Spitfire PR IV of No. 680 Squadron RAF
The development of the PR Mk IV Spitfire marked a significant advancement in the quest to increase the range of photo-reconnaissance (PR) Spitfires. However, progress was delayed due to the priority given to producing cannon-armed wings for fighter versions. Once the PR Mk IV, also known as PR Mk ID, finally appeared, it represented a substantial improvement in reconnaissance capabilities.
The PR Mk IV carried two F.24 cameras with either 8-inch or 20-inch focal length lenses, or two F.8 cameras with 20-inch lenses, all mounted vertically in the fuselage. Its main feature was its increased fuel capacity: it housed 228 gallons of fuel, more than two and a half times the capacity of the standard Mk I & II fighters. This earned it the nickname “The Bowser” due to its large fuel tanks, particularly those integrated into the leading edges of the wings.
However, the additional fuel caused some handling issues. The full load affected the aircraft’s center of gravity, making it unstable and difficult to manage until the fuel in the rear tank was consumed, restoring balance. To accommodate such a large fuel supply, an extra 14-gallon oil tank was fitted in the port wing, and this required the use of the rounded oil cooler intake, a design feature borrowed from the Mk V fighter variant.
The PR Mk IV made its operational debut in October 1940, with Fg Off S. Millen piloting it on a significant mission on the 29th of that month. Millen flew a PR Mk IV on a 5-hour and 20-minute flight to photograph Stettin in Poland (now known as Szczecin). The mission demonstrated that a Spitfire, initially designed as a short-range interceptor, had successfully transitioned into a long-range reconnaissance aircraft capable of deep penetration flights over enemy territory.
The PR Mk IV became the longest-ranging of the PR Spitfires based on the Mk I fuselage, entering service after the PR Mk V and PR Mk VI (designated PR Mk IE and PR Mk IF, respectively). This variant proved to be a key asset for strategic reconnaissance missions, providing invaluable intelligence for the Allies.