View source for Boeing YB-9

{{short description|Prototype bomber aircraft by Boeing}}
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{{Infobox aircraft
|name= YB-9
|image= File:Boeing Y1B-9 test flight USAF p29.jpg
|type= [[Bomber aircraft]]
|manufacturer=[[Boeing]]
|first_flight= 13 April 1931
|introduction= 5 November 1931
|retired= 1935
|status= No surviving examples
|primary_user= [[United States Army Air Corps]]
|produced= 1930–1933
|number_built= 7
}}
The '''Boeing YB-9''' was the first all-metal [[monoplane]] [[bomber]] aircraft designed for the [[United States Army Air Corps]]. The YB-9 was a much enlarged twin-engine development of Boeing's single-engine [[Boeing Monomail|Model 200 Monomail]] commercial transport.
==Design and development==
[[File:Boeing Y1B-9A and P-26 in flight (060421-F-1234P-043) (tight crop, contrast stretch).jpg|thumb|Boeing Y1B-9A in flight with a [[Boeing P-26 Peashooter|P-26]] fighter.]]
In May 1930, [[Boeing]] had flown its [[Boeing Monomail|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 [[biplane]]s built from steel-tube frames covered in doped fabric, such as the [[Keystone B-6]], 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.<ref name="Dino p44">Pelletier 2002, p. 44.</ref><ref name="Swan Mil p72">Swanborough and Bowers 1963, p. 72.</ref>
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]] engines while the Model 215 had two [[Pratt & Whitney R-1860 Hornet B]] [[radial engine]]s.<ref name="Bowers Boeing p200">Bowers 1989, p. 200.</ref> 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 (air force)|bombardier]] 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 [[conventional landing gear|tailwheel undercarriage]] was used.<ref name="Dino p44-5">Pelletier 2002, pp. 44–45.</ref><ref name="Bowers Boeing p200-1">Bowers 1989, pp. 200–201.</ref>
The first of the two prototypes to fly was the radial powered Model 215 which, carrying civil markings and the [[aircraft registration]] ''X-10633'', made its first flight on 13 April 1931.<ref name="Bowers Boeing p202-3">Bowers 1989, pp. 202–203.</ref><ref name="Dino p47">Pelletier 2002, p. 47.</ref> It was leased to the Air Corps for testing under the designation '''XB-901''', demonstrating a speed of {{cvt|163|mph}}.  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.<ref name="Swan Mil p72"/><ref name="Dino p46-7">Pelletier 2002, pp. 46–47.</ref>
The '''Y1B-9''' (''Y1'' indicating funding outside normal fiscal year procurement), powered by two liquid-cooled [[Curtiss V-1570]]-29 'Conqueror' engines, first flew on 5 November 1931. The increased power from these engines, combined with improved streamlining of the engine [[nacelle]]s, increased its top speed to {{cvt|173|mph}}. 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.<ref name="Swan Mil p72"/><ref name="Dino p46-7"/>
The five '''Y1B-9A''' service test aircraft (Boeing Model 246) had the [[Pratt & Whitney R-1860 Hornet B|Pratt & Whitney R-1860-11 Hornet B]] engines which powered the re-engined YB-9 and Y1B-9 and a redesigned [[vertical stabilizer]] modeled on the [[Boeing 247|247D]] transport. While enclosed canopies were considered and designed, the B-9 was never fitted with them.<ref name="Dino p46-7"/> Although it equaled the speed of existing American [[fighter aircraft]],<ref>[http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2446 "YB-9 factsheet."] {{webarchive |url=https://web.archive.org/web/20070829161537/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2446 |date=August 29, 2007 }} ''National Museum of the United States Air Force''. Retrieved 7 July 2010.</ref> no further aircraft were built, as the [[Glenn L. Martin Company]] had flown a prototype of a more advanced bomber, the XB-907, which was ordered into production as the [[Martin B-10]].<ref name="Bowers Boeing p202-3"/>
==Operational history==
The first of the five Y1B-9As entered service with the [[20th Bomb Squadron|20th]] and [[49th Test and Evaluation Squadron|49th Bombardment Squadrons]], [[2d Operations Group|2nd Bomb Group]] on 14 September 1932, with all examples built being in service by the end of March 1933.  The new bomber proved impossible to intercept during air exercises in May 1932, strengthening calls for improved air defense warning systems. Two B-9s were destroyed during crashes in 1933, one of the accidents being fatal, while the remaining aircraft were gradually phased out over the next two years, with the last being withdrawn on 26 April 1935.<ref name="Dino p48-9">Pelletier 2002, pp. 48–49.</ref>
==Variants==
[[File:Boeing Y1B-9 with Conqueror engines (060421-F-1234P-039).jpg|thumb|Boeing Y1B-9 with original [[Curtiss V-1570|Curtiss Conqueror]] liquid-cooled engines]]
*'''YB-9''' (one produced). [[Pratt & Whitney R-1860 Hornet B|Pratt & Whitney R-1860-13 Hornet B]] ({{cvt|575|hp|kW|disp=or}}). Reengined with supercharged [[Pratt & Whitney R-1860 Hornet B|Pratt & Whitney R-1860-11 Hornet B]] ({{cvt|600|hp|kW|disp=or}}) and was fitted with three-bladed propellers. Trim tab ran the full height of the rudder
::Boeing model B-215
::contract number: XB-901
* '''Y1B-9''' (one produced). [[Curtiss GIV-1570 Conqueror]] ([[Curtis V-1570-29 Conqueror]]) (600&nbsp;hp). Reengined with supercharged [[Pratt & Whitney R-1860 Hornet B|Pratt & Whitney R-1860-11 Hornet B]] (600&nbsp;hp) and was fitted with three-bladed propellers. Short trim tab on rudder.
::Boeing model B-214
* '''Y1B-9A''' (five produced). [[Pratt & Whitney R-1860 Hornet B|Pratt & Whitney R-1860-11 Hornet B]] (Y1G1SR-1860B) (600&nbsp;hp). Metal instead of fabric covering on the control surfaces. There were also many internal structural and equipment changes
::Boeing model B-246
* '''B-9B''' (not built). Proposed development of Y1B-9A with minor changes.
::Boeing model B-276
==Operators==
;{{USA}}
* [[United States Army Air Corps]]
==Specifications (Y1B-9A)==
{{Aircraft specs
|prime units?=imp
|ref=''United States Military Aircraft since 1909''<ref name="Swan Mil p73">Swanborough and Bowers 1963, p. 73.</ref>
|crew=four
|length ft=52|length in=0
|span ft=76
|span in=10
|height ft=12|height in=0
|wing area sqft=954
|empty weight lb=8,941 |max takeoff weight lb=14,320
|eng1 number=2|eng1 type=[[radial engine]]|eng1 name=[[Pratt & Whitney R-1860 Hornet B|Pratt & Whitney R-1860-11 Hornet B]]|eng1 hp=600
|max speed mph=188
|max speed note=at {{cvt|6000|ft}}
|cruise speed mph=165
|range miles=540
|ceiling ft=20,750
|climb rate ftmin=900
|guns=2 × {{cvt|.30|in|2}} [[M1919 Browning machine gun|machine guns]]
|bombs={{cvt|2260|lb}} bombs
}}
==See also==
{{aircontent
|related=
* [[Boeing Monomail]]
|similar aircraft=
* [[Martin B-10]]
* [[Tupolev TB-3]]
|lists=
* [[List of bomber aircraft]]
* [[List of military aircraft of the United States]]
}}
==References==
{{commons category|Boeing YB-9}}
===Citations===
{{Reflist}}
===Bibliography===
{{refbegin}}
*{{cite encyclopedia|last=Baugher|first=Joe|url=http://www.joebaugher.com/usaf_bombers/b9.html|title=Boeing B-9|encyclopedia=Encyclopedia of American Aircraft|date=10 September 2002|access-date=7 July 2010}}
*{{cite book|last=Bowers|first=Peter M.|title=Boeing Aircraft since 1916|location=London|publisher=Putnam|year=1989|isbn=0851778046}}
*{{cite book|last=Jones|first=Lloyd|title=U. S. Bombers|location=Fallbrook, CA|publisher=Aero Publishers|year=1974|isbn=0816891265}}
*{{cite magazine|last=Pelletier|first=Alain|title=End of the Dinosaurs: Boeing's B-9, Breaking the Bomber Mold|magazine=Air Enthusiast|volume=101|date= September–October 2002|pages=44–49}}
*{{cite book|last1=Swanborough|first1=F. G.|last2=Bowers|first2=Peter M.|title=United States Military Aircraft since 1909|location=London|publisher=Putnam|year=1963|isbn=}}
*{{cite book|last=Wagner|first=Ray|title=American Combat Planes|location=New York|publisher=Doubleday|year=1982|isbn=0930083172}}
{{refend}}
{{Boeing military aircraft}}
{{Boeing model numbers}}
{{USAF bomber aircraft}}
{{Wright Field project numbers}}
[[Category:Boeing military aircraft|B-09, Boeing]]
[[Category:1930s United States bomber aircraft|Boeing B-09]]
[[Category:Low-wing aircraft]]
[[Category:Aircraft first flown in 1931]]
[[Category:Twin piston-engined tractor aircraft]]
[[Category:Aircraft with retractable conventional landing gear]]