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prkaye

Well Known Member
Are wing ribs alclad? They have a duller finish than the rear spar and the skins, which is why I'm in doubt. If not Alclad, must they absolutely be primed? My strategy (not intending to open this debate here) has been to prime mating surfaces only.
 
Why do the ribs have a duller finish than other aluminum components (skins, spars)? What is different about the material?
 
I'm not dead sure, but it seems like I read somewhere that they aren't heat treated until after they're formed. If that's true, it would stand to reason that it could change the appearance a bit. I'm not sure what (if anything) that does to the alclad's ability to resist corrosion.

Cheers,
Rusty
 
Rusty is correct. The dull color is caused by heat treating after forming. They ARE alclad.
 
Here's a dumb question from someone who never scratch-built an airplane before....

Why are the ribs heat treated? To harden them, soften them or what?
 
Jamie said:
Here's a dumb question from someone who never scratch-built an airplane before....

Why are the ribs heat treated? To harden them, soften them or what?
Click to expand...

No such thing as a "dumb" question (except for the one that's not asked)!
The ribs are made from "0" material, which is very soft and easily formed. After forming they are heat treated to harden them to a T3 or T4 temper for strength. The heat treating dulls the alclad, but doesn't affect it's corrosion resistance.
 
I'm a bit confused. Just reviewed "The RV Story" and Ken Scott says and I quote: ".....ribs are heat treated and press formed." That statement would suggest to me the material is heat treated before forming. So which is it....before or after?
 
The ribs (and several other parts, bulkheads, etc) would be formed before being heat treated, otherwise the metal would crack during forming.
 
rodrv6 said:
The ribs (and several other parts, bulkheads, etc) would be formed before being heat treated, otherwise the metal would crack during forming.
Click to expand...

Actually they are heat treated before forming. They do not turn hard immediately... they can be put in a freezer and kept soft for a couple of days.

Remove part from the freezer, press to shape on the form block and allow to return to room temp. Very shortly after that they are fully hardened to T3 condition.
 
You're right! I forgot about that little trick with the freezer. It's been a long time since I actually heat treated something........
 
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