I'm reminded of a stunt my old foreman used to pull. He was not just an electrician, but an HVAC and plumbing guy... and part of HVAC is insulation.
He would have someone hold their hand out palm up. He would put a pile of this greyish squishy fuzzy stuff on said palm, and then a penny. Admonishing them to hold their hand well away from their face, he would then fire up a propane torch, and heat the penny to a glowing red... while they were still holding it. This is the stuff they blow in to spaces in a few minutes to a couple of hours. (Unfortunately, it does tend to settle... )
What's really cool is that *that* stuff is (at least somewhat) *structural*... *and* it's made exactly how I thought they would, just like cotton candy.
Having trouble imagining applications for it, though. Maybe a heat shield on a motorbike's exhaust?
The original article proposed firefighter gear. But you could use it to insulate anything that needs to move or flex, because very little high-grade insulation is really flexible. You can also use it to compensate for the fact that hot things expand, because it can compress.
Make a sandwich of that between plates of titanium and aviation grade carbon fibre composite and you have the basis for the skin of a lightweight space-plane on the cheap.
Well, it's cheaper than the alternatives. Hmm... you know, carbon/carbon composites are very cheap, and we know how to make them easily enough [they're used for high-end brake pads and all sorts of high temperature, high mechanical stress applications].
So, think of a sandwich, carbon/carbon composite tiles - ceramic foam 'fluff' - aviation grade carbon-fibre/epoxy body. Carbon/carbon composites have a maximum operating temperature of around 5,000 degrees C, according to the patent I just read, so that's easily able to survive re-entry.
Problem is, it's also fairly thermally conductive, which is why we need the insinuative fluff. To protect the actual body of the space plane, because the epoxy matrix that makes the carbon fibre rigid loses cohesion and turns rubbery at around 200-400 degrees C.
If the outer skin is going to turn all rubbery during re-entry, is the underlying stuff stiff enough to hold it in place? And will the matrix survive the requisite temperatures and re-assume its stiff qualities once it cools?
Questions to be answered ... but perhaps you're onto something!
Other way around... the under-lying skin is the rigid aviation grade carbon-fibre/epoxy matrix the fluff goes between that and carbon/carbon composite which is the outer most skin.
The carbon-carbon tiles are highly heat resistant and rigid, but it's thermally conductive [which is great for brake pads, means they cool down quick] the fluff protects the carbon-fibre/epoxy body of the plane from the tiles as they get hot. The carbon-fibre/epoxy body is what gives it mechanical strength, but it's flexible stuff [which is why it's great for planes] so... it's never been used like this before because most insulators of that quality are fragile and rigid. [space shuttle tiles basically, which worked because the shuttle space-frame was as rigid as the proverbial brick outhouse.]
I'm betting Elon Musk is very interested in this stuff, because his Mars colony conveyor ships will need to eb built like this. They're massive, and any weight they can save in construction will have a big impact.
Nice! Looks like they found a way to commercialize aerogel in a much more feasible way. I'm glad they finally did, that tech is amazing, even if it cost more per ounce than gold.
![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
dancing_serpent
![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
(no subject)
Date: 2017-06-03 06:31 am (UTC)He would have someone hold their hand out palm up. He would put a pile of this greyish squishy fuzzy stuff on said palm, and then a penny. Admonishing them to hold their hand well away from their face, he would then fire up a propane torch, and heat the penny to a glowing red... while they were still holding it. This is the stuff they blow in to spaces in a few minutes to a couple of hours. (Unfortunately, it does tend to settle... )
What's really cool is that *that* stuff is (at least somewhat) *structural*... *and* it's made exactly how I thought they would, just like cotton candy.
Having trouble imagining applications for it, though. Maybe a heat shield on a motorbike's exhaust?
Well...
Date: 2017-06-03 06:59 am (UTC)(no subject)
Date: 2017-06-03 03:09 pm (UTC)(no subject)
Date: 2017-06-03 04:23 pm (UTC)(no subject)
Date: 2017-06-03 05:07 pm (UTC)(no subject)
Date: 2017-06-03 06:39 am (UTC)(no subject)
Date: 2017-06-03 06:39 am (UTC)-Fallon~
(no subject)
Date: 2017-06-03 10:27 am (UTC)(no subject)
Date: 2017-06-03 04:25 pm (UTC)OTOH, CF *is*... :)
(no subject)
Date: 2017-06-03 08:27 pm (UTC)So, think of a sandwich, carbon/carbon composite tiles - ceramic foam 'fluff' - aviation grade carbon-fibre/epoxy body. Carbon/carbon composites have a maximum operating temperature of around 5,000 degrees C, according to the patent I just read, so that's easily able to survive re-entry.
Problem is, it's also fairly thermally conductive, which is why we need the insinuative fluff. To protect the actual body of the space plane, because the epoxy matrix that makes the carbon fibre rigid loses cohesion and turns rubbery at around 200-400 degrees C.
(no subject)
Date: 2017-06-03 08:34 pm (UTC)If the outer skin is going to turn all rubbery during re-entry, is the underlying stuff stiff enough to hold it in place? And will the matrix survive the requisite temperatures and re-assume its stiff qualities once it cools?
Questions to be answered ... but perhaps you're onto something!
(no subject)
Date: 2017-06-03 08:56 pm (UTC)The carbon-carbon tiles are highly heat resistant and rigid, but it's thermally conductive [which is great for brake pads, means they cool down quick] the fluff protects the carbon-fibre/epoxy body of the plane from the tiles as they get hot. The carbon-fibre/epoxy body is what gives it mechanical strength, but it's flexible stuff [which is why it's great for planes] so... it's never been used like this before because most insulators of that quality are fragile and rigid. [space shuttle tiles basically, which worked because the shuttle space-frame was as rigid as the proverbial brick outhouse.]
I'm betting Elon Musk is very interested in this stuff, because his Mars colony conveyor ships will need to eb built like this. They're massive, and any weight they can save in construction will have a big impact.
(no subject)
Date: 2017-06-03 09:06 pm (UTC)(no subject)
Date: 2017-06-03 12:22 pm (UTC)(no subject)
Date: 2017-06-03 12:50 pm (UTC)(no subject)
Date: 2017-06-03 06:17 am (UTC)Yes...
Date: 2017-06-03 06:21 am (UTC)