Author Topic: Starship Users Guide  (Read 33549 times)

Offline gaballard

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Re: Starship Users Guide
« Reply #40 on: 03/31/2020 06:09 pm »
Saw this bit at the bottom of the guide (emphasis mine):

Quote
For more information on additional capabilities or to conceptualize new ideas, please contact [email protected]

Well, fellow NSFers, you know what we have to do  ;D
"The only way of discovering the limits of the possible is to venture a little way past them into the impossible." - Clarke's Second Law

Offline ZachF

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Re: Starship Users Guide
« Reply #41 on: 03/31/2020 06:21 pm »
Starship will get a small boost for GTO payloads when launching from Boca Chica vs the Cape (28.6d vs 26.0d), about 65-70m/s.

Not a huge boost, but enough to theoretically add ~3 tonnes to the GTO-1800 payload vs the cape.
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Offline Thunderscreech

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Re: Starship Users Guide
« Reply #42 on: 03/31/2020 06:24 pm »
Can someone extrapolate from there if Dear Moon is still possible without refueling? When announced the mission profile did not show any tanker flights.
If you have a life support & habitat mass of 21 tons, then you can do a free return to GTO.  If you drop the mass of your hab in half, that's another 10.5 tons of propellant that can be used to push your mass further on the translunar injection burn.  So how far does 10 or so tons of propellant get you?  If the numbers I put into http://www.strout.net/info/science/delta-v/ are right, that's just 300 m/s (assuming a pre-hab dry mass of 110 tons) more impulse on that trans lunar burn.  If the hab and life support adds 5 tons onto a 110 ton baseline, then that goes to GTO+450 m/s. 

I might be messing something up really badly, but I can't figure out a way to shave the habitat mass down enough to get into the 3-4km/s that I think is needed for a free-return trajectory around the moon and it doesn't really even leave a reasonable amount of room for a landing fuel budget back on earth either.

Maybe expending the first stage (yikes) could help enough, but doesn't sound like it's an easy move from 21 tons to GTO->Lunar Free Return without refueling.
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Offline acsawdey

Re: Starship Users Guide
« Reply #43 on: 03/31/2020 06:29 pm »
Starship will get a small boost for GTO payloads when launching from Boca Chica vs the Cape (28.6d vs 26.0d), about 65-70m/s.

Not a huge boost, but enough to theoretically add ~3 tonnes to the GTO-1800 payload vs the cape.

Does that include the losses from the dogleg it has to do to get out of the Gulf of Mexico without overflying anyone?

Online Sciencefan

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Re: Starship Users Guide
« Reply #44 on: 03/31/2020 06:40 pm »
Please note the LEO payload is actually
Quote
Up to 500-km circular orbit at up to 98.9-deg inclination

I don't like statements like this because it don't mean up to 500 km orbit with 98.9-deg inclination.
On the other hand,
Quote
These performance numbers assume full Starship reuse, including Super Heavy return to launch site.
Landing somewhere else can add some perfomance for Dear Moon launch.

Online FutureSpaceTourist

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Re: Starship Users Guide
« Reply #45 on: 03/31/2020 07:04 pm »
twitter.com/erdayastronaut/status/1245052949170094082

Quote
Looks like @SpaceX is seriously underselling their LEO capability of #Starship. If Starship can send 21 tonnes to GTO-1800, assuming 120t dry mass and 380 ISP, thatís 156t to LEO 🤯 so either dry mass is less, ISP more or LEO will be over 150 tonnes 🤯 @elonmusk @flightclubio

https://twitter.com/elonmusk/status/1245063992361406464

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Mass of initial SN ships will be a little high & Isp a little low, but, over time, it will be ~150t to LEO fully reusable

Offline TrueBlueWitt

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Re: Starship Users Guide
« Reply #46 on: 03/31/2020 07:24 pm »
8 meter diameter works for LUVOIR A.. would it need the 22m length?

That looks like LUVOIR B  which would be a piece of cake for starship. Do they explicitly say LUVOIR A fits? I don't remember.

From The LUVOIR Final Report:

Quote
The final fairing dimensions are still being determined but SpaceX did conduct a preliminary analysis of a fairing whose shape was altered to fit LUVOIR-A (based on this studyís final concept models) and they reported that it was a viable option. Without modification, LUVOIR-B can fit into the currently plannedStarship fairing with room to spare as shown in Figure 10-9.
So the answer is "no, but we can work something up for you."

Thanks, was just reading through that myself. The picture was with B version.

I think A is where the "altered" longer 22m fairing comes in..  Can't think of anything else that would need it offhand?

Offline OTV Booster

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Re: Starship Users Guide
« Reply #47 on: 03/31/2020 08:21 pm »
(Pet peeve: "mT" means milli-tesla; the proper abbrevation for the metric tonne is "t".)

Lol, it always felt weird to me too, but I thought that was what US-ians used if they didn't want it confused with short tons.


Hey, them there is good ol merican tons. We donít short nobody, and we donít throw no extra letters in to make them heavier.  :o


Peace, Bro.


Phil
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Offline TheRadicalModerate

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Re: Starship Users Guide
« Reply #48 on: 03/31/2020 08:28 pm »
My initial thoughts:

1) Payload volume of the standard bay is 660 m≥ if you model the nose as a frustum (which it isn't, but pretty close).

2) This "extended payload volume" comment is interesting. I'm guessing that that's for an expendable system without header tanks. I can't imagine that they can stretch the nose with the canards there. I guess that it's possible that they're planning on adding an extra 5 m to the cylindrical section but that's not shown in the renderings.

3) If I'm right about #2, then that makes the header tanks have a volume of about 12 m≥. That's about 10.6 t of prop, which would be 290 m/s of delta-v on an empty ship if the average Isp is about 345 s. That might work to land empty on Earth, but it's nowhere close on Mars, especially when landing cargo. I wonder if the whole header tank idea has gone bye-bye. (It certainly has if that crew rendering is to be believed...)

4) They're sticking with the chomper! I simply don't understand this.

5) I especially don't understand the chomper in light of them offering the F9- and FH-compatible clamp-band payload attach fittings. Seems like you'd wind up with separation debris wandering around in the payload bay. Also, how does a system designed to move payload axially away from the vehicle suddenly wind up lifting them out to avoid the fixed clamshell at the bottom of the bay?

6) Vertical integration only!

7) They're advertising 100+ t payload to 500x500x98.9ļ polar orbits. I assume that that's with the KSC-based dogleg trajectory over Cuba. That implies that the normal 200x200x28.5ļ LEO capacity must be well over 100 t.

8) I'm a bit surprised to see the crew version with windows. I was almost certain that the first crew modules would be essentially payloads integrated into the regular payload bay. I suppose that the crew variants could just be "aspirational", to use one of Elon's favorite words. The point of this document is to drive non-crew payload planning.

9) Take a look at the legs in the lunar cargo picture. They're still just in-line telescoping legs. I've thought for a while that the only way you can do rough-surface landing is with self-leveling legs with linear brakes that clamp when all legs show that they're on the surface, and this seems to be headed in that direction. Wide-base fold-out legs have to be huge to handle the likely set of terrain cases.

10) I'll be very interested in seeing how SpaceX provides Shuttle-like supports for trunnions on co-manifested payloads. Given the enormous space, this seems like something where a lot more details will emerge as they get deeper into the program. It's not good practice for SpaceX to rely on payload integrators to devise and test that kind of hardware. Also, the "just mount stuff side-by-side on multiple PAFs" recommendation is interesting.

11) Note that the surface cargo payload bay is divided into shelves to offload separate modules. I wonder if this is just fanciful or whether there's engineering behind this.

12) It appears that for surface offload, they're using part of the fairing as the elevator platform. That's... interesting. I'll be curious to see how well they do packing it back in place for the return trip. Doesn't seem like a super-reliable plan to take part of your fairing, load it with random stuff, plunk it on the ground, roll stuff off of it, and then reposition it back in place for reentry.

Offline whitelancer64

Re: Starship Users Guide
« Reply #49 on: 03/31/2020 08:32 pm »
8 meter diameter works for LUVOIR A.. would it need the 22m length?

That looks like LUVOIR B  which would be a piece of cake for starship. Do they explicitly say LUVOIR A fits? I don't remember.

From The LUVOIR Final Report:

Quote
The final fairing dimensions are still being determined but SpaceX did conduct a preliminary analysis of a fairing whose shape was altered to fit LUVOIR-A (based on this studyís final concept models) and they reported that it was a viable option. Without modification, LUVOIR-B can fit into the currently plannedStarship fairing with room to spare as shown in Figure 10-9.
So the answer is "no, but we can work something up for you."

Thanks, was just reading through that myself. The picture was with B version.

I think A is where the "altered" longer 22m fairing comes in..  Can't think of anything else that would need it offhand?

Two Kibo modules welded end-to-end?
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Offline OTV Booster

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Re: Starship Users Guide
« Reply #50 on: 03/31/2020 08:32 pm »
I thought this was noteworthy:
"An extended payload volume is also available for payloads requiring up to 22 m of height."

So this and the way the payload gets integrated indicates (as others have noted) that the payload section of Starship will be separated from the propulsion section. Have we seen anything at Boca Chica with the current SNs that would be features involved in the mating and de-mating of these two pieces?

Mating different upper sections has been a point of debate, as has customized variants. If this doesnít change both questions have been answered.

The difference between 17.23m and 22 meters comes out to about 2.5 rings.

We havenít seen anything like a detach mechanism, but then we really havenít seen the upper section permanently mounted on any SS. Give it time. They need to fly before nose swap comes up high enough on the list to get detailed attention. Iíd guess an orbital flight before it shows up.

Phil
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

Re: Starship Users Guide
« Reply #51 on: 03/31/2020 08:35 pm »
Could someone please  add Version 1.0 to the thread title. We all know its going to change sooner rather then later. 

Offline whitelancer64

Re: Starship Users Guide
« Reply #52 on: 03/31/2020 08:41 pm »
My initial thoughts:

5) I especially don't understand the chomper in light of them offering the F9- and FH-compatible clamp-band payload attach fittings. Seems like you'd wind up with separation debris wandering around in the payload bay. Also, how does a system designed to move payload axially away from the vehicle suddenly wind up lifting them out to avoid the fixed clamshell at the bottom of the bay?


Based on the deployment render, I think the PAF must be hinged to angle the payload prior to deployment.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
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Offline Coastal Ron

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Re: Starship Users Guide
« Reply #53 on: 03/31/2020 08:41 pm »
Many of us have been working on space station designs, and no doubt all of us have been wondering how large of payloads we could fit inside of a Starship. Now we know, and I marked up the diagram in the Users Guide to make it easier to see what size cylindrical modules could fit.

As a note, for some of my rotating space station designs, I had been hoping for a minimum of 8m in diameter by 10m in length, but I can get by with 7m in diameter and 10m in length if it means transportation costs are significantly less.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline ZachF

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Re: Starship Users Guide
« Reply #54 on: 03/31/2020 08:44 pm »
Many of us have been working on space station designs, and no doubt all of us have been wondering how large of payloads we could fit inside of a Starship. Now we know, and I marked up the diagram in the Users Guide to make it easier to see what size cylindrical modules could fit.

As a note, for some of my rotating space station designs, I had been hoping for a minimum of 8m in diameter by 10m in length, but I can get by with 7m in diameter and 10m in length if it means transportation costs are significantly less.

It looks like there will be an "XL" variant that is ~5m longer if you need it.
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Offline TheRadicalModerate

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Re: Starship Users Guide
« Reply #55 on: 03/31/2020 08:45 pm »
> 21ton to GTO

That's somewhat unexpected. I remember claims that GTO payload was zero without a separate third stage.

It can't go direct to GEO without refueling, but GTO is another story.  I get almost exactly 21 t to GTO in my model (which is a first; it's hardly ever that accurate).  Note that the GTO that they're specifying is GEO-1800 m/s.

Offline TheRadicalModerate

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Re: Starship Users Guide
« Reply #56 on: 03/31/2020 08:47 pm »
My initial thoughts:

5) I especially don't understand the chomper in light of them offering the F9- and FH-compatible clamp-band payload attach fittings. Seems like you'd wind up with separation debris wandering around in the payload bay. Also, how does a system designed to move payload axially away from the vehicle suddenly wind up lifting them out to avoid the fixed clamshell at the bottom of the bay?


Based on the deployment render, I think the PAF must be hinged to angle the payload prior to deployment.

After a second read, that's what I think as well.

Anybody know about what kinds of separation debris you get coming off of a clamp-band PAF?

Offline TheRadicalModerate

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Re: Starship Users Guide
« Reply #57 on: 03/31/2020 08:52 pm »
The images are already out of date - leg fairing covers are so last week.

They are still showing the big picture window on the manned version. Weíve sort of assumed that the lox header in the nose killed that off, but that is not necessarily the case. The nose header is needed to bring CoG forward during entry with an empty fairing. The manned version will always have a lot of mass forward so the header could be mounted further aft.

I'm wondering if they've abandoned the header tanks in the nose.  Both the crew and chomper renders are inconsistent with header tanks.  I was also wondering whether the 22 m "extended" version was simply a version without header tanks, but I don't think the geometry works out as I look at it a bit more.
« Last Edit: 03/31/2020 08:52 pm by TheRadicalModerate »

Offline tbellman

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Re: Starship Users Guide
« Reply #58 on: 03/31/2020 09:00 pm »
Based on the deployment render, I think the PAF must be hinged to angle the payload prior to deployment.

That's even explicitly stated, on page 2 (the third page in the PDF):

Quote
To deploy the payload, the clamshell fairing door is opened, and the payload adapter and payload are tilted at an angle in preparation for separation.

Offline gpm

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Re: Starship Users Guide
« Reply #59 on: 03/31/2020 09:05 pm »
My initial thoughts:

8\) I'm a bit surprised to see the crew version with windows. I was almost certain that the first crew modules would be essentially payloads integrated into the regular payload bay. I suppose that the crew variants could just be "aspirational", to use one of Elon's favorite words. The point of this document is to drive non-crew payload planning.

I don't think windows are optional for dear moon considering the goal is a pleasure cruise around the moon for a rich patron and some artists. I suppose technically this could be done with a windowed vessel inside a chomper and have the chomper open, but that sounds like a big mass penalty for not much benefit.
« Last Edit: 03/31/2020 09:06 pm by gpm »

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