4cylndrfury wrote: Id read that the SR71 spyplane would actually leak fluids when siting in the hangar because the seals were made to expand due to the heat of friction from the air slipping over the skin of the plane at mach speeds. No idea if its true or not,.
it's true. I had an uncle who worked at the same base it was stationed at when they first came online.
Once upon a time I was on a WW2 age Destroyer Escort in a North Atlantic storm off Nova Scotia. That poor little ship did everything but tie itself into a knot. Sometimes I get visual memories and wake up sweating. Not fun at all.
FWIW get hold of a book called "WAVES". It is about deep sea waves and crazy surfers. Fascinating.
A modern middle age large bulk ore carrier can sink in less than two minutes after a giant wave crushes the foward hatches and the engines drive her under. "No more boys, no more. I'll go to sea no more."
Titanic stuff:
http://www.writing.eng.vt.edu/uer/bassett.html
mndsm wrote: All the bridges in the Mall of America are designed with the same properties in mind- It's a little freaky to be walking along and feel the floor shaking under you .
I was stuck in traffic on the old I-35 bridge across the Mississippi a few days before it collapsed. That thing was moving around quite a bit. 
Oooog.... lucky you weren't there that day. That footage blew my mind.
914Driver wrote: Titanic stuff: http://www.writing.eng.vt.edu/uer/bassett.html
Interesting reading
My uncle was killed in a Air Force C-47 crash in Feb. 1954 after it broke apart at ten thousand feet during a winter storm. The aircraft w/ 16 souls aboard was enroute from Anchorage to Fairbanks when it first encountered turbulence southeast of Mt. McKinley, went into two stalls falling a few thousand feet each time before the pilot recovered and regained altitude.
The third stall would prove fatal as the right wing and a large portion of fuselage (commercial garage door size) were ripped from the airframe including the canvas troop seats w/ passengers still attached. Others were strewn into the cold air or spiraled into the ground w/ the plane. Miraculously, six men survived after being ejected and deploying their chutes, they were rescued two days later by local bush pilots and AF personnel. It's quite the survival story and I've been fortunate to meet the survivors during reunions.
In '98 I was w/ a group that went to the crash scene, quite a sight. Much of the aircraft remains were demolished per AF policy in '54 to prevent future crash sighting reports but there was still plenty to sift through.
That right wing had actually remained intact to the fuselage. I remember being told by aircraft restorers there were 144 1/4" aircraft bolts fastening the wing to the fuselage, 300 plus overall per side. The Gooneybird is one tough aircraft. Some speculation around carburetor icing contributing to the stalls plus arctic temps stressing the airframe... it was '54 however.
Great survival story though... six men ejected from a disintegrating aircraft... at ten thousand feet.. in February... during a winter storm.. in Alaska
mad_machine wrote:4cylndrfury wrote: Id read that the SR71 spyplane would actually leak fluids when siting in the hangar because the seals were made to expand due to the heat of friction from the air slipping over the skin of the plane at mach speeds. No idea if its true or not,.it's true. I had an uncle who worked at the same base it was stationed at when they first came online.
Mickey Thompson built the engines that were in the start carts used to spin up the engines in the SR-71
Apparently they used a pair of Buick 425 nailhead engines, the later units used 455s
Shawn
I'm always curious about the flexing of airliner wings. I recognize the preference to bend before breaking, but I also know aluminum has a short life being flexed when compared to steel or titanium (or some composites, I suspect, with a Corvette leaf in mind).
My understanding is that for most structural work with aluminum, you want it to not flex, as every cycle is taking a real bite out of the life before failure.
I guess my surprise at being able to watch them flex during normal operation is that I would think of "bend before break" as a target for behavior when exceeding the design parameters. Once. At which point it is preferable to stop the exercise with a bent part than to have it stopped by a broken one. Watching an aluminum structure flexing during normal operation was unexpected. OTOH, I guess I don't know for sure what an airliner spar is made out of...
ransom wrote: I'm always curious about the flexing of airliner wings. I recognize the preference to bend before breaking, but I also know aluminum has a short life being flexed when compared to steel or titanium (or some composites, I suspect, with a Corvette leaf in mind). My understanding is that for most structural work with aluminum, you want it to *not* flex, as every cycle is taking a real bite out of the life before failure.
thats why they make them out of chromoly benedum... steel is real in flying machines just like it is in bikes ;-)
Fun is blowing up your aircraft carrier to see what breaks.
Strizzo wrote: i've been in the way back seats on the 737s and little regional jets in rough weather. flexing/bending is fine, when it gets a little nerve-wracking is when you can see the fuse twist as the wings rock
That's how I felt on my first flight, and it didn't help when the kid sitting next to me kept asking his mom, "What's that noise?", "WHY IS THE WING SHAKING LIKE THAT!?!"
The 787 will deflect 26 feet, and the 747 will go 33 before it snaps. Something to behold when it goes!
I'm soooo glad I sit forward of the wing and can't see the flex.
http://www.youtube.com/watch?v=QLuaNG9w3m8
4cylndrfury wrote: Id read that the SR71 spyplane would actually leak fluids when siting in the hangar because the seals were made to expand due to the heat of friction from the air slipping over the skin of the plane at mach speeds. No idea if its true or not,.
True, it also streched about 6" in flight.
914Driver wrote: I'm soooo glad I sit forward of the wing and can't see the flex. http://www.youtube.com/watch?v=QLuaNG9w3m8
other then the noise my fav is right behind the wing... not only do you see the wings flex, you also get to see the turbine spin and get to see the flaps doing all it's work... especially fun when you're getting tons of cross wind or flying in turbulence to see how much effort the pilot has to make to fly the freaking thing flat and straight haha... my wife on the other hand doesn't enjoy that so much
donalson wrote:914Driver wrote: I'm soooo glad I sit forward of the wing and can't see the flex. http://www.youtube.com/watch?v=QLuaNG9w3m8other then the noise my fav is right behind the wing... not only do you see the wings flex, you also get to see the turbine spin and get to see the flaps doing all it's work... especially fun when you're getting tons of cross wind or flying in turbulence to see how much effort the pilot has to make to fly the freaking thing flat and straight haha... my wife on the other hand doesn't enjoy that so much
If you look closely you can see the shock wave on the upper surface of the wing while at high speed. It looks like a pencil thin shadow that moves fore and aft about 1" or so. It is usually about 1/3 of the width of the wing back from the leading edge. The faster the airplane goes the farther back the shock wave moves. A film for your enjoyment.
http://www.youtube.com/watch?v=aASdYfl08ck&feature=related
ransom wrote: I'm always curious about the flexing of airliner wings. I recognize the preference to bend before breaking, but I also know aluminum has a short life being flexed when compared to steel or titanium (or some composites, I suspect, with a Corvette leaf in mind). My understanding is that for most structural work with aluminum, you want it to *not* flex, as every cycle is taking a real bite out of the life before failure. I guess my surprise at being able to watch them flex during normal operation is that I would think of "bend before break" as a target for behavior when exceeding the design parameters. Once. At which point it is preferable to stop the exercise with a bent part than to have it stopped by a broken one. Watching an aluminum structure flexing during normal operation was unexpected. OTOH, I guess I don't know for sure what an airliner spar is made out of...
There is a large amount of Aluminum in an aircraft wing. The arrangement of spars and longerons and stringers will usually make it behave as a monocoque which is designed to have a fatigue life longer than the life of the aircraft.
The A-10 has a huge percentage of Aluminum sheetmetal parts that make up the wing. Some are even chemically etched to make them lighter...
Stuff like airplanes and boats are built with a lot of engineering and design and if the engineers design something to flex I trust them. My Dad works as a test engineer for a large aerospace company and does a lot of material/fastener testing, the design, engineering, and testing of material should assuage your fears. My Dad runs fatigue tests on fasteners in a cycle machine and other departments do large scale testing of components. I'm sure much of the engineering involved was learned the "hard way" by taking a failed structure and figuring out why it failed.
I did hear about metal fatigue in a passenger plane in Hawaii, I guess the pressurizing and depressurizing of the plane eventually fatigued the structure and the damn thing popped. So failures do happen even with the best engineering.
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