Posted on 11/17/2010 5:00:55 PM PST by ErnstStavroBlofeld
The aft bulkhead of the F-35B BH-1 fatigue-test specimen has developed cracks after 1,500 hours of durability testing, Ares has learned. This is less than one-tenth of the planned fatigue test program, which is designed to prove an 8,000-hour airframe life with a safety factor of two.
The bulkhead design was modified in the course of the jet's weight-saving redesign in 2004-05, switching from forged titanium - proven on the F-22 - to a new aluminum forging process developed by Alcoa.
According to Lockheed Martin,"the cracks were discovered during a special inspection when a test engineer discovered an anomaly." The company says that flight-test aircraft have been inspected and found crack-free and that flight testing has not been affected.
(Excerpt) Read more at aviationweek.com ...
Make it out of forged steel.
“In theory, there is no difference between theory and practice. But, in practice, there is.”
Problem is that it has to fly, carry payload and fuel.
Steel is fine for a gateguard.
F-100s had some big chunks of steel.
It’s also a requirement to be able to make it home.
“The bulkhead design was modified in the course of the jet’s weight-saving redesign in 2004-05, switching from forged titanium - proven on the F-22 - to a new aluminum forging process developed by Alcoa.”
F-100s were also fifty-nine years ago.
If this is the bulkhead between the pilot and the VTO&L engine they have a problem. My understanding was that titanium was used to protect the pilot if that engine blew up. It may be that they use aluminum on the other two (non VTO&L) models and left that bulkhead titanium on the vertical model. That would not necessarily be a problem except for the cracks. Guess they didn’t design it well enough.
Alcoa had a program on this forging process in a TV show it looked like 30+year old technology.
Hire some midget pilots.
Hate to see it break. But - That’s why you test.
Now - if they made it to a safety factor of 1.25 or 1.55 or 2.55 instead of 1.025 .... It might not break (at least not at that same place!) but it would be able to carry less fuel, less aero electronics, less payload, less armor, smaller engines ... and we’d be back flying the Wright bro’s original airplane.
Did they take off our land vertically?
Only by accident - not the midgets, the planes.
True, true. I’m just glad these craft will never be under any structural stress during operation. ;’)
They are using Aluminum? Is that wise?
Isn’t aluminum a fire hazard?
Shredded (tinfoil thick) Al is a fire hazard - as is the Titanium, Magnesium, and the jet fuel and the explosive hardware carried underneath. But, as a piece of thick plate, none of the metals can burn unless its hit and heated up way past its melting temperature. And, if hit by a high temperature or flame or explosions lasting more than a few micro-seconds, the plane is coming apart anyway.
You have to accept some hazards to fly in combat. And, flying a bad plane made too heavy is a guaranteed loss.
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