| XPTBH | |
|---|---|
 The XPTBH-2 in flight | |
| General information | |
| Type | Seaplanetorpedo-bomber |
| Manufacturer | Hall Aluminum Aircraft Corporation |
| Primary user | United States Navy |
| Number built | 1 |
| Serial | 9721[1] |
| History | |
| First flight | February 1937 |
| Retired | September 21, 1938 |
| Fate | Destroyed in hurricane September 21, 1938 |
TheHall XPTBH was a prototypeAmerican twin-enginedseaplane, submitted to theUnited States Navy by theHall Aluminum Aircraft Corporation in response to a 1934 specification for new bomber and scout aircraft. Constructed in an innovative fashion that made extensive use ofaluminum, the XPTBH proved successful in flight testing, but failed to win favor with the U.S. Navy. No production contract was awarded, and the single aircraft built served in experimental duties before its destruction in ahurricane during 1938.
In late 1934, the U.S. Navy'sBureau of Aeronautics (BuAer) issued a specification for newscout bomber andtorpedo bomber designs.[2] Eight companies submitted a total of ten designs in response, evenly split betweenmonoplanes andbiplanes.[3][N 1] The Hall Aluminum Aircraft Company submitted the only seaplane design;[3] a single prototype was ordered by the Navy for evaluation on June 30, 1934. Given the designation XPTBH-1,[5] it became the only aircraft to receive three mission-type letters under theU.S. Navy's designation system used between 1922 and 1962.[6][7][8]
Hall's choice of the twin-float seaplane configuration was dictated by the Navy's requirement that the new torpedo-bomber design should be capable of carrying a standard navaltorpedo of the type carried bydestroyers.[9] As ordered, the XPTBH-1 was intended to be fitted withWright R-1820 "Cyclone"radial engines;[5] delays in design caused by Hall relocating their production facility, difficulties with the contract, and doubts about the aircraft's performance potential led to a redesign, the aircraft becoming slightly smaller and the engines being changed to a pair ofPratt & Whitney R-1830 "Twin Wasp" radials.[10] The changes to the aircraft resulted in it receiving the revised designation XPTBH-2.[9]
Utilising Hall's standard aluminumtubular spar,[9] the fuselage and wing leading edges were covered in aluminum, while the rest of the wing and the control surfaces were fabric-covered.[9] The aircraft was well-armed defensively by 1930s standards, with a powered turret, designed by Hall, mounted in the nose and carrying a single .30-calibermachine gun.[9]Hand-traversed mountings for a pair of machine guns were fitted in dorsal (top) and ventral (belly) positions aft.[9] Anoptically flat glass panel was fitted in the nose below the turret for use by thebombardier;[9] the aircraft's offensive weaponry, consisting of aMark XIIIaerial torpedo or, alternatively, up to 2,000 pounds (910 kg) of bombs,[9] was carried in an internalbomb bay, the twin-float arrangement allowing for a clear release of the weaponry.[5]
Delivered to the Navy on January 30, 1937,[5][11][N 2] the aircraft was officially presented to the public at Hall'sBristol, Pennsylvania, factory in April of that year.[9] The aircraft's early flight testing, starting in February[10] and conducted by test pilotBill McAvoy,[5][9] showed that the XPTBH had few faults, with the only significant issue being a lack of roll authority – a reduction of the ability of theailerons to turn the aircraft – as a result of the surface area of the floats.[9] A modification to increase the area of the rudder solved the issue.[9] The aircraft's water-handling characteristics were found to be excellent;[13] the only significant complaints that surfaced during the testing period concerned the XPTBH-2'sbeaching gear, which was found to be extremely difficult to use in anything other than the calmest water.[13]
Although the XPTBH-2 met most of its design specifications and was rated overall very good in flight testing,[5][13] it failed to meet the contractual requirements for top speed and attack speed.[10] In addition, the U.S. Navy did not consider a seagoing torpedo-bomber to be an aircraft for which there was an operational requirement;[9] the fact that as a floatplane the aircraft was restricted to operation from water was also considered a negative,[4] while the aircraft's "three-in-one" role led it to be viewed as ajack of all trades, purpose-designed aircraft for each role being considered superior.[14] The company, however, blamed Navy politics for the lack of a production order.[13]
Following the conclusion of its test program, the XPTBH-2 was used for experimental duties at theNaval Torpedo Station inNewport, Rhode Island, participating in trials of aerial torpedoes.[10] Its service at Newport came to an end on September 21, 1938, when the XPTBH-2 was destroyed during theGreat New England Hurricane.[13] The XPTBH-2 was the last aircraft designed by Hall Aluminum;[9] the company remained in business until 1940, when it was bought out byConsolidated Aircraft.[15][N 3]
Data from Wegg 1990,[5] Trimble 2005,[10] Boyne 2001[13]
General characteristics
Performance
Armament
Aircraft of comparable role, configuration, and era
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