F-15 breakup

Mike · 02-02-08, 01:05 AM

As some of you are probably aware, the USAF F-15 fleet was grounded for structural problems that became evident when a Missouri Guard Eagle ( my old unit ) came apart in mid air a few months ago. A very interesting video animation has recently been released, depicting the event, with actual voice recordings overlaid. The voice is from Mick one, the flight lead who also is the squadron commander. Several versions of this video are available, just google "F-15 break-up".

Steve Kulper · 02-02-08, 02:24 AM

Maybe the fleet should be shipped off to the bone yard, I watched an interesting program screened here in OZ the other night about the bone yard (davis monthan air force base) it is an amazing place.

Steve

Simon · 02-02-08, 05:17 AM

Wow that was VERY scary! I presume the pilot was OK? If so he was DAMN lucky to get out of that.

Simon

Dave Bilyk · 02-02-08, 05:59 AM

Scary
is right Simon, he was so lucky to get away with the injuries he did.
I googled it and at first only came across the animation, but after a couple of tries, this F-15 Breakup Report, January 2008

was a well produced and comprehensive news report, even showing a view of the airframe and the failure location.
The repercussions of this seem to be severe with some aircraft being decommissioned as a result of 'fatigue cracking' in the failure area. Anyone know what the materials of the longerons are?

Hellem · 02-02-08, 09:05 AM

Dave,

I believe they are Aluminium. Carbon does not fatigue it shatters!

Dave Bilyk · 02-02-08, 11:52 AM

hellem Thanks for that.
Yes CF shatters under extreme - sudden or impact loading.
That doesnt mean that it doesn't fatigue under more moderate cyclic loading. The mechanism is different to steel or aluminium, but CF does have fatigue properties.
Have a look at this book preview entitled 'Fatigue in Composites', showing fatigue life cycle diagrams.

Fatigue in Composites: Science and ... - Google Book Search

Dave

Mike · 02-03-08, 03:01 PM

The pilot (Steve) was indeed lucky to get out (he managed to get his right hand down to the ejection handle by his right thigh). The sad news is that he is also an airline pilot, and it looks doubtful if he will ever regain full use of his left arm or ever fly again. The harness in the jet, like all fighters I can think of, keeps you tied down vertically, for positive (+ 9)and negative (-3) g. There's really nothing that specifically keeps you from moving laterally, since there's very little side to side g available. His injury was primarily due to being smashed into the side of the cockpit when the nose section came off and tumbled in the roughly 450+ kt airstream.
A little more than half the jets are back flying again.