BAE says: "Building one of the most advanced jet fighters in the world is a challenge for any aerospace company – but the one thing you might think you don’t have to worry about when you start such a job is the pull of the moon."
But that is exactly the challenge faced by workers at BAE Systems on the Lancashire coast every time the Typhoon build process begins, the company says, because the moon’s gravitational pull actually causes the ground to move beneath their feet.
So fine are the tolerances now used to build the Typhoon that even the movements of the tide could throw the jet fighter tolerances out. The Lancashire coast has the highest tides of the month today and tomorrow, which bring with them the greatest distortion of the earth's surface.
Martin Topping, Typhoon final assembly operations manager explains: “Every time the moon pulls the tide in and out, the ground under our feet actually moves by between one and two millimetres. That might not sound a lot, but given the tolerances we are working to on Typhoon, two millimetres is 2mm [7.8 thous] too much.”
To get round the problem BAE Systems says it has spent over £2.5million ($4.8 million) installing automated alignment facilities which use laser-trackers and computer-automated jacks. Additionally, there are 3m x 18m (9ft10in x 59ft3in) floating concrete rafts on which the aircraft and measuring equipment sit (pictured above).
BAE says each Typhoon requires such build accuracy means pilots require less trim of the aircraft in flight, saving up to 60litres (15.8USGal) in a typical sortie.