Editing Hawker Hurricane (section)

===Operation Dynamo===
During [[Dunkirk evacuation|Operation Dynamo]] (the evacuation from Dunkirk of British, French and Belgian troops cut off by the German army during the [[Battle of Dunkirk]]), the Hawker Hurricanes operated from British bases. Between 26 May and 3 June 1940, the 14 Hurricane units involved were credited with 108 air victories. A total of 27 Hurricane pilots became aces during Operation Dynamo, led by Canadian Pilot Officer W. L. [[Willie McKnight]] (10 victories) and Pilot Officer [[Percival Stanley Turner]] (seven victories), who served in No. 242 Squadron, consisting mostly of Canadian personnel.<ref name="Holmes p.58">Holmes 1996, p. 58.</ref> Losses were 22 pilots killed and three captured.<ref name="Holmes p.57">Holmes 1996, p. 57.</ref>

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| quote = Over Dunkirk, the Luftwaffe suffered its first serious rebuff of the war. As Galland has noted, the nature and style of the air battles over the beaches should have provided a warning as to the inherent weaknesses of the Luftwaffe's force structure. ...[T]he Bf 109 was at the outer limits of its range and possessed less flying time over Dunkirk than did the "Hurricanes" and "Spitfires" operating from southern England. German bombers were still located in western Germany and had even farther to fly. Thus, the Luftwaffe could not bring its full weight to bear so that when its bombers hammered those on the beaches or embarking, the RAF intervened in a significant fashion. German aircraft losses were high, and British fighter attacks often prevented German bombers from performing with full effectiveness. Both sides suffered heavy losses. During the nine days from May 26 through June 3, the RAF lost 177 aircraft destroyed or damaged; the Germans lost 240. For much of the Luftwaffe, Dunkirk came as a nasty shock. Fliegerkorps II reported in its war diary that it lost more aircraft on the 27th attacking the evacuation than it had lost in the previous ten days of the campaign.
| source = Murray. ''Strategy for Defeat: The Luftwaffe 1935–1945''<ref>Murray 2002, pp. 38–39.</ref>
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On 27 May 1940, in one of the final mass encounters of the ''Blitzkrieg'', 13 Hurricanes from 501 Squadron intercepted 24 [[Heinkel He 111]]s escorted by 20 Bf 110s; during the ensuing battle, 11 Heinkels were claimed as "kills" and others damaged, with little damage to the Hurricanes.<ref>Bader 2004, pp. 50–55.</ref> On 7 June 1940, "Cobber" Kain, the first RAF ace of the war, got word that he was to return to England for "rest leave" at an [[Operational Training Unit]]. On leaving his airfield, he put on an impromptu aerobatic display and was killed when his Hurricane crashed after completing a [[Aerobatic maneuver|loop]] and attempting some low altitude [[Aerobatic maneuver|"flick" rolls]].<ref>Burns 1992, pp. 165–167.</ref>

Initial engagements with the Luftwaffe showed the Hurricane to be a tight-turning and steady platform, but the Watts two-bladed propeller was clearly unsuitable. At least one pilot complained of how a Heinkel 111 was able to pull away from him in a chase, yet by this time the Heinkel was obsolete.<ref name="Hiscock p. 12" /> At the start of the war, the engine ran on standard 87 [[octane]] [[avgas|aviation spirit]]. From early 1940, increasing quantities of 100 octane fuel imported from the U.S. became available.<ref>Wood and Dempster 1990, p. 87.</ref><ref>[http://www.nationalarchives.gov.uk/catalogue/displaycataloguedetails.asp?CATLN=6&CATID=4223197&FullDetails=True&Gsm=2008-02-12&j=1 "10/282 Minutes of Oil Policy Committee meetings."] ''National Archives AVIA'', 2 April, 18 May, 7 August 1940. Retrieved: 15 June 2009.</ref> In February 1940, Hurricanes with the Merlin II and III engines began to receive modifications to allow for an additional {{cvt|6|psi}} of [[supercharger]] boost for five minutes (although there are accounts of its use for 30 minutes continuously).<ref name="Gleed 1942, p. 61." />

The extra supercharger boost, which increased engine output by nearly {{cvt|250|hp}}, gave the Hurricane an approximate increase in speed of {{cvt|25|to|35|mph}}, under {{cvt|15000|ft}}<ref name="Gleed 1942, p. 61.">Gleed 1942, p. 61.</ref> altitude and greatly increased the aircraft's climb rate. "Overboost" or "pulling the plug", a form of [[war emergency power]] as it was called in later Second World War aircraft, was an important wartime modification that allowed the Hurricane to be more competitive against the [[Messerschmitt Bf 109|Bf 109E]] and to increase its margin of superiority over the [[Messerschmitt Bf 110|Bf 110C]], especially at low altitude. With the +{{cvt|12|psi|kPa}} "emergency boost", the Merlin III was able to generate {{cvt|1310|hp}} at {{cvt|9000|ft}}.<ref>Harvey-Bailey 1995, p. 155.</ref>

[[Flight Lieutenant]] Ian Gleed of 87 Squadron wrote about the effect of using the extra boost on the Hurricane while chasing a Bf 109 at low altitude on 19 May 1940: "Damn! We're flat out as it is. Here goes with the tit.{{refn| This was the pilot's term for the Boost Cut-Out Control which was adjacent to the throttle lever.|group=N}} A jerk&nbsp;– boost's shot up to 12 pounds; speed's increased by 30 mph. I'm gaining ground&nbsp;– 700, 600, 500 yards. Give him a burst. No, hold your fire you fool! He hasn't seen you yet..."<ref name="Gleed 1942, p. 61." /> Gleed ran out of ammunition before he could shoot the 109 down although he left it heavily damaged and flying at about {{cvt|50|ft}}.{{refn| Gleed rose through the ranks to become a wing commander flying Spitfire VBs over North Africa; he was shot down and killed by ''[[Oberleutnant]]'' [[Ernst-Wilhelm Reinert]] on 16 April 1943. Gleed was credited with 15 victories.|group=N}}

Hurricanes equipped with [[Dowty Rotol|Rotol]] constant-speed propellers were delivered to RAF squadrons in May 1940, with deliveries continuing throughout the Battle of Britain. According to aviation author David Donald, the Rotol propeller had the effect of transforming the Hurricane's performance from "disappointing" to "acceptable mediocrity"; modified aircraft were reportedly much sought after among squadrons which had also been equipped with Hurricanes that were fitted with the older de Havilland two-position propeller.<ref>Donald 1999, p. 38.</ref><ref name="mason 5 6">Mason 1967, pp. 5–6.</ref>