Long before Boeing became a household name with its B-17 "Flying Fortress" bombers of World War 2 fame, it developed the first all-metal monoplane bomber for the United States Army Air Corps (USAAC) as the "B-9". The aircraft was based on Boeing's single-engined "Monomail" Model 200 of 1930 which served as a mail carrier and passenger airliner through advanced design. Its wings were low-set under the fuselage and ahead of midships while featuring all-metal construction and lacking any supporting struts. The fuselage was well-contoured and streamlined with a specially-developed cowling sat over the engine at front. The cockpit position (seating one) was at midships with a conventional tail unit fitted at the rear of the fuselage. The undercarriage was a tail-dragging design and retractable to which begat a very aerodynamically efficient hauler which helped to usher in the age of the monoplane for American military service.
In 1931, Boeing engineers had developed a larger airframe powered by two radial engines as a private company venture. It featured a pencil-like, streamline fuselage with lessons gleaned from the Monomail project including its low-mounted, all-metal monoplane wing approach. The tail featured a high-reaching vertical fin with low-set tailplanes. The undercarriage retracted though the main legs only partially under the wings while the tail wheel was static. First flight of the prototype YB-9 was on April 13th, 1931, the aircraft known to Boeing as "Model 214". A second prototype followed as "Model 215" and key differences in the two became the Model 214's use of Curtiss V1570-29 "Conqueror" engines of 600 horsepower and the Model 215's Pratt & Whitney R1860 "Hornet" radial engines of 575 horsepower. Model 215 became the USAAC's "Y1B-9A".
Key to the YB-9 was its performance which was able to match, or even best in some cases, the fastest fighter aircraft of the period with its maximum speed of 186 miles per hour. It unsurprisingly cruised at the much lower speed of 158mph and featured a range out to 1,150 miles and operational service ceiling of 20,150 feet. These qualities played well enough to interest the USAAC as a modern, all-metal monoplane bomber and the aircraft was formally evaluated as "XB-901".
The aircraft was crewed by five and the militarized version was outfitted with 2 x 0.30 caliber medium machine guns for local defense while its bombload was a serviceable 2,400 pounds (held externally). The crew included two pilots sitting inline, both in open-air cockpits, with the co-pilot seated ahead nd doubling as the flight bombardier. A radio operator held a position with the fuselage and the remaining two crew were dedicated machine gunners seated forward and aft along the fuselage spine in open-air cockpits.
The Y1B-9A became five evaluation aircraft for the USAAC and these were taken on during September of 1932, joining the two completed prototypes. Total production became these seven aircraft for none more were added from serial production. The Y1B-9As quickly proved their speed in testing and made existing pursuit fighters of the USAAC more or less obsolete - none could catch the streamlined beast in simulated interceptions. Despite this, the Y1B-9A managed only a short operational life with the USAAC, their attention soon falling to the adoption of the competing Martin B-10 bomber of 1934. The Y1B-9 was given up for good by April of 1935 with no exposure to actual combat and two were eventually lost in crashes. The Martin B-10 became the USAAC's first all-metal monoplane bomber to serve in quantity.
Nevertheless, the revolutionary features and performance qualities of the YB-9 line forced competitors to rewrite their bomber design approach and forced fighter developers to reevaluate their pursuit types which greatly influenced the air war of World War 2 in the upcoming decade. Boeing would eventually hit its stride with their B-17 Flying Fortress bomber model which led to the Atomic bomb-dropping, technology-laden B-29 Super Fortress still to come. The line culminated with Boeing's last Big Bomber in the B-52 Stratofortress of Vietnam War fame.
The Boeing YB-9 was unofficially known as the "Death Angel" and praised by Modern Mechanics as "...the World's Fastest Bomber".
Status Retired, Out-of-Service
[ 7 Units ] : Boeing - USA
- Ground Attack
- X-Plane / Developmental
52.00 ft (15.85 m)
76.84 ft (23.42 m)
12.01 ft (3.66 m)
(Showcased structural dimension values pertain to the Boeing Y1B-9A (Death Angel) production model)
8,960 lb (4,064 kg)
14,330 lb (6,500 kg)
(Showcased weight values pertain to the Boeing Y1B-9A (Death Angel) production model)
(Showcased powerplant information pertains to the Boeing Y1B-9A (Death Angel) production model)
188 mph (302 kph; 163 kts)
20,751 feet (6,325 m; 3.93 miles)
540 miles (869 km; 469 nm)
900 ft/min (274 m/min)
(Showcased performance values pertain to the Boeing Y1B-9A (Death Angel) production model; Compare this aircraft entry against any other in our database)
2 x 0.30 caliber machine guns held in forward and aft dorsal cockpit positions.
Up to 2,400lbs of externally-held ordnance.
(Showcased armament details pertain to the Boeing Y1B-9A (Death Angel) production model)
Model 200 - Boeing Commercial Model on which the YB-9 was based on; initial designation for YB-9.
Model 214 - Initial designation for Y1B-9.
XB-901 - Prototype Designation; two examples completed and leased for evaluation by the USAAC.
YB-9 - Developmental Designation; initial prototype model.
Y1B-9 - Alternative designation to signify funding outside of normal fiscal year; fitted with 2 x Curtiss V-1570-29 Conqueror engines.
Y1B-9A - Service Test Aircraft; five examples completed; fitted with R-1860-11 Hornet engines; revised vertical tail fin.
B-9 - Intended Production Designation
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