- Rush is described as being an aeronautical engineer
- Rush was working as such when the 787 was being born
- from the outset, I've been leary of the 787 plastic fuselage
- Rush decided, rather than going with the tried and true heavy metal sphere, he'd go with a cylinder
- Rush concluded, my biggest spitball, that carbon fiber was a good hull material because of the use in 787 fuselage
- maximum pressure differential seen by a 787 fuselage:
So if we assume a constant altitude of 43,000 (the 787's service ceiling), we would get a maximum differential of:- pressure differential at 12,500 feet of ocean:
6,000 ft Cabin Altitude = 9.06 psi
8,000 ft Cabin Altitude = 8.11 psi
The water pressure at 12,500 feet (3,800 meters) below the surface at the site of the Titanic wreck is roughly 400 atmospheres or 6,000 pounds per square inch.- note that the pressure vector in the 787 fuselage is outward, i.e. tensile, while in the Titan is inward i.e. compression and/or shear
- just another spitball: carbon fiber is strong in tensile strength, but not so much in compression or shear
- there has been lots of research on carbon fiber, and it's brittle and fatigue is nearly impossible to note
- so, what works in the air ain't close to what's needed in water
- Rush, just another spitball, decided that the carbon fiber cylinder would be strengthened by the titanium endcaps, in that the endcaps would push the cylinder along its major axis and keep the cylinder wall from failing; this is easily seen by standing on a soda can vs. squeezing it
- water pressure doesn't care about axis
- the pressure cylinder was replaced at least once after only a few dives -
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