Forum: Modern Military Aircraft

Typhoon Officially 'Over the Moon'

20 Feb 2007 | Ref. 057/2007
http://www.baesystems.com/Newsroom/NewsReleases/autoGen_107120145958.html

Typhoon – manufacture overcomes the pull of the moon
Warton, United Kingdom – 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 – 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, 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 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 leave BAE Systems in Warton varies from true 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). The advanced manufacturing technology pioneered first on Typhoon is now also being used on the F-35 Lightning II. The F-35 Lightning II will be the world’s first and only stealthy, supersonic, multi-role fighter.

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Interesting article Smile

. It makes me wonder a couple of things.

First off, wouldn't Lockheed have to have coped with the same issue on the F-22 and the F-117? I recall a story from flight testing on Have Blue (Proof of concept aircraft for the F-117) that the RCS suddenly jumped one flight. They found that one of the screws was backed out just enough to have part of the screw head visible. Makes me think that alignment might be that important.

Second, what's the effect on alignment over time from things like harder than normal landings and pulling G's with stores? I'd imagine that airframe fatigue might cause divergence from such precise alignment over time.

Thanks in advance Very Happy

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My dad was a tool and die engineer. My first thought on this was: "Interesting but isn't this common with a lot of high tech manufacturing today?" .... i.e. "gravity is a bitch". Laughing

So the factory floor doesn't move at the same rate towards the additional gravitational force in the UK as it does in the US? WTF, OVER...

That's easy JR!: we're the center of the universe!!! Amen!!!!

Quote:

That's easy JR!: we're the center of the universe!!! Amen!!!!

Hmmm...careful - looks like you're developing quite a superiority complex out there across the pond. I suppose the next step would be to regard the rest of the planet as being populated by "untermenschen"

Joking aside, what Mike posted got me thinking:why all the hassle, why bother to take into account even the most minute interaction (such as moon gravity) when during the flight an asymetric load (so popular these days on many planes) would completely ruin the purpose of thse efforts - or am I wrong?

Building to fine tolerances is very important in any manufacturing process, not just aircraft. It is more critical in the aircraft industry because of the loads and stress they have to endure.

High tolerances almost always equal - better reliability, longevity and safety. They also equate to consistency from aircraft to aircraft in terms of handling and flight characteristics. The work done to maintain high standards in Typhoon production are certainly not unusual in high tech` industry.
I use computer controlled laser alignment systems in my line of work to guarantee all of the previously mentioned attributes. I also worked for a firm which produced very high quality turbine bearings. The tolerances were so fine, that if you touched a bearing surface with your bare finger, you had to throw away the complete assembly!

Aircraft suffer from fatigue in the same way as any other machinery. There must be some misalignment that occurs through use. If the thing is built properly in the first place, you will have fewer problems down the line. Also remember that the Typhoon is built in kit form, you want all of the pieces built around Europe to fit together perfectly, that is another major reason for the extra effort IMO. I think if the work done at Samlesbury, (I live in the area). wasn`t required, it wouldn`t have been done.

I thought with the American fat epidemic, that we would be the ones affecting the tides and the phases of the moon.

But the moon affecting the production line. After they identify the "2nd Gunman", I will have officially heard it all. Laughing

What the article doesn`t mention is the close proximity of the Samlesbury plant to the river Ribble which runs into the Irish sea through an estuary. It is easy to see on a map why tides could give rise to small ground movements and these are well documented. There is sedimentary movement with the tides in the area and we all know the moon causes tidal movement through gravity; as well as the gravitation exerted by the sun.

Talk about fat epidemics, the UK is now the fattest country in Europe! You guys have a lot to answer for with those fast food chains!! Laughing

Luckily I haven`t succumbed to the pizza demon!

Quote:

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 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.

Way over my head!