View source for Bell P-76

{{short description|Canceled fighter aircraft project}}
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{{Infobox aircraft
  |name= P-76
  |image= File:Bell XP-39E.jpg
  |caption= XP-39E, the prototype of the P-76
  |type=[[Fighter aircraft]]
  |manufacturer=[[Bell Aircraft Corporation]]
  |designer=
  |first_flight=1942
  |introduction=
  |retired=
  |status=Did not enter mass-production
  |primary_user=[[United States Army Air Forces]]
  |more_users=
  |produced=
  |number_built=0 (3 prototypes built as XP-39Es)
  |unit cost=
  |developed_from=[[Bell P-39 Airacobra]]
  |variants=
}}

The '''Bell P-76''' was the proposed designation for a production model derivative of the XP-39E, a single-engine American [[fighter aircraft]] prototype of [[World War II]].

==Design and development==
On 26 February 1941 the [[United States Army Air Corps]] (USAAC) placed a contract with Bell for two prototypes (''41-19501'' and ''41-19502'') that were intended to be a major improvement on preceding P-39s. In particular, the XP-39E was intended to address the poor high-altitude performance of the Airacobra. 

The performance issues of previous P-39 variants were to be addressed by incorporating a new wing design with a lower [[wing loading]], a more powerful engine and redesigning the [[vertical stabilizer|tailfin]]. The wing span was increased to 35&nbsp;ft 10 in (10.9 m) and the total wing area to 236&nbsp;ft<sup>2</sup> (21.9 m<sup>2</sup>), was to be wider and thicker, with a symmetrical [[airfoil]]; the section chosen was [[NACA airfoil|NACA 0018]] at the wing-root tapering to an [[NACA airfoil|NACA 23009]] at the tip. (While the new wing was sometimes referred to as having a [[laminar flow]] profile, that was not technically the case.)<ref>[http://www.ae.uiuc.edu/m-selig/ads/aircraft.html UIUC incomplete guide to Airfoil usage] {{Webarchive|url=https://web.archive.org/web/20080515232025/http://www.ae.uiuc.edu/m-selig/ads/aircraft.html |date=2008-05-15 }} Retrieved: 9 August 2008</ref> The greater internal dimensions of the wing allowed an increase in the fuel capacity to 150 US gallons (568 L).<ref name="Bowers 1979, pp.21-25.">Bowers 1979, pp.21-25.</ref> The engine bay was modified to accept a more powerful [[Piston engine|engine]] in lieu of the [[Allison V-1710]]. Its origins lay in a 1941 project to equip three P-39Ds (''41-19501, 41-19502'' and ''42-7164'') with the [[Continental V-1430]]-1 liquid-cooled [[Supercharger|supercharged]] engine. The resultant XP-39E had a symmetrical airfoil wing with square wingtips, an elongated [[fuselage]] to accommodate the larger engine, and revised air intakes and [[radiator (engine cooling)|radiator]]s. In addition, each of the three prototypes featured a different, redesigned version of the P-39 tailfin.

Since the Continental engine was not available at rollout, the [[prototype]]s flew with a new variant of the V-1710, the Allison V-1710-E9. This version, which had the military designation of V-1710-47, used a two-stage mechanical [[supercharger]] to increase the engine power at altitude. (After the Continental V-1430 failed to live up to its potential, a later version of the V-1710, the Allison V-1710-93, was used in the [[P-63 Kingcobra|XP-63A]].)<ref name="Bowers 1979, pp.21-25."/>

The prototypes performed well and 4,000 P-39Es were ordered for the USAAF. However, the order was postponed to permit Bell to manufacture the [[Boeing B-29 Superfortress]], under license. Many elements of the P-39E were subsequently incorporated in the [[P-63 Kingcobra]], a parallel program to develop an enlarged version of the Airacobra; the XP-63 first flew in December 1942. While the P-39E was retrospectively redesignated '''P-76''', it never entered production.

==Specifications (P-76)==
{{Aircraft specs
|prime units?=imp

|crew=1
|length ft=31
|length in=11
|length m=9.7 
|span ft=35
|span in=10
|span m=10.9 
|wing area sqft=236 
|wing area sqm=21.9 
|empty weight lb=6,936 
|empty weight kg=3,150 
|max takeoff weight lb=8,918 
|max takeoff weight kg=4,050 

|eng1 name=[[Continental XI-1430|Continental I-1430]]-1
|eng1 number=1
|eng1 hp=2,100 
|eng1 kw=1,600 

|max speed mph=386 
|max speed kts=335
|max speed kmh=620
|max speed note=at 21,680 ft (6,600 m)
|climb rate ftmin=2,150 
|climb rate ms=11 
|power/mass= |guns=<br/>
** 1× 37 mm (1.46 in) [[M4 autocannon|Oldsmobile T9]] [[autocannon|cannon]], 30 rounds
** 2× 0.50 in (12.7 mm) [[M2 Browning machine gun]]s, 200 rounds per gun
** 4× 0.30 in (7.62 mm) M1919 machine guns, 1,000 rounds per gun
|bombs=500 lb (227 kg) externally
}}

==See also==
{{aircontent
|related=
* [[Bell P-39 Airacobra]]
* [[Bell P-63 Kingcobra]]
|similar aircraft=
|lists=
* [[List of military aircraft of the United States]]
}}

==References==
===Citations===
{{reflist}}

===Bibliography===
{{refbegin}}
* Bowers, Peter M. "Airborne Cobra Pt.II". ''Airpower magazine, Vol.9, No.1, January 1979.''
{{refend}}

{{P-39 Airacobra family}}
{{Bell Aircraft}}
{{USAF fighters}}

[[Category:Cancelled military aircraft projects of the United States|Bell XP-46]]
[[Category:Bell aircraft|P-076]]
[[Category:Mid-engined aircraft]]
[[Category:Single-engined tractor aircraft]]
[[Category:Low-wing aircraft]]
[[Category:1940s United States fighter aircraft]]
[[Category:Aircraft with retractable tricycle landing gear]]