Re: Gluing aluminum



David Billington wrote:



Ed Huntress wrote:

"David Billington" <djb@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:46FFAC22.4010402@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


Ed Huntress wrote:

"Jman" <mooglieman@xxxxxxxxxxx> wrote in message news:1191158765.159816.160540@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I think I'd rather take the train or bus thanks.......


http://seattletimes.nwsource.com/html/businesstechnology/2003612251_boeing111.html


http://findarticles.com/p/articles/mi_qa3618/is_199709/ai_n8765992/pg_4



I wrote articles almost identical to those 25 years ago. IIRC, the L-1011 had a carbon-fiber tailfin, as well. And the other story is the same old, same old for the high-performance composites business. Very little appears to have changed.

A lot of people don't realize how much epoxy is used throughout the structure of an airliner. They probably don't want to know. d8-)

However, they also don't know how much fatigue becomes a problem in all-aluminum aircraft that were designed over the last few decades. DC3's are still flying because the engineers didn't know what a reasonable safety margin was. Now they know, and the life of those planes is finite.

--
Ed Huntress

I was told by late father, who was in the aerospace industry in the UK and later US as a stress analyst, maybe 25 years ago that one of the reasons the DC3 kept flying because you could still get fuselages and wings. When the life of the wings was up you bought new ones and the same with the fuselage. I expect like many planes the airframe life is also re-evaluated after actual service conditions have been experienced and extended or otherwise revised.


Parts for the DC3/ C47 were easy to come by and most of the parts were stock items. Since the military had over 10,000 C-47s there were plenty of spare parts available. The DC3 itself was a very simple aircraft, not like todays flying electronic boxes. There were many variations depending on how the airline ordered the plane. The Pan Am ones had the biggest fuel tanks. You would almost never find any major structural cracks in the wings like you do with later jet aircraft. If you ever check an AD (sirworthness directive) list for a 747 you would probably not fly in one. There is a number of them that list cracks in the main spars of the wing and not to let them get bigger than a certain number of inches.








I think that's true, but I flew in DC3's in Canada's Northwest Territories that still had fabric-covered control surfaces. Those were *old* DC3's, and it was only 20 years ago that I flew in them.

If fabric covered what was the structure of the control surfaces made of?. I don't know much about wood structures so don't know if they suffer from fatigue.


The frame of the control surface was all metal.





They just stood up a lot longer. They also had severely reduced load capacities because of the overbuilding.

In the science museum in London there is a section of a 747 fuselage. It's quite surprising how thin the outer shell is, looks to be about 2.5mm from memory. Not that I have a problem with that as with a background in engineering I know some damn good people design these things and the 747 is a strong aircraft judging from the bits that has fallen off them and they still kept flying.\


The 747 was a well designed aircraft. It had triple redundant systems on all critical systems. The one engineer that I knew that was heavily involved in the design of that plane told me that they estimated a mechanical failure rate leading to a crash worked out to 1.3 aircraft in 20 years. The plane has a rate better than that, The crash of the one in Japan was due to improper maintenace. The others were from pilot errors or bombs and rockets.

There are still plenty of DC-3 flying, a lot of them are used in the Bahamas, West Indies and south florida. There was one that had been going over our place late in the evening, sounded like it had R1820 Wright engines on it, 9 cylinders with 200 cubic inch each you can tell the difference.


John



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