Editing Hyper engine (section)

==Request for data R40-C==

As 1938 came to an end, war in Europe was imminent. At this point, European aircraft had greatly surpassed US designs.<ref name="Balzer7">Balzer p 7</ref> The two top USAAC fighters, the [[Seversky P-35]] and the [[Curtiss P-36 Hawk|Curtiss P-36A]], were just able to hit {{convert|300|mph|km/h|abbr=on}}. Against the {{cvt|340|mph|km/h}} [[Messerschmitt Bf 109]] they would be completely outclassed. One of America’s answers to this issue, the twin-engined [[Lockheed P-38 Lightning|Lockheed XP-38]], was entering an extended test program.

Although the XP-38 was able to fly at speeds in excess of {{cvt|413|mph|km/h}}, its twin engines and relatively large frame meant it was large and heavy. This, in turn, meant the XP-38 was not as maneuverable as most single-engine fighters.<ref name="Balzer">Balzer pp 9, 10</ref> The XP-38 also had a newly introduced liquid-cooled engine, the [[Allison V-1710]]. The Allison's in-line vee cylinder arrangement allowed for a narrow aerodynamic shape that had less drag than the air-cooled radial engine fighters that predominated in America at the time.<ref name="Schlaifer">Schlaifer p 253</ref>

The fighter aircraft procurement program for FY 1940 was contained in a document that was approved by Assistant Secretary of War Louis K. Johnson on 9 June 1939.  That document was the "Request for Data R40-C", and unlike previous aircraft procurement requests, it was sent to only a limited number of aircraft manufacturers. The original document was to be sent to:<ref name="Balzer13">Balzer p 13</ref>
* [[Bell Aircraft|Bell Aircraft Corporation]]
* [[Consolidated Aircraft|Consolidated Aircraft Corporation]]
* [[Curtiss-Wright|Curtiss-Wright Corporation]] Curtiss Airplane Division
* Curtiss-Wright Corporation, St. Louis Airplane Division
* [[Grumman|Grumman Aircraft Engineering Corporation]]
* [[Lockheed Corporation|Lockheed Aircraft Corporation]]
* [[Republic Aviation|Republic Aviation Corporation]]
* [[Vought|Vought-Sikorsky Aircraft Division, United Aircraft Corporation]]
* [[Vultee Aircraft|Vultee Aircraft Division, Aviation Manufacturing Corporation]]

After final review and approval as Air Corps Type Specification XC-622, a further four manufacturers were added to the distribution:
* [[Hughes Aircraft|Hughes Aircraft Corporation]]
* [[McDonnell Aircraft|McDonnell Aircraft Company]]
* [[Boeing|Boeing Aircraft Company]]
* [[Northrop Corporation|Northrop Aircraft, Incorporated]]

These companies had only ten days to agree to the terms of the document, and only 30 days to submit their designs.

===FY 1940===
A total of 26 designs, with a mix of 16 engine models from six engine companies, were submitted by seven of the selected companies. These engines became known as the "Hyper Engines", a contraction of '''Hi'''gh-'''per'''formance engines. The submitted designs were graded using a "Figure of merit" (FOM) rating system, and then, using the FOM results (which ranged from 444.12 for the Allison V-1710-E8 to 817.90 for the Pratt and Whitney X-1800-A4G), they were separated into one of three groups.

* Those placed in the first group were little more than modifications to existing designs. They were not considered to be sufficiently advanced.
* Those placed in the third group proposed using an engine that was unlikely to be developed into flying condition by the time the airframe was ready to fly. They were not considered to be viable in the time frame allowed.
* The remaining ten designs were placed in the second group: those that were an advancement in aeronautical engineering, with an engine that would be ready to fly, when needed.

Only three of these ten designs were approved, and contracts were made for a limited prototype run of three aircraft for each.<ref name="Balzer15">Balzer p 15</ref>

The three aircraft/engine combinations that were selected:<ref name="Balzer24">Balzer p.24</ref>
# Vultee Aircraft's Model 70 Alternate 2, (FOM score: 817.9), which became the [[Vultee XP-54]], powered by the [[Pratt & Whitney X-1800|Pratt & Whitney X-1800-A4G]] engine
# Curtiss-Wright St Louis Model P248C, (FOM score: 770.6), which became the [[Curtiss-Wright XP-55 Ascender]], powered by the [[Continental IV-1430|Continental IV-1430-3]] engine
# Northrop's Model N2-B (FOM score: 725.8), which became the [[Northrop XP-56 Black Bullet]], powered by the [[Pratt & Whitney X-1800|Pratt & Whitney X-1800-A3G]] engine

{|class="wikitable"  width="90%" 
|+The high-performance engines of FY 1940<ref name="Balzer24"/>
|-valign=top
! Engine model
! Configuration
! Displacement
! Horsepower
! Specific<br>horsepower
! Weight
! Power to<br>weight ratio
|-
| [[Continental IV-1430|Continental IV-1430-3]]
| inverted V-12
| 1,430&nbsp;in³
| 1,600&nbsp;hp at 3,200&nbsp;rpm
| 1.12&nbsp;hp/in³
| 1,615&nbsp;lb
| 0.99&nbsp;hp/lb
|-
| [[Pratt & Whitney X-1800|Pratt & Whitney X-1800-A3G]]
| 24 cylinder H-block
| 2,600&nbsp;in³
| 2,200&nbsp;hp
| .85&nbsp;hp/in³
| 3,250&nbsp;lb
| 0.68&nbsp;hp/lb
|-
| [[Pratt & Whitney X-1800|Pratt & Whitney X-1800-A4G]]
| 24-cylinder H-block
| 2,600&nbsp;in³
| 2,200&nbsp;hp
| .85&nbsp;hp/in³
| 3,250&nbsp;lb
| 0.68&nbsp;hp/lb
|}

===FY 1941===
Three additional high-performance engines were considered for the USAAC's FY 1942 "Hyper" engine procurement program. They were:<ref name="Balzer24"/>
* [[Wright R-2160]] "Tornado"
* [[Pratt & Whitney XH-3130|Pratt & Whitney H-3130]]
* [[Allison V-3420]]

Not to be left out, the US Navy selected the [[Lycoming H-2470|Lycoming XH-2470]] for funding in FY 1942 as well.<ref name="Balzer24"/>

{|class="wikitable" width="90%"
|+The high-performance engines of FY 1941<ref name="Balzer24"/>
|-valign=top
! Engine model
! Configuration
! Displacement
! Horsepower
! Specific<br>horsepower
! Weight
! Power to<br>weight ratio
|-
| [[Allison V-3420]]
| 24-cylinder [[W engine]]
| 3,421.2&nbsp;in³
| 2,100&nbsp;hp
| .61&nbsp;hp/in³
| {{convert|2,600|lb|kg|abbr=on}}
| 0.81&nbsp;hp/lb
|-
|  [[Lycoming H-2470|Lycoming XH-2470]]
| 24-cylinder horizontal opposed
| 2,470&nbsp;in³
| 2,300&nbsp;hp
| .93&nbsp;hp/in³
| {{convert|2430|lb|kg|abbr=on}}
| 0.96&nbsp;hp/lb
|-
| [[Pratt & Whitney XH-3130]]
| 24-cylinder H-block
| 3,130&nbsp;in³
| 2,650&nbsp;hp
| .84&nbsp;hp/in³
| {{convert|3250|lb|kg|abbr=on}}
| 0.82&nbsp;hp/lb
|-
|  [[Wright R-2160]]
| 42-cylinder 7-bank
| 2,160&nbsp;in³
| 2,350&nbsp;hp
| 1.09&nbsp;hp/in³
| {{convert|2400|lb|kg|abbr=on}}
| 0.98&nbsp;hp/lb
|}