Click to enlarge image
Anonymous early Spitfire Mk. I on compass swing, location unknown. This view shows to advantage the dinstinctive features of the earliest production Spitfires Mk. I: wooden two-blade propeller, unarmoured windscreen, straight cockpit canopy, thin and tall aerial mast and (barely visible) rudder horn balance guard.
Compass swinging was a rather time-consuming task which could be simplified considerably by placing an aircraft on a rotating platform such as this. With a fitter sitting in the cockpit and the aircraft in flight-ready configuration, the engine was started and then the platform aligned so that the aircraft faced the 0 degree (north) heading. Then the fitter would check if the aircraft magnetic compass was in alignment with the magnetic north. If not, he would adjust the compensator screws with a non-magnetic screwdriver until the compass read 0 degrees. Then the procedure would be repeated for the 90-degree (east), 180 (south) and 270-degree (west) headings.
After these adjustments the compass was checked once again by turning it around stopping at each 30-degree heading and recording the compass readings, fine-tuning the compensator screws to ensure that there was no more than a few degrees difference between any of the indicated headings on the compass and the actual heading.
[Crown Copyright, via Jenny Scott]
I have seen your picture of the “Spitfire Mk. I on compass swing, location unknown” . If you have access tothe original picture can you tell me the number o nthe fusealage please . Is iy K38.. or K98.. Thanks. John Shipman
John,
Sadly I have only a scan of this photo from a contemporary HMSO publication. The serial is, for sure, K98xx.
Location unknown. It could be anywhere, however it could be Aldridge, West Midlands. Spitfires were repaired there (Heliwells) during the war, plus there is a circular piece of concrete in that position relative to the shape of the field and boundaries.