Hearted Youtube comments on NINO (@Ninogus) channel.
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Have you EVER had a piece of aviation aluminium (NOT aluminum) alloy in your hands? Obviously, no - or you would not ask such a question. The alloys commonly used are SAE 2024, SAE 7075, and SAE 2016. ( Look up "Mil Handbook 5" - it's freely available). 2024 and 7072 are, respectively, aluminium/copper and aluminium-zinc alloys, and these have about the strength of a biscuit after welding. 6061 is somewhat less strong, but is weldable - though the heat-affected zone is dead soft; it is often used for fuel tanks. 7075 is one third the weight of mild steel, and twice as strong; I've seen a fencing rapier made from it; it could be bent into a full circle and would spring back with no deformation. The Japanese WW2 fighter "Zero" was made from 7075; the American and British fighters were mainly 2024 - known in WW2 as "24 ST" - which is slightly less strong than 7075, but has much better fatigue life, and better corrosion resistance. Aircraft rivets are also made of far stronger grades than saucepans. I'm an aero engineer; the choice of which alloy to use depends on many factors; in a short-life military combat aircraft, high strength/weight is predominant. in a civil transport aircraft, fatigue life is nowadays most predominant. The Fokker F-27 pioneered adhesive bonding, but still had "chicken rivets" at the start and finish of the joint, because the adhesives were weak in "peeling". Yes, rivets do reduce the fatigue life, but at least you know where to look for a crack. The statistical data for calculating the fatigue life of a riveted aluminium aircraft was gathered in 1947 by the Australian Aviation Research Laboratory, which tested 100 sets of surplus P-51 wings to destruction; nobody has as yet placed in the public domain a similar set of tests for an adhesive-bonded airframe.
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For all practical purposes you can NOT weld Aluminum. specially high quality alloy thin sheet as used in aircraft. Now in the special case of thicker metal, under very high pressure and needing perfect sealing , as in a rocket motor tube, yes, welding is mandatory.
I once saw an Exocet missile from very near, as in touching it, and was surprised at the "Frankenstein scars" it had on its surface. TIG MIG soldering, they didn´t even grind them down, just white Epoxy painted over them. But then realized grinding them down would weaken them, and solid fuel rockets work at HIGH pressures, so ....
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From the Peanut Gallery in Military Aviation (only 4 decades doing this stuff). Great tutorial and I thank you ... would be a great tool for teaching the newbies before they begin their vocation on the Assy Line ! Some things to consider if you were to update/revise the video in the future. Worked for the World's largest Aerospace Firm (which I cannot name here of course) all over the World. Said Company manufactures many types of "Platforms", many of which are a combination of materials as you describe ... AL, Steel, Titanium and Composites. Each with a purpose and different in approach. For example, in Composites we attempt to stay away from "Riveting" as each hole drilled/fastened "Cuts" the carbon fiber strand and compromises the compression/tension qualities for which the call out to use them exists; sometimes "adhesives" are the preferred joining method.
Then there's the method used for joining the various "skins" ... Commercial, as your video shows, are "Lap or Butt Jointed". But not discussed is "Dimpling" construction. For example, a C-130J Super Hercules has approximately 100,000 manually bucked "AD" solid rivets in each Center Fuselage. The skins are "ALCLAD" (to reduce the Galvanic Corrosion you mention); a layered sheet aluminum that has almost pure aluminum surfaces with "alloyed" centers. They cannot be "Welded" ~ not just due to the process (the ALCLAD would melt first) but also it would change the "temper" of the skin metal resulting in annealed "soft spots" ... this is BAD of course.
And here's the unique part of a Super Herc. Most all of the rivet holes (which have to be very precise in diameter less you get a "Hawaiian Airlines" skin peeling off in-flight and killing people) are first "drilled" in a Jig with "Clecos" holding them in-place ... THEN fully disassembled and each hole "Dimpled" with a second/final assembly later... think of it as a "Bowl" in which the Solid Rivet will eventually rest. Now one might think this is "old school" ... and actually it is as it's been done since the first C-130's test flight out of Burbank happened in AUG 1954. But the amazing part isn't just the strength of compression/tension values (spreads the contact area) ... it is the "Rotational" torque it absorbs. Lots of vibration and stress in ALL directions going on in an Aircraft's Life Cycle and this method of construction allows for much "Flexing" without metal fatigue and cracking. As to "proof in the Pudding", there have been a few "Hard Landings" (even crashes) where the incident resulted in the Wings and Tail popping off but the Fuselage remained intact. Very, very sturdy method and sadly, the only current Production Aircraft that still uses this "old technology" as it is labor intensive and therefore costly. I can always spot a "Commercial" construction from area photos ... they're the ones with lap/butt joints and little to no sealant in the rivet holes or mating surfaces. That's how you end up with hard to pressurize Cabins and certain "Italian and Brazilian" aircraft that after landing in a rain storm ends up on the back of the Pilot's necks as they tap their brakes and the rain water accumulation on the fuselage surface above rushes forward, hits the aft facing mismatch joints and down to the cockpit area. Oh that Physics stuff ~ so annoying eh?
But enough from my soap box ... as Abraham Lincoln once said: "I'M SORRY I COULD NOT HAVE WRITTEN A SHORTER LETTER, BUT I DIDN'T HAVE THE TIME".
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