Comments by "David G" (@davidg3944) on "Solar Eclipse Timer" channel.

@stevehensley5096 I was going to ask a similar question, then thought to check the two comments already present. Glad I'm not alone in questioning that "leader's" fitness.
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@ The more we find out, the more shocking the whole damn thing becomes.
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@pyalot Consider this - as the tube of CF is radially squeezed, it assumes an "hour glass"-like waisted shape. As it does this, an angular deflection on the ends of the ~5" wall starts to form, with the displacement greatest at the largest diameter. As a simplification, this would then concentrate the stress of end compression at the innermost layer of CF, which could initiate local failure that would then propagate through the rest of the layers in successive order. I'm not saying this definitely happened, but it could, and is not something a unbonded "pressure mate from external forces" could survive, o-ring or not.
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@matthewswingle391 Hey, as a land-whale myself, I resent the implication. I like to think of myself as combination flotation device and impact cushioning!
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Given that the composite material itself (the tow) is a mix of carbon fiber and a pre-applied, uncured epoxy, I think it would be fair to say that rather than just ~550 square feet of adhesive, there was actually around 133 x 5 times that, given each of the five sections was made up of 133 or so layers.
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CF pressure vessels are (as stated in the video) anisotropic - they'll take better advantage of CF composite when under tensile loads than compressive. Metals tend towards isotropic properties - much closer mechanical behavior in all directions. So your general statement is not correct.
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Sloppy engineering and terrible execution. And "execution" it was...
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@Coffeemancer The "DEI trolls" are just letting everyone know how frightened they are of anyone more competent than they are. Which is to say, everyone...
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The winding machine was in the open, no easy way of ensuring air was not trapped between CF layers. Perhaps if the winding had been performed in a large vacuum chamber, but that would have been logistically difficult and expensive.
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@solareclipsetimer Pay no attention to the know-nothings. They provide algorithm fodder, nothing more.
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It's about lessons learned and how to avoid similar catastrophic failures. Your view is as shocking as the lack of testing - a manifestation that "ignorance is bliss". I certainly hope you're not an engineer. Oh, and there's the matter of not viewing and commenting on a video if you don't have interest in the subject. Try it...
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@ I was partly being a pedantic jerk, but it's also something to factor in. I think there was a reference to the CF material being aged-out Boeing stock? So there's another failure enhancer - potentially degraded uncured epoxy. The CF-itself doesn't really degrade unless exposed to certain chemicals/oxidants or thermal events.
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@ It's a little more complicated than that. Take a rope, soak it in water and then freeze it, and you'd have a similar situation to CF parts - you can push the rope, within limits. If you were to take the same volume of epoxy as a proper CF part and subject both to compressive stresses, the CF part would be dramatically stronger in compression and handle fatigue loads better too. When properly designed and manufactured, the orientation, density, and bond integrity between CF and the matrix will add significant strength and stiffness. But it would not use the CF itself as efficiently as when in a tensile load application.
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Unbridled ego over wisdom. Hmm, sounds like someone else I know of.
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@ Putting in a crown makes sense (like unloaded flatbed trailers). Just make sure the crew installs them hump up! 🙂
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In a comment above, I presented this possibility: ***Consider this - as the tube of CF is radially squeezed, it assumes an "hour glass"-like waisted shape. As it does this, an angular deflection on the ends of the ~5" wall starts to form, with the displacement greatest at the largest diameter. As a simplification, this would then concentrate the stress of end compression at the innermost layer of CF, which could initiate local failure that would then propagate through the rest of the layers in successive order. I'm not saying this definitely happened, but it could, and is not something a unbonded "pressure mate from external forces" could survive, o-ring or not.*** I am not an engineer (I do have an extensive background of practical mechanical design), so I invite review/critique of what I gave as a possibility.
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@dhoffnun "You jelly?" Stockton Rush: "Yes".
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@ Your second post does not correlate with your first post. It's clear that you haven't enough understanding of the basic issues to have meaningful conversation on the subject. Good day to you.
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@ Not sure if that's at me (YT comments are wack since J202025), but I suspect it would "in all cases" be deformation of the C/F casing that would exert the force to shear the Ti flanges. There's no way for an o-ring on its own to do so, and less likely that loads passed through a glue shear-line could remove the flange under tensile failure. Just my opinion, of course.
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@pyalot Maybe. Possible that the load in shear across the bond line could cause delamination of some of the cylinder layers, but that's not a given or possibly inconsequential given the speed of failure of the system.
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Interesting. Mind siting a source for that?
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Relatively speaking, titanium is much less still than a properly made CF structure (about 114 GPa vs CF laminate about 2-4 times as much), so you'd need a lot of Ti at significant section depth, losing interior volume and adding weight.
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@Nihility15 I think that's the case, and even if a thicker hull was used the same basic precursors to failure would be in place, and in some cases worse - the extra autoclave cycles and grinding spots if nothing else.
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@user-ct8my8rv9c At this point a lot of countries have landed on the Moon, sometimes integral, sometimes kinetically dissembled. Only one country has landed humans on it, so yes, Imperial units rule.
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For that sort of long span, what would (wood?) you recommend for structural elements?
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@voidedname You do not understand the difference in your first two posts, and the fundamental errors of the first. I will do me. You have little choice but to do you. Unfortunate...
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@ You need to change your name to voidedbrain.
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@voidedname You are wrong in your initial premise. What you think is not correct. S.T.O.P.
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@voidedname Your initial premise is wrong. Just wrong. Composites do not have the same compressive stress capabilities as their tensile. Simple fact, which you simply can't accept (understand). You are Stockton Rush reborn - misplaced arrogance, active ignorance personified.
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