National Security & Defense

unhappycamper

(60,364 posts) Thu Sep 4, 2014, 11:33 AM Sep 2014

F-35 Head Bogdan Explains The F135 ‘Bad Rub’ Fix

http://breakingdefense.com/2014/09/cost-for-f135-bad-rub-fix-should-be-low-mg-bogdan/

F-35 Head Bogdan Explains The F135 ‘Bad Rub’ Fix
By Colin Clark on September 03, 2014 at 7:43 PM

NATIONAL PRESS CLUB: It hasn’t been tested yet, and the “root cause” for the problem has not yet been identified, but Lt. Gen. Chris Bogdan, head of the F-35 program, expects upcoming tests to demonstrate a fix for the engine problem discovered when an Air Force F-35A engine exploded early this summer.

The fix will be made to the fan module, which will be replaced in all the 156 engines should the tests prove out, Bogdan said at the annual ComDef conference. Pratt & Whitney, maker of the F135 engine. is setting up a test in southern Florida at its treat facility next to the Everglades “to see what a good rub is and what a bad rub is,” he said to snickers from the juvenile press corps. Basically, the blades on the fan rub a spot on the engine cowl. The blades are expected to rub on the cowling and dig that trench. The problem is that the blades are getting hotter than expected.

Bogdan said that the plane that blew up was damaged during two seconds of flight when the test pilot — operating well within the safety envelope of the plane’s abilities — put G forces, yaw and roll stresses on the plane all at the same time. The titanium blades heated to 1,900 degrees, as opposed to the normal 1,000 degrees, and began to crack. The fissures grew over time until, on June 23, when the pilot was taking the plane down the runway for takeoff, the fan blade “cracked,” Bogdan said. The circular part of the engine stretched out and shot through the left fuel tank. Fire resulted. The plane, Bogdan said, is not a write-off but an opportunity for combat repairs…

Exactly why this happened isn’t exactly clear yet. The root cause, as engineering types call it, appears close. Initially, the program was searching through 138 possible reasons. “We are really close,” Bogdan told the ComDef audience, having whittled the number down to four.

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Two seconds of G force (within the safety envelope of the plane’s abilities) should not have caused this accident.

We have already spent almost $300 billion on about a hundred of these things. Is it time to pull the plug?

2 replies

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F-35 Head Bogdan Explains The F135 ‘Bad Rub’ Fix (Original Post) unhappycamper Sep 2014 OP

It's a very common irrational argument: DetlefK Sep 2014 #1

The F-35 story reminds me of the F-111 lemon. gordianot Sep 2014 #2

DetlefK

(16,423 posts)

1. It's a very common irrational argument:

Reply to unhappycamper (Original post)

Thu Sep 4, 2014, 11:50 AM

Sep 2014

"We can't give up now. If we do, everything up to this point will have been in vain."

Another way to look at it would be not to look at how much has been spent already, but how much will I have spent in total.

The F-35 program has so far cost $300 billion?
That does not mean that it equals a value of $300 billion.
As long as the F-35 doesn't work, $300 billion of investment has delivered precisely $0 of returns.

Let's say, a working product will be achieved. Exactly THAT is the moment when the F-35 suddenly becomes worth all the money that has been invested, no second earlier. Any other way to look at this problem is irrational and driven by prestige and politics.

gordianot

(15,238 posts)

2. The F-35 story reminds me of the F-111 lemon.

Reply to unhappycamper (Original post)

Thu Sep 4, 2014, 12:10 PM

Sep 2014

The F-111 was relegated to being a bomber it too was promised to be everything to both the Air Force and Navy. At least the f-111 had a dandy escape system.

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