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Old 01-06-2020, 12:18 PM
sblack sblack is offline
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Join Date: Sep 2011
Location: Montreal
Posts: 382
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Quote:
Originally Posted by crystallographic View Post
Hi Scott,
The problem with that tank is not the design. That design is proven by the tens of thousands of airplanes carrying fuel inside it, for decades, in rough environments. Had there been an issue with that design it would have been subject to an Airworthiness Directive, and the entire industry would have changed that design.
The problem is in the execution of that design, by the craftsman building that tank.
Example from real world aviation:

I have two wing tanks here that were made by a "pro fab/welder" shop.
.040 5052 with flanged ends that were fusion welded with a tig/TIG.
Made to "copy" an original 1940's existing pair of tanks.

The cracks in these end seams are not longer than 14 inches, and the fuel also splashed all over a hot engine and pilot, as he got down as fast as possible, and got it all shut off in time to exit safely and the plane was saved.
Problem: no baffles to support the long distances between end plates, so under positive and negative G's the seams failed, opposite each other and at the same end panel.

Attachment 54670
Attachment 54671
It does help to have some familiarity with the various aviation tank designs so as to make clear and accurate conclusions.
Thanks Kent. I was sure based on your writings that the flange weld design was not the issue. Given that there are many bushby mustangs flying without any problem and that the tank was supplied by the designer so presumably built to plan, i suspect poor metal prep. But I never saw the tank myself so I guess we will never know.
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Scott in Montreal
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