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The Boeing FB was the US Navy's version of the Boeing PW-9 biplane fighter and the first in a decade-long series of Boeing naval fighters.
Boeing had gained valuable experience building other people's fighters, most importantly the Thomas-Morse MB-3A. The company decided to begin developing their own single-seat fighter as a private venture, giving it the internal designation of Boeing Model 15.
The Model 15 was a single-bay biplane with wings of unequal span. The lower wing had a reduced span and chord. Both wings were tapered. The wings had a wooden structure with a fabric covering while the fuselage had a welded steel tube fuselage, also with a fabric covering. It had a braced tail unit with a variable-incidence tail-plane that could be controlled in flight. Three prototypes were produced - two with through-axle main landing gear and one with split axle landing gear. It was powered by a 435hp Curtiss D-12 inline engine.
The Model 15 made its maiden flight on 2 June 1923 with Captain Frank Tyndall at the controls. It was given the Air Corps designation XPW-9, and after early tests at the Boeing factory was sent to the Army for trials. The Army ordered two more prototypes on 28 September 1923, and these were delivered on 1 May 1924.
Boeing FB-1
The US Navy was also interested in the new fighter. Early in 1925 the Navy ordered sixteen Model 15s, giving them the designation Boeing FB-1. The first of these aircraft was delivered on 1 December 1925, but only 10 of the 16 were completed as FB-1s. The FB-1 was almost identical to the Army PW-1, with the same split axle undercarriage. They were not equipped for carrier use, and instead went to the US Marine Corps.
Nine of the ten FB-1s were deployed to China as part of the USMC Expeditionary Force that was sent in June 1928 to help protect the International Settlement in Shanghai at a time of increasing anti-foreign sentiment in China.
Boeing FB-2 (Boeing Model 53)
The 11th and 12th aircraft from the original Naval order were completed as the Boeing FB-2 or Model 53. These aircraft had carrier deck guide wire hooks installed to allow them to be used from carriers. They also had a stronger fuselage and a cross-axle undercarriage.
Boeing FB-3 (Boeing Model 55)
The 13th aircraft from the original order was completed as the FB-3 (Model 55). Another two FB-3s were ordered later. The FB-3 could use twin floats and had hoisting gear. Like the FB-2 they were designed for carrier operations. They had a change of engine, to the 510hp Packard 1A-1500, and used the same split-axle undercarriage as the FB-1 rather than the cross-axle type used on the FB-2. The first FB-3 was destroyed in a crash on Lake Washington in December 1925. The second and third aircraft were delivered in April 1926 and used as development aircraft. One of the changes made was the introduction of larger balanced rudders. This design later became standard for the entire PW-9/ FB-3 family of fighters.
Boeing FB-4 (Boeing Model 54)
The FB-4 (Model 54) was the 14th aircraft from the original Naval order. Like the FB-2 it could use twin floats. It also had the equipment to be hoisted mounted on the upper wing, but the most important change was the use of a 450hp Wright P-1 Radial engine. This engine would later evolve into the Wright Cyclone. The FB-4 was delivered to the Navy in January 1926. Tests with the FB-4 suggested that radial engines would be better suited for carrier operations than inline engines, but also that the Wright engine wasn't suitable for use on a fighter aircraft. The FB-4 was re-engined with a Pratt & Whitney Wasp and redesignated as the FB-6.
Boeing FB-5 (Boeing Model 67)
The FB-5 was the main naval production version of the FB family. Twenty seven were ordered. The FB-5 saw a number of changes made to the design. They used a 520hp Packard 2A-1500 engine. The wing stagger was significantly increased, with the upper wing moved forward and the lower wing moved back. The undercarriage had to be redesigned to make sure it still joined up with the wing structure. The first FB-5 made its maiden flight on 7 October 1926.
The entire production run was delivered to the Navy on 21 January 1927. They were shipped by barge from the Boeing factory to the carrier USS Langley, waiting in Seattle Harbour, and most made their maiden flights from a carrier.
The FB-5 was used to equip VF-1B and VF-6B on the Langley and VG-3B on the Lexington. They were also used by Marine Squadron VF-6M, based at San Diego.
The FB-5 was retired after only two years of service because of the Navy's decision to standardise on radial engines.
Boeing FB-6 (Boeing Model 54)
After undergoing Naval tests the sole FB-4 was re-engined with a 400hp Pratt & Whitney Wasp radial engine and given the FB-6 designation. The new engine was less powerful than the Wright P-1, but was also much lighter and the FB-6 had the same performance as the FB-4. Tests with the FB-6 convinced the Navy that it should standardize on radial engined aircraft - they were seen as more robust and easier to maintain in the limited space on carriers. In 1928 the majority of inline-engine powered aircraft were withdrawn from Naval service.
Boeing FB-7 (Boeing Model 67A)
The Boeing FB-7 (Model 67A) was to have been a version of the FB-7 powered by the Pratt & Whitney Wasp engine. The project was abandoned in favour of the Model 69, which entered service as the Boeing F2B-1.
Boeing FB-5 (Model 67)
Engine: Packard 2A-1500 inline piston engine
Power: 520hp
Crew: 1
Span: 32ft 0in
Length: 23ft 9in
Height: 9ft 5in
Empty Weight: 2,458lb
Maximum Take-off Weight: 3,249lb
Maximum Speed: 176mph at sea level
Cruising Speed: 150mph
Climb rate: 2,100ft/ min
Range: 420 miles
Guns: Two fixed forward firing 0.3in Browning machine-guns