Little known fact re the RAF PR (Photo Recon) Spitfires: Obviously in order to get to the height required to overfly and image enemy territory without fighter interception a number of modifications had to be made. Tweaking the engine, internal fuel increase and no guns or ammo were the main ways of saving weight and increasing range.
But in order to really streamline the drag factor they tested frames both in wind-tunnels (innovative at the time) and in the field high over friendly skies by.....glueing, wait for it, a half Lentil over each rivet to see which areas had the most drag when ensuing erosion had taken place. If only the RAF kept stuff as simple and cheap as this:-O
Laurie:t:
The PRMkIV Spitfire could reach Stettin (Szczecin) in the Baltic. Although this is about 600km in a straight line, direct routes, having the disadvantage to the enemy of predictability, seldom were chosen. Routes were chosen to keep the opposition guessing for as long as possible, especially for a single aircraft at high altitude in daylight! The flight planning also had to take in the most economical height outbound to minimise fuel consumption, cross into detection range at an altitude that would permit a fuel-efficient climb to photo altitude while being fast enough to make interception difficult, and to allow the pilot when in the danger zone to weave continuously to monitor the blind spots behind and below if he maintained only straight-line flight.
The outbound route to Stettin probably covered at least 900km. The return route continued in constant weaving flight, often with course changes when in the danger zone, and then, once over the North Sea, a speedy shallow low-consumption descent, preferably into cloud, or down to low level in clear air was the main option. In my early days in the RAF, there were still many serving pilots who had flown PR Spitfires operationally. In one of may later jobs, I was responsible for the entire wartime air film archive...
MJB
