Editing Curtiss P-40 Warhawk (section)

==Design and development==

===Origins===
[[File:Curtiss XP-40 in flight, circa in 1939.jpg|thumb|Curtiss XP-40 "11" used for test purposes by the [[Air Force Materiel Command|Materiel Division]] of the US Army Air Corps]]

On 14 October 1938, Curtiss test pilot Edward Elliott flew the prototype XP-40 on its first flight in Buffalo.<ref>[https://web.archive.org/web/20110223210821/http://www.airforcehistory.hq.af.mil/PopTopics/chrono1.htm "Chronology: The Army Air Corps to World War II".] ''Air Force Historical Studies Office''. Retrieved: 20 July 2011.</ref> The XP-40 was the 10th production Curtiss P-36 Hawk,<ref name="Famous Fighters">Green 1957, p. 43.</ref> with its [[Pratt & Whitney R-1830 Twin Wasp]] 14-cylinder air-cooled [[radial engine]] replaced at the direction of Chief Engineer [[Don R. Berlin]] by a liquid-cooled, supercharged Allison V-1710 [[V12 engine|V-12]] engine. The first prototype placed the glycol coolant radiator in an underbelly position on the fighter, just aft of the wing's trailing edge.<ref name=Merriam>Merriam 2000, p. 15.</ref> USAAC Fighter Projects Officer Lieutenant [[Benjamin S. Kelsey]] flew this prototype some 300 miles in 57 minutes, approximately {{convert|315|mph}}. Hiding his disappointment, he told reporters that future versions would likely go {{convert|100|mph}} faster.<ref>''American Aviation'', Volume 3, 1939, p. 2.</ref> Kelsey was interested in the Allison engine because it was sturdy and dependable, and it had a smooth, predictable power curve. The V-12 engine offered as much power as a radial engine but had a smaller frontal area and allowed a more streamlined cowl than an aircraft with a radial engine, promising a theoretical 5% increase in top speed.<ref name=Wilson1997>Wilson, Randy. [http://rwebs.net/dispatch/output.asp?ArticleID=19 "The Heart of the Cobra: Development of the Allison V-1710 Engine".] {{webarchive |url=https://web.archive.org/web/20160304061418/http://rwebs.net/dispatch/output.asp?ArticleID=19 |date=4 March 2016 }} ''Allison Press Release on the Certification of its V-1710 Engine by the Air Corps'' via ''The Dispatch'', Volume 22, Number 1, Spring, 1997. Retrieved: 20 July 2011.</ref>

Curtiss engineers worked to improve the XP-40's speed by moving the radiator forward in steps. Seeing little gain, Kelsey ordered the aircraft to be evaluated in a [[NACA]] wind tunnel to identify solutions for better aerodynamic qualities. From 28 March to 11 April 1939, the prototype was studied by NACA.<ref>Wagner, Ray. [http://www.americancombatplanes.com/p40_1.html "P-40".] {{Webarchive|url=https://web.archive.org/web/20150521015346/http://www.americancombatplanes.com/p40_1.html |date=21 May 2015 }} ''American Combat Planes of the 20th century''. Retrieved: 20 July 2011.</ref> Based on the data obtained, Curtiss moved the glycol coolant radiator forward to the chin; its new air scoop also accommodated the oil cooler air intake. Other improvements to the landing gear doors and the exhaust manifold combined to give performance that was satisfactory to the USAAC.<ref name=Merriam/> Without beneficial tail winds, Kelsey flew the XP-40 from [[Wright-Patterson Air Force Base|Wright Field]] back to Curtiss's plant in Buffalo at an average speed of {{convert|354|mph|abbr=on}}.{{refn|Due to the reporter's unfamiliarity with the type, the XP-40 was inaccurately identified as an upgraded P-36.<ref>"America Creeps Up". ''The Aeroplane'' (Temple Press), Volume 56, 1938, p. 730.</ref>|group=N}} Further tests in December 1939 proved the fighter could reach {{convert|366|mph|abbr=on}}.<ref>Molesworth 2008, p. 10.</ref>

An unusual production feature was a special truck rig to speed delivery at the main Curtiss plant in Buffalo, New York. The rig moved the newly built P-40s in two main components, the main wing and the fuselage, the eight miles from the plant to the airport where the two units were mated for flight and delivery.<ref>[https://books.google.com/books?id=ftkDAAAAMBAJ&pg=PA91 "New Army Warplane Rides a Trailer on Its First Trip to Airport".] ''Popular Mechanics'', January 1941, p. 91.</ref>

===Performance characteristics===
[[File:Curtiss P-40, ¾-front view, in flight (00910460 023).jpg|left|thumb|A three-quarter view of a P-40B, X-804 (s/n 39-184) in flight. This aircraft served with an advanced training unit at [[Luke Air Force Base|Luke Field]], Arizona.]]
The P-40 was conceived as a pursuit aircraft and was agile at low and medium altitudes but suffered from a lack of power at higher altitudes. At medium and high speeds it was one of the tightest-turning early monoplane designs of the war,<ref name="Flying">Higam 2004, p. 3.</ref> and it could out-turn most opponents it faced in North Africa and the Russian Front. In the Pacific Theater it was out-turned at lower speeds by the lightweight fighters [[Mitsubishi A6M Zero]] and [[Nakajima Ki-43 Hayabusa]] (known to Allies as "Oscar"). The American Volunteer Group Commander [[Claire Lee Chennault|Claire Chennault]] advised against prolonged dog-fighting with the Japanese fighters due to speed reduction favoring the Japanese.<ref name="Gunstonp68">Gunston 1981, p. 68.</ref>

Allison's V-1710 engines produced {{convert|1040|hp|kW|abbr=on}} at sea level and {{convert|14000|ft|m|abbr=on}}. This was not powerful compared with contemporary fighters, and the early P-40 variants' top speeds were only average. The single-stage, single-speed [[supercharger]] meant that the P-40 was a poor high-altitude fighter. Later versions, with {{convert|1200|hp|kW|abbr=on}} Allisons or more powerful 1,400&nbsp;hp [[Packard V-1650|Packard Merlin]] engines were more capable. Climb performance was fair to poor, depending on the subtype.<ref name="P40Zero"/> Dive acceleration was good and dive speed was excellent.<ref name="P40Zero"/> The highest-scoring P-40 [[Flying Ace|ace]], [[Clive Caldwell]] ([[Royal Australian Air Force|RAAF]]), who claimed 22 of his 28½ kills in the type, said that the P-40 had "almost no vices", although "it was a little difficult to control in terminal velocity".<ref>Alexander 2006, p. 22.</ref> The P-40 had one of the fastest maximum dive speeds of any fighter of the early war period, and good high-speed handling.

[[File:Kittyhawkdamaged.jpg|thumb|Evidence of the P-40's durability: in 1944 [[Flying Officer|F/O]] T. R. Jacklin (''pictured'') flew this [[No. 75 Squadron RAAF]] P-40N-5 more than {{convert|200|mi|0|abbr=on}} after the loss of the port aileron and 25% of its wing area, due to a mid-air collision with another P-40N-5.<ref>{{Cite web|url=http://www.adf-serials.com/2a29-N1.shtml|title=ADF Aircraft Serial Numbers - RAAF A29 Curtiss P-40N Kittyhawk IV|date=13 January 2005|website=www.adf-serials.com|access-date=25 August 2016|archive-url=https://web.archive.org/web/20160828165557/http://www.adf-serials.com/2a29-N1.shtml|archive-date=28 August 2016|url-status=dead}}</ref>{{Refn|The fighter was repaired and served out the war.|group=N}}]]
The P-40 tolerated harsh conditions and a variety of climates. Its semi-[[Modularity|modular]] design was easy to maintain in the field. It lacked innovations such as boosted [[aileron]]s or automatic [[Leading-edge slat|leading edge slats]], but its strong structure included a five-[[Spar (aviation)|spar]] wing, which enabled P-40s to pull high-G turns and survive some midair collisions. Intentional [[Aerial ramming|ramming attacks against enemy aircraft]] were occasionally recorded as victories by the [[Desert Air Force]] and [[Soviet Air Forces]].<ref name="Romanenko">Romanenko, Valeriy and James F. Gebhardt. [http://lend-lease.airforce.ru/english/articles/romanenko/p-40/index.htm "The P-40 in Soviet Aviation".] {{Webarchive|url=https://web.archive.org/web/20060505113914/http://lend-lease.airforce.ru/english/articles/romanenko/p-40/index.htm |date=5 May 2006 }} ''Lend-lease on airforce.ru''. Retrieved: 7 March 2006.</ref> Caldwell said P-40s "would take a tremendous amount of punishment, violent aerobatics as well as enemy action".<ref name="Alexander p.21"/> Operational range was good by early war standards and was almost double that of the [[Supermarine Spitfire]] or [[Messerschmitt Bf 109]], although inferior to the Mitsubishi A6M Zero, Nakajima Ki-43 and [[Lockheed P-38 Lightning]].

Caldwell found the P-40C Tomahawk's armament of two {{convert|.50|in|mm|adj=on}} [[Browning M2|Browning AN/M2]] "light-barrel" dorsal nose-mount synchronized machine guns and two {{convert|.303|in|mm|adj=on}} [[Browning machine gun]]s in each wing to be inadequate.<ref name="Alexander p.21">Alexander 2006, p. 21.</ref> This was improved with the P-40D (Kittyhawk I) which abandoned the synchronized gun mounts and instead had two {{convert|.50|in|mm|adj=on}} guns in each wing, although Caldwell still preferred the earlier Tomahawk in other respects. The D had armor around the engine and the cockpit, which enabled it to withstand considerable damage. This allowed Allied pilots in Asia and the Pacific to attack Japanese fighters head on, rather than try to out-turn and out-climb their opponents. Late-model P-40s were well armored. Visibility was adequate, although hampered by a complex windscreen frame, and completely blocked to the rear in early models by a raised turtledeck. Poor ground visibility and relatively narrow landing gear track caused many losses on the ground.<ref name="P40Zero"/>

Curtiss tested a follow-on design, the [[Curtiss XP-46]], but it offered little improvement over newer P-40 models and was cancelled.<ref>Berliner 2011, p. 18.</ref>