I was following an old thread ".032 vs. .040" in "Ribs, Skins & Rivets"
And Colin H said;
Quote:
The body of an Airstream IS structural, as the they are considered "semi monocoque". In a monocoque structure, like modern unibody cars, the floor, body, roof etc is all part of the structure, hence the name monocoque or "one shell". In a semi monocoque structure, there are several structural elements of differing materials that all contribute to the overall structural integrity. Alclad 2024 T3 was used by Airstream from 1936 through to around 1981, after that they moved to a softer & weaker alloy of 3003 & 3004. The shift from .032" alclad to .040" 3003 happend at the same time. Alclad is about double the ultimate shear strength & yield strength than the newer alloy, which I suspect is part of the reason why they added thickness with the change. Alclad 2024 also has great corrosion resistance, which is why it is used in the Aircraft Industry.
The frames on Airstream's are not strong enough to support the body etc on their own, in fact, they are not even strong enough to support themselves. Lift the body off one & shake one end of the chassis, it'll wobble all over, however add the floor & body & you'll have a very strong structure.
We use .032" alclad 2024 for all of the panel replacements on the pre 81 trailers & lesser alloys on the bellypan, as it is not a major structural element.
Thanks,
Colin
|
Is that true about the structural grade Alclad 2024 T3 used in older models being replaced with 3003 & 3004 grade which is like you said half the yield strength?
If so could you make ribbing from it? If you keep the exterior sheeting the same.
If so, what would be a minimal thickness required (for ribbing)?
Or because of it's semi-monocoque design if you starting changing the ribbing material & thickness the external sheeting, including the selection of rivets also has to be reviewed, correct? Which I understand without proper R&D would be difficult to estimate.
Is there any spec's provided by Airstream which could confirm that?
Aerowood, in the same thread said;
Quote:
Berry, Your Airstream could very well be 24ST. 24ST was the alloy number back in the "Old Days" The new alloy designations that we currently use today was changed in the mid 50's to 2024-T3. I have attached a couple of minimum bend radius charts and one hardness and temper chart for your use. As a side note you could use .040 2024-T3 for your front panels if you wish as it works very closely to the .032. I have bent 2024-T3 all the way up to .125, you just have to use the correct radius bar on your brake. If you look at my thread below you will see that I fabricated all of my stringers and replacement "C" channel from .063 2024-T3, and I used a .250 radius for this.
.040 is readily available from many of the aluminum suppliers and can be rolled for ease of shipment.
|
Saying that the channel or ribs are made from the same material as the external sheeting - just a-little thicker?
Linear Mode
