Yep you are right ... there are many cases where you don't want to use
2024-T3 just because it is the most common aircraft grade of alloy.

All alloys have the same modulus and hence commercial crap will perform just
as well as 2024-T3 or 7075-T6 etc in many applications where buckling is of
primary concern (NOT ALL THOUGH). Also there are many areas where stress is
not an issue but other issues such as formability, minimum bend radius,
availability, weldability and corrosion resistance are more important. I use
a lot of 6061-T6 to QQ-A-250/11 for these reasons in various applications.

However unless you know what you are doing just use what the designer
specified and don't try to cut corners to save a few bucks.



"Philippe" wrote in message
...
Orval Fairbairn wrote:



6063 is commercial cheese ... would be the lower strength of the three
alloys mentioned. Don't have data handly but you can find it on the
web.

Nothing stopping you using it in an airplane if you select an
appropriate
size to account for its lower strength. I have used it in some
modifications to a restricted category aircraft. Just be aware that you
cannot by 6063 to an accepted aeronautical spec such as QQ_A Fed Spec
etc
so you might want to allow an extra margin of safety to account for the
commercial nature of the material.


Bottom line: DON'T do it! Real, aircraft grade aluminum is not all that
expensive -- just check the Airparts catalog or their ad in Sport
Aviation. 2024-T3 is the standard aircraft structural aluminum, and
substituting a lesser grade only adds weight and can reduce safety in
structural applications.

Are you sure that all aircraft parts are designed for ultimate stress
ability. Sometime, it's for stability in compression and the best ultimate
resistance is not needed.
For example, a 0.5mm skin on a MCR01 is oversized.
Another example: Zenith aircraft don't use 2024.


By
--
Philippe Vessaire ҿӬ