X-1623A on May 24, 1928, and designated XP-9 by the Army when a contract for its design and construction was signed with Boeing on May 29,1928. The XP-9 was the first Boeing monoplane to start through the factory, but various delays postponed its scheduled delivery date from April 1929, to September 1930, so it was not the first to fly, having been beaten into the air by the new Model 200 Monomail and the Model 202 and 205 fighters.
The construction of the XP-9 was entirely new to Boeing practice, and both the 200 and the 202/205 designs drew heavily on it. The fuselage was the most advanced feature, using a semi-monocoque structure of sheet dural over metal formers for that portion aft of the rear undercarriage struts and welded steel tubing from that point forward to the engine. The original tail surfaces were identical to those of the P-12/F4B, and the conventional two-spar wing used metal framework with fabric covering. The general proportions were those of the P-12/F4B cut down to a high-wing monoplane.
The XP-9 was not test flown in Seattle as was customary, but flew on November 18, 1930, after delivery by rail to the Army Test Centre at Wright Field, Ohio. The XP-9 did not come up to expectations even though control was improved by replacement of the P-12 vertical tail with a larger design, and an option for five Y1P-9s to be built under the P-12D contract was not exercised. The 3-view shows the original aircraft.
Span: 36 ft 6 in (11.13 m)
Length: 25 ft 1.75 in (7.66 m)
Height: 7 ft 9 in (2.36 m)
Wing area: 210 sq.ft (19.51 sq.m)
Weight empty: 2,669 lb (1,210 kg)
Loaded weight: 3,623 lb (1,643 kg)
Max speed: 213 mph (343 kmh) at 12,000 ft (3,658 m)
Climb: 2,430 ft (741 m)/min