Quote:
Originally Posted by 68TT396
I have been wanting these for a very long time. Aluminum body panels when done right will work even better than steel. If this were not so then all our fighter aircraft would be made with steel skins.
Let me start by saying I have 13 years of experience working on US Air Force fighter aircraft in the repair & fabrication area.
Every fighter aircraft skin is made from aluminum, titanium or some form of composite. We make most of the skins from 2024 or 7075 grade aluminum. They are all installed with flush mount removable fasteners or with panel adhesive & flush mount rivets. The exotic materials are typically only used for radar tracking reasons and in high heat areas that would melt aluminum.
For the building of complex shapes like our fenders the material needs to be weldable so the higher strength 2024 & 7075 can not be used. We need to switch to 5052 or 6061 in an un-heat treated condition so they don't crack during forming. After they are formed the product needs to be annealed to remove the stresses put into the panel during forming then it needs to be heat treated.
An after fabrication heat treated 6061-T6 formed panel will be extremely tough to dent but if you do manage to dent it then it is as simple as lightly heating the area with a rosebud torch until the area returns to its as-heat treated shape. As long as the area is not too badly damaged (like a sharp crease) the light heating will bring the panel back into shape.
If these new aluminum fenders were dented from people knocking on the top surface then they were made from un-heat treated material and never annealed and heat treated as they need to be.
Another thing that needs to be done is to increase the panel thickness a little. From the photos it looks pretty close to the same thickness material that the stock steel panels are made from. This just won't work. The material needs to be about 50% thicker than steel to have the same dent resistance after it is heat treated. If it is un-heat treated and the same thickness as the steel counterpart it will dent if somebody even looks at it funny. This is probably what the Cobra's & early 60's light weight cars used, un-heat treated low strength aluminum that formed easily. It would explain why they all dent so easily and couldn't handle people leaning on them. We walk all over our fighter aircraft with no fear of denting the panels.
Aluminum body panels can be made to be very durable and light weight at a fraction of the cost of carbon fiber. They will be more expensive than steel but should not be $4000 for a front clip. I can see a 50% upcharge for the material change and heat treatment so a front clip should be in the $2000 range.
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To All:
This Post is Spot on. I worked in the Aerospace Industry a number of Years, and Aluminum Panels when properly Engineered, Formed, and Annealed and or Heat Treated are very stable, light and strong.
The Heat Treating and the annealing is the key to working with Aluminum. Plus Aluminum has a lower melting point making it easier to Anneal, Heat Treat, Acid Dip, Work harden etc.
It's all in the Technique used as to what your out come will be. I built numerous panel for the F-16 (Fort Worth, Texas) And Aluminum also stands up to many types of forming Techniques. You can hammer, draw, stretch draw, hydra-form and Hand work, etc. etc. Aluminum. The Key is getting it soft enough to be worked,(Annealed), then Harden it to make it strong.(Heat Treating) You also need a place to properly quench it.
If you have large panels, many times it is how the panel is engineered as to whether is has the strength necessary for a specific task.
Like anything else, understanding the material, and engineering around the weaknesses that you have to live with, will be your key to success with it.
Aluminum is a really cool metal to work with whether pressing or machining, and it comes in a variety of different types. You can also make tools and Die sets for it out with cast-able epoxy, so having a Foundry, die grinders and the expense and safety issues associated with it are not necessary. A DROP HAMMER die for 125/1000's Aluminum, forming a part with concave, convex and tight radiuses, can be formed off a checked piece in about 10-14 days, and that includes any stepped heat curing of the epoxy.
If you have never seen a Pneumatic Drop Hammer Machine Operate, it is really amazing how tough properly prepared epoxies can be, and they work like a charm with Aluminum, so it allows smaller shops the ability to construct parts that would normally not be able to due to lack of proper equipment. (This is the case in many Prototype Shops Around the Country)
Anyway, long story short Aluminum is a terrific material to construct high performance pieces out of.
Thanks for your patience's during this semi dissertation.
Regards,
Ty