Thursday, June 21, 2012

Does the F-35C have a tailhook problem?

The answer, obviously, is yes.  All one has to do is dial in any critical piece about the aircraft and you’re sure to hear it mentioned along with the usual conjecture that fixing it could involve “costly redesign”.

But it doesn’t appear that the fix will involve a “costly redesign” or that it is really that significant of a problem.

What one has to understand is that there has never been a reason to hide the tailhook in any other Navy carrier aircraft.  But with a stealth aircraft – a first for the Navy – such a requirement came into existence.  That caused some problems with design that have had to be addressed.  And it appears they have.

Lockheed Martin VP Steve O’Bryan recently detailed the problem and the fix.

First, the problem:

“The distance between the main landing gear and the tailhook on the F-35C is the shortest of any naval aviation carrier airplane that we’ve had. Because we have to hide the hook — because if you had a hook exposed you wouldn’t be as stealthy airplane, that distance is tighter than any other. So it means when you roll over the wire when you land on the deck, the wire goes flush to the deck, and then you have to pick that wire up as it’s generally on the deck. So what we’ve had to do is re-design the hook shank.


Every airplane’s hook shank — as you’d imagine, you ground those things down, dragging it around, so it’s a remove-and-replace kind of thing. It has a bolt through the back of it and it holds on to the hook and we’ve redesigned that to have a lower center of gravity, or in a more mundane way, to make it a sharper hook point. And that allows us to pick up the wire.

And, as he mentions (and we reported here), testing has gone well to this point on the new design.

CF-3 performed a total of 18 successful roll-in arrestments [MK-7 (6 with risers and 4 with no risers) and E-28 (8 arrestments)] at Lakehurst from 80 to 100 knots ground speed.

There’s actually more to the solution than just redesigning the hook.  That’s a requirement to put more pressure on the hook so it will stay down on the deck and not bounce or skip. 

The other thing we need to do is, we need to make sure that the hook stays flush on the deck. So what you don’t want — and I was a Navy pilot, so I apologize if I’m using a lot of vernacular here – you want to keep that hook on the deck so it doesn’t bounce, or the words we used was skip. It can do that a couple different ways. It can move laterally and it can hit other stuff and just bounce, if you will. Another technical term. So what we’ve done is we’re going to modify what’s called the hold-down damper, kind of a good name for a thing because it does exactly that, it holds the hooks down, it dampens any oscillation. We’ll increase pressure on hook to do that.

The whole thing is a remove-and-replace assembly so any modifications we make to it is an easy fix.”

In essence, modify the damper that holds the redesigned hook down to put more pressure on the hook than is now being exerted.  As O’Bryan says, an “easy fix”.

More discussion on the O’Bryan interview in the following days, but now when you see the usual “the plane can’t even land on an aircraft carrier” nonsense the critics like to throw out there, you’ll have a comeback.


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