SpaceX Super Heavy and Starship test fitting (Full Version)

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Neilster -> SpaceX Super Heavy and Starship test fitting (8/7/2021 5:39:07 AM)

SpaceX have surprised by fitting 29 engines to it's Super Heavy first stage, moving it to its test stand and test fitting the Starship second stage. Both vehicles are yet to be completely finished but this stack will probably make a test orbital launch before the end of the year.

It's about 120m tall, which is about 10m taller than the Saturn V. The first stage will have almost twice the thrust of that vehicle. The launch is going to be spectacular, either in a good or explodey kind of way.

I'm happy to answer any questions about this stuff as some of it is quite technical and, well, rocket science [:'(]

The first stage is craned onto the stand.



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Neilster -> RE: SpaceX Super Heavy and Starship test fitting (8/7/2021 5:44:47 AM)

A closer view of the Raptor engines. The middle nine can gimbal for directional control during ascent. SpaceX has calculated that they can actually put 33 engines on the booster, which is better, as more thrust in the first stage reduces gravity losses.

The engines of both stages use methane and oxygen as propellants. Propellant choices are complex. Oxygen is a very common oxidiser as it's relatively cheap and offers excellent performance. First stages often use highly refined kerosene as fuel but it produces a lot of soot that can clog up engines and make reuse harder. Methane is much better for this and is more dense (less volume required) than hydrogen. Then there's the hypergolic rabbit hole, but they tend to be highly toxic.


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Neilster -> RE: SpaceX Super Heavy and Starship test fitting (8/7/2021 5:48:49 AM)

The full stack. The plan is for the returning first stage to be caught at the grid fins by giant arms that will be attached to that tower, obviating the requirement for landing legs and hence saving mass. A system of pulleys and oil rig winch technology will be used to absorb the shock and then lower it back onto its launch stand. Although it's huge, the returning booster will be nearly empty of propellants and will have the density of an empty beer can.


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Lobster -> RE: SpaceX Super Heavy and Starship test fitting (8/7/2021 1:14:16 PM)

They could launch sooner but they have to wait for an environmental study. Some locals are complaining that the launches will disturb the fragile ecosystem. It takes about one minute on Google Earth to realize that's a load of b.s. The entire area is repleat with offroad vehicles tracks and trails. The beach is more like a freeway at rush hour on weekends. The 'fragile' ecosystem is already trashed by the people who are worried about it.



OldSarge -> RE: SpaceX Super Heavy and Starship test fitting (8/7/2021 3:09:39 PM)

Space exploration has mostly been beneficial for wildlife refuges as Merritt Island, NWR would seem to indicate. Largely because large tracts of nesting beaches, wetlands, seawater and fresh have remained untouched and relatively pristine.



OldSarge -> RE: SpaceX Super Heavy and Starship test fitting (8/7/2021 3:44:07 PM)

A Tweet from Elon Starship tweets.



Neilster -> RE: SpaceX Super Heavy and Starship test fitting (8/7/2021 4:02:47 PM)


quote:

ORIGINAL: Lobster

They could launch sooner but they have to wait for an environmental study. Some locals are complaining that the launches will disturb the fragile ecosystem. It takes about one minute on Google Earth to realize that's a load of b.s. The entire area is repleat with offroad vehicles tracks and trails. The beach is more like a freeway at rush hour on weekends. The 'fragile' ecosystem is already trashed by the people who are worried about it.

I think there's a lot of engineering to be done though. Those engines were attached suspiciously quickly and may not be fully connected. Some of this is for PR purposes and there needs to be plenty of testing too.

The FAA is also a potential issue. They seem to be used to the pace of development of the "Old Space" companies, who normally give years of notice. SpaceX moves much, much faster. It's suggested that Elon has been hiring big and moving people to Boca Chica lately to give the impression of an imminent launch in order to get the regulatory wheels moving.

Re environmental benefits of space industries, I agree. Military bases have a similar effect. My old Air Force base was the largest military establishment in Australia and it was an absolute wildlife haven. Most of the land near the runways etc was cleared to help prevent bird strikes and ingestion but that made it ideal for kangaroos. The forested and swampy areas had all sorts of stuff but unfortunately were the breeding grounds of the Hexham Grey, an enormous mosquito with a big appetite. They weren't much fun when you had both hands occupied in a jet and heaps of them were draining you of blood.



Neilster -> RE: SpaceX Super Heavy and Starship test fitting (8/7/2021 4:25:02 PM)

This shows the size of those grid fins. I saw Tim Dodd's interview with Elon and he mentioned that the current ones are very crude, as optimising them is immaterial for the test flight. He hopes to reduce their mass by about 50%. Also, on the Falcon 9 they fold against the side of the rocket during launch but apparently they've worked out that the weight penalty of the mechanism for that overrode the increased aerodynamic drag of just having them fixed. On launch, rockets are through the thickest part of the atmosphere quite quickly but mass is a penalty all the way. Also, the best component is no component.

For anyone who doesn't know, grid fins are aerodynamic surfaces that were developed by the Soviets in the 1950s. They work best in the hypersonic and subsonic regimes, but less well in the transonic. On booster return, they do most of the initial controlling as this is at hypersonic velocities.


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Neilster -> RE: SpaceX Super Heavy and Starship test fitting (8/8/2021 2:52:00 AM)


quote:

ORIGINAL: Grognerd_INC

Ha! Took us a day to install a pair of engines on the Titan II or the Titan IV, stage one - A lot of sponge counts when you open up a liquid propellant system! Look what no bureaucracy can do! (other than the FAA types).
We used to have 2 to 4 techs, 2 inspectors, 1 Quality Engineer, 1 Aerojet representative, 1 Air Force Representative occasionally an Air Force QA type. A lot of folks just standing around watching! (I was the Quality Engineer)

Were the nasty Aerozine 50/Dinitrogen tetroxide propellants anything to do with that though? Had there been propellants in the tanks?

In principle I agree that old space had too much bureaucracy but there was basically no commercial imperative then and, as I said above, I don't think these engines were fully connected. No doubt, however, that SpaceX will come up with a fast way to do the latter. They want to stamp these things out like Khrushchev's "sausages" [;)]

Also, design for ease of maintenance has improved with time. An engine could be replaced on an F-18 in, from memory, about an hour. The first jet I worked on, the mighty Aermacchi MB-326, required a field break to remove its Rolls-Royce Viper. That meant splitting the jet in half, rolling away the rear fuselage, removing the tailpipe and then the engine before doing all that in reverse. That took a team of about five a full day. If you've ever maintained an old Italian sports car, you'll get the idea.



Kuokkanen -> RE: SpaceX Super Heavy and Starship test fitting (8/9/2021 4:13:54 AM)

YouTuber on Twitter:
quote:

Why haven't you made Iron Man suit by now?


Elon Musk:
quote:

Building starship



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