Author Topic: SpaceX - now a satellite manufacturer (Starlink)  (Read 679044 times)

Online docmordrid

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2500 on: 02/11/2019 07:50 pm »
Quote
& will if BFR takes longer than expected

So no larger fairing for Starlink, based on current Starship timeline positivity.

Except that very recently  Musk said v1 of StarLink goes up on Falcon and v2 goes up on Starship.

If the #1 goal is getting v1 birds in orbit ASAP and the system producing income (stated: 800 satellites) the number of Falcon flights are minimized by a larger Falcon fairing.
« Last Edit: 02/11/2019 07:52 pm by docmordrid »
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Offline Cheapchips

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2501 on: 02/11/2019 08:39 pm »
My logic of saying no (meant probably not really) to a larger fairing, based on a Musk tweet is a pretty shaky assumption. A tweet from a year ago is a really shaky assumption.  :)

Insight on what goes into fairing development would be really interesting.

Would a longer fairing be even harder to recover?  That's something they need to factor in too.
« Last Edit: 02/11/2019 08:39 pm by Cheapchips »

Offline DistantTemple

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2502 on: 02/11/2019 09:01 pm »
My logic of saying no (meant probably not really) to a larger fairing, based on a Musk tweet is a pretty shaky assumption. A tweet from a year ago is a really shaky assumption.  :)

Insight on what goes into fairing development would be really interesting.

Would a longer fairing be even harder to recover?  That's something they need to factor in too.
mmm At first sight making something a bit longer like the F9 from V1 through to block5 just means making longer tanks, and tweaking a few things... however the fairing is a different matter. It takes the brutal air resistance through maxQ. and all it is, is a flimsy carbon fibre shell. Its a greater diameter than the S2 below it, and is only attached through a ring at its base. There will be lots of resonant vibration modes to mitigate. I bet any change would require quite a bit of analysis and experiment, at least about vibration and resonance. I've no idea if SX have sufficient facilities for these tests or if they have to use something like NASA's AAPL (Aero Acoustic Propulsion Laboratory). I would guess resonance could localise destructive vibrations, causing a breakdown of the laminate, and mission failure. So IMO (not an engineer) stretching the fairing is a much higher risk, and expensive issue than it appears. After all its not just a boat hull despite looking like it.
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Offline SDSmith

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2503 on: 02/12/2019 09:38 am »
My logic of saying no (meant probably not really) to a larger fairing, based on a Musk tweet is a pretty shaky assumption. A tweet from a year ago is a really shaky assumption.  :)

Insight on what goes into fairing development would be really interesting.

Would a longer fairing be even harder to recover?  That's something they need to factor in too.
mmm At first sight making something a bit longer like the F9 from V1 through to block5 just means making longer tanks, and tweaking a few things... however the fairing is a different matter. It takes the brutal air resistance through maxQ. and all it is, is a flimsy carbon fibre shell. Its a greater diameter than the S2 below it, and is only attached through a ring at its base. There will be lots of resonant vibration modes to mitigate. I bet any change would require quite a bit of analysis and experiment, at least about vibration and resonance. I've no idea if SX have sufficient facilities for these tests or if they have to use something like NASA's AAPL (Aero Acoustic Propulsion Laboratory). I would guess resonance could localise destructive vibrations, causing a breakdown of the laminate, and mission failure. So IMO (not an engineer) stretching the fairing is a much higher risk, and expensive issue than it appears. After all its not just a boat hull despite looking like it.
The fairing currently is road transportable. If they increase the size of the fairing it might might not be transportable by truck or cost prohibitive.

Offline OccasionalTraveller

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2504 on: 02/12/2019 02:57 pm »
The fairing currently is road transportable. If they increase the size of the fairing it might might not be transportable by truck or cost prohibitive.

The fairing is transported on two trucks, each one carrying half, tilted so that the separation plane is at 45° to the truck bed. Here's a photo from 2008 (I believe the process is still substantially the same):



(Source)

A longer fairing will require a longer truck bed, which will be more difficult to take round corners, but it's still going to be shorter than S1. The logical size would be designed around the Heavy Payload Class envelope from the EELV Standard Interface Specification - 480" tall in the barrel section (180" diameter), tapering to 57" diameter over 169". For those of us working in metric, that's a cylinder 4.5 x 12.1m plus 4.2m of truncated cone, for a total length of ~16.2m. This is about the same length as the second stage, based on Ed Kyle's estimate.

Increasing the diameter of the fairing is likely to be harder to transport by road, so I'd expect an increase in height rather than an increase in width, even if you don't take the USAF requirement into account.

Offline dglow

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2505 on: 02/12/2019 05:12 pm »
Why does SpaceX continue to research fairing recovery, and why have they flirted with S2 recovery despite BFR looming on the horizon? The need to launch 100s of satellites, sooner than later, and to do so in the most cost-effective manner, is why. Starlink is the motivating factor.

SpaceX will be designing the deployment tube for Starlink. If in that process a larger fairing proves beneficial, then it will be done. And they'll fold-in their latest recovery learnings and advancements.

ISTM the decision point is less likely to be the effort of designing and testing a larger fairing, and more likely whether F9 or FH becomes the most logistically efficient means of deployment.

It will be fun to watch and see.   :)

Online docmordrid

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2506 on: 02/12/2019 07:02 pm »
Why does SpaceX continue to research fairing recovery, and why have they flirted with S2 recovery despite BFR looming on the horizon?
>

Because Musk tweeted,

Quote
Starlink V1 on Falcon, V2+ on Starship. Basically, all future products will contain either the word “star” or “link” 😀

Meaning a bunch of Falcon StarLink launches, and recovering those fairings saves about $6 million a pop.
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Offline dglow

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2507 on: 02/12/2019 07:36 pm »
Why does SpaceX continue to research fairing recovery, and why have they flirted with S2 recovery despite BFR looming on the horizon?
>

Because Musk tweeted,

Quote
Starlink V1 on Falcon, V2+ on Starship. Basically, all future products will contain either the word “star” or “link” 😀

Meaning a bunch of Falcon StarLink launches, and recovering those fairings saves about $6 million a pop.


Exactly. But they are not pursuing S2 recovery, which could have saved far more than $6M/launch. Clearly they're picking their battles here, and it sounds like we both agree that developing a larger fairing would be fair game.

Speaking of which, I'd like to know what the consensus is on the "V2+" portion of Musk's quote: does this refer to hardware (satellite) iterations, phases of constellation build-out, or both?

Online ThomasGadd

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2508 on: 02/12/2019 08:02 pm »
Why does SpaceX continue to research fairing recovery, and why have they flirted with S2 recovery despite BFR looming on the horizon?
>

Because Musk tweeted,

Quote
Starlink V1 on Falcon, V2+ on Starship. Basically, all future products will contain either the word “star” or “link” 😀

Meaning a bunch of Falcon StarLink launches, and recovering those fairings saves about $6 million a pop.


Exactly. But they are not pursuing S2 recovery, which could have saved far more than $6M/launch. Clearly they're picking their battles here, and it sounds like we both agree that developing a larger fairing would be fair game.

Speaking of which, I'd like to know what the consensus is on the "V2+" portion of Musk's quote: does this refer to hardware (satellite) iterations, phases of constellation build-out, or both?

Don't know of course... but the initial launches were changed to 550 km which are within Falcon 9  reach.  The higher orbits are possible with fewer satellites per launch.  This gives them options to choose from.
« Last Edit: 02/12/2019 08:05 pm by ThomasGadd »

Online docmordrid

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2509 on: 02/12/2019 08:32 pm »
>
Speaking of which, I'd like to know what the consensus is on the "V2+" portion of Musk's quote: does this refer to hardware (satellite) iterations, phases of constellation build-out, or both?
I've been assuming V2 is upgraded birds for the VLEO constellation and follow-ons for LEO.
« Last Edit: 02/12/2019 08:39 pm by docmordrid »
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Offline Lar

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2510 on: 02/12/2019 08:36 pm »
Exactly. But they are not pursuing S2 recovery, which could have saved far more than $6M/launch. Clearly they're picking their battles here, and it sounds like we both agree that developing a larger fairing would be fair game.
S2 recovery might save more but it also would for sure cost more than fairing recovery.
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Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2511 on: 02/12/2019 09:14 pm »
Why does SpaceX continue to research fairing recovery, and why have they flirted with S2 recovery despite BFR looming on the horizon?
>

Because Musk tweeted,

Quote
Starlink V1 on Falcon, V2+ on Starship. Basically, all future products will contain either the word “star” or “link” 😀

Meaning a bunch of Falcon StarLink launches, and recovering those fairings saves about $6 million a pop.


Exactly. But they are not pursuing S2 recovery, which could have saved far more than $6M/launch. Clearly they're picking their battles here, and it sounds like we both agree that developing a larger fairing would be fair game.

Speaking of which, I'd like to know what the consensus is on the "V2+" portion of Musk's quote: does this refer to hardware (satellite) iterations, phases of constellation build-out, or both?

I don't think it would be "far more". The upper stage probably only costs about twice as much as the fairing, and the cost and mass penalty for reuse probably eats most of that back down to the $6m range. Fairings are much lower hanging fruit.

Offline Lar

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2512 on: 02/12/2019 11:16 pm »
It's a much more complex problem than catching a fluffy thing like a fairing. I think we have a thread for S2 reuse somewhere. And for fairing reuse. But I don't know if we have a thread for debating which is the better investment LOL.
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Online gongora

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2513 on: 02/12/2019 11:31 pm »
Don't know of course... but the initial launches were changed to 550 km which are within Falcon 9  reach.  The higher orbits are possible with fewer satellites per launch.  This gives them options to choose from.

They were never deploying directly to 1000km, they would be deployed around 500-600km and raise themselves.

Online gongora

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2514 on: 02/12/2019 11:34 pm »
>
Speaking of which, I'd like to know what the consensus is on the "V2+" portion of Musk's quote: does this refer to hardware (satellite) iterations, phases of constellation build-out, or both?
I've been assuming V2 is upgraded birds for the VLEO constellation and follow-ons for LEO.

I'm assuming V1 is either half or all of the initial ~1600 sats they want to deploy.  I doubt they have any firm plans past that, it will probably depend on how both satellite and launcher development are going.

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Offline dglow

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2516 on: 02/13/2019 01:21 am »
wow, nice

Offline Zed_Noir

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2517 on: 02/13/2019 02:37 am »
The fairing currently is road transportable. If they increase the size of the fairing it might might not be transportable by truck or cost prohibitive.

The fairing is transported on two trucks, each one carrying half, tilted so that the separation plane is at 45° to the truck bed.
....
A longer fairing will require a longer truck bed, which will be more difficult to take round corners, but it's still going to be shorter than S1. The logical size would be designed around the Heavy Payload Class envelope from the EELV Standard Interface Specification - 480" tall in the barrel section (180" diameter), tapering to 57" diameter over 169". For those of us working in metric, that's a cylinder 4.5 x 12.1m plus 4.2m of truncated cone, for a total length of ~16.2m. This is about the same length as the second stage, based on Ed Kyle's estimate.

Increasing the diameter of the fairing is likely to be harder to transport by road, so I'd expect an increase in height rather than an increase in width....

Can SpaceX make a wider payload fairing with 3 parts instead of the current 2 parts? So 3 semi-trailers instead of 2.

I recall one of the fairing used by the Titan have 3 parts.

Online gongora

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2518 on: 02/13/2019 02:44 am »
If SpaceX got to the point where they could recover a large fairing and refurbish it at the launch site then the cost of transporting them to the launch site would probably become irrelevant in the grand scheme of things.  If it's too big to take on the road then haul them in cargo planes.

Online ThomasGadd

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2519 on: 02/13/2019 02:44 am »
Don't know of course... but the initial launches were changed to 550 km which are within Falcon 9  reach.  The higher orbits are possible with fewer satellites per launch.  This gives them options to choose from.

They were never deploying directly to 1000km, they would be deployed around 500-600km and raise themselves.

I got that wrong then.  I'll find the fcc doc and reread it. 
It will take time and a lot of fuel for the satellites raise there orbits.  I thought they would be deployed closer to there final orbits.
 

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