Xd the great Posted January 25, 2019 Share Posted January 25, 2019 13 minutes ago, NSEP said: Is that a real actively cooled heatshield segment or are they just heating a sheet of stainless steel Im guessing a sheet of stainless steel, as 1100C is by no means a reentry temperature. Quote Link to comment Share on other sites More sharing options...
DDE Posted January 25, 2019 Share Posted January 25, 2019 1 hour ago, NSEP said: Is that a real actively cooled heatshield segment or are they just heating a sheet of stainless steel Temperature looks normal for uncooled steel. I’d have expected post-combustion otherwise, as heated methane would finally find oxygen to combine with. Compare with unburnt RP-1 injected into the nozzle skirt, leading to a flame front almost a nozzle’s length down from the actual end of the nozzle: Quote Link to comment Share on other sites More sharing options...
Xd the great Posted January 25, 2019 Share Posted January 25, 2019 (edited) Is that the F1? Also: How much does "aerospace grade 304 stainless steel" cost? $3 per KG sounds too cheap. Edited January 25, 2019 by Xd the great GRAMMAR Quote Link to comment Share on other sites More sharing options...
DDE Posted January 25, 2019 Share Posted January 25, 2019 (edited) 32 minutes ago, Xd the great said: Is that the F1? Naturally. 32 minutes ago, Xd the great said: Also: How much does "aerospace grade 304 stainless steel" cost? $3 per KG sounds too cheap. Bulk order, minimum machining? They probably charge per sheet area, not mass. Edited January 25, 2019 by DDE Quote Link to comment Share on other sites More sharing options...
Starman4308 Posted January 25, 2019 Share Posted January 25, 2019 24 minutes ago, Xd the great said: Is that the F1? Also: How much does "aerospace grade 304 stainless steel" cost? $3 per KG sounds too cheap. That is indeed the mighty Rocketdyne F1 engine. What you see wrapping around the middle of the nozzle is the exhaust manifold for the gas generator. Specifically, the F1 is a gas generator open-cycle engine, where some of the kerosene and LOX is diverted to power the turbopumps. The fuel-rich exhaust from the gas generator was then routed into the nozzle mid-way; the relatively cool generator exhaust gases would keep the nozzle extension cool, rather than requiring active regenerative cooling. The exhaust gases themselves are the dark band underneath the nozzle. Also, I'm not sure how much aerospace grade 304 steel costs, but SpaceX has in the past been willing to use non-aerospace-grade materials, something that may have contributed to the failure of CRS-7. Quote Link to comment Share on other sites More sharing options...
Racescort666 Posted January 25, 2019 Share Posted January 25, 2019 So a little bit of poking around regarding stainless steel, Alro sells 304 stainless that meets AMS 5513. "Aerospace grade" is vague at best so AMS 5513 is probably a good reference point but when it comes down to it, SpaceX is buying enough steel for this vehicle that a mill would probably make them their own grade. Anyway, Alro sells drops (left over pieces) that are around $5/pound. So maybe they're getting down to $3/kg but that's quite the jump. Also, the only thing that really makes it "aerospace grade" is inspection and certification. Hypothetically, without the inspections, a material is just as good but you can't guarantee that. @sevenperforce regarding the tank volumes, I screwed up the spherical cap volume. I didn't include the tube but my estimated dimensions are as follows: Spherical cap: a: 9 m, h: 1.71 m Upper tank cylinder length: 5.3 m Lower tank cylinder length: 4.1 m Fuel tank: 451 m3 Ox tank: 261 m3 Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2019 Share Posted January 25, 2019 My guess is that the "heat shield test" is really just them heating up a panel of steel on one side and then using a camera to measure radiative cooling on the other side. Alternately, they very well may have fabricated a laminated steel shield with (empty) cooling channels and they are testing its radiative and reradiative properties. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2019 Share Posted January 25, 2019 18 hours ago, Ultimate Steve said: I wonder if they could fly it without the fairing if they really wanted to. I am sure they still need to slap the avionics package somewhere on top of that upper bulkhead, under the cone. Then they could fly it without the fairing, but the avionics would get wet. They may also be running RCS out through the sides of the fairing. Don't know if those holes are for fuel lines. Also don't know if they have built the ten-tonne-class hot-gas thrusters yet. They can fly without RCS easily enough (I don't believe the original Grasshopper had cold-gas thrusters) but they will probably want them at some point. They could also bolt nitrogen bottles to the top of that bulkhead and just run cold-gas thrusters through the holes as a stopgap. With the fairing being so easily removable (and, now, replaceable) I can see them doing some incremental upgrades as they fly. Quote Link to comment Share on other sites More sharing options...
tater Posted January 25, 2019 Share Posted January 25, 2019 Yeah, the fairing is for looks as far as the hover tests go. No RCS required, at least for early testing and while the avionics need to go someplace, it doesn't matter where, really (unless they also plan on having radar/etc on the bottom). They could fly the thing sans fairing, but Musk wants it to look like a rocket. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted January 25, 2019 Share Posted January 25, 2019 11 minutes ago, tater said: Yeah, the fairing is for looks as far as the hover tests go. No RCS required, at least for early testing and while the avionics need to go someplace, it doesn't matter where, really (unless they also plan on having radar/etc on the bottom). They could fly the thing sans fairing, but Musk wants it to look like a rocket. Incidentally I do not see any ducting for wiring, etc running through the rocket internally. They can slap it to the side, sure, but I somehow doubt they would. The fairing has legitimate purpose -- first, to protect avionics, fuel lines, and so forth from the elements; second, to give a nice draggy element for later tests. They will want to test engine-out landings at high drop rates; at some point they are likely to do an ascent, then either cut engines or throttle them way down to pick up speed. Having the fairing up top will help keep it radial-out. Quote Link to comment Share on other sites More sharing options...
tater Posted January 25, 2019 Share Posted January 25, 2019 Absolutely. Might as well make it look cool, though, vs making the top a cylinder (like an F9 stage 1 interstage). What's cool is that they are in effect building a test stand to fire multiple Raptors, and a software test platform (to test control/landing/etc), and they will have done this, even with the fairing problem in less time, and with less money than it would have cost to build a static test stand for a single engine at Stennis. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted January 25, 2019 Share Posted January 25, 2019 It don’t mean a thing if you ain’t got that swing... Quote Link to comment Share on other sites More sharing options...
Xd the great Posted January 26, 2019 Share Posted January 26, 2019 (edited) Why not attach 2 flaps for simulating the canards and give them a better test for drag and landing? Edited January 26, 2019 by Xd the great Quote Link to comment Share on other sites More sharing options...
tater Posted January 26, 2019 Share Posted January 26, 2019 20 minutes ago, Xd the great said: Why not attach 2 flaps for simulating the canards and give them a better test for drag and landing? Not relevant for the hopper tests. This is a flying engine testbed. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted January 26, 2019 Share Posted January 26, 2019 11 hours ago, sevenperforce said: I am sure they still need to slap the avionics package somewhere on top of that upper bulkhead, under the cone. Then they could fly it without the fairing, but the avionics would get wet. They may also be running RCS out through the sides of the fairing. Don't know if those holes are for fuel lines. Also don't know if they have built the ten-tonne-class hot-gas thrusters yet. They can fly without RCS easily enough (I don't believe the original Grasshopper had cold-gas thrusters) but they will probably want them at some point. They could also bolt nitrogen bottles to the top of that bulkhead and just run cold-gas thrusters through the holes as a stopgap. With the fairing being so easily removable (and, now, replaceable) I can see them doing some incremental upgrades as they fly. Guess they have the aveonic at the bottom, easier access is one an lots of space down there. they will even have cargo at the bottom on final version. They would add rcs on top and bottom, and top don't have it. Original grasshopper did not have it, you see the One point with the fairing and the fins is that it make it behave more aerodynamic like the real thing. might also be center of gravity related. They have landing data but only for falcon 9 first stage with an different engine so they need to adjust software to new hardware. Might be relevant to test with RCS down the line, probably depend on how the orbital version comes along. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted January 26, 2019 Share Posted January 26, 2019 Spoiler Instead of RCS, should use steam nozzles to look true. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted January 26, 2019 Share Posted January 26, 2019 On 1/25/2019 at 2:33 PM, CatastrophicFailure said: Is that a raptor engine roasting the steel? Quote Link to comment Share on other sites More sharing options...
tater Posted January 26, 2019 Share Posted January 26, 2019 3 hours ago, Xd the great said: Is that a raptor engine roasting the steel? No, they're little torches. Quote Link to comment Share on other sites More sharing options...
Xd the great Posted January 27, 2019 Share Posted January 27, 2019 Did this go to waste, then? Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted January 27, 2019 Share Posted January 27, 2019 3 minutes ago, Xd the great said: Did this go to waste, then? Elon got a new swimming pool. Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted January 27, 2019 Share Posted January 27, 2019 1 minute ago, CatastrophicFailure said: Elon got a new swimming pool. “ A compact fuel tank, designed for small upper stages and landers. Rockomax takes no responsibility for the Dawton Kerman Aboveground Pool Company stickers on the inside because it totally is not a swimming pool frame we stole from their back lot. — Rockomax Conglomerate ” Quote Link to comment Share on other sites More sharing options...
tater Posted January 27, 2019 Share Posted January 27, 2019 34 minutes ago, Xd the great said: Did this go to waste, then? Quite possibly, yes. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted January 27, 2019 Share Posted January 27, 2019 Could they still make the SuperHeavy booster from CFC? It doesn’t face the same heating loads. It could at least be an interstage. Quote Link to comment Share on other sites More sharing options...
tater Posted January 27, 2019 Share Posted January 27, 2019 27 minutes ago, StrandedonEarth said: Could they still make the SuperHeavy booster from CFC? It doesn’t face the same heating loads. It could at least be an interstage. This would make zero sense, they won't do it. One of the reasons Falcon 9 is such a great rocket is commonality. Two highly related engines. One propellant, and one oxidizer. The "long pole" of BFR with CFC was in fact the CFC issues. The engine was a done deal. It might have issues, but they have a great propulsion team, and all it takes is blowing up some engines at this point. Software they have a handle on. The remaining issue is now transpirational cooling, but again, this has been a thing since the earliest days of rockets/ICBMs, so I think they can sort this out. The remaining issue on a crew version... life support (this is non-trivial). Quote Link to comment Share on other sites More sharing options...
Xd the great Posted January 27, 2019 Share Posted January 27, 2019 14 minutes ago, tater said: and all it takes is blowing up some engines at this point. Are they hiring engineerers now? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.