SpaceX

[docmordrid]

Matthew Keegan @keego73
Hi Elon. My 12yo son Finlay is doing an assignment on the colonisation of our solar system and wants to know how many crew members would be in the BFR on such a mission.
Thanks @elonmusk
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Elon Musk ✔ @elonmusk
Its designed for 100 people on a Mars journey
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Everyday Astronaut @Erdayastronaut
Replying to @elonmusk @keego73
I just realized another major advantage to stainless steel on Starship. It could literally be repaired with a welder!!!! Something thats not nearly as easy when dealing with composites. Imagine a super banged up Starship with patches and dings after decades of use ��
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Elon Musk ✔ @elonmusk
Absolutely. Youve touched on a very important point. The ship must be easy to repair on the moon and Mars.
5:13 PM - Jan 31, 2019
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Everyday Astronaut
@Erdayastronaut
· 2h
Replying to @elonmusk @keego73
Still planning to use methalox RCS thrusters and not cold gas? If so, how do you get those to be quick enough to function as RCS?
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Elon Musk ✔ @elonmusk
Cold gas thrusters only. Will use body flaps & main engines for landing orientation, so wont need high thrust reaction control. Simplifies things considerably
9:21 PM - Jan 31, 2019
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Anthony Iemole @SpaceXFan97
· 2h
Replying to @elonmusk and 4 others
How many engines will be on SuperHeavy? Looks like the engine is to big to fit 31 of them on there.
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Elon Musk ✔ @elonmusk
Still up to 31. Will probably fly with fewer initially in case it blows up.
9:30 PM - Jan 31, 2019

[docmordrid]

Super Heavy may get leg-fins too....

Elon Musk ✔ @elonmusk
Will probably make booster legs/flaps same as ship, instead of like F9
8:33 PM - Jan 31, 2019

[Nicolas]

Raptor certainly is a lot larger than Merlin. In terms of size, a Rocketdyne F-1 still is incredibly much larger though. But given the increased reliability and containment of the propulsion system since the '60s, it might be wiser and faster to go for 30 medium engines instead of 5 ginormous ones. And I'm just talking size here. Isp comparison is a more relevant one.

[docmordrid]

SpaceX VP of Propulsion Tom Mueller also stresses thrust to weight ratio. Most engines are 60-80:1. Merlin is over 100:1, and Mueller says Raptor will beat that. Guesses are running 150:1 or more.

[cjameshuff]

SpaceX VP of Propulsion Tom Mueller also stresses thrust to weight ratio. Most engines are 60-80:1. Merlin is over 100:1, and Mueller says Raptor will beat that. Guesses are running 150:1 or more.

Merlin Vacuum has a T/W of 180.

Between the less-dense propellant and more-complex driving machinery, Raptor seems unlikely to beat Merlin on that metric. Do you have a cite for Mueller's stating otherwise?

[docmordrid]

Merlin Vacuum has a T/W of 180.

Between the less-dense propellant and more-complex driving machinery, Raptor seems unlikely to beat Merlin on that metric. Do you have a cite for Mueller's stating otherwise?

GeekWire: May 24, 2018, quoting Mueller at ISDC

https://www.geekwire.com/2018/spacex...-engines-mars/

Engine development is on track for next year’s anticipated start of short-hop flight tests of the BFR upper-stage spaceship.
>
We’ve got the first flight version of that engine in work. We’ve been running the development engine quite a bit. It’s running great,” Mueller told the audience.

“The Merlin holds the thrust-to-weight record for now,” he said. “But the Raptor’s coming.”

[Nicolas]

Another thing is that, thanks to reusability, commercially it's not too relevant if 32 engines would be more expensive than 5 big ones.

[Trebuchet]

Maybe cheaper, even, if one fails. Less chance of affecting the mission and you only need to replace 1/32 of them when it gets back.

[docmordrid]

Incoming!!

Elon Musk ✔ @elonmusk
At @SpaceX Texas with engineering team getting ready to fire new Raptor rocket engine
2:15 AM - Feb 3, 2019

https://twitter.com/elonmusk/status/1091958352513425408

IMG_20190203_021936.jpg

[docmordrid]

YAY!!!!

Elon Musk ✔ @elonmusk
First firing of Starship Raptor flight engine! So proud of great work by @SpaceX team!!
10:49 PM - Feb 3, 2019

https://twitter.com/elonmusk/status/1092268892339273730

https://twitter.com/elonmusk/status/1092270756715737088

https://twitter.com/elonmusk/status/1092272377889738753

IMG_20190203_225532.jpg

[docmordrid]

Everyday Astronaut @Erdayastronaut
Replying to @elonmusk and 2 others
Methalox torch igniters... So what starts those? Is there like a spark plug or something?! OR LASERS?
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Elon Musk ✔ @elonmusk
Gaseous CH4/O2 & heavy duty spark plugs. Basically, a {fart emoji} of insane power
11:42 PM - Feb 3, 2019

[Swift]

[docmordrid]

SpaceX Instagram:

https://www.instagram.com/p/BteDxoUFUOX/

Completed a two-second test fire of the Starship Raptor engine that hit 170 bar and ~116 metric tons of force the highest thrust ever from a SpaceX engine and Raptor was at ~60% power.

Goal: 200 metric tons of thrust, then a 250 metric ton Raptor "Full Thrust"

Audio corrected for camera-engine audio delay by redditor u/melancholicricebowl

Careful with your audio levels

https://streamable.com/nl6y7

[bknight]

SpaceX Instagram:

https://www.instagram.com/p/BteDxoUFUOX/



Goal: 200 metric tons of thrust, then a 250 metric ton Raptor "Full Thrust"

Audio corrected for camera-engine audio delay by redditor u/melancholicricebowl

Careful with your audio levels

https://streamable.com/nl6y7

I wondered why they only briefly fired the engine?

[docmordrid]

SOP for them, especially with a new engine. They'll do a "burp test" like this, then ramp it up. Even with production Merlins they'll do a few burns before installing them on a stage for a full burn at McGregor, then they'll ship the dtage and do a static fire at the launch site before the launch.

They bake in the required toughness so they can test-test-test...

[publiusr]

Super Heavy may get leg-fins too....

Elon Musk ✔ @elonmusk
Will probably make booster legs/flaps same as ship, instead of like F9
8:33 PM - Jan 31, 2019

I wonder if that would get in the way of this notional three core super-heavy:
https://www.nextbigfuture.com/2019/0...-starship.html

That might allow Starship to have some weight creep and it not be as big a deal?

[docmordrid]

There won't be a 3 core Super Heavy Heavy. They'll grow it from 9 to 12 + meters.

In part ISS scheduling,

Michael Sheetz ✔ @thesheetztweetz
NASA will announce tomorrow @SpaceX Demo-1 is targeting no earlier than March 2 at 02:45 ET (07:45 UTC) for launch, a source familiar tells me.

This matches with the operation start date in SpaceXs FCC filing last week: https://apps.fcc.gov/oetcf/els/repor...stTimeout=1000
8:10 PM - Feb 5, 2019

https://twitter.com/thesheetztweetz/...53600773509127

[docmordrid]

SpaceX ✔ @SpaceX
Targeting March 2 for Crew Dragon's first flight to the @Space_Station http://blogs.nasa.gov/commercialcrew/2019/02/06/
4:23 PM - Feb 6, 2019

https://twitter.com/SpaceX/status/1093258801518530560

CrewDragonFeb6.jpg

[docmordrid]

This was quick! If I grok this correctly....

Boiling cryo: 172 tons = 1686.74 kN = 379,195 lbf

+10% for deep cryo gives: 189.2 tons = 1,855.414 kN = 417,114.5 lbf

with another ~10% on the table

Elon Musk ✔ @elonmusk
Raptor just achieved power level needed for Starship & Super Heavy

IMG_20190207_035259.jpg
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Elon Musk ✔ @elonmusk
Design requires at least 170 metric tons of force. Engine reached 172 mT & 257 bar chamber pressure with warm propellant, which means 10% to 20% more with deep cryo.
3:22 AM - Feb 7, 2019
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Andre Infante @AndreTI
Replying to @elonmusk
Did you folks track down the source of the green hue?
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Elon Musk ✔ @elonmusk
Vaporized some copper
3:39 AM - Feb 7, 2019
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Griddy McGridFinFace @FalconGridFin
Also wait. You're saying Raptor is designed to run at BOTH cryo and deep cryo temps? This engine is nuts! Thanks
3:25 AM - Feb 7, 2019

https://twitter.com/elonmusk/status/1093423297130156033

[Van Rijn]

I have to say until recently I was doubtful there would be any real BFR hardware, especially since this does seem to be pushing more into new technological territory, and am very happy to see they are moving forward with Raptor engines and a test rocket.

[docmordrid]

Here comes StarLink

FCC filing:

https://fcc.report/IBFS/SES-LIC-INTR2019-00217/1616678

>
The Commission has authorized Space Exploration Holdings, LLC (SpaceX) to launch and operate a constellation of 4,425 non-geostationary orbit (NGSO) satellites (call sign S2983/S3018) using Ku- and Ka-band spectrum. In doing so, the Commission recognized that granting the SpaceX Authorization would enable SpaceX to bring high-speed, reliable, and affordable broadband service to consumers in the United States and around the world, including areas underserved or currently unserved by existing networks. SpaceX intends to begin launching satellites to populate its constellation in 2019.

In this application, a sister company, SpaceX Services, Inc. (SpaceX Services) seeks a blanket license authorizing operation of up to 1,000,000 earth stations that end-user customers will utilize to communicate with SpaceXs NGSO constellation. These user terminals employ advanced phased-array beam-forming and digital processing technologies to make highly efficient use of Ku-band spectrum resources by supporting highly directive, steered antenna beams that track the systems low-Earth orbit satellites. Consistent with SpaceXs space station authorization, these earth stations will transmit in the 14.0-14.5 GHz band and receive in the 10.7-12.7 GHz band.
>

[docmordrid]

And...

Jeff Foust @jeff_foust
Hofeller: SpaceX is interested in doing dedicated rideshare missions like SSO-A on a regular basis. Would be great to do them one or two times a year. #smallsat2019
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Jeff Foust @jeff_foust
Hofeller says SpaceX will be rolling out a “more formalized” smallsat launch plan in the near future. #smallsat2019
7:23 PM - Feb 6, 2019

https://twitter.com/jeff_foust/statu...04287495704576

[7cscb]

docmordrid,

I agree the StarLink news is a bell ringer. It (and other similar services) will have a huge impact on personal internet BW worldwide. And if this all pans out Elon will make more money than all his other ventures combined. And he promises to continue plowing money right back into the business.

As to your other info on rideshare, I think these types of programs are bad news for the small launch businesses sprouting up across the globe.

[KaiYeves]

docmordrid,

I agree the StarLink news is a bell ringer. It (and other similar services) will have a huge impact on personal internet BW worldwide. And if this all pans out Elon will make more money than all his other ventures combined. And he promises to continue plowing money right back into the business.

As to your other info on rideshare, I think these types of programs are bad news for the small launch businesses sprouting up across the globe.

So, will StarLink unite the world? ;-)

[docmordrid]

So, will StarLink unite the world? ;-)

What the probability of StarLink, OneWeb, Telesat etc. being deployed has done is slow geostationary satellite procurements to a crawl. A very big deal.

[KaiYeves]

What the probability of StarLink, OneWeb, Telesat etc. being deployed has done is slow geostationary satellite procurements to a crawl. A very big deal.

I was joking about the arcade game Time Crisis 2 being based around a very-similarly-named fictional communications satellite network, StarLine. In the opening scene there, the leader of the project says “StarLine will unite the world!” (And, of course, being an arcade espionage game, the whole project turns out to have a darker side.)

[Extravoice]

...turns out to have a darker side.

As does widespread Internet connectivity, sadly.

But that’s pretty much true for any endeavor that involves humans.


Sent from my iPhone using Tapatalk

[docmordrid]

Darkaraus @Darkaraus_
Replying to @elonmusk @Zanfa
But Elon, did the Spaceship lost payload capacity with the stainless steel?
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Elon Musk ✔ @elonmusk
No, payload will actually increase

https://twitter.com/elonmusk/status/1091816304967790592

[publiusr]

I have to say until recently I was doubtful there would be any real BFR hardware, especially since this does seem to be pushing more into new technological territory, and am very happy to see they are moving forward with Raptor engines and a test rocket.

I'm just happy they abandoned composites for metal. Then too, did folks wrap cannon with piano wire to make it stronger. A composite wrap might not be out of the question, one day.

[Glom]

Another thing is that, thanks to reusability, commercially it's not too relevant if 32 engines would be more expensive than 5 big ones.

The airlines seem to consider engine count to be important. But then aeroengine reliability is ridiculous these days.