Author Topic: SpaceX News  (Read 127029 times)

WLJ

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Re: SpaceX News
« Reply #1525 on: July 20, 2022, 11:51:22 AM »
Artemis/SLS launch scheduled for Aug 29
Think Elon will try to beat that?
Does he even care?

I personally think there's at least 2-3 months of testing on SX's part still to do even if no more booms. If any issues found and/or another boom during testing it depends on what the problem is/cause the boom and what it damaged to guess on what effect that' would have on the timeline.

Of course Elon could just say ground testing is over and light it. Launching is testing
« Last Edit: July 20, 2022, 02:49:22 PM by WLJ »
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AZRedhawk44

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Re: SpaceX News
« Reply #1526 on: July 20, 2022, 12:12:42 PM »
There's been no static fire of the booster.  I don't think there's even been a nitrogen load/pressure test of B7 since the downcomer was replaced inside it.

I also don't think there's been a nitrogen load/pressure test of a full stack of B7 with S24 on top of it.  I'd expect that to happen prior to loading 7/24 with methalox, to confirm the ability of all structures to manage the load of a full rocket.

Finally, even the Starship hops had several scrubs due to variance between the 3 Raptors used for those hops.  33 Raptors on the booster along with 6 on Starship will result in a lot more opportunity for "out of range" variables to ship computer systems and lots of scrubs.
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WLJ

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Re: SpaceX News
« Reply #1527 on: July 20, 2022, 12:14:25 PM »
There's been no static fire of the booster.  I don't think there's even been a nitrogen load/pressure test of B7 since the downcomer was replaced inside it.

I also don't think there's been a nitrogen load/pressure test of a full stack of B7 with S24 on top of it.  I'd expect that to happen prior to loading 7/24 with methalox, to confirm the ability of all structures to manage the load of a full rocket.

Finally, even the Starship hops had several scrubs due to variance between the 3 Raptors used for those hops.  33 Raptors on the booster along with 6 on Starship will result in a lot more opportunity for "out of range" variables to ship computer systems and lots of scrubs.

Why I said "at least" 2-3 month barring problems.
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WLJ

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Re: SpaceX News
« Reply #1528 on: July 20, 2022, 12:15:43 PM »
Also Raptors 2s have never actually flown. Sill lots of unknowns with the 2s
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WLJ

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Re: SpaceX News
« Reply #1529 on: July 20, 2022, 02:25:47 PM »
LIVE: Starship 24 Conducts Engine Testing
https://www.youtube.com/watch?v=1fkXLP9MgdU
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kgbsquirrel

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Re: SpaceX News
« Reply #1530 on: July 21, 2022, 05:55:24 AM »
Also Raptors 2s have never actually flown. Sill lots of unknowns with the 2s

???

It's the functioning Raptor 1 minus all the excess instrumentation that was needed for the prototype development of said Raptor.  Why the doubt in the production model?

dogmush

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Re: SpaceX News
« Reply #1531 on: July 21, 2022, 06:50:47 AM »
I was under the impression that there were significant differences between the two. Big differences in the plumbing.




WLJ

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Re: SpaceX News
« Reply #1532 on: July 21, 2022, 08:01:15 AM »
???

It's the functioning Raptor 1 minus all the excess instrumentation that was needed for the prototype development of said Raptor.  Why the doubt in the production model?

They're really two different animals. Two is pushing the limits of what current rocket tech can do.
2 is leaner and meaner

Raptor 1 vs Raptor 2
https://everydayastronaut.com/spacex-raptor-engine-comparison/

Quote
Raptor 2’s MCC pressure is an astounding 300 bar, up 50 bar from Raptor 1 — the highest MCC pressure of any rocket engine ever. The previous record for the highest MCC pressure was the Russian RD-180, which runs at 267 bar pressure.

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WLJ

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Re: SpaceX News
« Reply #1533 on: July 21, 2022, 08:11:53 AM »
For comparison the Saturn V's F-1s were running at 70 bar. They produced so much thrust each by being so freaking big.

« Last Edit: July 21, 2022, 08:41:43 AM by WLJ »
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dogmush

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Re: SpaceX News
« Reply #1534 on: July 21, 2022, 08:14:31 AM »
I like how he still has the BE-4 on that chart, like it's a real engine and not vaporware.

WLJ

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Re: SpaceX News
« Reply #1535 on: July 21, 2022, 08:40:26 AM »
I like how he still has the BE-4 on that chart, like it's a real engine and not vaporware.

Last I saw flight engines were scheduled to be delivered to ULA for testing this month. Assuming that occurs and assuming they pass ULA's tests the first Vulcan Centaur launch could be as early as Dec. Subject to change of course.

Buuuut there could be delays due to issues with the payload.

The large Vulcan rocket is unlikely to make its debut in 2022
https://arstechnica.com/science/2022/06/the-large-vulcan-rocket-is-unlikely-to-make-its-debut-in-2022/
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WLJ

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Re: SpaceX News
« Reply #1536 on: July 21, 2022, 10:43:34 AM »
Quote
Falcon 9 is launching the Starlink 3-2 mission with 46 internet satellites onboard. Liftoff is scheduled for 10:39 a.m. PT (17:39 UTC) from SLC-4E, Vandenberg SFB, California.

SpaceX Falcon 9 Launches Starlink 3-2 Mission
https://www.youtube.com/watch?v=UP-1WXiRbXQ
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AZRedhawk44

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Re: SpaceX News
« Reply #1537 on: July 21, 2022, 10:58:32 AM »
For comparison the Saturn V's F-1s were running at 70 bar. They produced so much thrust each by being so freaking big.



One of the best metrics I've always liked about a liquid rocket engine is thrust per square meter of surface area.

The F1 has a diameter of 3.7 meters and generates 6.77MN.  That's a surface area of 10.75 square meters or 0.63 MN per square meter.
Raptor2 has a diameter of 1.3 meters and generates 2.00MN.  That's a surface area of 1.33 square meters or 1.50 MN per square meter.
BE-4 has a diameter of 1.9 meters (I think, harder to find numbers) and generates 2.4MN.  That's a surface area of 2.833 square meters or 0.85 MN per square meter.
Merlin has a diameter of 0.92 meters and generates 0.85MN.  That's a surface area of 0.66 square meters or 1.29 MN per square meter.
The RS-25/SSME has a diameter of 2.4 meters and generates 1.86-2.27MN, let's call it 2.0MN.  That's a surface area of 4.52 square meters or 0.44 MN per square meter.
The STS SRB's have a diameter of 3.7 meters and generate 14.7MN.  That's a surface area of 10.75 square meters or 1.37 MN per square meter.

The thing to keep in mind about a rocket engine is that it has to push the column of mass directly above it.  If the mass*gravity is greater than the engine's thrust, it's not going anywhere.  The stronger an engine is per square meter, the taller or heavier the column of fuel and payload can be above it, or the wider its column of responsibility can be for the total payload of the rocket.

BE-4 is kind of a depressing engine.  Less force-efficient for surface area than Merlin, let alone Raptor2.  It's barely half the engine that Raptor2 is.

Raptor2 is insane.  More thrust per square meter than a Shuttle SRB.
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WLJ

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Re: SpaceX News
« Reply #1538 on: July 21, 2022, 11:10:53 AM »
If you are comparing nozzle sizes for both Merlin and Raptor note there are sea-level nozzles and vacuum nozzles for both with the vacuum nozzles being far bigger. The vacuum nozzle Merlin is used on the Falcon 9's upper stage and Starship has both, 3 SL, 3 V (6 engines total) while the booster's 33 engines use SL nozzles only.
The engines don't change as far as I'm aware just the nozzles.

Not sure if BE-4 has both or not.
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AZRedhawk44

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Re: SpaceX News
« Reply #1539 on: July 21, 2022, 11:15:40 AM »
If you are comparing nozzle sizes for both Merlin and Raptor note there are sea-level nozzles and vacuum nozzles for both. The vacuum nozzles are far bigger. The vacuum nozzle Merlin is used on the Falcon 9's upper stage and Starship has both, 3 SL, 3 V (6 engines total) while the booster's 33 engines use SL nozzles only.
The engines don't change as far as I'm aware just the nozzles.

Right.  But with the exception of the RS-25, all these I listed are sea level dedicated engines (RS-25 is a hybrid that works in both regimes).  The Merlin, BE-4, and Raptor2 consider themselves reusable engines intended for booster functionality in an Earth environment only.  So their primary job is to lift a giant mass above them, then return to a landing site and safely recover the booster for another trip.  As such, the BE-4 is less capable than Merlin for force per square meter, let alone how impressive Raptor2 is for that task.
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WLJ

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Re: SpaceX News
« Reply #1540 on: July 21, 2022, 11:21:11 AM »
I was trying to add to what you said. Think my wording made it look otherwise    :-[
« Last Edit: July 21, 2022, 11:33:35 AM by WLJ »
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WLJ

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Re: SpaceX News
« Reply #1541 on: July 21, 2022, 11:22:09 AM »
For comparison

Sea-level nozzles inner
Vacuum nozzles outer
Same engines for both

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WLJ

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Re: SpaceX News
« Reply #1542 on: July 21, 2022, 11:54:04 AM »
There's also other factors in Raptors 2 favor, cost, product time, and suppositily better reliability
Don't have the number on hand but IIRC Raptor 2s will be far cheaper and with a far more rapid production rate than both Raptor 1s and BE-4s. I think something like one every 48 hours at half the of cost of R-1s.
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AZRedhawk44

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Re: SpaceX News
« Reply #1543 on: July 21, 2022, 12:13:09 PM »
Now I've started wondering about the mass of a fueled Shuttle era SRB versus a similar Raptor2-powered 3.7 meter diameter vehicle.

The SRB contained about 500 metric tons of solid propellant, that I bet per unit of volume is heavier than chilled Methalox. 

Wikipedia gives it a volume of 45 meters tall by 3.7 meters diameter, or 483.6 cubic meters.  That gives us a rate of 1.03 tons of propellant per cubic meter for the SRB in its solid configuration.  The SRB runs for 127 seconds during burn, giving us a burn rate of 3.94 metric tons per second and generating 14.7 MN thrust.

The SuperHeavy booster contains 3400 metric tons of Methalox, is 70 meters tall and a 9 meter diameter with a volume of 4451 cubic meters.  That gives us a rate of 0.76 tons of propellant per cubic meter, for volume of Methalox in the right ratio to run in a Raptor.  I've heard it reported that a Raptor2 burns about 600kg of propellant per second at full thrust.  Seven Raptor2's would generate 14 MN thrust and consume 4200kg methalox per second.  127 seconds of methalox at that rate would be a total volume of 533,400kg methalox, which is 33 tons heavier than an SRB's fuel payload.  And we're still 700kN short of the SRB's thrust.  Higher fuel consumption per second, more fuel needed, less power produced.  But at least it would be reusable, if you could come up with a landing regime for a side-strapped Raptor based booster.  Better solution is to use vertical staging with Raptor, as SuperHeavy's design shows.

The Shuttle SRB's really are amazing machines as far as thrust efficiency goes, it's just too bad they are effectively single-use and unthrottleable death traps.

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AZRedhawk44

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Re: SpaceX News
« Reply #1544 on: July 21, 2022, 12:17:54 PM »
There's also other factors in Raptors 2 favor, cost, product time, and suppositily better reliability
Don't have the number on hand but IIRC Raptor 2s will be far cheaper and with a far more rapid production rate than both Raptor 1s and BE-4s. I think something like one every 48 hours at half the of cost of R-1s.

I believe they're already past 1:48hours and are shooting for 1:24 hours.  Musk wants a $250k cost per unit but they're supposedly somewhere around $500k-$1M per unit right now.
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WLJ

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Re: SpaceX News
« Reply #1545 on: July 21, 2022, 12:55:54 PM »


The Shuttle SRB's really are amazing machines as far as thrust efficiency goes, it's just too bad they are effectively single-use and unthrottleable death traps.

They did fished them out of the ocean and reuse them, sort of.
Considering the fact they had to refurbish over 5,000 parts after each flight, yeah, I see your point.
Now I don't know if that over 5k number is for one or both. I suspect both.

Quote
Out of 270 SRBs launched over the Shuttle program, all but four were recovered – those from STS-4 (due to a parachute malfunction) and STS-51-L (Challenger disaster).[4] Over 5,000 parts were refurbished for reuse after each flight. The final set of SRBs that launched STS-135 included parts that had flown on 59 previous missions, including STS-1.[5] Recovery also allowed post-flight examination of the boosters,[6] identification of anomalies, and incremental design improvements.[7]
https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster
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WLJ

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Re: SpaceX News
« Reply #1546 on: July 21, 2022, 01:03:01 PM »
I believe they're already past 1:48hours and are shooting for 1:24 hours.  Musk wants a $250k cost per unit but they're supposedly somewhere around $500k-$1M per unit right now.

The reported numbers have been quite fluid. Problem is figuring out what are the real numbers and what are Elon's hoped for numbers.
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kgbsquirrel

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Re: SpaceX News
« Reply #1547 on: July 21, 2022, 01:09:17 PM »
They did fished them out of the ocean and reuse them, sort of.
Considering the fact they had to refurbish over 5,000 parts after each flight, yeah, I see your point.
Now I don't know if that over 5k number is for one or both. I suspect both.
https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster

And that is the distinction between reusable and refurbishable.  A Falcon-9 is reusable.  A space shuttle SRB (and the shuttle itself) is refurbishable.

dogmush

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Re: SpaceX News
« Reply #1548 on: July 21, 2022, 01:18:46 PM »
They did fished them out of the ocean and reuse them, sort of.
Considering the fact they had to refurbish over 5,000 parts after each flight, yeah, I see your point.
Now I don't know if that over 5k number is for one or both. I suspect both.
https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster

I was recently watching a documentary on the Challenger and it pointed out that fish them out for analysis and refurbishment plan, and how they knew they were having burn through issues at the joints, but the launch schedule was too full to do a redesign.

WLJ

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Re: SpaceX News
« Reply #1549 on: July 21, 2022, 01:24:49 PM »
And that is the distinction between reusable and refurbishable.  A Falcon-9 is reusable.  A space shuttle SRB (and the shuttle itself) is refurbishable.

Can remember them claiming a less than 1 week turnaround time then changing that to a 2 week turnaround time during the program's development for the entire vehicle package.
Looked it up. The fastest was 54 days pre Challenger, 88 days post Challenger.
Trying to find a reliable real world avg number But I'm pretty sure it was over 100 days
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