Boeing YB-9

https://en.wikipedia.org/wiki/Boeing_YB-9

The Boeing YB-9 was the first all-metal monoplane bomber aircraft designed for
the United States Army Air Corps. The YB-9 was an enlarged alteration of
Boeing's Model 200 Commercial Transport.

Using its own money, Boeing decided to build two prototypes of its new bomber
design as a private venture. The two aircraft differed only in the engines used,
with the Model 214 to be powered by two liquid-cooled Curtiss V-1570-29
Conqueror engines while the Model 215 had two Pratt & Whitney R-1860 Hornet B
radial engines.[3] 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 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 was used.

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 maiden
flight on 13 April 1931. It was leased to the Air Corps for testing under the
designation XB-901, demonstrating a speed of 163 mph (262 km/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 shortly.

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
increased streamlining of the engine nacelles, increased its top speed to 173
mph (278 km/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. With the exception of the B-2 Condor,
liquid-cooled engines were never used on production bombers for the United
States military. The air-cooled radial engine was lighter and more reliable than
the liquid-cooled engine, and less vulnerable to enemy damage.

The five Y1B-9A service test aircraft (Boeing Model 246) had the 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 247D transport. While enclosed
canopies were considered and designed, the B-9 was never fitted with them.
Although it equaled the speed of all existing American fighter aircraft,[9] 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.


Role
Bomber aircraft

Manufacturer
Boeing

Designer
John Sanders

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

Developed from
Boeing Monomail

The first of the five Y1B-9As entered service with the 20th and 49th Bombardment
Squadrons, 2nd Bomb Group on 14 September 1932, with all 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.

Specifications (Y1B-9A)

Crew: 4
Length: 52 ft 0 in (15.85 m)
Wingspan: 76 ft 10 in (23.42 m)
Height: 12 ft 0 in (3.66 m)
Wing area: 954 ft² (88.7 m²)
Empty weight: 8,941 lb (4,064 kg)
Max. takeoff weight: 14,320 lb (6,500 kg)
Powerplant: 2 × Pratt & Whitney R-1860-11 Hornet B radial engine, 600 hp (448
kW) each

Performance
Maximum speed: 188 mph (163 knots, 302 km/h) at 6,000 ft (1,830 m)
Cruise speed: 165 mph (143 knots, 265 km/h)
Range: 540 mi (470 nmi, 869 km)
Service ceiling: 20,750 ft (6,325 m)
Rate of climb: 900 ft/min (4.6 m/s)

Armament

Guns: 2× .30 in (7.62 mm) machine guns
Bombs: 2,260 lb (1,030 kg) bomb





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