Comment by ortusdux | Hacker News Reader

Comment by ortusdux | Hacker News Reader

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I thoroughly enjoyed the YouTube channel Real Engineering's two part series on all the innovations that were packed into the 787.

Part 1 is mostly about the body of the plane - https://youtu.be/lapFQl6RezA

& part 2 is mostly about the powertrain - https://youtu.be/Sf6H8kSunRA

They discuss the dramatic increase in the need for titanium parts around 18 minutes into the first video. https://youtu.be/lapFQl6RezA?t=1090

When aluminum and carbon are in direct contact, galvanic corrosion is an issue. The only way they could make a plane with carbon fiber wings, fuselage, and empennage, was to replace most metallic elements with titanium. The final 787 is 15% titanium by weight.

Titanium is tough to work with, and I can see how problems would arise when you redesign what must be thousands of parts.

Specialized used to make a bike out of coated carbon tubes glued into Aluminum lugs using the same manufacturing process that the aerospace industry used. The Allez.

Beautiful bike, I had one, but it suffered from two problems: it was overly flexible and if you got a nick in the coating on the fiber or water got into the lugs, you'd get the GC issue.

Of course, their marketing claimed they 'solved' the issue...

https://www.bikeforums.net/classic-vintage/422428-specialize...

Cadex made a similar bike, I rode it for years and never had any issues and I'm also not aware of any issues with that model. I wonder what the differences in processes and/or materials were.

Was there also a problem with the glue failing?

> The only way they could make a plane with carbon fiber wings, fuselage, and empennage, was to replace most metallic elements with titanium.

That's not really true: galvanic corrosion can be stopped if you simply anodize the aluminum parts. There is no titanium required to do this. This is a common practice when working with carbon fiber.

Maybe they wanted the lower CTE and higher fatigue resistance of the titanium, and one fewer process step to qualify and control (the anodization).

Came here to say this. Very informative, if somewhat laudatory, videos.

As comparison, the series "21st Century - Jet Building the Boeing 777 " is online.

https://www.youtube.com/watch?v=0oyWZjdXxlw

They have pretty intense meetings with the subcontractors.

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