History The Spitfire PR Mk XIX was the last photo-reconnaissance variant of the famous Supermarine Spitfire aircraft originally designed by Reginald (R.J.) Mitchell, and further developed by his assistant, Joseph Smith. Based upon the successful Mk XIV fighter, the PR Mk XIX is sometimes also said to be the fastest of all the wartime Spitfires, with a maximum speed of somewhere around 748 km/h (460 mph) at 6,000 meters (20,000 ft). It had a service ceiling somewhere around 13000 meters (42,000 ft). Introduced in mid 1944, 225 PR Mk XIXs were eventually produced. Like most photo-reconnaissance Spitfires, the PR Mk XIX was unarmed (very brave pilots indeed!), providing a weight savings, and making more room for fuel (often supplemented with an additional "slipper" type ventral fuel tank), giving the aircraft a range of about 2,250 kilometers (1,400 miles)--very long legged for what originated as a point-defense design. The aircraft was equipped with two vertical cameras and/or one oblique camera in a heated area behind the cockpit. The aircraft also had an unarmoured windscreen and was fitted with a pressurized cabin. A main contributing factor to the stellar performance was the Rolls Royce Griffon engine. No discussion of the PR Mk XIX would be complete without adding some details about this amazing powerplant. The Griffon was introduced into Spitfire production beginning in 1941, and for a time, both Griffons and the famous Merlin were used concurrently for Spitfire production, The Merlin, however, was eventually phased out altogether before the end of WWII. The Griffon, popularly thought to be a development of the Merlin, was in fact derived from the R-Type racing powerplant (it should be noted however, the Griffon project incorporated much knowledge "learned" during Merlin production). Many, many design improvements characterized the Griffon (more than will be listed here), a surprising number of which define internal combustion engines state-of-the-art even today. Without getting into too much detail however, the Griffon was basically the result of a quest for more power (insert manly grunt here!). The Griffon was designed to be retro-fitted into existing Merlin powered aircraft, but in the case of the Spitfire, that task turned out to be quite an engineering feat, requiring a hefty re-design of everything forward of the firewall. Characteristic bumps added to the cowling to allow for valve cover clearance characterize Griffon engine Spitfires, along with enlarged underwing radiators, required for increased engine cooling requirements. An enlarged rudder was added to help control the massive torque produced by the beastly Griffon. 4,700 ft-lbs of torque required almost full left rudder, and considerable aileron, at take-off, to prevent the tiny Spitfire from rolling up into a ball. This torque issue was not adequately addressed until the series 80 Griffons introduced counter-rotating three-bladed propellers, instead of the standard five-bladed unit. The Griffon also had a firing order and valve timing different from the Merlin, giving the Griffon a growling exhaust note, as opposed to the sweet sound of the Merlin. The Griffon also rotated in a direction opposite the Merlin, in response to a military specification requiring all subsequent RAF aircraft to share the same propellor rotation direction (clockwise, as viewed from the front). The PR Mk XIX used the Griffon model 66, producing about 2000HP at 7000 feet. The 66 was essentially the same as the model 65, with the addition of a blower used for cabin pressurisation. Interestingly, a few airworthy PR Mk XIX still survive, one actually owned by Rolls-Royce itself (!--scroll about halfway down the page). Excellent detail images of the Swedish Air Force Museum PR Mk XIX (S31) can also be seen at IPMS Stockholm. Sources: "Spitfire PR Mk XIX in Detail" by Joachim Smith (IPMS Stockholm) "The story of the Supermarine Spitfire" by Steve Birks Griffon engine development