{"id":261,"date":"2026-10-06T08:44:26","date_gmt":"2026-10-06T08:44:26","guid":{"rendered":"https:\/\/jfmwebsie.xyz\/my_website2\/aircraft\/boeing-yb-9\/"},"modified":"2026-10-20T06:50:48","modified_gmt":"2026-10-20T06:50:48","slug":"boeing-yb-9","status":"publish","type":"aircraft","link":"https:\/\/jfmwebsie.xyz\/my_website2\/aircraft\/boeing-yb-9\/","title":{"rendered":"Boeing YB-9"},"content":{"rendered":"\n

In May 1930, Boeing<\/a> had flown its Model 200 Monomail<\/a> single-engined mailplane<\/a>. The Monomail was of radical design for the time, being a semi-monocoque<\/a>, stressed skin<\/a> cantilever<\/a> monoplane<\/a> with a retractable undercarriage. Air Corps bomber squadrons of the day were largely equipped with slow strut-braced biplanes<\/a> built from steel-tube frames covered in doped fabric, such as the Keystone B-6<\/a>, and Boeing decided to design and build a twin-engined bomber using the same techniques used in the Monomail to re-equip the Air Corps.<\/p>\n\n\n\n

Boeing built two prototypes of a new bomber as a private venture, which differed in the engines used, with the Model 214 powered by two liquid-cooled Curtiss V-1570-29 Conqueror<\/a> engines while the Model 215 had two Pratt & Whitney R-1860 Hornet B<\/a> radial engines<\/a>. Both aircraft were low winged cantilever monoplanes with a slim, oval cross-section fuselage accommodating a crew of five. The pilot and co-pilot sat in separate open cockpits, with the co-pilot, who doubled as the bombardier<\/a> sitting forward of the pilot. Two gunners, each armed with a single machine gun sat in nose and dorsal positions, while a radio operator sat inside the fuselage. Like the Monomail, a retractable tailwheel undercarriage<\/a> was used.<\/p>\n\n\n\n

The first of the two prototypes to fly was the radial powered Model 215 which, carrying civil markings and the aircraft registration<\/a> X-10633<\/em>, made its first flight on 13 April 1931. It was leased to the Air Corps for testing under the designation XB-901<\/strong>, demonstrating a speed of 163\u00a0mph (262\u00a0km\/h). Testing was successful, and both the XB-901 and the as-yet incomplete Model 214 were purchased as the YB-9 and Y1B-9 respectively on 13 August 1931, with an order for a further five for service testing following.<\/p>\n\n\n\n

The Y1B-9<\/strong> (Y1<\/em> indicating funding outside normal fiscal year procurement), powered by two liquid-cooled Curtiss V-1570<\/a>-29 ‘Conqueror’ engines, first flew on 5 November 1931. The increased power from these engines, combined with improved streamlining of the engine nacelles<\/a>, increased its top speed to 173\u00a0mph (278\u00a0km\/h). The YB-9, meanwhile, had been re-engined with more powerful Hornet Bs, demonstrating slightly better performance than the Y1B-9, which was therefore also re-engined with Hornet Bs.<\/p>\n\n\n\n

The five Y1B-9A<\/strong> service test aircraft (Boeing Model 246) had the Pratt & Whitney R-1860-11 Hornet B<\/a> engines which powered the re-engined YB-9 and Y1B-9 and a redesigned vertical stabilizer<\/a> modeled on the 247D<\/a> transport. While enclosed canopies were considered and designed, the B-9 was never fitted with them.Although it equaled the speed of existing American fighter aircraft<\/a>,[9]<\/a><\/sup> no further aircraft were built, as the Glenn L. Martin Company<\/a> had flown a prototype of a more advanced bomber, the XB-907, which was ordered into production as the Martin B-10<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

In May 1930, Boeing had flown its Model 200 Monomail single-engined mailplane. The Monomail was of radical design for the time, being a semi-monocoque, stressed skin cantilever monoplane with a retractable undercarriage. Air Corps bomber squadrons of the day were largely equipped with slow strut-braced biplanes built from steel-tube frames covered in doped fabric, such […]<\/p>\n","protected":false},"featured_media":5764,"template":"","meta":{"_acdb_brands_pos":"bottom","_acdb_special_pos":"after_links","footnotes":""},"aircraft_manufacturer":[69],"aircraft_category":[6,7],"aircraft_country":[54],"class_list":["post-261","aircraft","type-aircraft","status-publish","has-post-thumbnail","hentry","aircraft_manufacturer-boeing","aircraft_category-aircraft","aircraft_category-bombers","aircraft_country-united-states"],"_links":{"self":[{"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/aircraft\/261","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/aircraft"}],"about":[{"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/types\/aircraft"}],"version-history":[{"count":2,"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/aircraft\/261\/revisions"}],"predecessor-version":[{"id":5762,"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/aircraft\/261\/revisions\/5762"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/media\/5764"}],"wp:attachment":[{"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/media?parent=261"}],"wp:term":[{"taxonomy":"aircraft_manufacturer","embeddable":true,"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/aircraft_manufacturer?post=261"},{"taxonomy":"aircraft_category","embeddable":true,"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/aircraft_category?post=261"},{"taxonomy":"aircraft_country","embeddable":true,"href":"https:\/\/jfmwebsie.xyz\/my_website2\/wp-json\/wp\/v2\/aircraft_country?post=261"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}