The Boeing XP-9 (company Model 96) was the first monoplane

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produced by the

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aircraft manufacturing company

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. It incorporated sophisticated structural refinements that were influential in later Boeing designs. The sole prototype exhibited unsatisfactory characteristics with its lack of pilot visibility directly leading to its cancellation.

Design and development

The XP-9 was designed in 1928 to meet the requirements of a

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request for a

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

fighter. Its primary contribution to aircraft design was its semi-

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

construction, which would become a standard for future aircraft. Boeing employed the structural features of the XP-9 into their contemporary P-12

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

fighter when the P-12E variant incorporated a semi-monocoque metal fuselage structure similar to that of the XP-9. The

undercarriage Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include: *The landing gear of an aircraft. *The ch ...

arrangement of the P-12C had also been first tried out on the XP-9 and then transferred into the production model.''Pedigree of Champions: Boeing Since 1916'' 1969

Operational history

The prototype XP-9, marked ''A 028-386'', was first flown on 18 November 1930. It had impressive stats on the specification sheet, but it quickly became apparent that its large (6 ft chord) wing, which was placed atop the fuselage directly in front of the pilot, obstructed downward visibility so badly that simple landing maneuvers were hazardous. Test pilots at the Army Test Centre at Wright Field found that the XP-9's inherent instability was so severe that immediate modifications were requested to increase the size of the vertical tail.Baugher, Joe. ''Boeing XP-9''. 6 June 1998. Access date: 17 March 2007. An enlarged vertical tail surface with smooth metal skinning was introduced, but failed to effect any significant improvement, and this revised XP-9 was grounded for instructional airframe use in August 1931, after only 15 hours of test flying, due to the impossibility of its being landed safely.Eden and Moeng 2002, p. 74-77.

Variants

;Model 96, XP-9: one built ;Y1P-9: option for five service test aircraft under the P-12D contract, option was not taken up

Operators (planned)

; *

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Specifications (Boeing XP-9)

References

Notes

Bibliography

* Eden, Paul and Moeng, Soph. ''The Complete Encyclopedia of World Aircraft''. London: Amber Books Ltd., 2002. . * ''Pedigree of Champions: Boeing Since 1916, Third Edition'' (booklet). Seattle, WA: The Boeing Company, 1969.

External links

United States Air Force Museum: Boeing XP-9
{{Boeing model numbers Boeing P-09 P-09, Boeing Single-engined tractor aircraft High-wing aircraft