SpaceX Falcon 9 historic landing thread (1st landing attempt & most recent missions)

georgegassaway said:

For a "normal" rocket, yes. The "header tanks" however, will probably be full or close to it. Think of a small tank inside of a big tank, in the middle of the tank.

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Some nice challenges in the tank design however they do it. Going from falling flat to rotating ~90deg and coping with the dynamic CG shift (longitudinal and radial) and expecting the fuel to be presented nicely to the inlet pipes and impellers? Some finesse will be required .

Illustration of an earlier version of Starship, showing the header tanks:



Meanwhile, today in Boca Chica, they transported the main body of MK1 from the assembly area to the pad area. Well, LOTS of assembly still to be done, at the pad.

Thanks for the info George. Having the smaller tanks buried in the larger one is a great idea.

Wednesday's move, time-lapse video.

After a long hiatus, SpaceX is planning to launch a Falcon-9 tomorrow.

“SpaceX is targeting Monday, November 11 at 9:56 a.m. EST, 14:56 UTC, for launch of 60 Starlink satellites from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station, Florida. A backup launch opportunity is available at 9:34 a.m. EST, 14:34 UTC, on Tuesday, November 12.

Falcon 9’s first stage supported the Iridium-7, SAOCOM-1A, and Nusantara Satu missions, and the fairing was previously flown on Falcon Heavy’s Arabsat-6A mission earlier this year.

Following stage separation, SpaceX will land Falcon 9’s first stage on the “Of Course I Still Love You” droneship, which will be stationed in the Atlantic Ocean. Approximately 45 minutes after liftoff, SpaceX’s two fairing recovery vessels, “Ms. Tree” and “Ms. Chief,” will attempt to recover the two fairing halves.”

The successful fairing catch from Falcon Heavy was for one of the fairing halves. So this must be a reflight of that one half, plus a new flight for another half. Unless they are re-using a fairing half that was not caught, and landed in the ocean. SpaceX did say they'd be willing to risk the use of a seawater-soaked fairing for their own Starlink Satellite launches, so possibly the other fairing half is one that landed in the ocean.



The 60-stack of satellites:


In other news, no news. The Dragon-2 static fire test (first try since the kaboom-anomaly in April) for Nov 2nd, was moved to Nov 9th. But before Nov 9th, it was moved to indefinitely delayed.

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I hope we have live video feed of the fairing captures .

A totally successful launch. F-9 booster landed on the drone ship OCISLY. For once, the live onboard ASDS video did not cut out during landing, so you could see the beginnings of exhaust effects on the deck, then the F9 booster land smoothly.

There was a lot of work done on the fleet during the long dry spell between launches. MAYBE they did a hardware upgrade, or some other technical solution to solve the video cut-outs that have happened during previous landings. If we see good on-deck video for the next 2 landings, then I figure yes, otherwise maybe a fluke today.

4th flight for this booster. I note the commentator said today the F9 is good for up to 10 flights. Didn't say 10 flights between major overhauls (and then another 10, and another 10, as SpaceX announced for Block-5). Hopefully they mis-spoke.

Satellite deploy went well. All 60 of them. Odd tidbit is that one of the 60 was found to be defective (in some manner) a few days before launch. They decided it was better to launch 59 good ones now rather than delay the launch (probably by weeks) to de-stack all 60, replace that one, and start over. So, the bad one will just re-enter early (each of these have ion engines to get to their final individual orbits and to help maintain orbit for years).

I've not seen any info yet on whether the 2 fairings were caught or not.
UPDATE - seas were too rough, the fairing recovery ships were sent back to port before launch.
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Got a nice shot of the barge landing. Was worried after the stage 1 onboard camera cut out on the way down.

A "slightly excited" videographer who got footage of the 60 Starlink Satellite "train" going across the sky shortly after local sunset on Monday.

The "straggler" is most likely the defective one that SpaceX chose to launch anyway rather than do a long (weeks) launch delay to replace it.
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georgegassaway said:

In other news, no news. The Dragon-2 static fire test (first try since the kaboom-anomaly in April) for Nov 2nd, was moved to Nov 9th. But before Nov 9th, it was moved to indefinitely delayed.

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Successful SuperDraco test today. https://spaceflightnow.com/2019/11/...-thrusters-in-key-test-after-april-explosion/

Arg. Starship had a mishap.

So, SpaceX claims they had already decided not to ever fly it, using it as an assembly testbed. Which must have been pretty recent, as I ran across a news article Oct 29th saying it would fly by the end of the year. Probably was turning out to be a "lemon".

Moving on to the MK3 version. As I type this, I'm not sure if MK3 is being built in Florida, or Texas. I know MK2 is in Florida, and that means MK2 isn't going to fly either.

OK, something I ran across later indicates MK3 at Boca Chica.

Something to be learned. That's why they test.

Scott Manley did a video on it

Big Bada Boom.

No badaboom. If it had been full of Lox instead of liquid nitrogen, then either a big boom, or a "whooomph" of a big fricking fire if any spark ignited the oxygen cloud. It had no fuel onboard, but even dry grass would make for a good oxidizer for a high percentage oxygen cloud.

Sounds like the result of pitting the TX and FL sites against each other in vehicle development

georgegassaway said:

No badaboom. If it had been full of Lox instead of liquid nitrogen, then either a big boom, or a "whooomph" of a big fricking fire if any spark ignited the oxygen cloud. It had no fuel onboard, but even dry grass would make for a good oxidizer for a high percentage oxygen cloud.

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What??? I don't think oxygen burns. And you don't need an oxidizer for oxygen. Or am I missing something?

Mushtang said:

What??? I don't think oxygen burns. And you don't need an oxidizer for oxygen. Or am I missing something?

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Looks like a typo. What George is probably referring too, if a big amount of LOX is spilled, especially if it is in a violent way (e.g. with sparking metal), things can get quite exciting in a hurry.

But I think it gets even "better" than that. Apparently all tanks failed, because liquid was also pouring out from the aft end of the rocket. If you mix LOX with LCH4, you get a very sensitive and energetic liquid high explosive, that's roughly twice as powerful as TNT per weight. Heavy rockets contain thousands of tons of propellant, so kilotons are an oddly appropriate unit to quantify the worst case scenario then.
Other propellant combinations are a bit more benign in this case, because they are usually not miscible. On one hand, the temperature ranges where LOX and RP1 or LH2 are liquid don't overlap and on the other hand hypergolics can't be premixed to an explosive at all.

Of course, a failure on a methalox rocket will not mean that all the propellant mixes perfectly before everything goes boom, but the potential yield is quite bigger than in other combinations.

Reinhard

I’ve worked a lot with shipyards that build outdoors in the Gulf, and it is really hard to get good welds under those conditions. If asked to speculate, I would guess that they found enough weld defects in inspection that they decided to take this to high pressure to see how well the welds would hold up. If that was what was intended, they could well have been using LN2 to pressurize the tanks.

boatgeek said:

I’ve worked a lot with shipyards that build outdoors in the Gulf, and it is really hard to get good welds under those conditions. If asked to speculate, I would guess that they found enough weld defects in inspection that they decided to take this to high pressure to see how well the welds would hold up. If that was what was intended, they could well have been using LN2 to pressurize the tanks.

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Humidity and salt contaminants? Plus wind disrupting shielding gas?

Lox itself does not burn. Massive spill of Lox let loose in a dry Texas field with grass, weeds, wood, and other things that can burn (including insects, and birds and snake and ants, or people if there were any nearby, which there were not)....BIG fireball if theres is the slightest spark.

An incident occurred in 1971 before Apollo-13 launched, near the pad area. Security cars blithely drove thru low level "fog" of vented LOx, on a very calm day. The cars caught fire, the occupants got out without injury.

Story/details and more pics at:
https://www.collectspace.com/ubb/Forum29/HTML/001686.html

boatgeek said:

If asked to speculate, I would guess that they found enough weld defects in inspection that they decided to take this to high pressure to see how well the welds would hold up. If that was what was intended, they could well have been using LN2 to pressurize the tanks.

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It's my understanding, that pressure testing with LN2 is a standard procedure, regardless how confident they are in the welds. LOX is more expensive, requires more careful handling and will generate additional headaches in cause of an error.

Reinhard

Nytrunner said:

Humidity and salt contaminants? Plus wind disrupting shielding gas?

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All of the above plus everything takes more time to do when you’re not in a shop so it’s more tempting to call it good enough. Lack of temperature control doesn’t help either.

You know there is an old Murphy's corollary that goes, "Everything takes longer then it should." I think Space-X's prediction that they will land the Star Ship on the moon in 2022 is way over optimistic. Though, I love the pictures of the Star Ship landing on the moon. The artist conceptions remind me of Chesley Bonestell's paintings from a half-century ago. It is a good way to make publicity.

https://techcrunch.com/2019/10/25/s...22-then-do-cargo-runs-for-2024-human-landing/

georgegassaway said:

Lox itself does not burn. Massive spill of Lox let loose in a dry Texas field with grass, weeds, wood, and other things that can burn (including insects, and birds and snake and ants, or people if there were any nearby, which there were not)....BIG fireball if theres is the slightest spark.

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Still wouldn't be a BIG fireball. The stuff would burn, no doubt, and much much faster than in normal atmosphere if ignited, but the large cloud of oxygen wouldn't burn, just the stuff under it. The grass, birds, animals, would burn quickly and when done wouldn't burn anymore. People and cars would burn and take longer to finish burning, but no fireball of the cloud. Just a larger and hotter fire.

And it would take more than a slightest spark, unless the spark was so close to some fuel (grass, weeds, woods, insects, birds, snakes, etc.) that the hot spark would ignite the fuel. Otherwise the spark would burn brightly and burn itself out.

What you're describing is a large cloud of hydrogen or other fuel, not oxygen.

This infamous film (from around the early-mid 1970's?) shows what LOX can do without what many would think of as "fuel".

Try not to act like 10 year old boys or make sexist cracks about parts of it, and no "film critic" comments. Stick to the science/dangers involved.

"THE MAN FROM LOX, a liquid oxygen safety training film, is one of the most infamous films ever produced by the U.S. Government.
Created in the aftermath of a series of accidents involving liquid oxygen, the film uses ironic humor to disarm the skeptical viewer, all the while setting up a very real, deeply disturbing, and quite serious finale."



Be my guest to do your own test to show that dumping a few thousands of gallons of LOX onto an area like Boca Chica's would not be a problem if there was a spark.

Mushtang said:

Still wouldn't be a BIG fireball. The stuff would burn, no doubt, and much much faster than in normal atmosphere if ignited, but the large cloud of oxygen wouldn't burn, just the stuff under it. The grass, birds, animals, would burn quickly and when done wouldn't burn anymore. People and cars would burn and take longer to finish burning, but no fireball of the cloud. Just a larger and hotter fire.

And it would take more than a slightest spark, unless the spark was so close to some fuel (grass, weeds, woods, insects, birds, snakes, etc.) that the hot spark would ignite the fuel. Otherwise the spark would burn brightly and burn itself out.

What you're describing is a large cloud of hydrogen or other fuel, not oxygen.

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So why did the Apollo capsule burn so violently then?

Lots of insulation on wires and other materials used in the construction became the fuel.