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  On 1/25/2019 at 10:48 AM, NSEP said:

Is that a real actively cooled heatshield segment or are they just heating a sheet of stainless steel

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Looks actively cooled to me. All that white stuff around the hot bit looks an awful lot like the frost that forms on the Falcon 9 LOX tank before liftoff.

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  On 1/26/2019 at 4:08 AM, Xd the great said:

Why not attach 2 flaps for simulating the canards and give them a better test for drag and landing?

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They're still building that version. Elon expects it to begin testing later this summer. Which means doing this simpler hopper at the same time gives them months more testing.

Edited by Rakaydos
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  On 1/25/2019 at 10:16 PM, CatastrophicFailure said:

It don’t mean a thing if you ain’t got that swing...

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Will the test launch carry crash test dummies to evaluate loads?

  On 1/27/2019 at 2:59 AM, tater said:

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).

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The StarShip+SuperHeavy combo has taken this to the next level by using a single engine design for both stages. This was driven by reuse, to be sure---vacuum engines take up too much space, are too hard to cool, and are useless to land---but it also means a massively simplified production line. 

What's the closest we've ever come to getting a working transpiration-cooled active heat shield?

  On 1/27/2019 at 5:27 AM, IncongruousGoat said:

Looks actively cooled to me. All that white stuff around the hot bit looks an awful lot like the frost that forms on the Falcon 9 LOX tank before liftoff.

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Definitely insulating foam.

  On 1/27/2019 at 12:21 PM, Rakaydos said:

They're still building that version. Elon expects it to begin testing later this summer. Which means doing this simpler hopper at the same time gives them months more testing.

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On Elon time, which means fall at the earliest.

The hopper is, as others have said, just a flying testbed for the engines. They want to test for a lot of things: pogo, turbine spin-up rates, throttle cycling, gimbal authority, and so forth. This is about validating the simulated aspects of the model before they start flying the full-size version. 

The fairing is much higher than it needs to be for aerodynamic and element protection purposes---the cylindrical portion is completely unnecessary---so I suspect that the sizing is intended to approximate the CoM of the larger vehicle so that they can get meaningful data from pitch correction on descent.

Edited by sevenperforce
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  On 1/27/2019 at 4:53 PM, sevenperforce said:

Will the test launch carry crash test dummies to evaluate loads?

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  On 1/27/2019 at 4:53 PM, sevenperforce said:

What's the closest we've ever come to getting a working transpiration-cooled active heat shield?

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My answer to both is "I don't know."

I do know that transpirational cooling was tested (lab, not in flight) a long time ago for reentry vehicles (nuclear weapons).

https://apps.dtic.mil/dtic/tr/fulltext/u2/a379308.pdf

Another interesting paper:

http://adsabs.harvard.edu/full/2006ESASP.631E..35K

(check what they cited, as well. Stuff back into the 1950s).

Edited by tater
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  On 1/27/2019 at 11:21 PM, Starman4308 said:

The scaffolding brought home to me for the first time just how massive the Hopper is. That thing is a monster.

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yes, remember stating working in the oil industry. Saw an compressor yes it larger than normal, probably the size of an car.
Then I saw the walkway halfway up on it and realized it was more like 4 shipping containers. 

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  On 1/20/2019 at 11:52 PM, cubinator said:

It would look more or less like this:

iVOA0I0.jpg

So, not quite blending in with the rest of the greeble. An Imperial-class Star Destroyer is 1600 m long, or almost exactly one mile.

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Great picture! Star Wars is my favorite movie, and I like the design of Star Destroyers. However, I prefer the design of Republic Venator-Class Star Destroyer.

Edited by johnmorris
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  On 1/28/2019 at 12:32 PM, KSK said:

Forget about building a rocket in a clean room. In American America, rocket is clean room.

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Clean room?  I thought the VAB had its own weather.  Build a big building in Florida and you get strange effects.  Although the payload/spacecraft often is built in a clean room.

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  On 1/28/2019 at 4:02 PM, wumpus said:

Clean room?  I thought the VAB had its own weather.  Build a big building in Florida and you get strange effects.  Although the payload/spacecraft often is built in a clean room.

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My understanding is that it would have its own weather if not for air conditioning. That must be one (or several) big honkin AC unit. 

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