keesje
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Airbus Has Begun The A380’s Flutter-test Campaign

Tue Aug 16, 2005 11:03 pm

Regulators impose requirements aimed at ensuring double-deck giant’s crashworthiness matches existing airliners



Flight International

The US Federal Aviation Administration and European Aviation Safety Agency are seeking to make Airbus prove that passengers’ chances of survival in an A380-800 crash are equal to or better than in any other airliner.

The FAA proposal notes the A380’s greater volume should allow the airframe to absorb more energy on impact, which could reduce the forces felt by passengers and increase their chances of surviving the crash.

Airbus has begun the A380’s flutter-test campaign, which it expects to complete within 10 or 15 flights. The trials will be flown at progressively higher speeds up to the ultra-large aircraft’s maximum of 375kt (690km/h)/Mach 0.96.

http://www.flightinternational.com/A...vivability%E2%80%99+test+goal.html
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kc135topboom
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Wed Aug 17, 2005 12:26 am

Quoting Keesje (Thread starter):
The trials will be flown at progressively higher speeds up to the ultra-large aircraft’s maximum of 375kt (690km/h)/Mach 0.96.

Mach 0.96? I thought the max Mach number for the A-380 is 0.86. But, it should easily be able to get to 375 KIAS, at and below FL290. Above FL290, 375 KIAS will be above Mach 0.86.

Quoting Keesje (Thread starter):
The US Federal Aviation Administration and European Aviation Safety Agency are seeking to make Airbus prove that passengers’ chances of survival in an A380-800 crash are equal to or better than in any other airliner.

The FAA proposal notes the A380’s greater volume should allow the airframe to absorb more energy on impact, which could reduce the forces felt by passengers and increase their chances of surviving the crash.

The A-380 should easily have the same or better crash survivability than any other modern airliner.

But, it's greater volumn (and weight and fuel capacity) would produce greater crash forces than, say a B-747-400 (given the same speed and other factors).

But, the greater size should spread any impact over a larger area. Thus spreading the impact and actually reducing impact forces on different sections while increasing it in other sections.
 
eatmybologna
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Wed Aug 17, 2005 12:57 am

So, how do they test for this? They can't crash one into the ground obviously.

e-m-b
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Vasu
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Wed Aug 17, 2005 1:45 am

Quoting Eatmybologna (Reply 2):
So, how do they test for this? They can't crash one into the ground obviously.

I was wondering the same...
 
OldAeroGuy
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Wed Aug 17, 2005 2:55 am

Timing for the flutter testing is interesting. I know flutter clearance is one first things that Boeing does when flight testing a new model. The logic is that if structural changes are needed, they should be started as soon as possible to preserve the Certification date, if feasible. In addition, you should show that the airplane structure is OK for all parts of the flight envelope as you're never sure of the flight conditions you may encounter as you explore handling characteristics.

Starting flutter tests four months after first flight seems a bit late, but I'm not sure if this is an Airbus standard practice.
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A350
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Fri Aug 19, 2005 8:50 am

Quoting Eatmybologna (Reply 2):
So, how do they test for this? They can't crash one into the ground obviously.

They can, but they probably won't do it  biggrin 

Quoting KC135TopBoom (Reply 1):

But, the greater size should spread any impact over a larger area. Thus spreading the impact and actually reducing impact forces on different sections while increasing it in other sections.

That's a very important point. Actually, it makes the A380 unattractive for terrorists.

A350
 
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Vasu
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Fri Aug 19, 2005 4:03 pm

Quoting A350 (Reply 5):
That's a very important point. Actually, it makes the A380 unattractive for terrorists.

Maybe, but think of all those people onboard ... eek!
 
Udo
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Fri Aug 19, 2005 4:23 pm

Quoting Vasu (Reply 6):
Maybe, but think of all those people onboard ... eek!

Not worse than on Corsair or Japanese domestic B747s.


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Udo
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stealthpilot
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Fri Aug 19, 2005 7:37 pm

The flutter test is an extremely important test. One method is to attach 'fluttering' appendages to the wing tips which cause major disturbances to the aerodynamics and flight control characteristics. It is amazing how something as small as they are can cause a huge aircraft to behave so sporadically.
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art
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Fri Aug 19, 2005 7:49 pm

Quoting Keesje (Thread starter):
The trials will be flown at progressively higher speeds up to the ultra-large aircraft’s maximum of 375kt (690km/h)/Mach 0.96.

Just a query on the figures here:

Mach 1 at sea level = ca 760mph/1260kph

Mach 1 at 36000ft = ca 640mph/1025kph

Can't see 690kph equalling mach 0.96 at any service altitude. Also, would they actually test an airliner up to mach 0.96 - strange things start happening this close to mach 1, don't they?
 
cfalk
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RE: Airbus Has Begun The A380’s Flutter-test Campaign

Fri Aug 19, 2005 8:02 pm

Quoting Art (Reply 9):
Can't see 690kph equalling mach 0.96 at any service altitude. Also, would they actually test an airliner up to mach 0.96 - strange things start happening this close to mach 1, don't they?

They are talking about indicated airspeed, which indicates far slower than true airspeed due to the thin air at high altitude.

Charles
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