Quote from: Proxima_Centauri on 02/18/2018 09:11 pm787's wings are not made of carbon composites, and it is they that carry the fuel.The Boeing 787's wings are carbon fiber composites. See Boeing's web site: http://www.boeing.com/commercial/787/by-design/#/advanced-composite-use
787's wings are not made of carbon composites, and it is they that carry the fuel.
Right now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELV
Quote from: john smith 19 on 02/18/2018 05:11 pmRight now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELVThis is incorrect. COPVs are composite tanks subjected to cryocycles and structural loads and carried through the entire flight. They are used in many vehicles and SpaceX has plenty of experience with them.
Quote from: envy887 on 02/19/2018 01:18 pmQuote from: john smith 19 on 02/18/2018 05:11 pmRight now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELVThis is incorrect. COPVs are composite tanks subjected to cryocycles and structural loads and carried through the entire flight. They are used in many vehicles and SpaceX has plenty of experience with them.Those are aluminum wrapped tanks, they would not scale to BFS propellant tank dimensions. Not applicable.
Quote from: envy887 on 02/19/2018 01:18 pmQuote from: john smith 19 on 02/18/2018 05:11 pmRight now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELVThis is incorrect. COPVs are composite tanks subjected to cryocycles and structural loads and carried through the entire flight. They are used in many vehicles and SpaceX has plenty of experience with them.Irrelevant. COPVs are lined with aluminum. COPVs are orders of magnitude smaller. COPVs are not subject to widely varying environment, since they are immersed in the LOX tank. One major problem with unlined LOX tanks is the energy given off when fibers break under stress. Special matrix material has been used to address this problem. The CH4 tanks are not as much of a problem.John
SpaceX also said they would line the BFR tanks with invar if necessary, but they don't expect it to be needed.
What do you mean by "widely varying environment"?
The LOX tanks will hold cryogenic LOX and will use autogenous pressurization. Autogenous pressurization means sending hot, gaseous oxygen from the engines into the tanks. Talk about "widely varying environment".
They are not Al-wrapped, they are Al-lined.
They are not Al-wrapped, they are Al-lined. The LOX-facing side is CRFP, not Al. SpaceX also said they would line the BFR tanks with invar if necessary, but they don't expect it to be needed.
The COPV CRFP is unlined on the LOX side.What do you mean by "widely varying environment"? They go from STP to cryo temps and flight pressures at negative and positive g loads (they float in LOX but sink in GHe). That's the same environments that the main tanks will see, except for entry (which is demonstrated by the interstage, legs and fairings).
I find this thread interesting Does anyone have a bona fide source that the Electron tanks are free from metal? If Rocket Lab only claim that they use carbon fibre composites for their tanks, then I suppose it could well be that the carbon fibre is used as part of the load-carrying honeycomb sandwich. At the very least, the tanks may well be lined with an Al-Li "membrane".
Propellant tanks are constructed entirely from carbon fiber composite.
Quote from: envy887 on 02/19/2018 03:03 pmThey are not Al-wrapped, they are Al-lined. The LOX-facing side is CRFP, not Al. SpaceX also said they would line the BFR tanks with invar if necessary, but they don't expect it to be needed.Weren't they implicated in 2 F9 stage failures?
Quote from: envy887The COPV CRFP is unlined on the LOX side.What do you mean by "widely varying environment"? They go from STP to cryo temps and flight pressures at negative and positive g loads (they float in LOX but sink in GHe). That's the same environments that the main tanks will see, except for entry (which is demonstrated by the interstage, legs and fairings).Except they will be "the main tank" It seems a key issue is energy release if fibers are split within the tank, and the classic way to deal with that is to "grade" the inside of the tank (and possibly the outside, depending what it's immersed in) from fiber to a pure resin "skin" layer. However the "hot" Oxygen pressurization system does complicate things. But keep in mind that the "hot" Hydrogen in the RL10 turbine drive is only about 100c, allowing turbines of Aluminum.So the question would be how "hot" is this Oxygen flow? -100c? (IE 173k) 0c? 100c?
Quote from: matthewkantar on 02/19/2018 02:43 pmQuote from: envy887 on 02/19/2018 01:18 pmQuote from: john smith 19 on 02/18/2018 05:11 pmRight now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELVThis is incorrect. COPVs are composite tanks subjected to cryocycles and structural loads and carried through the entire flight. They are used in many vehicles and SpaceX has plenty of experience with them.Those are aluminum wrapped tanks, they would not scale to BFS propellant tank dimensions. Not applicable.They are not Al-wrapped, they are Al-lined. The LOX-facing side is CRFP, not Al. SpaceX also said they would line the BFR tanks with invar if necessary, but they don't expect it to be needed.The construction method for COPVs would not scale, but the COPV experience shows that the material itself is capable of cryocycles, structural loads, and flight with suitable tank construction.Quote from: livingjw on 02/19/2018 02:41 pmQuote from: envy887 on 02/19/2018 01:18 pmQuote from: john smith 19 on 02/18/2018 05:11 pmRight now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELVThis is incorrect. COPVs are composite tanks subjected to cryocycles and structural loads and carried through the entire flight. They are used in many vehicles and SpaceX has plenty of experience with them.Irrelevant. COPVs are lined with aluminum. COPVs are orders of magnitude smaller. COPVs are not subject to widely varying environment, since they are immersed in the LOX tank. One major problem with unlined LOX tanks is the energy given off when fibers break under stress. Special matrix material has been used to address this problem. The CH4 tanks are not as much of a problem.JohnThe COPV CRFP is unlined on the LOX side.What do you mean by "widely varying environment"? They go from STP to cryo temps and flight pressures at negative and positive g loads (they float in LOX but sink in GHe). That's the same environments that the main tanks will see, except for entry (which is demonstrated by the interstage, legs and fairings).
nickel-iron-lead isn't light weight. How thick a layer do they need? Does it flake off? Or wear away? How much mass is that for large tanks?
AIUI the layer would be thin, mainly to protect the carbon from warm to hot oxygen generated for autogenous pressurization. Invar because of its low coefficient of thermal expansion.
I believe the shuttle lox tank used about 100 deg c GOX for tank pressurization.John