Hi folks,

A quick question for the guys in aerospace and materials science. A long time ago, I remember hearing about an aircraft alloy (I think it was aluminium based) which followed a hardness curve over about 40 years during normal use (i.e., at normal aircraft operating temperatures). This meant that it was strongest after about 20 years, and then became weaker with age. Can anyone tell me the name of this alloy?

Thanks!

Chris

Duralumin - Al-Cu alloy - hardens over days at room-temperature after
being quenched from solution-treated (essentially annealed state) -
but as far as I know that then stays permanent. There isn't really
any driving-force even in geological time (for mountains to flow into
the sea (!)) for the structure to coarsen and loose yield strength.
As far as I know ???
Rich S

On 2/23/2020 7:45 AM, Christopher Tidy wrote:
Hi folks,

A quick question for the guys in aerospace and materials science. A long time ago, I remember hearing about an aircraft alloy (I think it was aluminium based) which followed a hardness curve over about 40 years during normal use (i.e., at normal aircraft operating temperatures). This meant that it was strongest after about 20 years, and then became weaker with age. Can anyone tell me the name of this alloy?

Thanks!

Chris


Airplanes can experience fatigue overtime, but its from vibration and
flex. You really shouldn't barrel roll a jumbo jet. LOL.

Bob La Londe writes:

On 2/23/2020 7:45 AM, Christopher Tidy wrote:
Hi folks,

A quick question for the guys in aerospace and materials science. A long time ago, I remember hearing about an aircraft alloy (I think it was aluminium based) which followed a hardness curve over about 40 years during normal use (i.e., at normal aircraft operating temperatures). This meant that it was strongest after about 20 years, and then became weaker with age. Can anyone tell me the name of this alloy?

Thanks!

Chris


Airplanes can experience fatigue overtime, but its from vibration and
flex. You really shouldn't barrel roll a jumbo jet. LOL.

The Duralumins (Al-Cu alloys) have low very predictable fatigue crack
growth rates - reason they are still used for the bidirectionally
stressed underwing panels of aircraft wings (?).

Am Sonntag, 23. Februar 2020 20:37:44 UTC+1 schrieb Richard Smith:

The Duralumins (Al-Cu alloys) have low very predictable fatigue crack
growth rates - reason they are still used for the bidirectionally
stressed underwing panels of aircraft wings (?).

Thanks for the thoughts. I'm at a loss to remember what the alloy was. It's possible (now I think about it) that it was for an engine part with a normal operating temperature which was a long way above room temperature.

Chris

On 2/23/2020 1:37 PM, Richard Smith wrote:
Bob La Londe writes:

On 2/23/2020 7:45 AM, Christopher Tidy wrote:
Hi folks,

A quick question for the guys in aerospace and materials science. A long time ago, I remember hearing about an aircraft alloy (I think it was aluminium based) which followed a hardness curve over about 40 years during normal use (i.e., at normal aircraft operating temperatures). This meant that it was strongest after about 20 years, and then became weaker with age. Can anyone tell me the name of this alloy?

Thanks!

Chris


Airplanes can experience fatigue overtime, but its from vibration and
flex. You really shouldn't barrel roll a jumbo jet. LOL.

The Duralumins (Al-Cu alloys) have low very predictable fatigue crack
growth rates - reason they are still used for the bidirectionally
stressed underwing panels of aircraft wings (?).


There's transparent aluminum. The alloy is strong enough to be used for
water tanks for whales but extremely light weight. I'm not sure of the
long term fatigue rate. It's pretty hard to get as each time I've tried
it's on back order with no delivery date. It's probably because the
alloy contains a fair amount of Unobtainium.

Steve

On Monday, February 24, 2020 at 1:10:02 PM UTC-5, googlemyass wrote:
On 2/23/2020 1:37 PM, Richard Smith wrote:
Bob La Londe writes:

On 2/23/2020 7:45 AM, Christopher Tidy wrote:
Hi folks,

A quick question for the guys in aerospace and materials science. A long time ago, I remember hearing about an aircraft alloy (I think it was aluminium based) which followed a hardness curve over about 40 years during normal use (i.e., at normal aircraft operating temperatures). This meant that it was strongest after about 20 years, and then became weaker with age. Can anyone tell me the name of this alloy?

Thanks!

Chris


Airplanes can experience fatigue overtime, but its from vibration and
flex. You really shouldn't barrel roll a jumbo jet. LOL.

The Duralumins (Al-Cu alloys) have low very predictable fatigue crack
growth rates - reason they are still used for the bidirectionally
stressed underwing panels of aircraft wings (?).


There's transparent aluminum. The alloy is strong enough to be used for
water tanks for whales but extremely light weight. I'm not sure of the
long term fatigue rate. It's pretty hard to get as each time I've tried
it's on back order with no delivery date. It's probably because the
alloy contains a fair amount of Unobtainium.

Steve


It is only available to Starfleet Rear Admiral, or higher.

On Sun, 23 Feb 2020 12:12:54 -0700, Bob La Londe
wrote:

You really shouldn't barrel roll a jumbo jet. LOL.

I absolutely agree that you shouldn't. But, technically speaking,
there is nothing wrong with that. The barrel roll is a 1 G maneuver,
so in principle, every airplane can do it.

Tex Johnston became famous for barrel rolling the 707, which at the
time was a very large aircraft.

https://www.youtube.com/watch?v=AaA7kPfC5Hk
--
RoRo

On Sun, 23 Feb 2020 12:12:54 -0700, Bob La Londe
wrote:

On 2/23/2020 7:45 AM, Christopher Tidy wrote:
Hi folks,

A quick question for the guys in aerospace and materials science. A long time ago, I remember hearing about an aircraft alloy (I think it was aluminium based) which followed a hardness curve over about 40 years during normal use (i.e., at normal aircraft operating temperatures). This meant that it was strongest after about 20 years, and then became weaker with age. Can anyone tell me the name of this alloy?

Thanks!

Chris


Airplanes can experience fatigue overtime, but its from vibration and
flex. You really shouldn't barrel roll a jumbo jet. LOL.

Oh, NOW you tell me...

--
There is nothing more frightening than ignorance in action.

--Johann Wolfgang von Goethe

On Mon, 24 Feb 2020 12:09:57 -0600, shiggins
wrote:

On 2/23/2020 1:37 PM, Richard Smith wrote:
Bob La Londe writes:

On 2/23/2020 7:45 AM, Christopher Tidy wrote:
Hi folks,

A quick question for the guys in aerospace and materials science. A long time ago, I remember hearing about an aircraft alloy (I think it was aluminium based) which followed a hardness curve over about 40 years during normal use (i.e., at normal aircraft operating temperatures). This meant that it was strongest after about 20 years, and then became weaker with age. Can anyone tell me the name of this alloy?

Thanks!

Chris


Airplanes can experience fatigue overtime, but its from vibration and
flex. You really shouldn't barrel roll a jumbo jet. LOL.

The Duralumins (Al-Cu alloys) have low very predictable fatigue crack
growth rates - reason they are still used for the bidirectionally
stressed underwing panels of aircraft wings (?).


There's transparent aluminum. The alloy is strong enough to be used for
water tanks for whales but extremely light weight. I'm not sure of the
long term fatigue rate. It's pretty hard to get as each time I've tried
it's on back order with no delivery date. It's probably because the
alloy contains a fair amount of Unobtainium.

Scotty and the mouse. CLASSIC ST.

--
There is nothing more frightening than ignorance in action.

--Johann Wolfgang von Goethe