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Comment by jaytaylor | Hacker News Reader

TFA includes this image of an F-35 underbelly:

https://s3-us-west-2.amazonaws.com/the-drive-cms-content-sta...

The exotic curves are visually exquisite, and I'm curious what the production and fabrication technique and processes are.

Particularly for the jet engine housing. Is it comprised of a few large sheets, or many smaller pieces? Not sure how to get the curvature and bends consistently correct within tolerance limits for large sheets. It seems like it would be extremely challenging.

It looks like it might be titanium?

If you know about this or have ideas, please do tell!

P.S.

What a cool read! This is the type of article I come to hacker news hoping to find :)

View on HN

>It looks like it might be titanium?

it's a coated composite similar to carbon, but with specified radio properties. It looks like carbon fiber with a large weave before coating.

I dropped a panel almost exactly like the one in question that was scrap from mis-machining, and it nearly deafened me, it rings like a toilet lid; like a ceramic.

source : I had a small involvement with recent US planes.

There was a recent post about someone who damaged his hearing from dropping a toilet lid that didn't shatter.

Look at those High-Tech Hexagons[1]! The F-35 designers knew their tropes.

[1] https://tvtropes.org/pmwiki/pmwiki.php/Main/HighTechHexagons

The starship heatshield too. Even cooler than the space shuttle RCC bricks.

https://twitter.com/elonmusk/status/1107378575924035584

Hexagons are the most efficient way to tile a 2D surface.

Fun trivia I learned while ago.

So before computer assisted drafting/manufacturing showed up, it was quite common to see Rubber Mallet in use on the production floor of the expensive planes. Workers literally had to beat certain parts of the plane into place using Rubber Mallets.

A rubber mallet in general is a time tested tool of any worthwhile mechanic.

Haha very true. However using rubber mallet on stealthy aircraft would be strictly prohibited as just a small imperfection on skin of aircraft would make it show up prominently in radar.

You can get nice curves in sheet metal by pounding it with a bag filled with metal spheres, like large ball bearings.

Sort of like hand-grinding a telescope mirror, or polishing stuff. The dents average out.

Not a good way to build anything with close tolerances, but a way to manually build a thing.

Good to know. The rubber mallet in aircraft production in analog era was more for pounding ill fitting part into submission and into place.

Any reason they couldn't just stamp, then CNC route the final profile for high tolerance?

I don't know if it works the same way for titanium but aluminium has been shaped like this for aircraft. https://boingboing.net/2012/02/13/machines.html

Who said it was made of titanium?

I had thought that fighter jets used more specific aluminum alloys than titanium, but I found this on the f-35 specifically (Bruce Tanner is Lockheed Martin's CFO):

"Tanner says Lockheed uses more aluminum than steel on its aircraft projects, which in addition to the F-35, include the C-130 cargo plane, and F-16 fighter. And the F-35 uses more titanium than aluminum and steel, he said. "

https://www.defenseone.com/business/2018/03/how-much-do-amer...

I swear I've seen someone put a very similar comment on another F35 article, time to scrub HN as a sanity check.

> The exotic curves are visually exquisite...

I would even say there is some sensual, if not sexual, feminine reminiscence.

I guess too bad the job of the machine is to kill humans.

at great expense.

Why is that bad? We're in an era of unprecedented stability, if anything walking strongly and having large sticks is working.

In a way, but the real job of the F-35 is transfer wealth from the federal treasury to the stockholders and executives of Lockheed Martin.

And it has been an incredible success!

The real job of the f-35 is to project power.

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