But that is exactly the challenge faced by workers at BAE Systems on the Lancashire coast every time the Typhoon build process begins – 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.
Martin Topping, Head of Typhoon Maintenance and Upgrade 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 two millimetres too much.”
To get round the problem BAE Systems has spent over £2.5million putting in special automated alignment facilities which use laser-trackers and computer-automated jacks. But what really ensures that each Typhoon’s airframe is built as close to perfection as is humanly possible are the giant ‘floating’ concrete rafts on which the aircraft and measuring equipment sit.
“Each of these concrete rafts is over three metres deep and 18 metres long,” says Martin. “All 9 automated jacks and both laser trackers are positioned on one surface ensuring all movement is relative, achieving a near perfect alignment whatever the moon may be doing.”
The result is one of the most perfectly aligned fast jet airframes in the world. Although 15 metres long from tip to tip, every Typhoon that leaves BAE Systems in Warton varies from true to no more than the thickness of a match stick – and that helps its ‘fly by wire’ computer system accurately control the aircraft, designed to be unstable but hugely agile.
Because of this build accuracy there is minimal need to ‘trim’ the flying surfaces and pilots can fly the fighter to its maximum potential. On a typical sortie, this build precision will save enough fuel to fill up an average family car (60 litres).