the biplane configuration. Aware that the biplane fighter design had reached its full potential, the company offered Models 202 and 205 to the military in an effort to introduce new concepts by expanding slowly on an already established design. Boeing removed the lower wing of the biplane, then added struts to support the remaining upper wing and moved it closer to the rear of the fuselage. The single-wing construction increased the top speed, but the rate of climb, manueverability, and landing speed suffered from lack of wing area, so the design was rejected.