Betcha y’all didn’t know 208

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July 27, 1949, the world’s first jet-propelled airliner, the British De Havilland Comet, makes its maiden test-flight in England. The jet engine would ultimately revolutionize the airline industry, shrinking air travel time in half by enabling planes to climb faster and fly higher.

[8ntruck 9,059]

The Comet was a lesson in the failure analysis class I took in college.  Several of them fell out of the sky.  Turns out that fatigue cracks in the fuselage were the cause.  Seems the stress concentrations caused by the small radii in the corners of the passenger windows provided places for the cracks to start, while cabin pressurization and flight stresses caused them to grow.

 

This lesson is why passenger windows in airliners are that odd shape that is a combination of a square and a circle today.

[Sparky-(Admin) 25,945]

2 hours ago, 8ntruck said:

The Comet was a lesson in the failure analysis class I took in college.  Several of them fell out of the sky.  Turns out that fatigue cracks in the fuselage were the cause.  Seems the stress concentrations caused by the small radii in the corners of the passenger windows provided places for the cracks to start, while cabin pressurization and flight stresses caused them to grow.

 

This lesson is why passenger windows in airliners are that odd shape that is a combination of a square and a circle today.

  Didnt know that…I’ll be looking at the window  on my next flight a bit more closely! 

[SylvanLakeWH 31,755]

2 hours ago, 8ntruck said:

odd shape that is a combination of a square and a circle

Ahh... that's why 's are designed that way... to address the incredible forces brought to bear on the frame due to speed and g-forces... 

[ri702bill 12,498]

Yup - you get a WH airborne, the re-entry & landing can be sketchy at best!!

[Beap52 2,389]

I always check for cracks when flying.  Now I'll start checking radii of windows as well!

[rmaynard 17,433]

And this is why you drill a hole at the end of a crack in metal to keep the crack from growing. 

[SylvanLakeWH 31,755]

2 hours ago, rmaynard said:

And this is why you drill a hole at the end of a crack in metal to keep the crack from growing. 

I wonder why the airlines don't just do this?

 

Works great on a ... 

[Beap52 2,389]

12 minutes ago, SylvanLakeWH said:

I wonder why the airlines don't just do this?

 

Works great on a ... 

Maybe I'll start flying with my cordless drill and a 1/8" drill bit

[8ntruck 9,059]

20 hours ago, rmaynard said:

And this is why you drill a hole at the end of a crack in metal to keep the crack from growing. 

 

18 hours ago, SylvanLakeWH said:

I wonder why the airlines don't just do this?

 

Works great on a ... 

 

 

Airlines have done this.  I was on a Convair 580 turbo prop twin for a short flight, probably in the 1990's.  Had a wing seat, and was idly looking out the windows when I saw 2 'rivets' on the wing that were not lined up with any of the other rivets.  On a closer look, I noticed a crack running between them, probably about 2" long.

 

This will bring up the subjects of critical crack length and minimum detectable crack lengths in fatigue theory.

[SylvanLakeWH 31,755]

1 minute ago, 8ntruck said:

I noticed a crack running between them, probably about 2" long.

 

No duct tape?

[8ntruck 9,059]

10 minutes ago, SylvanLakeWH said:

 

No duct tape?

Nope, they had drilled the stopper holes.

 

That was on Northwest Airlines.  I bet you've had a flight or two on that airline. 

Edited 1 hour ago by 8ntruck