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SpaceX Vehicles and Missions => SpaceX General Section => Topic started by: Jim on 05/03/2017 05:55 PM

Title: Raptor Upper Stage consolidated thread
Post by: Jim on 05/03/2017 05:55 PM
Edit/Lar: This thread exists for all  "Raptor Upper Stage" (RUS) related discussion. From this time point forward, posts about RUS may be, in fact should be, moved to this thread. The following commercial announcement explains why this thread exists.

Links to pertinent discussion threads with significant RUS discussion pre this time point:
<PM me>

---
The proposal is that talk of "Raptor Upper Stage" be eliminated from any thread not dealing with "Raptor Upper Stage".  So threads like those dealing with generic FH updates or discussion should have no posts regarding "Raptor Upper Stage".  And that goes for any other generic pre existing threads.  Also, new threads such as NASA's lunar RFI should have no discussion of "Raptor Upper Stage" since that is not in Spacex's plans.  If you want to talk about "Raptor Upper Stage" wrt to another topic, then make a new thread.
Title: Re: Raptor Upper Stage consolidated thread
Post by: M.E.T. on 05/03/2017 05:59 PM
The proposal is that talk of "Raptor Upper Stage" be eliminated from any thread not dealing with "Raptor Upper Stage".  So threads like those dealing with generic FH updates or discussion should have no posts regarding "Raptor Upper Stage".  And that goes for any other generic pre existing threads.  Also, new threads such as NASA's lunar RFI should have no discussion of "Raptor Upper Stage" since that is not in Spacex's plans.  If you want to talk about "Raptor Upper Stage" wrt to another topic, then make a new thread

My only question is how do you know it is not in their plans? If Musk's update in 6 weeks time states that it IS in their plans, then what? Now, you might well have insight into information directly from SpaceX which others don't have, in which case the matter would be settled. But I don't think you have claimed that, have you?
Title: Re: Raptor Upper Stage consolidated thread
Post by: DavidH on 05/03/2017 06:07 PM
The proposal is that talk of "Raptor Upper Stage" be eliminated from any thread not dealing with "Raptor Upper Stage".  So threads like those dealing with generic FH updates or discussion should have no posts regarding "Raptor Upper Stage".  And that goes for any other generic pre existing threads.  Also, new threads such as NASA's lunar RFI should have no discussion of "Raptor Upper Stage" since that is not in Spacex's plans.  If you want to talk about "Raptor Upper Stage" wrt to another topic, then make a new thread

My only question is how do you know it is not in their plans? If Musk's update in 6 weeks time states that it IS in their plans, then what? Now, you might well have insight into information directly from SpaceX which others don't have, in which case the matter would be settled. But I don't think you have claimed that, have you?

Because it's been hashed over and over and over and over and the rest of us are sick of hearing about it. I don't have time to keep hearing about it in every thread that has nothing to do with a Raptor Upper Stage. Please keep it off the other threads.
Title: Re: Raptor Upper Stage consolidated thread
Post by: abaddon on 05/03/2017 07:36 PM
If Musk's update in 6 weeks time states that it IS in their plans, then what?
Then.... there's this great thread to discuss it?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jdeshetler on 05/03/2017 07:44 PM
If Musk's update in 6 weeks time states that it IS in their plans, then what?
Then.... there's this great thread to discuss it?
What event is going to be held around the middle of June?
Title: Re: Raptor Upper Stage consolidated thread
Post by: sevenperforce on 05/03/2017 08:26 PM
Can you perhaps explain (at least generally) why you're so certain a Raptor US for F9/FH is completely out of the question? Because the AF Press Release from last January seemed really specific.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Eagandale4114 on 05/03/2017 08:30 PM
If Musk's update in 6 weeks time states that it IS in their plans, then what?
Then.... there's this great thread to discuss it?
What event is going to be held around the middle of June?

Musk tweeted that there will be an ITS update in about 6 weeks.

Quote from: elon
https://twitter.com/elonmusk/status/858908487018926080

Erik Cleven: I really enjoyed watching it! Can we expect an update on the ITS soon? Curious to learn more about the architecture and new developments.

Elon: Yeah, will probably publish an update in six weeks or so

Title: Re: Raptor Upper Stage consolidated thread
Post by: GWH on 05/03/2017 08:40 PM
I agree that the Raptor Upper stage shouldn't creep into every thread, even though I personally think it would be a worthwhile development for SpaceX.  It's still off topic for any thread not dedicated to this one thing in particular.
Title: Re: Raptor Upper Stage consolidated thread
Post by: MikeAtkinson on 05/03/2017 08:42 PM
The proposal is that talk of "Raptor Upper Stage" be eliminated from any thread not dealing with "Raptor Upper Stage".  So threads like those dealing with generic FH updates or discussion should have no posts regarding "Raptor Upper Stage".  And that goes for any other generic pre existing threads.  Also, new threads such as NASA's lunar RFI should have no discussion of "Raptor Upper Stage" since that is not in Spacex's plans.  If you want to talk about "Raptor Upper Stage" wrt to another topic, then make a new thread

Agree totally.

I personally think there will be a Raptor upper state at some point, however we know that SpaceX are putting lots of investment into the existing upper stage for reuse and longer duration, so lets talk about those developments that are happening in the appropriate threads and confine speculation to a single thread. That way the same speculation will not be made a dozen times.

If Musk's update on ITS plans say there is going to be a Raptor upper stage for FH, or F9 or a mini-ITS or whatever, we can then discuss that information in the relevant threads. Until that time there is little extra that can be added to what has already been said (and usually said many times in many threads).
Title: Re: Raptor Upper Stage consolidated thread
Post by: Lar on 05/03/2017 08:59 PM
I think the RUS [1] is polluting a lot of otherwise fairly nonwandery[2] threads. Clearly at least one other user does too, so they started this most meta of meta threads.

How about this. When you see a RUS[1] post, don't let it bite you. Press the report to mod button. If you're feeling particularly helpful, include the thread number you think it belongs in (I just did a quick boo and didn't see a thread in the 19 seconds I searched or else I would have put it here). Mods will remove or delete.

Because yeah.

Also, don't start metathreads like this please... no matter how vexed you are. Or at least put it in the right section!  http://forum.nasaspaceflight.com/index.php?board=50.0 (the NSF internal help/questions section)  Because, believe it or not, not every thread belongs in SpaceX general. I know, right?

 I might turn this thread into the actual thread we discuss RUS in from now on if I can't find a better one ... Jim'll LOVE it that HIS post is the thread starter (just wait till I edit it... LOL)

Edit: Did.


1 - no, not Rodents of Unusual Size
2 - what do you mean that's not a word????
Title: Re: Raptor Upper Stage consolidated thread
Post by: Nomadd on 05/03/2017 09:16 PM
Can you perhaps explain (at least generally) why you're so certain a Raptor US for F9/FH is completely out of the question? Because the AF Press Release from last January seemed really specific.
Because it hasn't been done, and nothing new is possible.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/03/2017 09:18 PM
I've been converted to the "no raptor upper stage on falcon family" belief.

It does provide some benifit, before ITS comes online. But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage, rebuild a launch site for mixed propellants (displacing normal paying flights, which counts as a cost), and other expences of such a program.

Edit: Concerning the air force contract- Goverment asks for crazy stuff all the time. SpaceX already filled out the minimum to get paid, and while they will be using what they learned to get ITS ready, they have no reason to follow george lucas into prequel-land.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Johnnyhinbos on 05/03/2017 09:19 PM
I think the RUS [1] is polluting a lot of otherwise fairly nonwandery[2] threads. Clearly at least one other user does too, so they started this most meta of meta threads.

How about this. When you see a RUS[1] post, don't let it bite you. Press the report to mod button. If you're feeling particularly helpful, include the thread number you think it belongs in (I just did a quick boo and didn't see a thread in the 19 seconds I searched or else I would have put it here). Mods will remove or delete.

Because yeah.

Also, don't start metathreads like this please... no matter how vexed you are. Or at least put it in the right section!  http://forum.nasaspaceflight.com/index.php?board=50.0 (the NSF internal help/questions section)  Because, believe it or not, not every thread belongs in SpaceX general. I know, right?

 I might turn this thread into the actual thread we discuss RUS in from now on if I can't find a better one ... Jim'll LOVE it that HIS post is the thread starter (just wait till I edit it... LOL)




1 - no, not Rodents of Unusual Size
2 - what do you mean that's not a word????
Oh - I was confident RUD stood for Rapid Unsolicited Speculation...
Title: Re: Raptor Upper Stage consolidated thread
Post by: whitelancer64 on 05/03/2017 09:27 PM
Can you perhaps explain (at least generally) why you're so certain a Raptor US for F9/FH is completely out of the question? Because the AF Press Release from last January seemed really specific.

1. The USAF contract calls only for the development and build of a prototype, to be demonstrated in a USAF-supervised set of tests. No upper stage vehicle design/redesign is funded by the contract.

2. It would require a ton of new infrastructure on their launch pads.

3. Minimal benefit and great increase in complexity that becomes obsolete with BFR / ITS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: nacnud on 05/03/2017 09:29 PM
2 - what do you mean that's not a word????

Did you know all words are invented...
Title: Re: Raptor Upper Stage consolidated thread
Post by: mikelepage on 05/04/2017 04:31 AM
I might turn this thread into the actual thread we discuss RUS in from now on if I can't find a better one ... Jim'll LOVE it that HIS post is the thread starter (just wait till I edit it... LOL)

Quite possibly the most mischievous thing I've seen a moderator do on any forum, ever.  ;D

It seems to me the main issue is, how does creating a raptor upper stage make it more reusable? (since that's the only thing that could pay for the added logistics costs of using/storing multiple propellents on the pad).

EDIT: and 2) does this serve as a developmental pathway to ITS? or will it be obsoleted by ITS?
Title: Re: Raptor Upper Stage consolidated thread
Post by: M.E.T. on 05/04/2017 04:41 AM
And there is the scenario that ITS proves far more difficult- perhaps almost impossible - to build, whether due to fatal flaws in the composite construction approach, or due to the impracticality of using 42 engines etc. In that case, a more powerful Falcon Heavy upper stage may be the consolation prize they settle for while going back to the drawing board for their BFR.

Not saying that will happen, in fact I fervently hope ITS develops as planned. But it is not set in stone yet.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 05/04/2017 08:20 AM
I've been converted to the "no raptor upper stage on falcon family" belief.

It does provide some benifit, before ITS comes online.

It's not known when ITS would come online. 2022, say? That's 5 years from now.

Quote
But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage

A large fraction of the cost is in developing the engine, and know what? SpaceX is _already_ developing this engine. They already spending these money, they can not be "saved".

Also, with Raptor upper stage, they can drop MVac (which is "three times more expensive than sea-level Merlins").
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/04/2017 08:38 AM
I've been converted to the "no raptor upper stage on falcon family" belief.

It does provide some benifit, before ITS comes online.

It's not known when ITS would come online. 2022, say? That's 5 years from now.

Quote
But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage

A large fraction of the cost is in developing the engine, and know what? SpaceX is _already_ developing this engine. They already spending these money, they can not be "saved".

Also, with Raptor upper stage, they can drop MVac (which is "three times more expensive than sea-level Merlins").

Yes, yes, "It wont cost THAT much to make" and "It does things Falcon heavy cant now." I get that.

The problem is that the "things it does that falcon cant" isnt big enough to cover even "Doesnt cost that much," especially since infrastructure changes (fuel lines on the erector, ect) actually would -reduce- the number of paying flights compared to a kerlox-only falcon family.

ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.
Title: Re: Raptor Upper Stage consolidated thread
Post by: M.E.T. on 05/04/2017 09:12 AM
I've been converted to the "no raptor upper stage on falcon family" belief.

It does provide some benifit, before ITS comes online.

It's not known when ITS would come online. 2022, say? That's 5 years from now.

Quote
But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage

A large fraction of the cost is in developing the engine, and know what? SpaceX is _already_ developing this engine. They already spending these money, they can not be "saved".

Also, with Raptor upper stage, they can drop MVac (which is "three times more expensive than sea-level Merlins").

Yes, yes, "It wont cost THAT much to make" and "It does things Falcon heavy cant now." I get that.

The problem is that the "things it does that falcon cant" isnt big enough to cover even "Doesnt cost that much," especially since infrastructure changes (fuel lines on the erector, ect) actually would -reduce- the number of paying flights compared to a kerlox-only falcon family.

ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

Yip. I'm pretty much converted to this viewpoint. But it would be sad if this situation (Falcon architecture only) lasts much longer than planned, if ITS say only comes online in 2035 instead of 2025 or something along those lines. Then SpaceX is going to start falling behind their competitors, and that doesn't seem like the type of company they aspire to be.

Hence my view that ITS has to be developed as soon as possible, then.
Title: Re: Raptor Upper Stage consolidated thread
Post by: JamesH65 on 05/04/2017 10:02 AM
I've been converted to the "no raptor upper stage on falcon family" belief.

It does provide some benifit, before ITS comes online.

It's not known when ITS would come online. 2022, say? That's 5 years from now.

Quote
But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage

A large fraction of the cost is in developing the engine, and know what? SpaceX is _already_ developing this engine. They already spending these money, they can not be "saved".

Also, with Raptor upper stage, they can drop MVac (which is "three times more expensive than sea-level Merlins").

Yes, yes, "It wont cost THAT much to make" and "It does things Falcon heavy cant now." I get that.

The problem is that the "things it does that falcon cant" isnt big enough to cover even "Doesnt cost that much," especially since infrastructure changes (fuel lines on the erector, ect) actually would -reduce- the number of paying flights compared to a kerlox-only falcon family.

ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

Yip. I'm pretty much converted to this viewpoint. But it would be sad if this situation (Falcon architecture only) lasts much longer than planned, if ITS say only comes online in 2035 instead of 2025 or something along those lines. Then SpaceX is going to start falling behind their competitors, and that doesn't seem like the type of company they aspire to be.

Hence my view that ITS has to be developed as soon as possible, then.

I don't think you can make any of those statements given what is publicly available.

F9 architecture is going to be around for at least a decade, probably two, because it's efficient and it works and it caters for most of the current possible payloads. And that could be exactly what SpaceX are planning...
Title: Re: Raptor Upper Stage consolidated thread
Post by: macpacheco on 05/04/2017 11:07 AM
A Raptor Upper Stage for Falcon 9/Heavy would make a lot of sense if ITS (or mini ITS) will actually take a long time to fly.
But lets think rationally.
 Without a fully certified Raptor, there's neither ITS nor any raptor upper stage.
 Reportedly the next big technical challenge is the big composite fuel tank, which is already being tested.
 Perhaps building the full sized ITS could require several billion to make (including the cost to prepare a new factory), but so far Elon Musk has been on a huge roll and have ZERO problems raising capital for either SpaceX or Tesla.
 The assumption of 3.66m diameter stages makes every sense for rockets that aren't reusable, but for a fully reusable system (that requires zero refurb on a launch by launch basis and only need refurb every 20-100 launches), the road transportable model is mostly obsolete.
Yes, a Raptor Upper Stage would deliver significant performance improvements to F9/FH, but F9 Block V + FH Block V will be performance beasts with full booster reuse.
Reusing a F9/FH upper stage (either M1D or Raptor based) is far, far harder than reusing a ITS/mini ITS upper stage that has dedicated vacuum and sea level engines to cover the full range of the flight regime and can eliminate N2 thrusters, use larger grid fins to produce more drag and more lift (better cross range capability to allow for RTLS every time).
The massive performance and ultra long upper stage missions even a mini ITS would have could enable extensive usage of dog legs/bi elliptical transfers which could eliminate the need for VAFB launch pads for ITS. One pad in Boca Chica plus one pad in either cape ranges would do very nicely. If needed be, use the tanker to refuel the upper stage.

The nail in the coffin is the massive scale even of a 1/3 size mini ITS, that could deliver over 50 tons worth of GEO satellites directly to a GEO-500 (or even GSO) insertion, eliminating months of transit time for pure electric satellites, massively reducing payload mass dedicated to chemical propulsion and propellant present in most current GEO satellites being launched even today.

If you assume ITS will take 5 years to become operational, then you should assume a Raptor Upper Stage would take at least half a much to become operational, which possibly doesn't even recoup the waste in design talent taken away from ITS to build this new upper stage. Building more upper stages cost money, but I think the truly scarce resource is the engineering talent.
Title: Re: Raptor Upper Stage consolidated thread
Post by: macpacheco on 05/04/2017 11:22 AM
In reply to a post on: SpaceX Falcon Heavy Discussion (Thread 5)

Profit is only one of SpaceX's internal goals, and only a means at that - not an end of itself.
A common characteristic of people that keep defending this raptor upper stage is the unwillingness to accept that SpaceX must at least break even. In fact, it must produce LOTS of CASH on a variable per launch calculation basis, so that per launch positive cash flow can pay for the massive SpaceX payroll and other fixed and R&D costs.

If you take a few days to understand the business side of things, you'll see that this whole raptor upper stage endeavour could make a lot of sense technically, but makes ZERO sense when you consider $$$.

Elon Musk has said several times, that he doesn't care too much about profit, but that if his companies don't at least nearly break even, he can't justify them to investors and the whole effort become a house of cards.

Remember Musk has two degrees, Physics and Economics. He seems to use both skills very wisely.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Eerie on 05/04/2017 11:28 AM
have ZERO problems raising capital for either SpaceX or Tesla.

Capital for things investors hope to profit from. Like the Internet constellation.

If you have evidence of SpaceX receiving funding from philanthropic billionaires, I'd really like to hear about it.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 05/04/2017 11:35 AM
If you assume ITS will take 5 years to become operational, then you should assume a Raptor Upper Stage would take at least half a much to become operational

Because a 5 meter wide, 15 meter long Al-Li tank with a single Raptor is not very different from 12m wide, 120m long composite tank behemoth with 42 Raptors, with thrust high enough to shatter LC-39a. Riiiight...
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/04/2017 12:29 PM
A Raptor Upper Stage for Falcon 9/Heavy would make a lot of sense if ITS (or mini ITS) will actually take a long time to fly.
But lets think rationally.
 Without a fully certified Raptor, there's neither ITS nor any raptor upper stage.
 Reportedly the next big technical challenge is the big composite fuel tank, which is already being tested.
 Perhaps building the full sized ITS could require several billion to make (including the cost to prepare a new factory), but so far Elon Musk has been on a huge roll and have ZERO problems raising capital for either SpaceX or Tesla.
 The assumption of 3.66m diameter stages makes every sense for rockets that aren't reusable, but for a fully reusable system (that requires zero refurb on a launch by launch basis and only need refurb every 20-100 launches), the road transportable model is mostly obsolete.

No, it's not "mostly obsolete". It's completely and totally dead. A 6m booster needs new transport and test facilities, and a 12m booster needs new transport, test, manufacturing, integration, and launch facilities. As soon as a new booster is required you add at least 3 years , and a 12m booster at least 5 years, to any plans for an upper stage that uses existing (slightly modified) infrastructure.

Quote
Yes, a Raptor Upper Stage would deliver significant performance improvements to F9/FH, but F9 Block V + FH Block V will be performance beasts with full booster reuse.

The goal of ITS isn't just capacity, it's capability. Capabilities that Falcon will never have: full and rapid reuse; on-orbit refueling; lifting entry with retropropulsive landing; ISRU for propellants on Mars; Mars ascent and return.

Quote
If you assume ITS will take 5 years to become operational, then you should assume a Raptor Upper Stage would take at least half a much to become operational, which possibly doesn't even recoup the waste in design talent taken away from ITS to build this new upper stage. Building more upper stages cost money, but I think the truly scarce resource is the engineering talent.

Jim assumes ITS will take at least 10 years to be operational, and I don't think he's far off (it needs new transport, test, manufacturing, integration, and launch facilities). A Raptor upper stage could yield the same capability (at lower but still sufficient capacity) in 2-3 years.

In reply to a post on: SpaceX Falcon Heavy Discussion (Thread 5)

Profit is only one of SpaceX's internal goals, and only a means at that - not an end of itself.
A common characteristic of people that keep defending this raptor upper stage is the unwillingness to accept that SpaceX must at least break even. In fact, it must produce LOTS of CASH on a variable per launch calculation basis, so that per launch positive cash flow can pay for the massive SpaceX payroll and other fixed and R&D costs.

If you take a few days to understand the business side of things, you'll see that this whole raptor upper stage endeavour could make a lot of sense technically, but makes ZERO sense when you consider $$$.

Elon Musk has said several times, that he doesn't care too much about profit, but that if his companies don't at least nearly break even, he can't justify them to investors and the whole effort become a house of cards.

Remember Musk has two degrees, Physics and Economics. He seems to use both skills very wisely.

Profit isn't remotely an argument that favors a full ITS system (or even an intermediate methalox booster) over using Raptor on Falcon. There are enormous upfront costs for required extra infrastructure, and no clear path to any breakeven payback. Raptor on Falcon has incremental infrastructure costs (or nearly none at all if they build Boca Chica to support it from day 1).
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/04/2017 12:42 PM
ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

The current plan for ITS is launching from 39A, which just happens to be a Falcon pad. At least acknowledge the clearly stated plan before speculating the complete opposite.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 05/04/2017 12:43 PM
I do not think there would be that much infrastructure change.  Liquid methane can be produced near the pad like liquid oxygen, then piped to the upper stage.  A 5.2m upper stage would match the same diameter as the existing fairing, just extended down to the interstage where the second stage is now.  A new interstage could actually be attached to the upper stage to protect the bell on the Raptor vacuum engine on reentry.  It could be built line the ITS, but 5.2m wide and as long as the existing upper stage + fairing.  A bay could open near the nose to release satellites.  It would be an iconic cylinder type re-entry.  It could land via parachute in the desert, or have three small landing thrusters using methalox so no extra fuel would be needed, then land vertically near the launch site.  It may start with aluminum tanks, then later proceed to composite to save weight and add payload. 

A lot of different experimentation could be done.  It could actually start as expendable, then add the return components over time.  In the meantime in expendable mode, F9/FH could increase their payload size, and deep space abilities. 

Also, remember, pad 39A has limited thrust of 12 million lbs for a future ITS/BFR booster.  Anything more and a complete new infrastructure would have to be built. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/04/2017 12:54 PM
...

The goal of ITS isn't just capacity, it's capability. Capabilities that Falcon will never have: full and rapid reuse; on-orbit refueling; lifting entry with retropropulsive landing; ISRU for propellants on Mars; Mars ascent and return.

...

Unless a mini-ITS ship is built as a second stage for FH...
Not only could have all these capabilities, but could be the test platform to demonstrate each of them.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RedLineTrain on 05/04/2017 12:57 PM
Let's put it this way.  Musk has even refused to build a longer fairing for Bigelow.

Bigelow has the cash, he has the payloads, and no additional infrastructure would be required.  But SpaceX isn't going to do it, presumably because they would then have two fairing types to manufacture.

No need to see eye-to-eye with Jim on the reasons in order to see that his conclusion is correct.
Title: Re: Raptor Upper Stage consolidated thread
Post by: robert_d on 05/04/2017 01:09 PM
I agree with Jim that any speculation regarding a Raptor powered or 1/3rd scale Raptor powered F9upper stage should be in a separate thread and not just thrown into any discussion at hand. Having said that -
I also believe that ITS will not even see a test stand in the next ten years, and that in-space refueling will be the next technology hurdle to attract full attention. So that some sort of Methane powered in-space stage will become a SpaceX goal.

We may see in 6 weeks, but a 9 engine Raptor first stage with a refuelable 2nd stage and possibly returnable version seems to me the way forward more likely than a dedicated Falcon 1/3rd scale 2nd stage. My impression is that E.M. will be keen on getting a full sized Raptor into service somehow.  Since pad 39B is supposed to be a "Clean Pad" what are the chances that the Methane could be added there? Otherwise with SLC-40 in service 39A could be worked between Crewed dragon flights to add Methane.

Edit: removed reference to Boca Chica.
Title: Re: Raptor Upper Stage consolidated thread
Post by: macpacheco on 05/04/2017 01:43 PM
No, it's not "mostly obsolete". It's completely and totally dead. A 6m booster needs new transport and test facilities, and a 12m booster needs new transport, test, manufacturing, integration, and launch facilities. As soon as a new booster is required you add at least 3 years , and a 12m booster at least 5 years, to any plans for an upper stage that uses existing (slightly modified) infrastructure.

The goal of ITS isn't just capacity, it's capability. Capabilities that Falcon will never have: full and rapid reuse; on-orbit refueling; lifting entry with retropropulsive landing; ISRU for propellants on Mars; Mars ascent and return.

Jim assumes ITS will take at least 10 years to be operational, and I don't think he's far off (it needs new transport, test, manufacturing, integration, and launch facilities). A Raptor upper stage could yield the same capability (at lower but still sufficient capacity) in 2-3 years.

Profit isn't remotely an argument that favors a full ITS system (or even an intermediate methalox booster) over using Raptor on Falcon. There are enormous upfront costs for required extra infrastructure, and no clear path to any breakeven payback. Raptor on Falcon has incremental infrastructure costs (or nearly none at all if they build Boca Chica to support it from day 1).
If you read carefully, I said ITS  OR  MINI ITS. Not AND.
A full scale ITS might indeed require a new pad, but a mini ITS could be sized up to the limit of LC39A (1/3 of ITS lift off thrust matches Saturn V very well).
The performance capability of FH is too small even with a substantial Raptor upper stage to throw a large mass towards Mars.
The expected refurb costs of FH boosters would be a significant bottleneck to send a large volume of people and cargo towards Mars.
I don't see a reason for anxiety even if it takes 10 years for ITS to be flying. Even IF there's no mini ITS in between.
If it takes 5 or 8 years to a mini ITS, so be it. I think SpaceX can do it within 3-5 years after Raptor is flight qualified.
A larger single core methane booster is a huge part of the ITS solution.
I think people should have some humility and accept that SpaceX knows a heck of a lot more than you or me, they say the path forward is ITS, with people conjuring this Raptor upper stage to F9/FH based on a contract with USAF that clearly is for the engine only, mentioning an upper stage strictly as one possible application for the engine (as well as the unlikely usage of Raptor for non SpaceX rockets). The USAF contract doesn't mention ITS cause mentioning ITS on a development contract isn't strategical for either USAF nor SpaceX.
Maybe the path forward is a mini ITS to reduce infrastructure costs. A mini ITS would be even better as a complete replacement to FH and likely F9 too.
Mini ITS would both reduce SpaceX margins to access to orbital payloads, bring substantial capabilities towards other non Mars revenue too.

My hunch is this Raptor development contract was one of the agreements that came out of the Falcon 9 USAF certification settlement. One of the several ways in which USAF agreed to make up for SpaceX. I wouldn't read that much further than a means to incentive SpaceX to bring new LVs to market which then USAF/DoD can use.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/04/2017 02:38 PM
If you read carefully, I said ITS  OR  MINI ITS. Not AND.
A full scale ITS might indeed require a new pad, but a mini ITS could be sized up to the limit of LC39A (1/3 of ITS lift off thrust matches Saturn V very well).

I was addressing either case. The problem for a 7 to 9 Raptor booster is not launch. SpaceX has nowhere to build or test a vehicle that size and length, and no way to move it to the facilities they do have. They would need new manufacturing and test facilities either at the Cape, or on a waterway. For a 12m booster it only gets worse.

Quote
The performance capability of FH is too small even with a substantial Raptor upper stage to throw a large mass towards Mars.
The expected refurb costs of FH boosters would be a significant bottleneck to send a large volume of people and cargo towards Mars.

Wrong. An upper stage optimally sized for FH could most likely land 40 to 50 tonnes on Mars, if the assumptions inherent to the ITS design are correct. And SpaceX expects to refurbish F9 boosters in 24 hours, which basically means just inspecting them before reflight. So FH turnaround would be reasonably fast and cheap.

Besides, there's no need to send "large" volumes of people or cargo to Mars in the next decade - at least not significantly larger than the 40-50 tonnes or cargo and 6-8 people that could be delivered with 5 FH/Raptor upper stage flights. There's nothing inherent to the ITS plan that requires 100 or 300 tonne payloads. It's a problem of capability, not capacity.

Quote
I don't see a reason for anxiety even if it takes 10 years for ITS to be flying. Even IF there's no mini ITS in between.
If it takes 5 or 8 years to a mini ITS, so be it. I think SpaceX can do it within 3-5 years after Raptor is flight qualified.
A larger single core methane booster is a huge part of the ITS solution.
I think people should have some humility and accept that SpaceX knows a heck of a lot more than you or me, they say the path forward is ITS, with people conjuring this Raptor upper stage to F9/FH based on a contract with USAF that clearly is for the engine only, mentioning an upper stage strictly as one possible application for the engine (as well as the unlikely usage of Raptor for non SpaceX rockets). The USAF contract doesn't mention ITS cause mentioning ITS on a development contract isn't strategical for either USAF nor SpaceX.
Maybe the path forward is a mini ITS to reduce infrastructure costs. A mini ITS would be even better as a complete replacement to FH and likely F9 too.
Mini ITS would both reduce SpaceX margins to access to orbital payloads, bring substantial capabilities towards other non Mars revenue too.

My hunch is this Raptor development contract was one of the agreements that came out of the Falcon 9 USAF certification settlement. One of the several ways in which USAF agreed to make up for SpaceX. I wouldn't read that much further than a means to incentive SpaceX to bring new LVs to market which then USAF/DoD can use.

The only reason to put Raptor on HF is if there if significant doubt about the feasibility of the whole ITS (or mini ITS) plan in a reasonable timeframe. It really comes down to how large a bite SpaceX thinks they can chew. ITS is extremely optimistic. Mini ITS considerably less so. But a mini ITS upper stage on FH is the minimum viable product that can demonstrate the ITS architecture.

I don't put any stock in the "USAF upper stage" theories, because it's pretty obvious that the contract was only for an engine. SpaceX will do with that engine as they see fit.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 05/04/2017 04:54 PM
Using the ITS presentation schedule I made the attached spreadsheet to play with. I've added other projects and speculation on how mini ITS or Rvac US would fit in. I hope it's formated clearly.

The green years are approximate Mars windows. Everything below the double line is speculative.

I assume they are doing some development on Mars Infrastructure; The Boring Company is an example. They'll probably be doing that sort of dev forever.

Edit: i got the date wrong for the Lunar mission...
Title: Re: Raptor Upper Stage consolidated thread
Post by: GWH on 05/04/2017 05:13 PM
Nice work.  Some questions on the schedule that can't necessarily be answered without knowing internal development schedule:
-Is the RVac US for FH able to land cargo on Mars? Namely in the 2020 window vs the ITS planned 2022 window.
-Mars infrastructure: how much can be tested via Red Dragon Flights or would these items need to be larger?
-If ITS flights to Mars slip to the right what does this mean to the development of ground infrastructure?
-Would the RVac FH US allow for development of Mars infrastructure concurrent to ITS development, so that a slip in ITS first flight to Mars doesn't cause a slip in ground hardware testing on Mars?
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 05/04/2017 05:36 PM
Nice work.  Some questions on the schedule that can't necessarily be answered without knowing internal development schedule:
-Is the RVac US for FH able to land cargo on Mars? Namely in the 2020 window vs the ITS planned 2022 window.
if you mean take the US to Mars, not unless they develop it for that use. but then it's really more a Mini ITS so would take longer to dev.

Quote
-Mars infrastructure: how much can be tested via Red Dragon Flights or would these items need to be larger?
Yes? by infrastructure i mean everything left on the surface.

Quote
-If ITS flights to Mars slip to the right what does this mean to the development of ground infrastructure?
If i was making the decision, i wouldn't spend a ton of time developing ground infrastructure if i wasn't sure i'd be able to get it on the surface. I assume it'd push it to the right as well.

Quote
-Would the RVac FH US allow for development of Mars infrastructure concurrent to ITS development, so that a slip in ITS first flight to Mars doesn't cause a slip in ground hardware testing on Mars?
If they're developing the ground hardware for ITS, the whole plan goes back to the drawing board without ITS. They'll need a lot more than just a Rvac US.
Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 05/04/2017 05:44 PM
have ZERO problems raising capital for either SpaceX or Tesla.

Capital for things investors hope to profit from. Like the Internet constellation.

If you have evidence of SpaceX receiving funding from philanthropic billionaires, I'd really like to hear about it.

WSJ has estimated "CommX's" net revenue potential at up to ~$22B a year, >$2B more than NASA's current budget. If that project works out half as well as WSJ thinks funding will be the least of their problems.
Title: Re: Raptor Upper Stage consolidated thread
Post by: GreenShrike on 05/04/2017 05:45 PM
It does provide some benifit, before ITS comes online. But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage, rebuild a launch site for mixed propellants (displacing normal paying flights, which counts as a cost), and other expences of such a program.

How much it can earn? That's spoken like someone who hasn't heard that SpaceX would very much like to orbit 10K+ satellites.

Who cares about their paying flights, when to launch 4400 LEO sats they themselves will need almost 90 Falcon Heavy launches at 50 sats per FH launch? That's three times the number of current *F9* flights and almost as many as the current number of Atlas V and Delta 4 flights combined. Double that or more if they're restricted to launching them on F9s due to lack of fairing volume (a topic for another thread).

And then there's also another 7000-odd VLEO sats, so double or triple the 90 FH or 180 F9 flights.

At this point, SpaceX's commercial *paying* flights are a somewhat rough rounding error.

A Raptor S2 doesn't need to earn SpaceX a thing when at $10M per Merlin S2, 200 or 300 launches represents a couple or three billion of capital just in Merlin S2s -- and never mind the CommX payloads. It's possible SpaceX could save a good portion of that by developing a fully reusable upper stage. A billion saved is a billion earned -- isn't that how the saying goes?

And a Raptor stage won't eat performance margins for lunch like the relatively low ISP Merlin upper stage will -- a 20-30% performance penalty to the current S2 would, at flight rates of 200-300 launches, mean 40 on the low end and 90 on the high end more launches.  Even assuming a heavily discounted $30M per FH launch, 40 launches is again over $1 billion in additional costs. At a discounted $20M per F9, 90 launches is almost $2B.

The problem is that the "things it does that falcon cant" isnt big enough to cover even "Doesnt cost that much," especially since infrastructure changes (fuel lines on the erector, ect) actually would -reduce- the number of paying flights compared to a kerlox-only falcon family.

Unfortunately, "things Falcon can't" currently include launching 10K+ sats in as economical a manner as SpaceX likely needs if Elon wants to maintain control of the company.

Compared to current flight rates, a few hundred million to design and build a Raptor upper stage (hopefully with integrated sat dispenser, which, indeed, may look like a mini-ITS) and a couple hundred more to modify the GSE is blinking expensive.

Compared to what SpaceX plans, however, it's practically peanuts.


You need to keep in mind that, if you're trying to suss out what SpaceX is going to do, SpaceX will act based on the requirements of their own dreams and schemes -- which most certainly include the CommX constellation.

And those plans present SpaceX with a stark choice: a fully reusable Raptor upper stage, a reusable Merlin upper stage that adds 40 or 60 or 80 launches to a manifest that already strains credulity, or an expendable Merlin that results in $2-3 billion of SpaceX cash burned up on re-entry.

If after all's said and done, it costs SpaceX $1 billion to field a Raptor upper stage, well, even to a billionaire like Musk saving another billion in costs isn't chump change.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/04/2017 06:30 PM
have ZERO problems raising capital for either SpaceX or Tesla.

Capital for things investors hope to profit from. Like the Internet constellation.

If you have evidence of SpaceX receiving funding from philanthropic billionaires, I'd really like to hear about it.

WSJ has estimated "CommX's" net revenue potential at up to ~$22B a year, >$2B more than NASA's current budget. If that project works out half as well as WSJ thinks funding will be the least of their problems.

Minor nit: That's Spacex's internal projection, leaked by WSJ. The folks at the Journal probably think it's loony.
Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 05/04/2017 07:04 PM
Fair enough, but a recent Senate hearing had much to say about net service to unserved and underserved remote US regions. Note was made by the chair and ranking member of SpaceX's minimal surface infrastructure, especially given the years conventional  base station permitting takes. This could prove critical to favorably influencing pending legislation with proposed changes to FAA and FCC regs geared to accelerate such low infrastructure deployments. If this goes that way the revenue estimates for SpaceX and others like them may be low.

Sent from my K88 using Tapatalk
Title: Re: Raptor Upper Stage consolidated thread
Post by: whitelancer64 on 05/04/2017 08:49 PM
ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

The current plan for ITS is launching from 39A, which just happens to be a Falcon pad. At least acknowledge the clearly stated plan before speculating the complete opposite.

That's a concept. It can't be "the plan" because LC-39A can't handle the thrust a BFR would produce. 39A would have to be stripped down, dug out, and completely rebuilt to fly the BFR.

It would be cheaper and easier to build a new pad.
Title: Re: Raptor Upper Stage consolidated thread
Post by: GreenShrike on 05/04/2017 08:51 PM
If you take a few days to understand the business side of things, you'll see that this whole raptor upper stage endeavour could make a lot of sense technically, but makes ZERO sense when you consider $$$.

So... when you took your "few days to understand the business side of things", how did SpaceX's 10K+ satellite constellation factor in?

Because it's certainly a factor in Elon's and SpaceX's thinking...


"$$$" is what it's going to take to build the constellation, and that constellation is what's going to pay for Mars.


Elon Musk has said several times, that he doesn't care too much about profit, but that if his companies don't at least nearly break even, he can't justify them to investors and the whole effort become a house of cards.

Remember Musk has two degrees, Physics and Economics. He seems to use both skills very wisely.

Both degrees involve lots of math, so basic math should be a snap for him. Saving even relatively small amounts of money per launch (like $10M for a Merlin upper stage) grows very large very quickly when multiplied by the few hundred launches needed for the constellation.

Delaying the constellation until ITS is flying is putting the cart before the horse -- both will take billions to build, but the former will thereafter generate many more billions, while the latter will quickly suck up every dollar SpaceX can earn in its quest for Mars.

The Falcon series is what they have now, so *that* is what's going to orbit and build out the initial constellation, not ITS.

So the question becomes, how do you use the Falcon family the most economically to launch the constellation? You fly fully reusable and make certain that the reuse penalty doesn't balloon the number of flights needed too badly.

A Raptor upper stage fits the bill.

Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/04/2017 09:10 PM
ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

The current plan for ITS is launching from 39A, which just happens to be a Falcon pad. At least acknowledge the clearly stated plan before speculating the complete opposite.

That's a concept. It can't be "the plan" because LC-39A can't handle the thrust a BFR would produce. 39A would have to be stripped down, dug out, and completely rebuilt to fly the BFR.

It would be cheaper and easier to build a new pad.

I've seen this repeated many times, but never with any kind of actual data to support it. Surely that data or a way to calculate it exists somewhere. Can you provide a reference?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Negan on 05/04/2017 09:36 PM
ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

The current plan for ITS is launching from 39A, which just happens to be a Falcon pad. At least acknowledge the clearly stated plan before speculating the complete opposite.

That's a concept. It can't be "the plan" because LC-39A can't handle the thrust a BFR would produce. 39A would have to be stripped down, dug out, and completely rebuilt to fly the BFR.

It would be cheaper and easier to build a new pad.

I've seen this repeated many times, but never with any kind of actual data to support it. Surely that data or a way to calculate it exists somewhere. Can you provide a reference?

Doesn't exactly say either way, but here's an interesting quote from an NSF article:

"The rocket is shown to be launching from SpaceX’s 39A launch site, which was in doubt based on its thrust margins. However, the rocket is close to the limitations of the pad’s 28 million pound parameter and is likely to be provided with a level of pad engineering mitigation to allow ITS to launch from this site."

https://www.nasaspaceflight.com/2016/09/spacex-reveals-mars-game-changer-colonization-plan/
Title: Re: Raptor Upper Stage consolidated thread
Post by: mme on 05/04/2017 09:59 PM
...
I've seen this repeated many times, but never with any kind of actual data to support it. Surely that data or a way to calculate it exists somewhere. Can you provide a reference?

Doesn't exactly say either way, but here's an interesting quote from an NSF article:

"The rocket is shown to be launching from SpaceX’s 39A launch site, which was in doubt based on its thrust margins. However, the rocket is close to the limitations of the pad’s 28 million pound parameter and is likely to be provided with a level of pad engineering mitigation to allow ITS to launch from this site."

https://www.nasaspaceflight.com/2016/09/spacex-reveals-mars-game-changer-colonization-plan/
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/04/2017 10:10 PM
It does provide some benifit, before ITS comes online. But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage, rebuild a launch site for mixed propellants (displacing normal paying flights, which counts as a cost), and other expences of such a program.

How much it can earn? That's spoken like someone who hasn't heard that SpaceX would very much like to orbit 10K+ satellites.

Who cares about their paying flights, when to launch 4400 LEO sats they themselves will need almost 90 Falcon Heavy launches at 50 sats per FH launch? That's three times the number of current *F9* flights and almost as many as the current number of Atlas V and Delta 4 flights combined. Double that or more if they're restricted to launching them on F9s due to lack of fairing volume (a topic for another thread).

And then there's also another 7000-odd VLEO sats, so double or triple the 90 FH or 180 F9 flights.

At this point, SpaceX's commercial *paying* flights are a somewhat rough rounding error.

A Raptor S2 doesn't need to earn SpaceX a thing when at $10M per Merlin S2, 200 or 300 launches represents a couple or three billion of capital just in Merlin S2s -- and never mind the CommX payloads. It's possible SpaceX could save a good portion of that by developing a fully reusable upper stage. A billion saved is a billion earned -- isn't that how the saying goes?

And a Raptor stage won't eat performance margins for lunch like the relatively low ISP Merlin upper stage will -- a 20-30% performance penalty to the current S2 would, at flight rates of 200-300 launches, mean 40 on the low end and 90 on the high end more launches.  Even assuming a heavily discounted $30M per FH launch, 40 launches is again over $1 billion in additional costs. At a discounted $20M per F9, 90 launches is almost $2B.

The problem is that the "things it does that falcon cant" isnt big enough to cover even "Doesnt cost that much," especially since infrastructure changes (fuel lines on the erector, ect) actually would -reduce- the number of paying flights compared to a kerlox-only falcon family.

Unfortunately, "things Falcon can't" currently include launching 10K+ sats in as economical a manner as SpaceX likely needs if Elon wants to maintain control of the company.

Compared to current flight rates, a few hundred million to design and build a Raptor upper stage (hopefully with integrated sat dispenser, which, indeed, may look like a mini-ITS) and a couple hundred more to modify the GSE is blinking expensive.

Compared to what SpaceX plans, however, it's practically peanuts.


You need to keep in mind that, if you're trying to suss out what SpaceX is going to do, SpaceX will act based on the requirements of their own dreams and schemes -- which most certainly include the CommX constellation.

And those plans present SpaceX with a stark choice: a fully reusable Raptor upper stage, a reusable Merlin upper stage that adds 40 or 60 or 80 launches to a manifest that already strains credulity, or an expendable Merlin that results in $2-3 billion of SpaceX cash burned up on re-entry.

If after all's said and done, it costs SpaceX $1 billion to field a Raptor upper stage, well, even to a billionaire like Musk saving another billion in costs isn't chump change.
SpaceX only needs to put up 800 or so to start earning money- not the full multi billion per year, certiantly, but enough to make launching CommX self sustaining. They dont need FalconRaptor to do that, and need to launch into an absurd number of different inclined orbits anyway, so extra capability doesnt help their goals. FalconMvac is mature, they dont need to fund designing an entire new rocket just to launch CommX, they can just start sending up sats when they have them built. Which gets the multibillion income stream going faster than if they waited for FalconRaptor.
Title: Re: Raptor Upper Stage consolidated thread
Post by: abaddon on 05/04/2017 10:24 PM
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.
If 39A is ITS capable (or would be with some not huge upgrades) it would likely be much cheaper to use it for ITS and retrofit LC40 for crew than build a new ITS capable pad from scratch.  Just look at 39A in comparison with the other SpaceX pads.  It is tremendously overbuilt for Falcon 9.  It was built that way to handle really big rockets.  Something that could handle ITS thrust levels would need to be much bigger and more robust (and more expensive) than any other SpaceX pad is now, by far.  Then there's also distance/overpressure concerns, other sites might not allow for as big a rocket as 39A does due to those concerns as well.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rsdavis9 on 05/04/2017 10:37 PM
have ZERO problems raising capital for either SpaceX or Tesla.

Capital for things investors hope to profit from. Like the Internet constellation.

If you have evidence of SpaceX receiving funding from philanthropic billionaires, I'd really like to hear about it.

didnt google invest 1b in spacex?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Negan on 05/04/2017 10:40 PM
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.

The revenue lost could be less than the cost of building a new pad.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/04/2017 11:54 PM
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.

The revenue lost could be less than the cost of building a new pad.

They have two other East Cost pads coming online soon. The only unique thing about 39A is crew access.
Title: Re: Raptor Upper Stage consolidated thread
Post by: corneliussulla on 05/05/2017 06:58 AM
I think raptor upper stage is off the table....until there is money in producing such a thing....NASA just sent out a RFI for delivering material to the moons surface, maybe a raptor equipped upper stage of a falcon heavy would be a good solution for this requirement.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/05/2017 07:09 AM
I think raptor upper stage is off the table....until there is money in producing such a thing....

With the upcoming satellite constellation there is a lot of money in a reusable upper stage that does not reduce present capability of the Falcon family.

A Raptor upper stage is also a great risk reduction strategy for building ITS.

If they can also serve NASA needs to the moon that is great. It would require a engine powered landing capability with landing legs. I was never comfortable with parachutes and bouncy castles or helicopters.

Sending them to Mars, I wonder if a much smaller stage than ITS can handle boiloff efficiently.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Semmel on 05/05/2017 12:03 PM
I agree with Jim, it probably does not make sense to develop a raptor upper stage economically if it is expendable. So I agree with the opposite argument as well, if a RUS is done so that it can be re-used, it can make economic sense. Despite all the trouble in ground systems.

In terms of performance, a RUS is clearly superior. But again, Jims argument holds that F9 does not need more performance. It can serve the current market just fine as it is. Also, I dont think F9 can deliver the payload advertised on the web page. Not for lack of dV, but for structural and horizontal integration design reasons.

For the CommX constellation, it might make sense to consider some redesigns. Its a large enough number of flights to do changes to the architecture.
Lets start with F9. It currently costs, when reused and with reusable fairings in the order of $30M. It is limited to 10.5 mT in a fairing because the payload, after integration is suspended on the fairing. Since FH supposedly uses the same integration strategy, its also limited to 10.5 mT payload in a fairing. SpaceX develops FH not to lift heavier payloads, but to lift moderately heavy payloads, up to 10 mT to a high energy orbit. It can do that just fine for the current market and there is no economical incentive to change that. Since F9 is most likely volume limited for the constellation, it would make sense to develop a version of the second stage that is reusable at the cost of payload mass. Since F9 is not mass limited anyway, no performance in terms of number of satellites launched is lost. This might drop the cost per launch from $30M to $20M for some investment into a reusable version of the current upper stage, say $100M. No alteration of ground support is necessary.

So, what can be done for the constellation? First off, given the weight of the sats (<400kg each), F9 s probably volume limited, not mass limited. So in order to increase the number of sats per launch, a bigger fairing is necessary. But then, the structural loads during integration will still limit the payload mass to 10.5 mT. Given that, a redesign of the second stage and payload adapter and fairings and integration strategy is needed, so vertical integration. This limits the launch to be done from 39A but, which I understand is not SpaceXes desire. But it could be done to send large batches of sats on a FH. As a result, the number of sats to orbit can already be increased without a RUS but requires some redesign. We dont know if that might already be part of Block 5. Lets guesstimate (you can argue the numbers of course) that the redesign would cost in the order of $80M and that a FH launch including the above would cost $60M to launch.

A RUS, in order to provide its most advantage, would require a larger diameter. This is already a big minus in terms of logistics, factory, tooling and re-certification of F9. A completely new payload adapter, fairing design and ground support are also necessary. This would cost up front, say $500M, due to factory, tooling, infrastructure and ground support changes on all launch pads as well as design and engineering work. This kind of investment would only make sense if it was re-usable. If it is, it might be possible to conduct a launch for $20M, eliminating $10M for the reusable second stage from the unchanged F9 with reusable first stage and fairings. This kind of rocket might be able to get in the order of 15mT for F9 and maybe 70mT in terms of FH into a valid constellation orbit.

To summarize:
Option 1: no change, launch cost $30M a piece. No additional investment. Volume limited number of sats, say 20 sats.
Option 2: re-usable version of the current upper stage, investment ~$100M, $20M per launch. Volume limited number of sats, say 20 sats.
Option 3: Redesign to max out the mass to orbit for the constellation. Investment ~$80M, only beneficial at 39A, mass limit of sats to orbit, say 125 sats per $60M launch of FH.
Option 4: Raptor based upper stage, investment $500M, mass limited number of sats. 37 or F9 of $20M a piece and 175 for FH with $50M a launch.

That are the tradeoffs to make for the constellation. It seems to me, that a RUS is far more expensive up front than a reusable second stage version of the current one. So as Musk hinted in a tweet to look into reusing the upper stage. And it makes sense if you assume that the constellation is really volume limited and not mass limited. A Raptor upper stage, being viable if it flies often enough and allows for mass limited launches of the constellation. But it comes with a much much higher risk if re-usability doesnt work out as advertised. So I think its not a good option, given the tradeoff above. Also, if BFR/ITS comes online in 10 years or so. The second generation of the constellation might just be launched on BFR/ITS, eliminating the need for the raptor upper stage all together. In THAT light, RUS is taking highly needed funds from ITS, delaying ITS and is a lot more risky than trying to develop a reusable upper stage based on the current design. Gwynne will make sure that Elon doesn't go off on a tangent with RUS. SpaceX will have the same trade offs I outlined above, more refined of course. But even if my numbers are wrong by a factor of 2, RUS still doesnt make economic sense. The only benefit would be to give Raptor some flight history. But I think thats not enough of an incentive.
Title: Re: Raptor Upper Stage consolidated thread
Post by: jpo234 on 05/05/2017 12:18 PM
http://aviationweek.com/space/us-air-force-lines-space-launch-vehicle-investments talks about possible updates for FH helped by the Air Force.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 05/05/2017 12:48 PM
I think raptor upper stage is off the table....until there is money in producing such a thing....

With the upcoming satellite constellation there is a lot of money in a reusable upper stage that does not reduce present capability of the Falcon family.

LEO communications satellites are very light, and the payload capasity is often not the bottleneck; the bottleneck might be different destination orbits required and/or fairing volume.

Then can recover merlin 1d-based second stage while still launching MANY satellites per launch, and methane-based upper stage might just make price/satellite more expensive due more complex launch site needed.

For big GTO/BEO payloads, methane-based second stage would help.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 05/05/2017 01:48 PM
Negan, Pad 39A's thrust limit is 12 million lbs.  (Originally designed for a Nova Class rocket, with 8 F-1 engines).  ITS proposed 28 million will not launch from 39A.  It will require a new launch pad. 

This is why all the talk of a Raptor upper stage.  With FH coming on line, and a proposed reusable upper stage late this year, there is speculation of a Raptor based upper stage, giving FH about 10 tons extra payload to LEO.  This would put it in the lower range of the SLS which was to be 70-130 tons to LEO with upgrades. 

A Raptor upper stage might be a little too large for F9, but not for FH.  If it is a Raptor upper stage, it would need to be reusable, and test various components for future ITS. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/05/2017 02:42 PM
I think raptor upper stage is off the table....until there is money in producing such a thing....

With the upcoming satellite constellation there is a lot of money in a reusable upper stage that does not reduce present capability of the Falcon family.

LEO communications satellites are very light, and the payload capasity is often not the bottleneck; the bottleneck might be different destination orbits required and/or fairing volume.

Then can recover merlin 1d-based second stage while still launching MANY satellites per launch, and methane-based upper stage might just make price/satellite more expensive due more complex launch site needed.

For big GTO/BEO payloads, methane-based second stage would help.

The constellation is LEO but quite high. If they circularize to 1000km payload capacity can quickly become a bottleneck. They can decide to let the satellites do circularization, that would reduce lift requirements.

When they redesign the upper stage for reusability they have a strong incentive to do it with methalox. Not only so they can fly all payloads, including GTO, but also because they learn a huge amount for ITS technology with limited financial risk.

IMO it is all or nothing. Since they seem to have decided for something, I believe it will be all.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/05/2017 02:45 PM
@Semmel

I like your summary. But about vertical integration. If they need it for lifting higher mass I am quite confident they can do it at LC-40 with something as simple as a crane. I doubt their constellation satellites will have requirements to be accessed after integration into the fairing.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RonM on 05/05/2017 02:46 PM
Negan, Pad 39A's thrust limit is 12 million lbs.  (Originally designed for a Nova Class rocket, with 8 F-1 engines).  ITS proposed 28 million will not launch from 39A.  It will require a new launch pad. 

This is why all the talk of a Raptor upper stage.  With FH coming on line, and a proposed reusable upper stage late this year, there is speculation of a Raptor based upper stage, giving FH about 10 tons extra payload to LEO.  This would put it in the lower range of the SLS which was to be 70-130 tons to LEO with upgrades. 

A Raptor upper stage might be a little too large for F9, but not for FH.  If it is a Raptor upper stage, it would need to be reusable, and test various components for future ITS.

I think a smaller first generation ITS with a thrust under 12 million lbs would make more sense than a RUS for FH. A Nova sized ITS would be good for satellite deployment and Mars exploration.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/05/2017 03:21 PM
Negan, Pad 39A's thrust limit is 12 million lbs.  (Originally designed for a Nova Class rocket, with 8 F-1 engines).  ITS proposed 28 million will not launch from 39A.  It will require a new launch pad. 

This is why all the talk of a Raptor upper stage.  With FH coming on line, and a proposed reusable upper stage late this year, there is speculation of a Raptor based upper stage, giving FH about 10 tons extra payload to LEO.  This would put it in the lower range of the SLS which was to be 70-130 tons to LEO with upgrades. 

A Raptor upper stage might be a little too large for F9, but not for FH.  If it is a Raptor upper stage, it would need to be reusable, and test various components for future ITS.

What's the 12 mlbf number based on? SpaceX says they are going to launch ITS from 39A. Maybe they are, maybe they aren't.

But if you're going to argue that they CAN'T launch form 39A, you should have some analysis to back that up. "Designed for 8x F-1" just puts a minimum bound on the thrust ceiling, it doesn't automatically follow that a larger vehicle cannot launch.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Negan on 05/05/2017 03:36 PM
Negan, Pad 39A's thrust limit is 12 million lbs.  (Originally designed for a Nova Class rocket, with 8 F-1 engines).  ITS proposed 28 million will not launch from 39A.  It will require a new launch pad. 

Why are you addressing me on this? You beef is with the authors of the article which I quoted and sited.
Title: Re: Raptor Upper Stage consolidated thread
Post by: macpacheco on 05/05/2017 04:30 PM
So... when you took your "few days to understand the business side of things", how did SpaceX's 10K+ satellite constellation factor in?

Because it's certainly a factor in Elon's and SpaceX's thinking...


"$$$" is what it's going to take to build the constellation, and that constellation is what's going to pay for Mars.
The estimate is SpaceX will begin launching CommX in 2019 through 2024. That's if there's zero delays.
As I have been saying, SpaceX isn't going to launch 4425 satellites in a hurry. It will take time. It will start with a bare minimal constellation.
It makes more sense to design and built the largest pure Raptor rocket that can be launched from LC39A foundation, with modest adaptation.
Even if it isn't flying for the first CommX launch.
Once upper stages are reusable, the next key cost to be reduced is refurb costs.
Merlins are expected to need refurb every 10 flights, while Raptor might fly 1000 times between refurb.
A single stick methane booster gets less wear on each re-entry cause it can do a longer entry burn.

At the same time, in the long run, F9/FH makes no sense, can't achieve the kind of economics needed for Mars Colony and just outright 3 zeros reduction in access to space cost. Might as well go all the way.
9 full sized merlins on the booster would save a bundle in refurb in the long run, methane is a greener fuel.

But above all, I think the Musk way is a brand new rocket. Time will tell of course. I'll shut up and let EM decide either way.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/05/2017 04:35 PM
It makes more sense to design and built the largest pure Raptor rocket that can be launched from LC39A foundation, with modest adaptation.

If that were their plan then the IAC announcement would have been very different.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 05/05/2017 04:59 PM
making it reusable means a longer dev and testing cycle, which will mean more chance for a schedule slip. SpaceX is not likely to prioritize a Raptor 2nd stage over ITS.

Propulsive landed 1st stage announced Sept 2011, Grasshopper tested Sept 2012, landed 1st stage Dec 2015.
Propulsive landed Dragon 2  announced May 2014, not yet landed (not even tested?).
FH hasn't even flown yet. 

Even a regular S2 is not something you just whip together in a couple years. It's mission critical. And changing it might require further changes to the core and boosters. The core would have to be further reinforced to accommodate the new payload+S2 mass. it'd need a much larger fairing or it'd be even more volume limited than FH.

And if you're going to create tooling and rework your transport logistics for a larger tank size, change to Methalox, re-engineer S1 and the fairing; Why not a F9-style Raptor first stage as well? Then you'd truly have a New Glenn competitor.

I think all of that is likely to happen only after ITS, though.

edit: I just realized that such a Raptor F9 would be exactly like the Falcon X leaked in 2013 (https://www.nasaspaceflight.com/2013/05/from-atlas-v-falcon-xx-commercial-suitors-wanted-pad-39a/). SpaceX decided to leapfrog the Falcon X and go straight for the XX with ITS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/05/2017 06:18 PM
Lets not forget that the current speculation for near-term S2 reuse is a Dragon derived architecture, not an ITS derived one.

On any volume limited mission (which is pretty much anything to leo these days), an extra, optional module would be added between S2 and the fairing/payload adapter- it's outside the fairing, so it doesnt affect the volume limits, just the mass limits.

This extra module, about half the height of Dragon 2, can eject the entire fairing/payload adapter assembily, revealing a heat shield. (the moduel's mass is enough to rebalance S2 for nose first entry) After max heating from reentry, this module opens up Superdraco nozzles on the sides, and conducts a landing burn, with the entire (empty, 5 ton-ish) Stage 2 upside down on it's nose, and finally deploys (very wide) landing legs.

This is plausible with a MerlinVac upperstage, and uses expertise they have already developed. It's also easy to plug in when possible and ignore when not, without running separate S2 production lines.

What would changing to a Raptor Upperstage do?

Raptor has a higher TWR than merlin, but also has a higher base mass, moving the upper stage mass closer to the rear. Composite tankage only makes that issue more pronounced. This makes nose entry less stable, risking exposing the delicate vacbell to the hypersonic airstream.

Redesiging raptor upper to use an ITS style recovery would be research for ITS, but it would delay any actual recovery attempts until the new recovery was researched, developed, and debugged. This would delay any cost reduction from recovery, and accelerate ITS making said upperstage completely obsolete.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 05/05/2017 07:15 PM
Negan, Sorry if I offended you, I quickly read what you posted, and wanted everyone to know the limitations of 30A flame trench.  Some newbies don't realize that. 

Anyway, that is why I think SpaceX should build an intermediate launcher based on the infrastructure limitations.  A 12 million lb launcher is no slouch, 37% greater thrust, and  would give 150-160 tons to LEO, more than Saturn V. 

Maybe Elon is going to build the infrastructure at Boca Chica.  However, his ambition for Mars colonization will require many ITS launches, and that being from at least more than one launch pad in case of a shutdown, due to explosion, or hurricane. 

I think for Mars colonization, two identical ITS should go to Mars together in case of one failure.  If both make it and can return, it is just more equipment for Mars colonization growth. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: TomH on 05/06/2017 12:59 AM
As originally built, Pads 39-A and 39-B could withstand a maximum of 12m lb thrust which was what the Nova LV would have produced. Saturn and STS launches eroded concrete on both and each has now been renovated, but not for greater thrust. The current major concern regarding super and ultra heavy LVs is the acoustic impact. Titusville is now far larger than it was in the 1960s. ITS would definitely require a new pad, either on the same site or on a new site, as the thrust is far too high. Pad 39-C was actually developed recently, but for small LVs. NASA originally was going to build 3 pads (A-C) for the Apollo program and the map had designated locations for potential pads D and E within the Complex 39 area.

A new pad, regardless of location, would have to pass environmental review. An LV the size of ITS could not be approved due to acoustic impact to the surrounding wildlife preserve and to the now much larger Titusville area. The potential for NASA and SpaceX to face innumerable (or a class action) lawsuit(s) for broken windows and flying glass, induced heart attacks, ear damage, freeway accidents, etc. are a risk that will not be allowed either.

Musk's video animation of ITS launching from 39-A is not a declaration of intent. It is merely conceptual and an appeal to nostalgia.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Lars-J on 05/06/2017 01:06 AM
Musk's video animation of ITS launching from 39-A is not a declaration of intent. It is merely conceptual and an appeal to nostalgia.

Oh I disagree. It is a declaration of intent, but that doesn't mean it will happen.

So unless you redefine what 'intent' means, it is intent.
Title: Re: Raptor Upper Stage consolidated thread
Post by: TomH on 05/06/2017 01:15 AM
Then we agree to disagree. Musk is smarter than you give him credit for. He is too smart to declare he is going to do something that he has no chance of being permitted to do.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/06/2017 02:15 AM
I agree with Jim, it probably does not make sense to develop a raptor upper stage economically if it is expendable. So I agree with the opposite argument as well, if a RUS is done so that it can be re-used, it can make economic sense. Despite all the trouble in ground systems.

In terms of performance, a RUS is clearly superior. But again, Jims argument holds that F9 does not need more performance. It can serve the current market just fine as it is. Also, I dont think F9 can deliver the payload advertised on the web page. Not for lack of dV, but for structural and horizontal integration design reasons.

For the CommX constellation, it might make sense to consider some redesigns. Its a large enough number of flights to do changes to the architecture.
Lets start with F9. It currently costs, when reused and with reusable fairings in the order of $30M. It is limited to 10.5 mT in a fairing because the payload, after integration is suspended on the fairing. Since FH supposedly uses the same integration strategy, its also limited to 10.5 mT payload in a fairing. SpaceX develops FH not to lift heavier payloads, but to lift moderately heavy payloads, up to 10 mT to a high energy orbit. It can do that just fine for the current market and there is no economical incentive to change that. Since F9 is most likely volume limited for the constellation, it would make sense to develop a version of the second stage that is reusable at the cost of payload mass. Since F9 is not mass limited anyway, no performance in terms of number of satellites launched is lost. This might drop the cost per launch from $30M to $20M for some investment into a reusable version of the current upper stage, say $100M. No alteration of ground support is necessary.

So, what can be done for the constellation? First off, given the weight of the sats (<400kg each), F9 s probably volume limited, not mass limited. So in order to increase the number of sats per launch, a bigger fairing is necessary. But then, the structural loads during integration will still limit the payload mass to 10.5 mT. Given that, a redesign of the second stage and payload adapter and fairings and integration strategy is needed, so vertical integration. This limits the launch to be done from 39A but, which I understand is not SpaceXes desire. But it could be done to send large batches of sats on a FH. As a result, the number of sats to orbit can already be increased without a RUS but requires some redesign. We dont know if that might already be part of Block 5. Lets guesstimate (you can argue the numbers of course) that the redesign would cost in the order of $80M and that a FH launch including the above would cost $60M to launch.

A RUS, in order to provide its most advantage, would require a larger diameter. This is already a big minus in terms of logistics, factory, tooling and re-certification of F9. A completely new payload adapter, fairing design and ground support are also necessary. This would cost up front, say $500M, due to factory, tooling, infrastructure and ground support changes on all launch pads as well as design and engineering work. This kind of investment would only make sense if it was re-usable. If it is, it might be possible to conduct a launch for $20M, eliminating $10M for the reusable second stage from the unchanged F9 with reusable first stage and fairings. This kind of rocket might be able to get in the order of 15mT for F9 and maybe 70mT in terms of FH into a valid constellation orbit.

To summarize:
Option 1: no change, launch cost $30M a piece. No additional investment. Volume limited number of sats, say 20 sats.
Option 2: re-usable version of the current upper stage, investment ~$100M, $20M per launch. Volume limited number of sats, say 20 sats.
Option 3: Redesign to max out the mass to orbit for the constellation. Investment ~$80M, only beneficial at 39A, mass limit of sats to orbit, say 125 sats per $60M launch of FH.
Option 4: Raptor based upper stage, investment $500M, mass limited number of sats. 37 or F9 of $20M a piece and 175 for FH with $50M a launch.

That are the tradeoffs to make for the constellation. It seems to me, that a RUS is far more expensive up front than a reusable second stage version of the current one. So as Musk hinted in a tweet to look into reusing the upper stage. And it makes sense if you assume that the constellation is really volume limited and not mass limited. A Raptor upper stage, being viable if it flies often enough and allows for mass limited launches of the constellation. But it comes with a much much higher risk if re-usability doesnt work out as advertised. So I think its not a good option, given the tradeoff above. Also, if BFR/ITS comes online in 10 years or so. The second generation of the constellation might just be launched on BFR/ITS, eliminating the need for the raptor upper stage all together. In THAT light, RUS is taking highly needed funds from ITS, delaying ITS and is a lot more risky than trying to develop a reusable upper stage based on the current design. Gwynne will make sure that Elon doesn't go off on a tangent with RUS. SpaceX will have the same trade offs I outlined above, more refined of course. But even if my numbers are wrong by a factor of 2, RUS still doesnt make economic sense. The only benefit would be to give Raptor some flight history. But I think thats not enough of an incentive.

Regarding option 4, why estimate $500M given that the engine already exists?  The entirety of F9 and Merlin was that.  Yes, they need "an entire" payload adapter, and "an entire" interstage, but $500M?

I think it's a no-brainer that a hypothetical RUS will not be expendable. That would be a step backwards, and is a straw-option.

But you left out what I think is a strong argument - SpaceX's MO.   All components are developed and tested in small steps.

Merlin was developed on F1, where the cost of failure was low.
F9 used and incremented Merlin, and is perfecting re-use, in preparation for FH - again with a lower cost of failure.

When you count the cost of a RUS, think about the savings when applied to BFR.  If you can get even equivalent value out of a RUS, then it saves a lot more money down the road, when you gain experience with using Methane "for real".  You get to practice handling it in zero g, you get to give Raptor flight experience - all priceless, and all while generating revenue. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: jketch on 05/06/2017 02:39 AM
As originally built, Pads 39-A and 39-B could withstand a maximum of 12m lb thrust which was what the Nova LV would have produced. Saturn and STS launches eroded concrete on both and each has now been renovated, but not for greater thrust. The current major concern regarding super and ultra heavy LVs is the acoustic impact. Titusville is now far larger than it was in the 1960s. ITS would definitely require a new pad, either on the same site or on a new site, as the thrust is far too high. Pad 39-C was actually developed recently, but for small LVs. NASA originally was going to build 3 pads (A-C) for the Apollo program and the map had designated locations for potential pads D and E within the Complex 39 area.

A new pad, regardless of location, would have to pass environmental review. An LV the size of ITS could not be approved due to acoustic impact to the surrounding wildlife preserve and to the now much larger Titusville area. The potential for NASA and SpaceX to face innumerable (or a class action) lawsuit(s) for broken windows and flying glass, induced heart attacks, ear damage, freeway accidents, etc. are a risk that will not be allowed either.

Musk's video animation of ITS launching from 39-A is not a declaration of intent. It is merely conceptual and an appeal to nostalgia.

If Titusville precludes a launch of ITS due to proximity, it's hard for me to see ITS launching from anywhere in the country, at least on the coast. Titusville is over 11 miles from pad 39A, there's really no where along the Atlantic Coast significantly further from a town. There are a couple of islands, without roads, off the coast of Georgia 12-13 miles from a town. As far as the Texas site, even if you ignore Boca Chica Village, South Padre Island is only 5 miles away.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RonM on 05/06/2017 03:31 AM
As originally built, Pads 39-A and 39-B could withstand a maximum of 12m lb thrust which was what the Nova LV would have produced. Saturn and STS launches eroded concrete on both and each has now been renovated, but not for greater thrust. The current major concern regarding super and ultra heavy LVs is the acoustic impact. Titusville is now far larger than it was in the 1960s. ITS would definitely require a new pad, either on the same site or on a new site, as the thrust is far too high. Pad 39-C was actually developed recently, but for small LVs. NASA originally was going to build 3 pads (A-C) for the Apollo program and the map had designated locations for potential pads D and E within the Complex 39 area.

A new pad, regardless of location, would have to pass environmental review. An LV the size of ITS could not be approved due to acoustic impact to the surrounding wildlife preserve and to the now much larger Titusville area. The potential for NASA and SpaceX to face innumerable (or a class action) lawsuit(s) for broken windows and flying glass, induced heart attacks, ear damage, freeway accidents, etc. are a risk that will not be allowed either.

Musk's video animation of ITS launching from 39-A is not a declaration of intent. It is merely conceptual and an appeal to nostalgia.

If Titusville precludes a launch of ITS due to proximity, it's hard for me to see ITS launching from anywhere in the country, at least on the coast. Titusville is over 11 miles from pad 39A, there's really no where along the Atlantic Coast significantly further from a town. There are a couple of islands, without roads, off the coast of Georgia 12-13 miles from a town. As far as the Texas site, even if you ignore Boca Chica Village, South Padre Island is only 5 miles away.

As has been discussed in other threads, ITS can operate from offshore platforms.
Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 05/06/2017 07:14 AM
But will the environmental crowd allow several offshore of Cape Canaveral? I thought that area was rich in coral.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/06/2017 07:24 AM
But will the environmental crowd allow several offshore of Cape Canaveral? I thought that area was rich in coral.

It would also have the disadvantage of rockets from different pads launching over it depending on inclinations. Brownsville seems a natural location for off shore launch sites. Hard to place foundations but the oil drilling experience should cover that. Far enough out to put a distance to South Padre Island.
Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 05/06/2017 08:37 AM
Boca Chica is also only 6+ miles the new Texas LNG facility going in on the shipping channel. The question is, who purifies it to Raptors methane standard?
Title: Re: Raptor Upper Stage consolidated thread
Post by: MP99 on 05/06/2017 09:02 AM


And if you're going to ... rework your transport logistics for a larger tank size...

AIUI, a 5m upper stage could be (would be?) transported by air, something not possible for a first stage.

Cheers, Martin
Title: Re: Raptor Upper Stage consolidated thread
Post by: Semmel on 05/06/2017 10:18 AM
Boca Chica is also only 6+ miles the new Texas LNG facility going in on the shipping channel. The question is, who purifies it to Raptors methane standard?

Whoever does it, I dont think the location of the LNG facility is a coincidence.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 05/06/2017 11:04 AM
Purification of Natural gas probably will not be necessary.  Strainers can filter out liquids before liquification.  Natural gas is about 95% methane already.  Then during liquification, some of the 4-5% remaining ethane, butane, nitrogen, etc, will settle to the bottom of a liquification tank.  Just don't draw off the bottom, but slightly up.  Also tapping the bottom will remove some impurities.  I worked in the natural gas industry for 40 years.  This is not an expensive, nor a big deal to get almost pure methane.  Not much difference in making liquid oxygen from the air. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Semmel on 05/06/2017 02:36 PM
Regarding option 4, why estimate $500M given that the engine already exists?  The entirety of F9 and Merlin was that.  Yes, they need "an entire" payload adapter, and "an entire" interstage, but $500M?

I think it's a no-brainer that a hypothetical RUS will not be expendable. That would be a step backwards, and is a straw-option.

But you left out what I think is a strong argument - SpaceX's MO.   All components are developed and tested in small steps.

Merlin was developed on F1, where the cost of failure was low.
F9 used and incremented Merlin, and is perfecting re-use, in preparation for FH - again with a lower cost of failure.

When you count the cost of a RUS, think about the savings when applied to BFR.  If you can get even equivalent value out of a RUS, then it saves a lot more money down the road, when you gain experience with using Methane "for real".  You get to practice handling it in zero g, you get to give Raptor flight experience - all priceless, and all while generating revenue.

The reason I think its that expensive is due to change in diameter of the RUS. The $500M include changes to the pad infrastructure of all pads, tooling in the factory, possibly a new factory all-together. Alll handling equipment has to be upgraded for the larger diameter. Thats a lot of stuff. Also, Falcon 9 is relatively cheap because first and second stages are so similar. This advantage would be gone. Also, please note how I did not include any cost estimation for development and manufacture of Raptor. It would come off of the BFR/ITS assembly process anyway. So its not extra cost and therefore, does not provide any savings.

In one point you are correct, SpaceX can use some flight experience with Raptor. And I think Elon also mentioned something like this at some point, that they want to have flight experience with Raptor before launching BFR/ITS for real. Not sure what that includes though. Can be interpreted in a lot of ways, for example grasshopper style hops of some kind. Anyway, I dont think a RUS would save much money BFR/ITS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/06/2017 02:48 PM
Regarding option 4, why estimate $500M given that the engine already exists?  The entirety of F9 and Merlin was that.  Yes, they need "an entire" payload adapter, and "an entire" interstage, but $500M?

I think it's a no-brainer that a hypothetical RUS will not be expendable. That would be a step backwards, and is a straw-option.

But you left out what I think is a strong argument - SpaceX's MO.   All components are developed and tested in small steps.

Merlin was developed on F1, where the cost of failure was low.
F9 used and incremented Merlin, and is perfecting re-use, in preparation for FH - again with a lower cost of failure.

When you count the cost of a RUS, think about the savings when applied to BFR.  If you can get even equivalent value out of a RUS, then it saves a lot more money down the road, when you gain experience with using Methane "for real".  You get to practice handling it in zero g, you get to give Raptor flight experience - all priceless, and all while generating revenue.

The reason I think its that expensive is due to change in diameter of the RUS. The $500M include changes to the pad infrastructure of all pads, tooling in the factory, possibly a new factory all-together. Alll handling equipment has to be upgraded for the larger diameter. Thats a lot of stuff. Also, Falcon 9 is relatively cheap because first and second stages are so similar. This advantage would be gone. Also, please note how I did not include any cost estimation for development and manufacture of Raptor. It would come off of the BFR/ITS assembly process anyway. So its not extra cost and therefore, does not provide any savings.

In one point you are correct, SpaceX can use some flight experience with Raptor. And I think Elon also mentioned something like this at some point, that they want to have flight experience with Raptor before launching BFR/ITS for real. Not sure what that includes though. Can be interpreted in a lot of ways, for example grasshopper style hops of some kind. Anyway, I dont think a RUS would save much money BFR/ITS.
Qualitatively, yes.

But $500M is a huge number.   Looking at what SpaceX has accomplished for similar amounts, and that the engine is already there, I think you're off by at least 2x.  But anyway, we both agree an expendable RUS is nonsensical, right?

Flight history is key here. Money saved from the ITS program using smaller rockets, and while generating revenue - it's 100% SpaceX's MO.

My other question is how they'll test Raptor for a three month cruise, then ignition a Mars.  Definitely something you'd like to test before trying to land a BFS there.

Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/06/2017 03:17 PM
An LV the size of ITS could not be approved due to acoustic impact to the surrounding wildlife preserve and to the now much larger Titusville area. The potential for NASA and SpaceX to face innumerable (or a class action) lawsuit(s) for broken windows and flying glass, induced heart attacks, ear damage, freeway accidents, etc. are a risk that will not be allowed either.
The sound levels in Titusville during an ITS launch would be roughly 6 times LOWER than those in Boca Chica Village during a Falcon Heavy launch, which is allowed.

So again, is there any data and analysis to back this assertion up?
Title: Re: Raptor Upper Stage consolidated thread
Post by: wdobner on 05/06/2017 05:29 PM
Is this where we go to register our totally uninformed, L2-less opinion that the Falcon Heavy demo will use a Raptor upper stage from the first flight, every flight after that, and that change accounts for the delays.  I admit there's no documentation of methane fueling facilities as part of the conversion to LC39A for the FH.  But again, IMUHO SpaceX realized they would be able to get through much of their backlog with improvements to the Falcon 9 while developing a reusable methane powered upper stage for the Falcon Heavy, and so deferred the FH to this point.
Title: Re: Raptor Upper Stage consolidated thread
Post by: cppetrie on 05/06/2017 06:52 PM
Is this where we go to register our totally uninformed, L2-less opinion that the Falcon Heavy demo will use a Raptor upper stage from the first flight, every flight after that, and that change accounts for the delays.  I admit there's no documentation of methane fueling facilities as part of the conversion to LC39A for the FH.  But again, IMUHO SpaceX realized they would be able to get through much of their backlog with improvements to the Falcon 9 while developing a reusable methane powered upper stage for the Falcon Heavy, and so deferred the FH to this point.
How does a methane upper stage and all the conversion work required to make it work help them get through their backlog faster? The thing that will get them through their backlog quickest is not having a RUD and just sticking with what they have been doing. New stuff interrupts cadence not speeds it up. Any significant delay beyond their expected two week cadence has been outside their control and thus not fixable with a new upper stage.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RotoSequence on 05/06/2017 07:04 PM
The sound levels in Titusville during an ITS launch would be roughly 6 times LOWER than those in Boca Chica Village during a Falcon Heavy launch, which is allowed.

Where can I learn about calculated launch noise levels?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Semmel on 05/06/2017 07:19 PM
Qualitatively, yes.

But $500M is a huge number.   Looking at what SpaceX has accomplished for similar amounts, and that the engine is already there, I think you're off by at least 2x.  But anyway, we both agree an expendable RUS is nonsensical, right?

Sure, I can be off with the costs by quite a bit. And also, I assumed in Option 4 that RUS would be reusable. The development would not make sense otherwise.

Flight history is key here. Money saved from the ITS program using smaller rockets, and while generating revenue - it's 100% SpaceX's MO.

My other question is how they'll test Raptor for a three month cruise, then ignition a Mars.  Definitely something you'd like to test before trying to land a BFS there.

I am interested as well. Lets wait and see.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/06/2017 10:16 PM
Qualitatively, yes.

But $500M is a huge number.   Looking at what SpaceX has accomplished for similar amounts, and that the engine is already there, I think you're off by at least 2x.  But anyway, we both agree an expendable RUS is nonsensical, right?

Sure, I can be off with the costs by quite a bit. And also, I assumed in Option 4 that RUS would be reusable. The development would not make sense otherwise.

Flight history is key here. Money saved from the ITS program using smaller rockets, and while generating revenue - it's 100% SpaceX's MO.

My other question is how they'll test Raptor for a three month cruise, then ignition a Mars.  Definitely something you'd like to test before trying to land a BFS there.

I am interested as well. Lets wait and see.
Yup.

If anything, any work on reusing the current F9 US is actually a counter-indicator for RUS...  For that exact reason...

Making a raptor based technology scout vehicle more likely (long duration, methane based, ITS-like EDL, useful for precursor missions).

Something that will follow RD, but have lineage to ITS..
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 05/07/2017 02:39 AM
LNG has been transported via tractor-trailer truck.  How many would it take to fill a Raptor upper stage?  LNG is not hard.  Facilities could be built quickly. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/07/2017 02:51 AM
LNG has been transported via tractor-trailer truck.  How many would it take to fill a Raptor upper stage?  LNG is not hard.  Facilities could be built quickly.

One LNG railcar should be enough, assuming the stage is sized as an operational upper stage for both F9 and FH. Most complex pad equipment probably the subcooling unit.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/07/2017 03:03 AM
LNG has been transported via tractor-trailer truck.  How many would it take to fill a Raptor upper stage?  LNG is not hard.  Facilities could be built quickly.

One LNG railcar should be enough, assuming the stage is sized as an operational upper stage for both F9 and FH. Most complex pad equipment probably the subcooling unit.

Ze teknology reqvired is eezily vithin ze means of even the zmallest of space companies.  It reqvires only the VILL to do it!

Title: Re: Raptor Upper Stage consolidated thread
Post by: Nomadd on 05/07/2017 03:09 AM
The sound levels in Titusville during an ITS launch would be roughly 6 times LOWER than those in Boca Chica Village during a Falcon Heavy launch, which is allowed.

Where can I learn about calculated launch noise levels?
I think most people just find a reference, like an FH being 117db at 1.5 miles, and add 3db for twice the thrust, subtract 6db for twice the distance and so on. Not perfect, because different fuels and engine configurations are different sound levels, but it's a start.
 I'm not exactly sure what "6 times lower" means.
Title: Re: Raptor Upper Stage consolidated thread
Post by: TomH on 05/07/2017 05:58 AM
LNG has been transported via tractor-trailer truck.  How many would it take to fill a Raptor upper stage?  LNG is not hard.  Facilities could be built quickly.

One LNG railcar should be enough, assuming the stage is sized as an operational upper stage for both F9 and FH. Most complex pad equipment probably the subcooling unit.

Another question is whether they will try to sub chill/densify it. If so, will they need extra refrigeration equipment in situ and will that require distilling off all of the 18 substances that make up the other 5% of NG?
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/07/2017 10:07 AM
As subchill is part of Raptor specs, I expect it and have identified it as maybe the most complex component of the methane GSE.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/07/2017 12:15 PM
The sound levels in Titusville during an ITS launch would be roughly 6 times LOWER than those in Boca Chica Village during a Falcon Heavy launch, which is allowed.

Where can I learn about calculated launch noise levels?
I think most people just find a reference, like an FH being 117db at 1.5 miles, and add 3db for twice the thrust, subtract 6db for twice the distance and so on. Not perfect, because different fuels and engine configurations are different sound levels, but it's a start.
 I'm not exactly sure what "6 times lower" means.
It means the acoustic energy intensity level with be about 17% that of a FH at 6 times the distance.
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/07/2017 03:12 PM
First, thanks for starting this thread.  ;)
RUS is such a no-brainer that a dedicated thread is helpful.

Don't know if this is already mentioned, but the Air Force could pay SpaceX to build a big fairing for the FH.  From an Av Week article U.S. Air Force Lines Up Space Launch Vehicle Investments (http://aviationweek.com/space/us-air-force-lines-space-launch-vehicle-investments), the government has a pool of money for DOD specific features that launch vendors can bid on:

Quote
SpaceX may offer modifications to the Falcon Heavy for government missions and launch infrastructure.

“Even after the Falcon Heavy is in place, they’ll still need to strengthen their entire heavy rocket to handle the bigger payloads that take a bigger fairing,” Leon says. “There’s no business case for SpaceX to do that without government investment.”

EDIT:  Leon, in this quote, is Claire Leon, head of the  Air Force’s launch enterprise directorate.

Not finding a back door to read this article.  Can you highlight the size of money pool, guidelines for proposing, range of Launch Vehicle Investments anticipated... is there a formal solicitation out there?
Pool is $1.6B.  In addition to the FH big fairing, they seem to expect Atlas to propose developing Vulcan (that's a lock in my mind), Orbital ATK to propose their all-solid design, maybe BO to propose New Glenn for DOD use, and perhaps other entries.  A draft RFP was issued in March, and the full RFP will be released later this year.  Their main goal is two independent vendors for all nine of the EELV mission profiles.

This would be the perfect pot of money for funding the RUS as a continuation of the OTA funding metted out by USAF for the prototype Raptor upper stage engines for F9/FH.  Whatever logic USAF used for the first installment can easily be used for getting to flight hardware.  (If the upper stages happen to be reusable and are capable of being refueled, USAF won't object.)

A bigger fairing?? Sounds useful, too.

Nice of USAF to fund these items for which SpaceX could not close a business case.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/07/2017 05:44 PM

If anything, any work on reusing the current F9 US is actually a counter-indicator for RUS...  For that exact reason...

Making a raptor based technology scout vehicle more likely (long duration, methane based, ITS-like EDL, useful for precursor missions).

Something that will follow RD, but have lineage to ITS..

I was thinking about this.  Red Dragon is happening, but Red Dragon in some way is a technological dead-end. 

I am also thinking that it's a no-brainer for SpaceX to put a Raptor on a second stage - not because FH needs it, but because it save a huge amount of risk with ITS.

Given that SpaceX is looking into recovering the current upper stage, perhaps what they will do is have a Falcon-sized Mars precursor vehicle.  Nothing like ITS scale (let's say 5 m diameter), but using as much technology as possible:

- Raptor engine for earth departure and for landing
- In orbit fueling
- Composite body
- ITS-like EDL and landing.

Just think how much risk mitigation there is with such a vehicle.  ITS will of course still be a completely new vehicle, but one that uses techniques that were tested with a FH stack, so at much lower cost.

If such a system fails at least once - it already paid for itself 10 times over...
Title: Re: Raptor Upper Stage consolidated thread
Post by: dror on 05/07/2017 06:07 PM

If anything, any work on reusing the current F9 US is actually a counter-indicator for RUS...  For that exact reason...

Making a raptor based technology scout vehicle more likely (long duration, methane based, ITS-like EDL, useful for precursor missions).

Something that will follow RD, but have lineage to ITS..

I was thinking about this.  Red Dragon is happening, but Red Dragon in some way is a technological dead-end. 

I am also thinking that it's a no-brainer for SpaceX to put a Raptor on a second stage - not because FH needs it, but because it save a huge amount of risk with ITS.

Given that SpaceX is looking into recovering the current upper stage, perhaps what they will do is have a Falcon-sized Mars precursor vehicle.  Nothing like ITS scale (let's say 5 m diameter), but using as much technology as possible:

- Raptor engine for earth departure and for landing
- In orbit fueling
- Composite body
- ITS-like EDL and landing.

Just think how much risk mitigation there is with such a vehicle.  ITS will of course still be a completely new vehicle, but one that uses techniques that were tested with a FH stack, so at much lower cost.

If such a system fails at least once - it already paid for itself 10 times over...
Something like that:
https://forum.nasaspaceflight.com/index.php?topic=42783.msg1670447#msg1670447
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/07/2017 06:30 PM

If anything, any work on reusing the current F9 US is actually a counter-indicator for RUS...  For that exact reason...

Making a raptor based technology scout vehicle more likely (long duration, methane based, ITS-like EDL, useful for precursor missions).

Something that will follow RD, but have lineage to ITS..

I was thinking about this.  Red Dragon is happening, but Red Dragon in some way is a technological dead-end. 

I am also thinking that it's a no-brainer for SpaceX to put a Raptor on a second stage - not because FH needs it, but because it save a huge amount of risk with ITS.

Given that SpaceX is looking into recovering the current upper stage, perhaps what they will do is have a Falcon-sized Mars precursor vehicle.  Nothing like ITS scale (let's say 5 m diameter), but using as much technology as possible:

- Raptor engine for earth departure and for landing
- In orbit fueling
- Composite body
- ITS-like EDL and landing.

Just think how much risk mitigation there is with such a vehicle.  ITS will of course still be a completely new vehicle, but one that uses techniques that were tested with a FH stack, so at much lower cost.

If such a system fails at least once - it already paid for itself 10 times over...
Something like that:
https://forum.nasaspaceflight.com/index.php?topic=42783.msg1670447#msg1670447

Maybe.

I also think that with ramping up >100 flight just for the constellation, they're going to recover the second stage - and the best way to do that is to have an integrated second-stage/deployer.

I just don't know if this and the RUS are aligned.

The goal of a constellation deployer is to reduce cost on constellation launches.  It's an operational vehicle.
The goal of that Mars precurser vehicle (MPV?) is to A) reduce ITS risk, and B) get Mars work done (scouting, surface tech testing)  It's an R&D bed.

Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/07/2017 06:54 PM
So, kill two birds with one (reusable, raptor-powered) stone.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/07/2017 07:06 PM
It could be in the competition for a moon lander too.
Title: Re: Raptor Upper Stage consolidated thread
Post by: symbios on 05/07/2017 07:06 PM
Just to put it in here...

How many RUS would they actually need to build?

It would not be expendable... 3-5 max... (plus test articles)

This is a one of, specialized build, times x

I'm not for it, or against it, just like the discussion  ;)
Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 05/07/2017 07:13 PM
Just to put it in here...

How many RUS would they actually need to build?

It would not be expendable... 3-5 max... (plus test articles)

This is a one of, specialized build, times x

I'm not for it, or against it, just like the discussion  ;)

ISTM once you have it, you use it and build enough they can go into rotation like the S1's. Only one S2 type to build, if it also uses autogenous pressurization it retires risk for that feature on ITS, it gives Raptor flight history and it retires the S2 helium issues on F9 and FH once and for all.

Win-win-win-win.
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/07/2017 10:04 PM
Here's a quote by Claire Leon, director of the Space and Missile Systems Center's Launch Enterprise Directorate, to dispel the 'prototype engine only, no intention to build a second stage' argument from the last funding round:

Quote
The strategy builds on previous investments the service has made to mature rocket propulsion technology and support plans for new systems. In fiscal years 2014 and 2015, the service provided a series of rocket propulsion system technology awards, and early last year it awarded public-private partnership agreements to SpaceX, Aerojet Rocketdyne, Orbital ATK and the United Launch Alliance to advance development of their propulsion work.  Companies were required to demonstrate that their systems were part of a larger Evolved Expendable Launch Vehicle-class launch system development effort.

https://insidedefense.com/daily-news/air-force-says-final-launch-services-rfp-slated-august
bold mine

So when USAF funded a prototype upper stage engine for F9/FH, it was based on a larger EELV-class system development effort.  Couldn't be much clearer than that.
Title: Re: Raptor Upper Stage consolidated thread
Post by: cppetrie on 05/07/2017 10:08 PM
Here's a quote by Claire Leon, director of the Space and Missile Systems Center's Launch Enterprise Directorate, to dispel the 'prototype engine only, no intention to build a second stage' argument from the last funding round:

Quote
The strategy builds on previous investments the service has made to mature rocket propulsion technology and support plans for new systems. In fiscal years 2014 and 2015, the service provided a series of rocket propulsion system technology awards, and early last year it awarded public-private partnership agreements to SpaceX, Aerojet Rocketdyne, Orbital ATK and the United Launch Alliance to advance development of their propulsion work.  Companies were required to demonstrate that their systems were part of a larger Evolved Expendable Launch Vehicle-class launch system development effort.

https://insidedefense.com/daily-news/air-force-says-final-launch-services-rfp-slated-august
bold mine
That just says the engine has to be destined to be used as part of a launch system not part of a F9 upper stage. BFR is a launch system, and we know Raptor is destined for use on it. Done. Contract obligations met.
Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 05/07/2017 10:18 PM
FH isn't certified yet, so wouldn't it be a "new launch system" - especially with a RUS? Further, it would need a 19+m fairing to meet all DoD flight profiles.

Also, same source

Quote
The Air Force is aiming to release a final request for proposals in August for its next phase of investment in new launch systems --

USAF wants alternative vehicles and is willing to pony up the bux & tolerate the changes.
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/07/2017 10:52 PM
Here's a quote by Claire Leon, director of the Space and Missile Systems Center's Launch Enterprise Directorate, to dispel the 'prototype engine only, no intention to build a second stage' argument from the last funding round:

Quote
The strategy builds on previous investments the service has made to mature rocket propulsion technology and support plans for new systems. In fiscal years 2014 and 2015, the service provided a series of rocket propulsion system technology awards, and early last year it awarded public-private partnership agreements to SpaceX, Aerojet Rocketdyne, Orbital ATK and the United Launch Alliance to advance development of their propulsion work.  Companies were required to demonstrate that their systems were part of a larger Evolved Expendable Launch Vehicle-class launch system development effort.

https://insidedefense.com/daily-news/air-force-says-final-launch-services-rfp-slated-august
bold mine
That just says the engine has to be destined to be used as part of a launch system not part of a F9 upper stage. BFR is a launch system, and we know Raptor is destined for use on it. Done. Contract obligations met.

The award was specifically for a prototype F9/FH second stage engine.

By no stretch of the imagination is BFR an EELC-class launch system, nor is it an F9 or a FH. 
Payload capability is about 100x larger than typical USAF spacecraft. 
Just no.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/07/2017 11:24 PM
Here's a quote by Claire Leon, director of the Space and Missile Systems Center's Launch Enterprise Directorate, to dispel the 'prototype engine only, no intention to build a second stage' argument from the last funding round:

Quote
The strategy builds on previous investments the service has made to mature rocket propulsion technology and support plans for new systems. In fiscal years 2014 and 2015, the service provided a series of rocket propulsion system technology awards, and early last year it awarded public-private partnership agreements to SpaceX, Aerojet Rocketdyne, Orbital ATK and the United Launch Alliance to advance development of their propulsion work.  Companies were required to demonstrate that their systems were part of a larger Evolved Expendable Launch Vehicle-class launch system development effort.

https://insidedefense.com/daily-news/air-force-says-final-launch-services-rfp-slated-august
bold mine
That just says the engine has to be destined to be used as part of a launch system not part of a F9 upper stage. BFR is a launch system, and we know Raptor is destined for use on it. Done. Contract obligations met.

In what universe is BFR an "EELV-class" vehicle ?!
Title: Re: Raptor Upper Stage consolidated thread
Post by: groundbound on 05/07/2017 11:38 PM

In what universe is BFR an "EELV-class" vehicle ?!

Mission creep.  :)
Title: Re: Raptor Upper Stage consolidated thread
Post by: BobHk on 05/08/2017 02:43 AM
What is the minimum amount of changes required to operate the 2nd stage with a raptor... would plumbing be simplified or more complex?  Not talking reuse here.  Just changing the guts to accommodate the raptor.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Nomadd on 05/08/2017 03:00 AM
The sound levels in Titusville during an ITS launch would be roughly 6 times LOWER than those in Boca Chica Village during a Falcon Heavy launch, which is allowed.

Where can I learn about calculated launch noise levels?
I think most people just find a reference, like an FH being 117db at 1.5 miles, and add 3db for twice the thrust, subtract 6db for twice the distance and so on. Not perfect, because different fuels and engine configurations are different sound levels, but it's a start.
 I'm not exactly sure what "6 times lower" means.
It means the acoustic energy intensity level with be about 17% that of a FH at 6 times the distance.
In any case, sound pressure at 9 miles should be around 110db for ITS if I'm doing it in my head while eating pizza right, which is 5db below FAA standards for airliner takeoff noise without hearing protection.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 05/08/2017 11:54 AM
What is the minimum amount of changes required to operate the 2nd stage with a raptor... would plumbing be simplified or more complex?  Not talking reuse here.  Just changing the guts to accommodate the raptor.

Everything, literally, has to change. A  Full Flow Staged Combustion engine is completely different from the current gas generator MD1 engine. Larger tanks (for same mass methane vs RP1) but also larger just for more lift capacity. Autogenus pressurization, larger plumbing, they might even go for carbon fiber tanks. This will be a new stage from the ground up. About the only thing that could remain the same is computer hardware.
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/08/2017 12:28 PM
What is the minimum amount of changes required to operate the 2nd stage with a raptor... would plumbing be simplified or more complex?  Not talking reuse here.  Just changing the guts to accommodate the raptor.

Everything, literally, has to change. A  Full Flow Staged Combustion engine is completely different from the current gas generator MD1 engine. Larger tanks (for same mass methane vs RP1) but also larger just for more lift capacity. Autogenus pressurization, larger plumbing, they might even go for carbon fiber tanks. This will be a new stage from the ground up. About the only thing that could remain the same is computer hardware.

Would be far superior and probably easier to start from scratch.  Current second stage can remain in assembly line production, since it is more than adequate to service the manifest backlog.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 05/08/2017 12:51 PM
What is the minimum amount of changes required to operate the 2nd stage with a raptor... would plumbing be simplified or more complex?  Not talking reuse here.  Just changing the guts to accommodate the raptor.

Everything, literally, has to change. A  Full Flow Staged Combustion engine is completely different from the current gas generator MD1 engine. Larger tanks (for same mass methane vs RP1) but also larger just for more lift capacity. Autogenus pressurization, larger plumbing, they might even go for carbon fiber tanks. This will be a new stage from the ground up. About the only thing that could remain the same is computer hardware.

Would be far superior and probably easier to start from scratch.  Current second stage can remain in assembly line production, since it is more than adequate to service the manifest backlog.

Exactly.
Also, wider stage can't be road-transported, so it can't be manufactured on the current factory. Couple this with the fact that SpaceX needs a new factory anyway for much wider rocket (ITS). If RUS happens, I think it will be built there.
Title: Re: Raptor Upper Stage consolidated thread
Post by: MP99 on 05/08/2017 01:06 PM
Just to put it in here...

How many RUS would they actually need to build?

It would not be expendable... 3-5 max... (plus test articles)

This is a one of, specialized build, times x

I'm not for it, or against it, just like the discussion  ;)

ISTM once you have it, you use it and build enough they can go into rotation like the S1's. Only one S2 type to build, if it also uses autogenous pressurization it retires risk for that feature on ITS, it gives Raptor flight history and it retires the S2 helium issues on F9 and FH once and for all.

Win-win-win-win.

I'd suggest there are three categories of use for RUS.

1. Reusable for LEO.

2. Higher performance for BLEO missions. Expendable, of course.

3. Reusable for GTO (and maybe expendable for GSO).

The third one, being the most difficult may well follow after the other usages (assuming it ever happens at all, of course).

Cheers, Martin
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 05/08/2017 04:49 PM
I'd suggest there are three categories of use for RUS.

1. Reusable for LEO.

2. Higher performance for BLEO missions. Expendable, of course.

3. Reusable for GTO (and maybe expendable for GSO).

The third one, being the most difficult may well follow after the other usages (assuming it ever happens at all, of course).

Cheers, Martin

What would be the limitations, when GTO does not work? I think not the heat shield, PicaX can do that without becoming too heavy. It would be the structural load during reentry.

If the stage can not come back from GTO they will need to fly the present Merlin upper stage or else launches to GTO become a lot more expensive. The Raptor upper stage will have a higher price tag.

So my guess at least reusable from GTO, if not return from lunar orbit or free return around the moon.
Title: Re: Raptor Upper Stage consolidated thread
Post by: launchwatcher on 05/08/2017 05:39 PM
What is the minimum amount of changes required to operate the 2nd stage with a raptor... would plumbing be simplified or more complex?  Not talking reuse here.  Just changing the guts to accommodate the raptor.

Everything, literally, has to change. A  Full Flow Staged Combustion engine is completely different from the current gas generator MD1 engine. Larger tanks (for same mass methane vs RP1) but also larger just for more lift capacity. Autogenus pressurization, larger plumbing, they might even go for carbon fiber tanks. This will be a new stage from the ground up. About the only thing that could remain the same is computer hardware.

Would be far superior and probably easier to start from scratch.  Current second stage can remain in assembly line production, since it is more than adequate to service the manifest backlog.

Exactly.
Also, wider stage can't be road-transported, so it can't be manufactured on the current factory. Couple this with the fact that SpaceX needs a new factory anyway for much wider rocket (ITS). If RUS happens, I think it will be built there.
Here's a picture of a Saturn's S-IVB being loaded into a Super Guppy: https://history.nasa.gov/MHR-5/Images/fig343.jpg

Wikipedia says it was 6.6m diameter, 17.8m long; it's not clear if the length includes the engine.   The hypothetical RUS will presumably be smaller than this in any event.

So wider stages that aren't too long could go by air.   The Hawthorne plant is adjacent to an airport, and is not far from a much larger airport (LAX).   

Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 05/08/2017 05:56 PM
What is the minimum amount of changes required to operate the 2nd stage with a raptor... would plumbing be simplified or more complex?  Not talking reuse here.  Just changing the guts to accommodate the raptor.

Everything, literally, has to change. A  Full Flow Staged Combustion engine is completely different from the current gas generator MD1 engine. Larger tanks (for same mass methane vs RP1) but also larger just for more lift capacity. Autogenus pressurization, larger plumbing, they might even go for carbon fiber tanks. This will be a new stage from the ground up. About the only thing that could remain the same is computer hardware.

Would be far superior and probably easier to start from scratch.  Current second stage can remain in assembly line production, since it is more than adequate to service the manifest backlog.

Exactly.
Also, wider stage can't be road-transported, so it can't be manufactured on the current factory. Couple this with the fact that SpaceX needs a new factory anyway for much wider rocket (ITS). If RUS happens, I think it will be built there.
Here's a picture of a Saturn's S-IVB being loaded into a Super Guppy: https://history.nasa.gov/MHR-5/Images/fig343.jpg

Wikipedia says it was 6.6m diameter, 17.8m long; it's not clear if the length includes the engine.   The hypothetical RUS will presumably be smaller than this in any event.

So wider stages that aren't too long could go by air.   The Hawthorne plant is adjacent to an airport, and is not far from a much larger airport (LAX).

Is Hawthorne big enough for 3 stage assembly lines and 4 engine assembly lines?
Title: Re: Raptor Upper Stage consolidated thread
Post by: RedLineTrain on 05/08/2017 07:55 PM
Is Hawthorne big enough for 3 stage assembly lines and 4 engine assembly lines?

As I understand it, there is plenty of space to do whatever SpaceX wishes, since Triumph Aerostructures is shrinking its footprint while SpaceX is growing its footprint.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/08/2017 08:25 PM
I'm not sure why people are insisting a hypethetical raptor upper stage would be resuable, and the merlin upper stage would not.

Since the block 5 upgrades, Merlin has mass to spare for almost any payload that fits in the fairing. The Reusable Rocket's subforum here has plotted a relatively simple, Dragon derived recovery architecture for merlin S2, that doesnt take fairing space, protects the delicate engine bell, uses off-the-shelf parts from Dragon 2, and most importantly, can be left OFF on missions where the extra mass is needed.

But everything that makes Raptor great for increasing payload capacity makes it awful for this recovery architecture. You'd need to do half the ITS developent before it could fly recoverable at all, and once there's an ITS Cargo making shipments to a LEO tug dock, that extra capacity that was the raptor falcon's reason to exist is massively overshadowed.
Title: Re: Raptor Upper Stage consolidated thread
Post by: whitelancer64 on 05/08/2017 08:36 PM
The Reusable Rocket's subforum here has plotted a relatively simple, Dragon derived recovery architecture for merlin S2, that doesnt take fairing space, protects the delicate engine bell, uses off-the-shelf parts from Dragon 2, and most importantly, can be left OFF on missions where the extra mass is needed.
Can you link to that?
Title: Re: Raptor Upper Stage consolidated thread
Post by: TomH on 05/08/2017 08:42 PM
Also, wider stage can't be road-transported, so it can't be manufactured on the current factory.

Sure it can. You can fly it out. Road transportability was a money saver for the disposable F9. With reusability, the added cost of flying the stage out is amortized by the number of reuses.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 05/08/2017 08:53 PM
Is Hawthorne big enough for 3 stage assembly lines and 4 engine assembly lines?

As I understand it, there is plenty of space to do whatever SpaceX wishes, since Triumph Aerostructures is shrinking its footprint while SpaceX is growing its footprint.

That's not within the current factory, though. if they need to lease another building, why lease one in LA? The only benefit would be that their workforce is there, but they'd need to be retrained anyway to assemble a RUS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/08/2017 08:59 PM
The Reusable Rocket's subforum here has plotted a relatively simple, Dragon derived recovery architecture for merlin S2, that doesnt take fairing space, protects the delicate engine bell, uses off-the-shelf parts from Dragon 2, and most importantly, can be left OFF on missions where the extra mass is needed.
Can you link to that?

Probably a reference to this: https://forum.nasaspaceflight.com/index.php?topic=42637.0
Title: Re: Raptor Upper Stage consolidated thread
Post by: RedLineTrain on 05/08/2017 09:18 PM
if they need to lease another building, why lease one in LA?

As I understand it, the buildings have already been leased.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 05/08/2017 11:56 PM
Is Hawthorne big enough for 3 stage assembly lines and 4 engine assembly lines?

As I understand it, there is plenty of space to do whatever SpaceX wishes, since Triumph Aerostructures is shrinking its footprint while SpaceX is growing its footprint.

That's not within the current factory, though. if they need to lease another building, why lease one in LA? The only benefit would be that their workforce is there, but they'd need to be retrained anyway to assemble a RUS.

Exactly.
And they need a new factory *anyway*, for ITS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/09/2017 01:03 AM
Just to put it in here...

How many RUS would they actually need to build?

It would not be expendable... 3-5 max... (plus test articles)

This is a one of, specialized build, times x

I'm not for it, or against it, just like the discussion  ;)

ISTM once you have it, you use it and build enough they can go into rotation like the S1's. Only one S2 type to build, if it also uses autogenous pressurization it retires risk for that feature on ITS, it gives Raptor flight history and it retires the S2 helium issues on F9 and FH once and for all.

Win-win-win-win.

I'd suggest there are three categories of use for RUS.

1. Reusable for LEO.

2. Higher performance for BLEO missions. Expendable, of course.

3. Reusable for GTO (and maybe expendable for GSO).

The third one, being the most difficult may well follow after the other usages (assuming it ever happens at all, of course).

Cheers, Martin

None of these IMO justifies the development.  Risk reduction to BFS is IMO the biggest driver, and of course you get the other benefits too.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/09/2017 07:03 AM
The Reusable Rocket's subforum here has plotted a relatively simple, Dragon derived recovery architecture for merlin S2, that doesnt take fairing space, protects the delicate engine bell, uses off-the-shelf parts from Dragon 2, and most importantly, can be left OFF on missions where the extra mass is needed.
Can you link to that?

Probably a reference to this: https://forum.nasaspaceflight.com/index.php?topic=42637.0
indeed.

The discussion starts to focus on the current approach around here: http://forum.nasaspaceflight.com/index.php?topic=42637.msg1669625#msg1669625
Title: Re: Raptor Upper Stage consolidated thread
Post by: GreenShrike on 05/09/2017 06:09 PM
I'm not sure why people are insisting a hypethetical raptor upper stage would be resuable, and the merlin upper stage would not.

I don't think anyone would claim a Merlin upper stage couldn't be made reusable -- it certainly could. It's more can it be made reusable while retaining a sufficient amount of performance.

Since the block 5 upgrades, Merlin has mass to spare for almost any payload that fits in the fairing.

The issue comes about when you consider something other than monolithic comsats -- e.g. the multi-launch of a mega-constellation of small satellites. If the reuse penalty on a Merlin S2 causes the number of required launches to balloon by only 10%, when you're talking ~11,000 sats / ~20 sats per launch = ~550 launches to fill the constellation, that adds 55 additional launches. Even at a discounted SpaceX rate of $30M per launch, that increases the launch costs by over $1.5B -- easily enough to pay for the development of a higher performance S2 which can be reused with no penalty to current performance.

Of course, with the Air Force suggesting they could maybe pay SpaceX to develop a larger fairing (https://forum.nasaspaceflight.com/index.php?topic=41019.msg1675390#msg1675390), that naturally opens up the possibility of using Falcon Heavy for constellation launches. Even so, leaving the Merlin S2 alone and simply building a RUS to handle a standard fairing as well as the higher loads of a larger fairing would make sense.

But everything that makes Raptor great for increasing payload capacity makes it awful for this recovery architecture.

Err... what? Recovery is straightforward, if you're willing to pay the one-to-one performance penalty for strapping additional equipment to the stage and reserving recovery propellant. It may be *expensive* to design and build the stage, but when you can reuse it, the increased capital costs can be amortized away. This is unlike an expendable design -- such as the current Merlin S2 -- where "cheap as possible to get the job done" is called for.

You'd need to do half the ITS developent before it could fly recoverable at all,

Half? I'd think an *interplanetary spaceship* is a hell of a lot more complicated than a rocket stage with a single Raptor, a 5m tank and an adaption of whatever recovery equipment they've been working on. On the other hand, as meekGee says, having a recoverable RUS would retire a lot of risk in ITS development. I'd hate to think that the first launch, on-orbit ops, and recovery for Raptor would be on that first ridiculously expensive BFS -- that launch will be enough of a gamble as it is.

and once there's an ITS Cargo making shipments to a LEO tug dock, that extra capacity that was the raptor falcon's reason to exist is massively overshadowed.

"LEO tug dock"? Heh -- good one. :-)

I'm fond of fantasizing, too, but I do try to keep in mind that there's a butt load of steps between where we are now and a robust on-orbit industry. Just like Falcon Heavy and New Glenn, ITS won't immediately obsolete every other rocket in the world when it's built, and F9 and FH will have roles long after ITS is in regular use. And before that point, SpaceX needs the Falcons and the CommX constellation to pay for ITS, and the more they pay to build the constellation, the less they have for ITS and the longer ITS will take.
Title: Re: Raptor Upper Stage consolidated thread
Post by: dror on 05/09/2017 08:35 PM
I'm not sure why people are insisting a hypethetical raptor upper stage would be resuable, and the merlin upper stage would not.


I think this is based on Elon's remarks such as
Quote from: Elon
I[What about the second stage?] The next generation vehicles after the Falcon
architecture will be designed for full reusability. I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles, which is going to be a sub-cooled methane/oxygen system where the propellants are cooled close to their freezing temperature to increase the density, we could definitely do full reusability - and that system is intended to be a fully reusable Mars transportation system. So, not merely to low Earth orbit but all the way to Mars and back, with full reusability. [Within 3 years?] Ha. I am an optimistic person, but - I think we could expect to see some test flights in the five or six year time frame. But, we're talking about a much bigger vehicle, and we're also going to be upgrading to a new generation - a harder engine cycle, which is a full-flow staged combustion. What we have right now is an open cycle engine. Right now, I'd say, engines are our weakest point at SpaceX, but they will become as strong as the structures and avionics in the next generation.

http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24
Title: Re: Raptor Upper Stage consolidated thread
Post by: rockets4life97 on 05/09/2017 08:53 PM
I think this is based on Elon's remarks such as

To be fair, Elon also said that they wouldn't try for upper stage re-use. Then, he changed his mind with the more recent comments. So, chronology matters here.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Kaputnik on 05/09/2017 10:19 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 05/09/2017 11:11 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.

I am pretty sure he is talking about the sophistication of the engine cycle only, and with respect to the amount of innovation they have put into other aspects of the rocker. The T:W turns out to be awesome for re-use but by all other measures it is no RD-180. The usual trap of wanting the most efficient cycle with a high energy fuel. In this case you kind of need that level of tech for Mars reuse. Lets hope they can keep those eye popping T:W numbers with raptor.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/10/2017 03:01 AM
I'm not sure why people are insisting a hypethetical raptor upper stage would be resuable, and the merlin upper stage would not.


I think this is based on Elon's remarks such as
Quote from: Elon
I[What about the second stage?] The next generation vehicles after the Falcon
architecture will be designed for full reusability. I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles, which is going to be a sub-cooled methane/oxygen system where the propellants are cooled close to their freezing temperature to increase the density, we could definitely do full reusability - and that system is intended to be a fully reusable Mars transportation system. So, not merely to low Earth orbit but all the way to Mars and back, with full reusability. [Within 3 years?] Ha. I am an optimistic person, but - I think we could expect to see some test flights in the five or six year time frame. But, we're talking about a much bigger vehicle, and we're also going to be upgrading to a new generation - a harder engine cycle, which is a full-flow staged combustion. What we have right now is an open cycle engine. Right now, I'd say, engines are our weakest point at SpaceX, but they will become as strong as the structures and avionics in the next generation.

http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24
keep in mind in 2014, they'd just managed to return their first core. Full thrust didnt arrive until 2015, and there's been multiple thrust upgrades announced since. He's ramped up his margins enough that he can actually play with kerosene upper stage reuse.
Title: Re: Raptor Upper Stage consolidated thread
Post by: MP99 on 05/10/2017 05:58 AM


I'm not sure why people are insisting a hypethetical raptor upper stage would be resuable, and the merlin upper stage would not.

Since the block 5 upgrades, Merlin has mass to spare for almost any payload that fits in the fairing.

Surely, that's only true for LEO payloads, otherwise, there would be no point in FH.

Cheers, Martin
Title: Re: Raptor Upper Stage consolidated thread
Post by: GORDAP on 05/10/2017 01:21 PM
I think this is based on Elon's remarks such as

To be fair, Elon also said that they wouldn't try for upper stage re-use. Then, he changed his mind with the more recent comments. So, chronology matters here.

It's interesting that development of a Raptor US for use with the FH (or even perhaps F9) would be consistent with both of Elon's statements, without any change of mind.  I don't really think this will be the case (especially if he thinks they could have it ready and in use by the end of '18), but I've long since stopped being surprised at what SpaceX attempts.  More likely is that Block 5 improvements have led him to think they have the margin to do reuse with the existing Merlin stage.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 05/10/2017 01:40 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.

isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.

RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.

Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 05/10/2017 02:17 PM
But Merlin kills it with mass production, T/W, cost, etc. etc.

Chevy small block vs Ferrari V12.
Title: Re: Raptor Upper Stage consolidated thread
Post by: DOCinCT on 05/10/2017 03:12 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.
isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.
RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.
RS-68 and RS-25 don't count as they are LH2/LOX engines.
The RD-180 has similar ISP (SL,VAC) to Merlin 1D
Title: Re: Raptor Upper Stage consolidated thread
Post by: Basto on 05/10/2017 04:25 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.
isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.
RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.
RS-68 and RS-25 don't count as they are LH2/LOX engines.
The RD-180 has similar ISP (SL,VAC) to Merlin 1D

RD-180 has better ISP.  Merlin 1D uses a less efficient gas generator cycle.


Title: Re: Raptor Upper Stage consolidated thread
Post by: rsdavis9 on 05/10/2017 04:26 PM
The RD-180 has similar ISP (SL,VAC) to Merlin 1D

I have:
rd-180 4.15 MN,  26 MPa Pc, 338 isp
Merlin 0.9 MN, 10 MPa Pc, 311 isp

I think both of those are sea level numbers.
So is it the cycle (gasgen vs oxyrich) or the chamber pressure or both?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Ictogan on 05/10/2017 04:31 PM
The RD-180 has similar ISP (SL,VAC) to Merlin 1D

I have:
rd-180 4.15 MN,  26 MPa Pc, 338 isp
Merlin 0.9 MN, 10 MPa Pc, 311 isp

I think both of those are sea level numbers.
So is it the cycle (gasgen vs oxyrich) or the chamber pressure or both?
Those are vac numbers. For sea level, RD-180 has 3.83MN and 311 Isp, Merlin has 845kN and 282 Isp.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Kaputnik on 05/10/2017 04:51 PM
Is there a GG kerolox engine that outperforms Merlin? I can't name one.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 05/10/2017 05:20 PM
RS-68 and RS-25 don't count as they are LH2/LOX engines.

If we are talking about all liquid engines, then they do count. LH2/LOX are liquids.

That spacex chose to use low-isp fuel does not make the isp of their engines any better, but it does make impulse DENSITY better, and if we were talking about impulse density, then in that Merlin might beat those LH2/LOX engines.

Quote
The RD-180 has similar ISP (SL,VAC) to Merlin 1D

Wrong. It has over 25, almost 30 seconds better isp.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 05/10/2017 05:26 PM
Is there a GG kerolox engine that outperforms Merlin? I can't name one.

doesn't matter.

Is there a biplane faster than polikarpov I-15? I can't name one.

Still there are lots of aeroplanes much faster than polikarpov I-15, and polikarpov I-15 could not have been considered a fast aeroplane for the last 75 years.

Title: Re: Raptor Upper Stage consolidated thread
Post by: Lars-J on 05/10/2017 06:02 PM
The RD-180 has similar ISP (SL,VAC) to Merlin 1D

Wrong. It has over 25, almost 30 seconds better isp.

If any engine has proved the folly of ISP measuring, it would have to be Merlin.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 05/10/2017 06:08 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.

isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.

RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.

True.
That's why Sea Launch has such a huge backlog. Their engine is so much better! :P
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 05/10/2017 06:33 PM
The RD-180 has similar ISP (SL,VAC) to Merlin 1D

Wrong. It has over 25, almost 30 seconds better isp.

If any engine has proved the folly of ISP measuring, it would have to be Merlin.

True-ish, Merlin and falcon 9 have amply demonstrated that there are big wins to be had in mass fraction. But the returns are logarithmic. Eventually you do need to start paying attention to ISP again.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Kaputnik on 05/10/2017 08:24 PM
Is there a GG kerolox engine that outperforms Merlin? I can't name one.

doesn't matter.

Is there a biplane faster than polikarpov I-15? I can't name one.

Still there are lots of aeroplanes much faster than polikarpov I-15, and polikarpov I-15 could not have been considered a fast aeroplane for the last 75 years.



The point of this whole diversion was that I was surprised that Elon considers SpaceX to be weak when it comes to engines.
The only type of engine they make is a GG, so that is all we can judge them by. Does it stand judgement against its peers? Hell yeah, it's perhaps the best example of a GG engine that we can find. To me that suggests that they are pretty good at building engines.
If their GG engine was inferior to other engines using the same prop and cycle, then I would agree that they suck at making engines.
Perhaps what Elon is alluding to is that they are weak when it comes to engines running on different cycles or propellants. Hardly surprising given that they have yet to finish developing one.
Title: Re: Raptor Upper Stage consolidated thread
Post by: JamesH65 on 05/10/2017 09:02 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.

isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.

RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.

And yet, here it is, powering the F9 to orbit, launching payloads cheaper than anyone else, returning the booster and landing it, unlike anyone else.

It may be the worst liquid fuel rocket - but just look at what it achieves. More than any of the other engines quoted are doing.

The engine is a triumph of pragmatism.

Title: Re: Raptor Upper Stage consolidated thread
Post by: TrueBlueWitt on 05/10/2017 11:03 PM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.

isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.

RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.

And yet, here it is, powering the F9 to orbit, launching payloads cheaper than anyone else, returning the booster and landing it, unlike anyone else.

It may be the worst liquid fuel rocket - but just look at what it achieves. More than any of the other engines quoted are doing.

The engine is a triumph of pragmatism.



Merlin may have the "Lowest" ISP.. But that's just one part of the equation..
It's far from a slouch..
For it's Fuel and engine cycle I believe it has the highest ISP. 
Also the best T/W of any liquid Fueled engine in the US, or being used anywhere!
T/W is almost as big a deal as ISP.. Which is part of the reason they also have super high stage pmfs.. 
Most likely the lowest $/performance of any engine..
It's about optimizing the whole system, not just one piece.
ISP will only help so much if you have terrible T/W and pfm for the stage. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: TomH on 05/10/2017 11:37 PM
...the lowest $/performance of any engine..

THIS.......matters most.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 05/11/2017 03:06 AM
Is there a GG kerolox engine that outperforms Merlin? I can't name one.

doesn't matter.

Is there a biplane faster than polikarpov I-15? I can't name one.

Still there are lots of aeroplanes much faster than polikarpov I-15, and polikarpov I-15 could not have been considered a fast aeroplane for the last 75 years.



The point of this whole diversion was that I was surprised that Elon considers SpaceX to be weak when it comes to engines.
The only type of engine they make is a GG, so that is all we can judge them by. Does it stand judgement against its peers? Hell yeah, it's perhaps the best example of a GG engine that we can find. To me that suggests that they are pretty good at building engines.
If their GG engine was inferior to other engines using the same prop and cycle, then I would agree that they suck at making engines.
Perhaps what Elon is alluding to is that they are weak when it comes to engines running on different cycles or propellants. Hardly surprising given that they have yet to finish developing one.
its not that the engine design sucked. Its that, in 2014, they couldnt build them well enough to get full performance from them. Then in 2015, they improved to the point elon called "full thrust".
Block 5 is another step past that.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 05/11/2017 05:21 AM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.

isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.

RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.

And yet, here it is, powering the F9 to orbit, launching payloads cheaper than anyone else, returning the booster and landing it, unlike anyone else.

It may be the worst liquid fuel rocket - but just look at what it achieves. More than any of the other engines quoted are doing.

The engine is a triumph of pragmatism.

I have not claimed it as worst liquid fuel rocket.

I've just said it has the worst isp, and so it has ONE clear weakness.

For practically all the OTHER metrics, it's great engine, and falcon 9 is a great rocket,
and overall I consider merlin 1d to be much better engine than for example RS-68. Because impulse density, price/thrust, thrust/weight are all MUCH better with merlin 1d AND the smaller size allows better flexibility for EELV-size vehicle (for upper stage use, landing and engine-out capability)





Title: Re: Raptor Upper Stage consolidated thread
Post by: rsdavis9 on 05/11/2017 10:41 AM
So how is impulse density defined?
Weight of fluids and engine/weight of engine?
Thrust/weight of engine?

EDIT:
Sorry answered my own question:

Quote
Higher density fuels have a higher Impulse Density because Impulse density is basically the propellants Specific Impulse multiplied by it's density.
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 05/11/2017 01:59 PM
So how is impulse density defined?
Weight of fluids and engine/weight of engine?
Thrust/weight of engine?

Force per flowrate? which give Newton Seconds per Kilogram? Not sure that is any different than ISP.

Though I suppose if you want a definition that Merlin wins at maybe Force per volumetric flow rate.
Title: Re: Raptor Upper Stage consolidated thread
Post by: JamesH65 on 05/11/2017 03:36 PM
So how is impulse density defined?
Weight of fluids and engine/weight of engine?
Thrust/weight of engine?

Force per flowrate? which give Newton Seconds per Kilogram? Not sure that is any different than ISP.

Though I suppose if you want a definition that Merlin wins at maybe Force per volumetric flow rate.

There really doesn't need to be a definition at what the Merlin 'wins' at - just look at the accomplishments of the whole system. Those are wins all the way down.
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 05/11/2017 04:00 PM
So how is impulse density defined?
Weight of fluids and engine/weight of engine?
Thrust/weight of engine?

Force per flowrate? which give Newton Seconds per Kilogram? Not sure that is any different than ISP.

Though I suppose if you want a definition that Merlin wins at maybe Force per volumetric flow rate.

There really doesn't need to be a definition at what the Merlin 'wins' at - just look at the accomplishments of the whole system. Those are wins all the way down.

I fully agree, I was just responding to a specific question and disregarding the usefulness of such definitions. Merlin is excellent in that it does many things "good enough" within the design requirements of the falcon9 reusable launch system.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 05/11/2017 06:04 PM
isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.

RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.
I have not seen an ISP figure from SpaceX since the first version of the Merlin 1D. Since then we have seen a 26% increase in thrust. Now I am not a rocket scientist, but as I understand, increasing thrust requires either larger throat or higher ISP. I have no reason to believe the throat or other physical dimensions of the Merlin 1D have changed so I believe the ISP has gone up a lot.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rsdavis9 on 05/11/2017 07:35 PM
I have not seen an ISP figure from SpaceX since the first version of the Merlin 1D. Since then we have seen a 26% increase in thrust. Now I am not a rocket scientist, but as I understand, increasing thrust requires either larger throat or higher ISP. I have no reason to believe the throat or other physical dimensions of the Merlin 1D have changed so I believe the ISP has gone up a lot.

probably just higher chamber pressure which translates to higher exhaust velocity which is ISP.
Title: Re: Raptor Upper Stage consolidated thread
Post by: acsawdey on 05/11/2017 07:55 PM
I have not seen an ISP figure from SpaceX since the first version of the Merlin 1D. Since then we have seen a 26% increase in thrust. Now I am not a rocket scientist, but as I understand, increasing thrust requires either larger throat or higher ISP. I have no reason to believe the throat or other physical dimensions of the Merlin 1D have changed so I believe the ISP has gone up a lot.

probably just higher chamber pressure which translates to higher exhaust velocity which is ISP.

Increasing chamber pressure will improve ISP a little but the trouble is with a GG cycle you spend more propellant in the gas generator to provide the increased power to the pumps which does not contribute to thrust. The big gains would be if they were able to improve pump efficiency and GG turbine efficiency. Has anybody tried to back-calculate ISP from those simulations of F9 flights?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 05/11/2017 08:25 PM
I have not seen an ISP figure from SpaceX since the first version of the Merlin 1D. Since then we have seen a 26% increase in thrust. Now I am not a rocket scientist, but as I understand, increasing thrust requires either larger throat or higher ISP. I have no reason to believe the throat or other physical dimensions of the Merlin 1D have changed so I believe the ISP has gone up a lot.

probably just higher chamber pressure which translates to higher exhaust velocity which is ISP.

Increasing chamber pressure will improve ISP a little but the trouble is with a GG cycle you spend more propellant in the gas generator to provide the increased power to the pumps which does not contribute to thrust. The big gains would be if they were able to improve pump efficiency and GG turbine efficiency. Has anybody tried to back-calculate ISP from those simulations of F9 flights?
Ok, I buy the concept that the GG has to provide more pressure and will consume energy to do so. Does this mean the GG runs hotter? We are still told that there is a 26% increase in thrust, if most of this is not due increased chamber pressure, then is there significant increased thrust from the GG exhaust?
Title: Re: Raptor Upper Stage consolidated thread
Post by: livingjw on 05/11/2017 08:54 PM
Density Impulse  = The product of the specific impulse of a propellant combination and the average specific gravity of the propellants. Density impulse is important because tank weight is proportional to average specific gravity of the engine's propellants. As an example, LOX/LH2 engine's wonderful ISP is almost, but not quite, negated by its horrible propellant density.

The Merlin engine has very good performance for a gas generator cycle rocket engine. Thrust increases are probably from a combination of higher pressure and larger throats. ISP has probably not changed much.

To get significant improvements in ISP, one needs to use a staged combustion cycle like the Russian engines, BE-4 and Raptor. Note: The small improvement that LOX/CH4 has over LOX/RP1 is almost completely canceled out by its lower propellant density. Use of CH4 is favored for reusability, self pressurization and cost.
Title: Re: Raptor Upper Stage consolidated thread
Post by: acsawdey on 05/11/2017 10:04 PM
Ok, I buy the concept that the GG has to provide more pressure and will consume energy to do so. Does this mean the GG runs hotter? We are still told that there is a 26% increase in thrust, if most of this is not due increased chamber pressure, then is there significant increased thrust from the GG exhaust?

So, this goes to explain what livingjw is saying about needing to go to a staged combustion cycle.

The whole point of the GG is to produce gasses that are expanded through the turbine to do work. The exhaust of the GG doesn't produce much thrust because it's energy has been used and it doesn't have much pressure left. The problem is that mass flow is just lost. A staged combustion cycle doesn't dump that overboard, so all the mass flow eventually ends up in the combustion chamber. You have the same amount of chemical energy, but more mass because you don't waste anything, so ISP is higher. Being able to use a higher chamber pressure is another benefit that comes from not losing any mass, and it means you can have a higher expansion ratio at sea level, which leads to even better ISP.

I think increased chamber pressure is the only possibility if you have more thrust from the same size nozzle and same expansion ratio. Since we know the nozzle size on M1D has not changed significantly I think we can also conclude the throat size is the same because if they made it larger, it would reduce expansion ratio and hurt ISP, especially vacuum ISP.
Title: Re: Raptor Upper Stage consolidated thread
Post by: deruch on 05/12/2017 12:35 AM
Here's a quote by Claire Leon, director of the Space and Missile Systems Center's Launch Enterprise Directorate, to dispel the 'prototype engine only, no intention to build a second stage' argument from the last funding round:

Quote
The strategy builds on previous investments the service has made to mature rocket propulsion technology and support plans for new systems. In fiscal years 2014 and 2015, the service provided a series of rocket propulsion system technology awards, and early last year it awarded public-private partnership agreements to SpaceX, Aerojet Rocketdyne, Orbital ATK and the United Launch Alliance to advance development of their propulsion work.  Companies were required to demonstrate that their systems were part of a larger Evolved Expendable Launch Vehicle-class launch system development effort.

https://insidedefense.com/daily-news/air-force-says-final-launch-services-rfp-slated-august
bold mine

So when USAF funded a prototype upper stage engine for F9/FH, it was based on a larger EELV-class system development effort.  Couldn't be much clearer than that.

I couldn't disagree with your interpretation more.  I think it doesn't do anything at all to "dispel the 'prototype engine only, no intention to build a second stage' argument."  Building a prototype engine that theoretically could be used in an EELV-class launch system, is pretty much by definition "part of a larger EELV-class launch system development effort" regardless of the fact that, in truth, there may be absolutely zero intention to ever use it as such.  I get your point.  I think we all do.  With a Plain English reading of Congress's language in the 2015 NDAA it seems like there should have to be actual "system development" (meaning stage design), but IMO that's a perfect example of how you can't always (ever?) read legislative language in that way and expect it to match reality with high fidelity. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/12/2017 12:44 AM
I understand where you are coming from on this.
I want to believe that they will make a high energy upper stage to counter the only real weakness of the Falcon design... one that supporters of Atlas V, for instance continually point out.  You want to believe that SpaceX won't.
So, we disagree... not a problem. 

Either they will or not.  Let's wait and see what is awarded in the next round and revisit this.
Title: Re: Raptor Upper Stage consolidated thread
Post by: deruch on 05/12/2017 01:15 AM
I understand where you are coming from on this.
I want to believe that they will make a high energy upper stage to counter the only real weakness of the Falcon design... one that supporters of Atlas V, for instance continually point out.  You want to believe that SpaceX won't.
So, we disagree... not a problem. 

Either they will or not.  Let's wait and see what is awarded in the next round and revisit this.
No.  It has nothing to do with what I want.  My point doesn't have anything to do with whether SpaceX will actually build a RUS but only that the language used in that award or the underlying NDAA cannot be used to support the position that they will or have to. 

Personally, I think any added capability is awesome.  So, if SpaceX decides (or has already decided) to actually build a RUS that would be great.  I'll be very surprised because, as an outsider, who isn't privy to their internal cost and engineering trades, I find the financial and logistics arguments against doing so persuasive.  But, I'll be perfectly happy to be surprised if it turns out that SpaceX sees it the way you do. 

You're absolutely right.  Either they will or they won't.  Looking forward to finding out.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Robotbeat on 05/12/2017 01:41 AM
It's remarkable that Elon thinks engines are their weak point- the Merlin has outstanding T:W, impressive isp, and they churn out more of them than any other engine builder.
It's the structures that have caused their LOVs so far- the engines have had a good track record.

isp of merlin is the worst of all liquid fueled rocket engines used in any orbital-capable rocket in USA today.

RD-170-derivates used by Atlas and Antares, RS-68 used by Delta, RS-25 that will be used by SLS all have considerably better isp.

And yet, here it is, powering the F9 to orbit, launching payloads cheaper than anyone else, returning the booster and landing it, unlike anyone else.

It may be the worst liquid fuel rocket - but just look at what it achieves. More than any of the other engines quoted are doing.

The engine is a triumph of pragmatism.

I have not claimed it as worst liquid fuel rocket.

I've just said it has the worst isp, and so it has ONE clear weakness.

For practically all the OTHER metrics, it's great engine, and falcon 9 is a great rocket,
and overall I consider merlin 1d to be much better engine than for example RS-68. Because impulse density, price/thrust, thrust/weight are all MUCH better with merlin 1d AND the smaller size allows better flexibility for EELV-size vehicle (for upper stage use, landing and engine-out capability)
Except you're wrong. Delta II is still flying and has a first stage Isp of just 255s vs 282s for the older version of Merlin 1D.
Title: Re: Raptor Upper Stage consolidated thread
Post by: TomH on 05/12/2017 04:34 AM
I think increased chamber pressure is the only possibility if you have more thrust from the same size nozzle and same expansion ratio.

Is it possible to gain higher thrust by pumping the propellants faster? If the vehicle and payload mass stay the same ISTM that would increase T/W, increase G, increase Max Q and Max Drag (unless you throttle down on those), and reduce gravity losses.  If you increase prop flow for greater thrust, but want to increase payload and have the same run time, you then need more prop, by either tank stretch or densification.

Is this correct or am I misunderstanding something?
Title: Re: Raptor Upper Stage consolidated thread
Post by: IainMcClatchie on 05/12/2017 08:21 AM
I think increased chamber pressure is the only possibility if you have more thrust from the same size nozzle and same expansion ratio.

Is it possible to gain higher thrust by pumping the propellants faster?

Yes.  Increased mass flow is the same thing as increased chamber pressure if you keep Isp, nozzle exit area, and expansion ratio the same.

Exit area and expansion ratio the same => throat area is the same.

Isp the same means the exit velocity and thus velocity at the throat remain the same, although I think the throat velocity is sonically choked and so it's dependent on chamber temperature and maybe gas composition and can't really change very much.

So if you want more propellant mass flow through the same throat diameter at the same velocity, you must have higher density.  Higher density at the same temperature means higher pressure.

Voila, you are both saying the same thing.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 05/12/2017 02:26 PM
Yes.  Increased mass flow is the same thing as increased chamber pressure if you keep Isp, nozzle exit area, and expansion ratio the same.

Exit area and expansion ratio the same => throat area is the same.

Isp the same means the exit velocity and thus velocity at the throat remain the same, although I think the throat velocity is sonically choked and so it's dependent on chamber temperature and maybe gas composition and can't really change very much.

So if you want more propellant mass flow through the same throat diameter at the same velocity, you must have higher density.

I agree with the above statements. However I disagree with the following.

Quote
Higher density at the same temperature means higher pressure.

I think the only way to get more mass through the same throat without higher velocity (ISP) is to increase the density by having lower temperature. Starting with sub cooled propellant may accomplish this.
Title: Re: Raptor Upper Stage consolidated thread
Post by: livingjw on 05/12/2017 06:17 PM
Yes.  Increased mass flow is the same thing as increased chamber pressure if you keep Isp, nozzle exit area, and expansion ratio the same.

Exit area and expansion ratio the same => throat area is the same.

Isp the same means the exit velocity and thus velocity at the throat remain the same, although I think the throat velocity is sonically choked and so it's dependent on chamber temperature and maybe gas composition and can't really change very much.

So if you want more propellant mass flow through the same throat diameter at the same velocity, you must have higher density.

I agree with the above statements. However I disagree with the following.

Quote
Higher density at the same temperature means higher pressure.

I think the only way to get more mass through the same throat without higher velocity (ISP) is to increase the density by having lower temperature. Starting with sub cooled propellant may accomplish this.

Lowering temperature will reduce performance since temperature is what drives the nozzle exit velocity. Temperature is primarily driven by the chemistry. All you have to play with is throat area and chamber pressure.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 05/14/2017 03:54 PM
Is it possible to calculate ISP given that the block 5 Merlin 1D has an exhaust velocity of 10,500 ft/sec? I don't know if that is for the vacuum version or not.

Another tid-bit from Mueller's interview. The Raptor combustion chamber runs at 4000psi. How does this compare with other engines?

Adding the quote from Mueller's speech.

"So I’m really excited about what we’re doing; we’re kind of hitting the limits of chemical rocket technology; the new engines we’re developing for the Mars ship are very high-pressure staged combustion engines. Getting all the energy you can out of fossil fuel propellants; you know, 99% combustion efficiency over four thousand PSi combustion chamber pressure; full-flow. So all of the propellant goes through the main combustor; it’s not an open-cycle; it’s a closed-cycle. It’s basically, you can’t get any more energy out of a chemical propellant."
Title: Re: Raptor Upper Stage consolidated thread
Post by: Ictogan on 05/14/2017 04:10 PM
Is it possible to calculate ISP given that the block 5 Merlin 1D has an exhaust velocity of 10,500 ft/sec? I don't know if that is for the vacuum version or not.
(10 500 (ft / second)) / (9.81 (m / (s^2))) = 326.2 seconds. Although that number is not including the part of the propellant that is exhausted at lower speeds from the gas generator.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 05/14/2017 04:58 PM
Ok, so just to consolidate the info above.

ISP   Merlin 1D block 1   Atlas 5   Merlin 1D block 5
Sea Level    282 isp    311 isp     ?
Vacuum    311 isp    338 isp    326 isp
Title: Re: Raptor Upper Stage consolidated thread
Post by: oldAtlas_Eguy on 05/14/2017 10:09 PM
Ok, so just to consolidate the info above.

ISP   Merlin 1D block 1   Atlas 5   Merlin 1D block 5
Sea Level    282 isp    311 isp     ?
Vacuum    311 isp    338 isp    326 isp
If the 326 ISP is real that means that the LEO payload increase being put out is heavily sandbagged. Such a increase in just ISP for a vehicle results in 5 to 8mt of payload increase for a 20+mt LEO capable vehicle. Which if you ran the F9 to the edge the LEO payload could be as high as 30mt!!!!!! (Speculation very rough estimate).

So there may be more new performance numbers once the fisrt Block 5 flights have occured.

Now what does that mean for the need of developing a Raptor US for F9. It says that such an upgraded is not required to achieve even US reuse on an F9. Where significant performance losses to reuse the US can be absorbed because of the large excess performance over that of the booked payloads allows the US to be reused.

A BTW does this mean that the FH currently posted 64mt to LEO is not the ultimate performance as well for the FH?
Title: Re: Raptor Upper Stage consolidated thread
Post by: livingjw on 05/14/2017 11:43 PM
Ok, so just to consolidate the info above.

ISP   Merlin 1D block 1   Atlas 5   Merlin 1D block 5
Sea Level    282 isp    311 isp     ?
Vacuum    311 isp    338 isp    326 isp

I would be surprised if the ISP numbers for the Block 5 engine varied more than 1 or 2 seconds different from current. You have to subtract the hit from the gas generator propellant flow.

John
Title: Re: Raptor Upper Stage consolidated thread
Post by: alang on 05/15/2017 04:41 AM
Is there a case for putting some of this on the Merlin thread instead? :
https://forum.nasaspaceflight.com/index.php?topic=41014.0
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 05/15/2017 04:47 AM
Ok, so just to consolidate the info above.

ISP   Merlin 1D block 1   Atlas 5   Merlin 1D block 5
Sea Level    282 isp    311 isp     ?
Vacuum    311 isp    338 isp    326 isp

You are forgetting the tumbopump exhaust. That has MUCH lower velocity, so the average exhaust velocity is considerably less.

Title: Re: Raptor Upper Stage consolidated thread
Post by: oldAtlas_Eguy on 05/15/2017 02:12 PM
The missing piece of information to determine the probable effect of the GG on ISP is the percent of fuel of the total consumed per sec by the GG. The calculation is:

Combined ISP = ISPGG*(1-PRCNT)+ISPTC*PRCNT
We do not know the values for ISPGG or the PRCNT.

For a guess of the values PRCNT=90% and ISPGG in VAC = 250 the combined is 318. This is a lot more than 1 or 2 points.

For PRCNT=95% and ISPGG=200 the result is 319.

For PRCNT =98% and ISPGG=0 the result is 319.
Title: Re: Raptor Upper Stage consolidated thread
Post by: baldusi on 05/15/2017 02:43 PM
GG are usually 2% or so of the mass flow.
Title: Re: Raptor Upper Stage consolidated thread
Post by: oldAtlas_Eguy on 05/15/2017 04:06 PM
GG are usually 2% or so of the mass flow.
With a ISPGG in VAC of 150 and a PRCNT of 98% gives the combined VAC ISP of =322.

Added:
Now back to what a higher ISP M1D means for a Raptor US usage on Falcon. The one item that generally comes up as a reason for Raptor US is to have enough extra performance to then be able to reuse the US. If the Block 5 M1D engines increase the F9 performance yet again they may give it that little extra to make reusability of the M1DVAC stage feasible for the mid to smaller booked payloads in SpaceX's future. It could also impact the costs for deployment of "CommX".
Title: Re: Raptor Upper Stage consolidated thread
Post by: Okie_Steve on 05/16/2017 02:24 AM
 Remember who asked for the raptor derived US engine to begin with. What if any sort of launch profile might they be interested in that even the super duper M1D of the future might not be able to hack?
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 05/16/2017 02:00 PM
Remember who asked for the raptor derived US engine to begin with. What if any sort of launch profile might they be interested in that even the super duper M1D of the future might not be able to hack?

Only direct insertion of 15,000+ kg payloads to GEO.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Nathan2go on 05/21/2017 12:01 AM
Remember who asked for the raptor derived US engine to begin with.
Take a look at the SpaceX Mars presentation, then look at what NASA says about Mars, then checkout the Boeing or Lockmart websites.  Outside of the SpaceX fanbase, the rest of the world (including the investment community) does not believe ITS is going to happen any time soon. 

To change that perception, SpaceX needs to use the Falcon family to demonstrate more ITS technology.  Landing F9 S1 repeatedly is great, but they must go further:  flying Raptor on paying missions would help, as would demonstrations of S2 re-use, and a few successful Red Dragon missions.   Demo of on-orbit propellant transfer would be good, but there's little market for that now.

People seem to assume a Raptor upper stage needs to be 5m diameter.  Sure, that's lighter, stronger, and more aesthetic.  But it is also more expensive and less compatible with their existing infrastructure.  F9 is near the limit of too skinny now, but the skinniness pain threshold is higher for the FH (because the benefit is higher due to the US/LS mass imbalance on FH).  Even with 3.7m diameter, some tank stretching is likely.

I'm not expecting a 300% tank stretch on the FH upper stage, but I think a >=20% is very likely (assuming a Merlin engine), and 50-100% with Raptor is very plausible.  That would provide a useful improvement in the payload limit with 3-core S1 re-use, and thus improve competitiveness with New Glenn.
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 05/21/2017 12:12 AM
Remember who asked for the raptor derived US engine to begin with.
Take a look at the SpaceX Mars presentation, then look at what NASA says about Mars, then checkout the Boeing or Lockmart websites.  Outside of the SpaceX fanbase, the rest of the world (including the investment community) does not believe ITS is going to happen any time soon. 
...

The Kremlin and China's leadership would agree... so might lots of Arianespace folks.
Senator Shelby would agree, as would every member of the Alabama mafia.
Same group would have voted in unison about reusable launch vehicles a couple years ago.

Notice a pattern?

What they collectively believe is immaterial to the pace of SpaceX's technological achievement.
Title: Re: Raptor Upper Stage consolidated thread
Post by: BobHk on 05/21/2017 12:46 AM

Landing F9 S1 repeatedly is great, but they must go further:

The day landing rockets became old hat.... eagles cried.
Title: Re: Raptor Upper Stage consolidated thread
Post by: su27k on 05/21/2017 03:58 AM
I think the odds of seeing a RUS is significantly reduced after the Tom Mueller interview, he gave no hints this is happening, instead he talked about the Mars rocket, hundreds of tons to orbit, etc. Also when he talked about 2nd stage reuse, it sounds like the stage is still performance challenged, which would not be the case for a big RUS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 05/21/2017 04:40 AM
I think the odds of seeing a RUS is significantly reduced after the Tom Mueller interview, he gave no hints this is happening, instead he talked about the Mars rocket, hundreds of tons to orbit, etc. Also when he talked about 2nd stage reuse, it sounds like the stage is still performance challenged, which would not be the case for a big RUS.

Yup - any time there's indication of trying to reuse the current S2, that's a counte-indication for RUS. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/12/2017 08:54 PM
Could a full size Raptor fit in 3.7m?  That is why I thought if they made a 5m Raptor upper stage, the nozzle would fit.  It sure would make it more competitive with NG and even SLS. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Paul_G on 06/21/2017 03:58 PM
Is this new news:


Quote
from @Painkiller606

@elonmusk How will Raptor-vac engine bell be cooled? Will radiative cooling work with other engine bells surrounding it?

Quote
from @elonmusk

@Painkiller606
Will be full regen cooled all the way out to the 3 meter (10 ft) nozzle diameter. Heat flux is nuts & radiative view factor is low.

https://twitter.com/elonmusk/status/877341165808361472
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/21/2017 05:04 PM
So, if this test Raptor is made into an engine, would it be about the same size as the Merlin V?  And if so, could the existing size upper stage to increase ISP enough to get larger payloads into orbit off F9 and FH?  The existing upper stage is small enough to be filled by tanker LNG tractor trailer trucks it seems.  My company had one and it was used if there were low pressure areas of our natural gas distribution system during extremely cold weather.  It could supply a town of 25,000 for about a month with one truck load of LNG (residential/small commercial only, not industrial). 

So 2 or 3 of these tractor trailers could fill one upper stage. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: LastStarFighter on 06/21/2017 08:13 PM
So, if this test Raptor is made into an engine, would it be about the same size as the Merlin V?  And if so, could the existing size upper stage to increase ISP enough to get larger payloads into orbit off F9 and FH?  The existing upper stage is small enough to be filled by tanker LNG tractor trailer trucks it seems.  My company had one and it was used if there were low pressure areas of our natural gas distribution system during extremely cold weather.  It could supply a town of 25,000 for about a month with one truck load of LNG (residential/small commercial only, not industrial). 

So 2 or 3 of these tractor trailers could fill one upper stage.

Hypothetically (since I doubt they would just convert it) it would get less performance with the same volume upper stage. Lower density methane takes up more space and therefore you can't load nearly as much propellant. Same reason ULA's Vulcan has to be a 5+m first stage instead of keeping the Atlas tankage. There are some gains due to a lighter overall weight but that makes the first stage separation velocity even higher which cant be great for recovery. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/21/2017 11:16 PM
So, if this test Raptor is made into an engine, would it be about the same size as the Merlin V?  And if so, could the existing size upper stage to increase ISP enough to get larger payloads into orbit off F9 and FH?  The existing upper stage is small enough to be filled by tanker LNG tractor trailer trucks it seems.  My company had one and it was used if there were low pressure areas of our natural gas distribution system during extremely cold weather.  It could supply a town of 25,000 for about a month with one truck load of LNG (residential/small commercial only, not industrial). 

So 2 or 3 of these tractor trailers could fill one upper stage.

Hypothetically (since I doubt they would just convert it) it would get less performance with the same volume upper stage. Lower density methane takes up more space and therefore you can't load nearly as much propellant. Same reason ULA's Vulcan has to be a 5+m first stage instead of keeping the Atlas tankage. There are some gains due to a lighter overall weight but that makes the first stage separation velocity even higher which cant be great for recovery.

Not necessarily true. Depending on the exact values they achieve for engine mass, thrust, and efficiency, the Raptor stage would be anywhere from considerably better to slightly worse for the same volume (the volume ratio of subcooled kerolox to subcooled methalox is 1.209:1.000).

The difference depends on delta-v and payload mass. A typical GTO injection requires the upper stage to provide ~7800 m/s after staging. For a max payload to that delta-v, the Raptor is likely better (see attached graph). You can adjust the sensitivity to engine parameters in the attached spreadsheet...

Edit: I did not include the reduced gravity loss the RUS would incur due to lighter lift-off and staging mass and shorter burn time for both S1 and S2. This would favor the Raptor stage by a couple more percent.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/21/2017 11:31 PM
So, would it help at all, OR, would you have to make the stage wider, or longer to achieve upgraded capabilities?
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/22/2017 12:25 AM
So, would it help at all, OR, would you have to make the stage wider, or longer to achieve upgraded capabilities?

Maybe a little. Probably not much.

But with a 2m stretch to the F9 US (basically what they did from v1.1>v1.2), a methalox RUS would have the same wet mass as the current kerolox US. Which would bump the performance considerably if they hit Raptor performance specs. Full expendable would be about:

27.5 tonne to LEO
11 tonne to GEO-1800
7.3 tonne to TLI
Title: Re: Raptor Upper Stage consolidated thread
Post by: Rik ISS-fan on 06/22/2017 08:06 AM
Could a 1.5 stage to orbit using two Falcon Heavy boosters and a core (orbital stage) powered by a single vacuum optimized Merlin Raptor 3MN engine. The core could be derived from an expendable falcon heavy core.
I'm very sceptical about upperstage reusability, so the core will be expendable.
If required an small in orbit maneuvering stage (Hypergolic Draco, or LOx-Methane) could be added.
Could this work? What will be it's performance? And is it a good idea?

I think for a Falcon 9 upper-stage a Raptor 1MN would be required. I do like the idea.
A methane merlin (Merlin 1D.M / 1DV.m) could be an intermediate development before the FFSC Raptor 3MN.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 06/22/2017 05:07 PM
Could a 1.5 stage to orbit using two Falcon Heavy boosters and a core (orbital stage) powered by a single vacuum optimized Merlin 3MN engine. The core could be derived from an expendable falcon heavy core.
I'm very sceptical about upperstage reusability, so the core will be expendable.
If required an small in orbit maneuvering stage (Hypergolic Draco, or LOx-Methane) could be added.
Could this work? What will be it's performance? And is it a good idea?

I think for a Falcon 9 upper-stage a Raptor 1MN would be required. I do like the idea.
A methane merlin (Merlin 1D.M / 1DV.m) could be an intermediate development before the FFSC Raptor 3MN.

What are you trying to gain by going 1.5 stage over 2.5 stage?
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/22/2017 05:23 PM
Could a 1.5 stage to orbit using two Falcon Heavy boosters and a core (orbital stage) powered by a single vacuum optimized Merlin 3MN engine. The core could be derived from an expendable falcon heavy core.
I'm very sceptical about upperstage reusability, so the core will be expendable.
If required an small in orbit maneuvering stage (Hypergolic Draco, or LOx-Methane) could be added.
Could this work? What will be it's performance? And is it a good idea?

I think for a Falcon 9 upper-stage a Raptor 1MN would be required. I do like the idea.
A methane merlin (Merlin 1D.M / 1DV.m) could be an intermediate development before the FFSC Raptor 3MN.

There is no "Merlin 3MN engine" or plans for one. Merlin is kerolox and SpaceX is going methalox.

1.5 parallel stage rockets are not very efficient: replacing a 5 tonne upper stage with a 25 tonne core means 20 fewer tonnes of payload to orbit. And now you expend a $30M booster instead of a $10M upper stage. You do gain the reliability of fewer staging events and all-groundlit engines, but SpaceX hasn't found this worthwhile compared to the efficiency of a serial TSTO. Especially since the engine has to be able to be lit on the ground, which costs some efficiency.

If SpaceX goes with a Raptor on Falcon, it will be an air-lit upper stage.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Lars-J on 06/22/2017 05:36 PM
Could a 1.5 stage to orbit using two Falcon Heavy boosters and a core (orbital stage) powered by a single vacuum optimized Merlin 3MN engine. The core could be derived from an expendable falcon heavy core.
I'm very sceptical about upperstage reusability, so the core will be expendable.
If required an small in orbit maneuvering stage (Hypergolic Draco, or LOx-Methane) could be added.
Could this work? What will be it's performance? And is it a good idea?

I think for a Falcon 9 upper-stage a Raptor 1MN would be required. I do like the idea.
A methane merlin (Merlin 1D.M / 1DV.m) could be an intermediate development before the FFSC Raptor 3MN.

What is Merlin 3MN? Raptor 1MN? Raptor 3MN?
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/22/2017 05:53 PM
So it seems the test Raptor, IF made into an upper stage vacuum engine, with a 2m stretch of the upper stage, gets the results you say, they should do that at least for FH.  Even with F9, it would cut into some of the FH launches.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/22/2017 06:48 PM
Could a 1.5 stage to orbit using two Falcon Heavy boosters and a core (orbital stage) powered by a single vacuum optimized Merlin 3MN engine. The core could be derived from an expendable falcon heavy core.
I'm very sceptical about upperstage reusability, so the core will be expendable.
If required an small in orbit maneuvering stage (Hypergolic Draco, or LOx-Methane) could be added.
Could this work? What will be it's performance? And is it a good idea?

I think for a Falcon 9 upper-stage a Raptor 1MN would be required. I do like the idea.
A methane merlin (Merlin 1D.M / 1DV.m) could be an intermediate development before the FFSC Raptor 3MN.

What is Merlin 3MN? Raptor 1MN? Raptor 3MN?

1MN = 1,000 kN which is the nominal thrust of the subscale Raptor demo engine fired last year.

3MN = ~3,000 kN which is the nominal thrust of the ITS Raptor proposed at IAC 2016.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Rik ISS-fan on 06/22/2017 08:08 PM
Sorry for the confusion my post has caused. I ment to propose a full raptor engine on the core stage of a Falcon heavy. Thanks Envy887 for clearing things up.

With Raptor 1MN I mean a 1000kN FFSC Methalox engine, a scaled down version of the full Raptor.
The full Raptor I call Raptor 3MN since it has ~3000kN thrust.
Most likely a Methalox merlin would be a beter idea for a falcon 9 upperstage then a scaled down Raptor.
A full Raptor on a upperstage won't work because it consumes about three times the fuel mass and volume.

I think there are two advantages to a 1.5 stage configuration.
1) All engines are ignited on the ground, eliminating a risky staging and in flight engine start.
2) One stage less is required.
This 1.5 stage launcher could only launch payloads or upper stages to LEO or GTO (eliptical orbits). Because I don't expect a engine restart capability. Most likely the payload capability would fall in between a expendable F9 and a 3core reuse FH.
This could be a nice way to use the Full Raptor early.
But possibly SpaceX already switches to Methalox with block5.

Edit. Is my thinking correct and will SpaceX use both LOx and LNG for regenerate cooling on Raptor?
Could a tapoff/expander cycle 1000kN engine be a good idea for a F9/FH upperstage?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Lars-J on 06/22/2017 08:53 PM
I think there are two advantages to a 1.5 stage configuration.
1) All engines are ignited on the ground, eliminating a risky staging and in flight engine start.

Has SpaceX had any problems with staging since Falcon 1 flight 3? No. And do they seem to have problems starting and re-starting the engines? No. So what problem are you attempting to solve exactly??

(And BTW, staging FH side boosters is not without risk either)


2) One stage less is required.

Don't let terminology marketing overrule your common sense. You have not removed staging events.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 06/22/2017 09:08 PM
Sorry for the confusion my post has caused. I ment to propose a full raptor engine on the core stage of a Falcon heavy. Thanks Envy887 for clearing things up.

With Raptor 1MN I mean a 1000kN FFSC Methalox engine, a scaled down version of the full Raptor.
The full Raptor I call Raptor 3MN since it has ~3000kN thrust.
Most likely a Methalox merlin would be a beter idea for a falcon 9 upperstage then a scaled down Raptor.
A full Raptor on a upperstage won't work because it consumes about three times the fuel mass and volume.

For same impulse, it does not.

When you have more powerful engine, you can burn for smaller time and save on gravity losses.

The potential pitfalls with raptor upper stage are not fuel consumption, but:
1) engine cost
2) engine weight
3) potentially too high g-forces, meaning at has to be throttled very deep to keep g-forces at allowable level

Quote
I think there are two advantages to a 1.5 stage configuration.
1) All engines are ignited on the ground, eliminating a risky staging and in flight engine start.

Not need to eliminate those.

Quote
2) One stage less is required.

One totally new type of stage and engine needed. Ned pad needed. Even though less stages, system complexity and price would still be higher than current FH/F9.

Quote
This 1.5 stage launcher could only launch payloads or upper stages to LEO or GTO (eliptical orbits). Because I don't expect a engine restart capability. Most likely the payload capability would fall in between a expendable F9 and a 3core reuse FH.

Capacity would be very bad for GTO, as the very heavy core stage weighting something like 20 tonnes would have to go the sam orbit as the destination.

Also, the center core could not use vacuum-optimized nozzle.

Practically the capacity for GTO would very probably be worse than expendable F9.

Quote
This could be a nice way to use the Full Raptor early.
But possibly SpaceX already switches to Methalox with block5.

No, it would be the most stupid way for it. Minimal gains, big pitfalls.

Quote
Edit. Is my thinking correct and will SpaceX use both LOx and LNG for regenerate cooling on Raptor?
Could a tapoff/expander cycle 1000kN engine be a good idea for a F9/FH upperstage?

No. Makes absolutely no sense to develop another engine that simply is not needed.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Rik ISS-fan on 06/23/2017 01:32 AM
My idea for the 1.5stage falcon was to start with the heavy configuration (center core expendable).
Instead of three 1.6T/W F9 block1.5 boosters you use two. Instead of nine Merlin 1D engines on the center core, only a single Raptor engine is used. (I know, the common bulkhead has to be moved.)

The centercore has a single Raptor optimised for higher altitudes. So under expanding at sealevel.
Given the lower density of Methalox compared to RP-1 LOx, about 1/3th the thrust and taking into account the higher ISP (vacume, not sea lvl in this case) I guess the core will burn roughty 3x as long as the FH boosters.
This is in my oppinion one of the simplest and most useful first applications of Raptor.

My critic to a Raptor F9 upperstage:
I have the impression that the current F9 upper-stage already exerts extreme accelerations (G-forces) onto the payloads. Replacing a Merlin 1DV with a Raptor V would only worsen this situation.
So instead of a Raptor such a configuration requires a scaled down Raptor or a Methalox Merlin.

But It's clear you don't like my idea. So, I agree to disagree!
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/23/2017 02:13 AM
Worth noting, of course, that RUS got a measure of viability today when GS  said on the Space Show that SpaceX is looking at the possibility.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/23/2017 02:14 AM
As it happens, SpaceX has a 1,000 kN Raptor, but not a 3,000 kN version (yet). So g loads with the current sized upper stage would be fine with that one. If they want to use a bigger engine, the stage wet mass just had to grow proportionally to thrust.

By my estimates the 1.5 stage FH with Merlin boosters and Raptor Vac sustainer gets 9.5 tonnes to GTO with 2 downrange landings. All kerolox FH gets about 16 tonnes with 3 downrange landings... not only are you throwing away more hardware, but you're getting less payload to orbit.
Title: Re: Raptor Upper Stage consolidated thread
Post by: ThePonjaX on 06/23/2017 04:06 AM
Well seems the idea of a Raptor S2 gets boost.

Interview with Gwynne Shotwell On the Space Show

from notes on reddit:

https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/ (https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/)

Quote
There have been dozens of Raptor tests(!) Initially intended for Mars, we are also looking at Raptor's utility for the Falcon program.

Take in account we've a thread here too:
https://forum.nasaspaceflight.com/index.php?topic=43197.msg1692769#msg1692769 (https://forum.nasaspaceflight.com/index.php?topic=43197.msg1692769#msg1692769)

Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 06/23/2017 05:00 AM
Jim's concerns about the raptor upper stage remain valid- mixed propellant types, redesigning and rebuilding pads, ect.

Shotwell is saying they are looking into whether the increased performance of a RUS would be worth that pain. It might be, it might not.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Nathan2go on 06/23/2017 05:53 AM
Jim's concerns about the raptor upper stage remain valid...
Yep, an RUS is very inconvenient.  However, the alternative stepping stones to the BFR/MCT/ITS are even less convenient (e.g. do BFR in one step, re-engine both Falcon stages with Raptor, or build a whole new intermediate sized rocket).

One more advantage to an RUS over the 1.5 stage suggestion is that RUS can be used to develop & demo stage 2 landing technology.  They really need to demonstrate a flight-weight reusable 2nd stage before moving onto the BFR.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/23/2017 07:06 AM
you know, given the challenges they are dealing with, I somehow don't see the mixed propellant issue being such a big deal.

The LOX part remains unchanged.

The RP1 gets replaced with Methane for the US.  It's not like the two stages were being fed by the same pipe though, right?    So there are new tanks, and LNG pumping equipment.  I don't think this compares in any way with things SpaceX does, like landing rockets, or fielding barges, etc.

If having a RUS gives them the opportunity to deploy Raptor early, and with lower cost of failure, not to mention higher performance and maybe reusability of second stage, then a somewhat more complex pad (only half of the main propellants of the second stage) is peanuts.

The reason they're not all over it, IMO, is that further F9 development means a slow-down of BFR development. That's the decision point - when to move on.
Title: Re: Raptor Upper Stage consolidated thread
Post by: M.E.T. on 06/23/2017 09:10 AM
Jim's concerns about the raptor upper stage remain valid- mixed propellant types, redesigning and rebuilding pads, ect.

Shotwell is saying they are looking into whether the increased performance of a RUS would be worth that pain. It might be, it might not.

Taking into account the concerns about mixed propellant types, are we sure Shotwell was talking only about Upper Stage Raptor use?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Confusador on 06/23/2017 12:17 PM
Jim's concerns about the raptor upper stage remain valid- mixed propellant types, redesigning and rebuilding pads, ect.

Shotwell is saying they are looking into whether the increased performance of a RUS would be worth that pain. It might be, it might not.

Taking into account the concerns about mixed propellant types, are we sure Shotwell was talking only about Upper Stage Raptor use?

If we know anything about SpaceX, it's that they'll run the numbers on anything.  I'm sure that they're looking at Raptor on Falcon US, on both Falcon stages, and on an intermediate LV.  "Looking at" is different from "have plans for", though, and this is the thread for the Raptor Upper Stage.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/23/2017 01:47 PM
Well seems the idea of a Raptor S2 gets boost.

Interview with Gwynne Shotwell On the Space Show

from notes on reddit:

https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/ (https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/)

Quote
There have been dozens of Raptor tests(!) Initially intended for Mars, we are also looking at Raptor's utility for the Falcon program.


Wrong.  Where is does she says just second stage? 
It be more likely both stages using Raptor.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/23/2017 02:11 PM
This metholox upper stage will not be huge, but could be filled by simple piping on the stand and using about 3-4 tractor trailer trucks of LNG, brought in from the nearest LNG facility until an LNG facility is built at the cape somewhere.  Not much different than lox now. 


Why does a LNG facility have to be built?  All cryogens are trucked in, LN2, LO2, LH2, LHe, etc
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/23/2017 03:23 PM
Well seems the idea of a Raptor S2 gets boost.

Interview with Gwynne Shotwell On the Space Show

from notes on reddit:

https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/ (https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/)

Quote
There have been dozens of Raptor tests(!) Initially intended for Mars, we are also looking at Raptor's utility for the Falcon program.


Wrong.  Where is does she says just second stage? 
It be more likely both stages using Raptor.

How would they implement this? They would have to convert a whole pad to methalox without interfering with launch operations, and build new stages without interfering with production of kerolox stages, then fly enough of them to qualify for Crew flights.

Seems like a lot of parallel ops that will put a crimp on Falcon operations for a while. Maybe build a new factory? And use Boca Chica for only methalox flights? But if building a new factory for new stages, does keeping Falcon's 12 foot diameter make sense? If they change diameter, does keeping Al-Li make sense?

I don't a clear incremental way to go to a all-methane vehicle. And if non-incremental, going right to a new ideal architecture seems to make more sense.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/23/2017 03:59 PM

How would they implement this? They would have to convert a whole pad to methalox without interfering with launch operations, and build new stages without interfering with production of kerolox stages, then fly enough of them to qualify for Crew flights.

Seems like a lot of parallel ops that will put a crimp on Falcon operations for a while. Maybe build a new factory? And use Boca Chica for only methalox flights? But if building a new factory for new stages, does keeping Falcon's 12 foot diameter make sense? If they change diameter, does keeping Al-Li make sense?

I don't a clear incremental way to go to a all-methane vehicle. And if non-incremental, going right to a new ideal architecture seems to make more sense.

All those apply to just the second stage too.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 06/23/2017 04:29 PM
All those apply to just the second stage too.

Not at all. The reaction frame can remain the same. Methane line up the TE is the needed modification. A fraction of the complexity.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/23/2017 04:40 PM
All those apply to just the second stage too.

Not at all. The reaction frame can remain the same. Methane line up the TE is the needed modification. A fraction of the complexity.

Wrong, all apply and still the same complexity.

Still need a methane farm, and all the controls and monitoring equipment for it.  Still need a T-0 vent umbilical and return lines to a flare stack. 
the only difference between the just the second stage and the whole vehicle is methane lines to the first stage TSM and a first stage T-0 vent umbilical.  All the other infrastructure has to be installed for a methane upper stage.

the second stage would be different, it is not going to have the same interfaces as the existing stage
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/23/2017 05:11 PM
I don't know.  ISP is more important for the US.

The first stage is performing well, and getting it to go further just complicated recovery.

The upper stage - more performance is great for high energy missions, for retrieval - and it requires a lot fewer changes, e.g. no reaction frame changes.

Mixed fuel is not a show stopper.  And it's not like we're talking about going to Hydrogen.

I see (and always have seen) every reason to put a raptor on the US, and no reason to change the first stage.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/23/2017 05:16 PM
1.   e.g. no reaction frame changes.

2.  Mixed fuel is not a show stopper. 

3.  I see (and always have seen) every reason to put a raptor on the US, and no reason to change the first stage.

1.  Wrong, it would not be the same stage structure

2.  Based on what information?

3. Your sight has been just as flawed as others.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/23/2017 05:18 PM
1.   e.g. no reaction frame changes.

2.  Mixed fuel is not a show stopper. 

1.  Wrong, it would not be the same stage structure

2.  Based on what information?
Rumor has it that some rockets have done it already, and with more disparate propellants.

Put a different way, based on what information do you think that a RUS is a non-starter?
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 06/23/2017 06:18 PM
1.   e.g. no reaction frame changes.

2.  Mixed fuel is not a show stopper. 

1.  Wrong, it would not be the same stage structure

2.  Based on what information?
Rumor has it that some rockets have done it already, and with more disparate propellants.

Put a different way, based on what information do you think that a RUS is a non-starter?

Other rockets have done it, but none cheaply. Stage commonality is one of the decisions that allow F9 to be less expensive than the competition. They could make a tri-propellant rocket but it will be more expensive to launch than the one they have now. Upper stage re-use is the only way it could conceivably be cheaper and you will eat into those savings by launching a more expensive rocket from a more expensive pad.

When Shotwell says that they are looking into using raptor on falcon, I read that to mean they are analyzing whether or not they can pay for some mars architecture development by making F9 Methalox.

Changing fuels on Falcon is definitely not the cost effective decision taken in isolation. It would have enable moving merlin engineers, testing in TX, GSE personnel and infrastructure, over to supporting methalox and raptor. All that being hopefully a cheaper move than creating a parallel program for ITS.

I think, possibly, what Jim is saying is that for Raptor upper only you get all the expense with none of the benefit.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/23/2017 06:22 PM
the second stage would be different, it is not going to have the same interfaces as the existing stage

That's not necessarily a problem, if they want to launch both the Block 5 upper stage and a new methalox upper stage off the same TEL: having the interfaces in different places allows flexibility.

The only difference between a all-methalox vehicle and just a upper stage is incremental. The smaller upper stage and single engine have less impact on manufacturing and test flow.

I don't think the incremental gain it worth the effort though. To be worthwhile it would have to meet larger goals, like upper stage reuse, biconic entry, orbital refueling, etc. which means a larger diameter stage, which means a dedicated TEL, which means a dedicated HIF and a dedicated pad unless they add a second HIF to one of the pads.

Those kind of changes for long-term goals would be worth the major effort to add some serious infrastructure. Just getting a couple more tonnes of payload out of F9 probably isn't.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/23/2017 06:25 PM
When Shotwell says that they are looking into using raptor on falcon, I read that to mean they are analyzing whether or not they can pay for some mars architecture development by making F9 Methalox.

Changing fuels on Falcon is definitely not the cost effective decision taken in isolation. It would have enable moving merlin engineers, testing in TX, GSE personnel and infrastructure, over to supporting methalox and raptor. All that being hopefully a cheaper move than creating a parallel program for ITS.

I think, possibly, what Jim is saying is that for Raptor upper only you get all the expense with none of the benefit.
Merlin is this close to a mature product that they can fly and make money on for years. Ditching it at this point doesn't make any sense. They will move the development engineers over to Raptor once block 5 is done, but not the manufacturing or operations teams.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/23/2017 06:28 PM
My company has two "methane farms", one near Montgomery and one near Birmingham.  They were expensive, but not that expensive.  They were tanks with 3' (1m) walls and vacuumed out between them.  LNG was made right off the pipelines and pumped in for storage during summer.  It was released during winter.  We did it to take advantage of low cost gas during the summer and released during winter to blend with higher priced gas.  Each farm probably cost about $1 million when built. 

This is not an insurmountable price.  So a few more million for metholox upper stage, that could potentially yield higher mass payloads and help with development of a reusable upper stage. 

One launch could probably pay for the costs of metholox with the profit from the launch.  It is going to have to be done at some point anyway. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 06/23/2017 06:39 PM
When Shotwell says that they are looking into using raptor on falcon, I read that to mean they are analyzing whether or not they can pay for some mars architecture development by making F9 Methalox.

Changing fuels on Falcon is definitely not the cost effective decision taken in isolation. It would have enable moving merlin engineers, testing in TX, GSE personnel and infrastructure, over to supporting methalox and raptor. All that being hopefully a cheaper move than creating a parallel program for ITS.

I think, possibly, what Jim is saying is that for Raptor upper only you get all the expense with none of the benefit.
Merlin is this close to a mature product that they can fly and make money on for years. Ditching it at this point doesn't make any sense. They will move the development engineers over to Raptor once block 5 is done, but not the manufacturing or operations teams.

I agree with respect to merlin. I assume that is why they are only evaluating. But there is no such thing as just moving your team from merlin to raptor. There will always need to be a sizable team to support merlin and it can't just be interns either. In an ideal world they would have a methalox falcon9 and be doing development off of that base. They just have to evaluate whether the cost of getting to that ideal world is worth it.

I would hate to see merlin go as well. Raptor has a long way to go to be the reusable booster engine that merlin is. Reliable, cheap, and astounding t/w. The only thing it isn't, is efficient.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/23/2017 07:01 PM
1.   e.g. no reaction frame changes.

2.  Mixed fuel is not a show stopper. 

1.  Wrong, it would not be the same stage structure

2.  Based on what information?
Rumor has it that some rockets have done it already, and with more disparate propellants.

Put a different way, based on what information do you think that a RUS is a non-starter?

Other rockets have done it, but none cheaply. Stage commonality is one of the decisions that allow F9 to be less expensive than the competition. They could make a tri-propellant rocket but it will be more expensive to launch than the one they have now. Upper stage re-use is the only way it could conceivably be cheaper and you will eat into those savings by launching a more expensive rocket from a more expensive pad.

When Shotwell says that they are looking into using raptor on falcon, I read that to mean they are analyzing whether or not they can pay for some mars architecture development by making F9 Methalox.

Changing fuels on Falcon is definitely not the cost effective decision taken in isolation. It would have enable moving merlin engineers, testing in TX, GSE personnel and infrastructure, over to supporting methalox and raptor. All that being hopefully a cheaper move than creating a parallel program for ITS.

I think, possibly, what Jim is saying is that for Raptor upper only you get all the expense with none of the benefit.

None of the benefits?

Look - an all methane rocket is a possibility, but then it's Falcon by name only.

But how can you argue that you get none of the benefits, if you have improved ISP on the second stage, get to deploy ITS technology early, can match the performance of the FH, and don't have to redesign the first stage?

An all-methane sub-ITS rocket is a likely step too, but that's a separate discussion altogether.
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 06/23/2017 07:35 PM
None of the benefits?

Look - an all methane rocket is a possibility, but then it's Falcon by name only.

But how can you argue that you get none of the benefits, if you have improved ISP on the second stage, get to deploy ITS technology early, can match the performance of the FH, and don't have to redesign the first stage?

An all-methane sub-ITS rocket is a likely step too, but that's a separate discussion altogether.

I mean the cost benefits. SpaceX's issue is how to pay for ITS. For the three possibilities they can
1) keep ITS and Falcon9 separate. That means that they have two propulsion teams, engine production lines, testing set-ups, GSE systems.
2) Go all methalox: propulsion team fully united, one engine production line, One set of test stands, one GSE system.
3) Raptor upper stage: Two propulsion teams, Two production lines, two sets of test stands, two types of GSE systems.

Yes you get experience with Raptor Vac and better performance under senario 3, but you can't save any money to be refocused on ITS.  The question is would the money saved under senario 2 be greater than the money spent to convert (completely redesign) Falcon.
Title: Re: Raptor Upper Stage consolidated thread
Post by: GreenShrike on 06/23/2017 08:10 PM
Merlin is this close to a mature product that they can fly and make money on for years. Ditching it at this point doesn't make any sense. They will move the development engineers over to Raptor once block 5 is done, but not the manufacturing or operations teams.

A mature product? It's a component of a launch system that's been a work in progress for years, and itself is an engine system that's also been a work in progress for years.

Yet another revision of their launch system tech would hardly be surprising given their history.

And remember that the goal of this rocket system is to make launch as inexpensive as possible, because with a mega-constellation to orbit, SpaceX will be its own biggest customer for launch services, and every dollar spent launching the constellation is one that's not going into BFR.

A mature-but-expensive platform is fine for other folks to buy and use when they only need to orbit single-digit numbers of satellites, and I'm sure that an all-Merlin F9 would be available for anyone who wishes to pay for the privilege.

But if spending even hundreds of millions up front might save you billions in the long run over the hundreds of flights the constellation will require, prudence suggests taking a long, hard look at the possibility is a good idea. Being penny-wise but pound-foolish at the quantities of cash under discussion would be very foolish indeed.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 06/23/2017 08:46 PM
Or just use a Raptor upper stage...

Can we just stop with this.  There is no such thing.

But the expendable Raptor upper stage

There is no such thing.

Quote
Quote
Quote from: go4mars on 05/29/2012 06:21 AM
Quote
Quote from: Jim on 05/23/2012 08:20 PM
What raptor upper stage?
The one SpaceX is still working on.

Who says.

Jim. You are a very knowledgeable person. It does not mean you will always be right. Don't assume so. As you see from above quotes from various past treads, people musing about RUS were not totally off base.
Title: Re: Raptor Upper Stage consolidated thread
Post by: GreenShrike on 06/23/2017 09:05 PM
I mean the cost benefits. SpaceX's issue is how to pay for ITS. For the three possibilities they can
1) keep ITS and Falcon9 separate. That means that they have two propulsion teams, engine production lines, testing set-ups, GSE systems.
2) Go all methalox: propulsion team fully united, one engine production line, One set of test stands, one GSE system.
3) Raptor upper stage: Two propulsion teams, Two production lines, two sets of test stands, two types of GSE systems.

Yes you get experience with Raptor Vac and better performance under senario 3, but you can't save any money to be refocused on ITS.

Come again?

If a reusable RUS saves per-launch costs versus an expendable Merlin upper stage, then launch costs of the constellation drop.

Conversely, if a higher performance RUS enables launch of the constellation in fewer flights versus a less efficient reusable Merlin stage, then, again, launch costs of the constellation drop.

As constellation revenues will be how SpaceX funds BFR, anything which reduces constellation costs leaves BFR development more resources to work with.


11,000+ sats will take a lot of flights. A couple hundred Falcon launches at $5M per Merlin upper stage is $1B in costs -- $2B if Merlin upper stages are $10M each -- maintenance costs for a second set of production and testing facilities would have to be pretty extreme to equal that kind of money.
Title: Re: Raptor Upper Stage consolidated thread
Post by: TrevorMonty on 06/23/2017 10:05 PM
If they did a methane US could they alternate between a Raptor and Merlin US.

As for Raptor powered booster they may as well go straight to larger stage 5-7m with performance in NG range and
 retire FH. There is not a lot to be gained by replacing F9 with methane version in same performance range. The operating costs of booster 2-3 size of F9R may not be much different from F9R especially as fuel costs are lot lower.
Title: Re: Raptor Upper Stage consolidated thread
Post by: DanielW on 06/23/2017 10:18 PM
I mean the cost benefits. SpaceX's issue is how to pay for ITS. For the three possibilities they can
1) keep ITS and Falcon9 separate. That means that they have two propulsion teams, engine production lines, testing set-ups, GSE systems.
2) Go all methalox: propulsion team fully united, one engine production line, One set of test stands, one GSE system.
3) Raptor upper stage: Two propulsion teams, Two production lines, two sets of test stands, two types of GSE systems.

Yes you get experience with Raptor Vac and better performance under senario 3, but you can't save any money to be refocused on ITS.

Come again?

If a reusable RUS saves per-launch costs versus an expendable Merlin upper stage, then launch costs of the constellation drop.

Conversely, if a higher performance RUS enables launch of the constellation in fewer flights versus a less efficient reusable Merlin stage, then, again, launch costs of the constellation drop.

As constellation revenues will be how SpaceX funds BFR, anything which reduces constellation costs leaves BFR development more resources to work with.


11,000+ sats will take a lot of flights. A couple hundred Falcon launches at $5M per Merlin upper stage is $1B in costs -- $2B if Merlin upper stages are $10M each -- maintenance costs for a second set of production and testing facilities would have to be pretty extreme to equal that kind of money.

Yes, I agree that is the only way to save money by doing raptor upper only. But it won't be quite Merlin Upper Cost * number of flights. You have to add back in the cost of the Raptor Upper + refurbishement + Cost of the extra personnel required to maintain the design, do the testing, and the GSE. I don't think the difference will be that large though.

it will be interesting to see what they decide.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 06/23/2017 11:22 PM
I mean the cost benefits. SpaceX's issue is how to pay for ITS. For the three possibilities they can
1) keep ITS and Falcon9 separate. That means that they have two propulsion teams, engine production lines, testing set-ups, GSE systems.
2) Go all methalox: propulsion team fully united, one engine production line, One set of test stands, one GSE system.
3) Raptor upper stage: Two propulsion teams, Two production lines, two sets of test stands, two types of GSE systems.

Yes you get experience with Raptor Vac and better performance under senario 3, but you can't save any money to be refocused on ITS.

Come again?

If a reusable RUS saves per-launch costs versus an expendable Merlin upper stage, then launch costs of the constellation drop.

Conversely, if a higher performance RUS enables launch of the constellation in fewer flights versus a less efficient reusable Merlin stage, then, again, launch costs of the constellation drop.

As constellation revenues will be how SpaceX funds BFR, anything which reduces constellation costs leaves BFR development more resources to work with.


11,000+ sats will take a lot of flights. A couple hundred Falcon launches at $5M per Merlin upper stage is $1B in costs -- $2B if Merlin upper stages are $10M each -- maintenance costs for a second set of production and testing facilities would have to be pretty extreme to equal that kind of money.

Yes, I agree that is the only way to save money by doing raptor upper only. But it won't be quite Merlin Upper Cost * number of flights. You have to add back in the cost of the Raptor Upper + refurbishement + Cost of the extra personnel required to maintain the design, do the testing, and the GSE. I don't think the difference will be that large though.

it will be interesting to see what they decide.
Another factor is the opportunity cost of not just making the Mvac stage reusable instead of a raptor reusable.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/23/2017 11:31 PM
Merlin is this close to a mature product that they can fly and make money on for years. Ditching it at this point doesn't make any sense. They will move the development engineers over to Raptor once block 5 is done, but not the manufacturing or operations teams.

A mature product? It's a component of a launch system that's been a work in progress for years, and itself is an engine system that's also been a work in progress for years.

Yet another revision of their launch system tech would hardly be surprising given their history.

And remember that the goal of this rocket system is to make launch as inexpensive as possible, because with a mega-constellation to orbit, SpaceX will be its own biggest customer for launch services, and every dollar spent launching the constellation is one that's not going into BFR.

A mature-but-expensive platform is fine for other folks to buy and use when they only need to orbit single-digit numbers of satellites, and I'm sure that an all-Merlin F9 would be available for anyone who wishes to pay for the privilege.

But if spending even hundreds of millions up front might save you billions in the long run over the hundreds of flights the constellation will require, prudence suggests taking a long, hard look at the possibility is a good idea. Being penny-wise but pound-foolish at the quantities of cash under discussion would be very foolish indeed.

Right now SpaceX owes those other folks a lot of launches, and they are more than willing to pay, so Merlin on Falcon isn't going anywhere.

The first 800 sats could go up on F9, but if they wait too long to develop a fully reusable launcher it will delay the bulk of the constellation. A Raptor upper stage would be the quickest way to get both performance and full reuse out of F9. I don't know that they could have a methane booster ready by the 2019 timeframe.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/24/2017 12:32 AM
All true - F9 will be replaced eventually.

But why not start with RUS?  Get some benefits early with a much smaller redesign effort, and be smarter when you decide to completely move away from F9?
Title: Re: Raptor Upper Stage consolidated thread
Post by: woods170 on 06/24/2017 12:58 PM
Well seems the idea of a Raptor S2 gets boost.

Interview with Gwynne Shotwell On the Space Show

from notes on reddit:

https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/ (https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/)

Quote
There have been dozens of Raptor tests(!) Initially intended for Mars, we are also looking at Raptor's utility for the Falcon program.


Wrong.  Where is does she says just second stage? 
It be more likely both stages using Raptor.
Unlikely. Boosters and first stages will need to be recovered. Which cannot be done when they are sporting Raptors. Raptor will likely be on upper stage only simply because only the upper stage really in need of the improved performance.
You seem to be forgetting that re-designing things such as the pad and GSE is something SpaceX does for a living. It's part of the agile culture instilled in SpaceX.
Yes, SpaceX likes KISS very much. But they have shown multiple times that they are willing to go less KISS when needed. For example the current pad-and-TEL setup of 39A. Or recovering a first stage and re-using it.
Every time you state that the changes needed for Raptor on Falcon (Heavy) are non-starters you show off a complete lack of understanding of the SpaceX corporate culture, despite the fact that you have been embedded with them for quite some time.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/24/2017 02:12 PM

Jim. You are a very knowledgeable person. It does not mean you will always be right. Don't assume so. As you see from above quotes from various past treads, people musing about RUS were not totally off base.

Yes, they are because there is a big difference between a RUS and Raptor F9.
Title: Re: Raptor Upper Stage consolidated thread
Post by: livingjw on 06/24/2017 06:22 PM
All true - F9 will be replaced eventually.

But why not start with RUS?  Get some benefits early with a much smaller redesign effort, and be smarter when you decide to completely move away from F9?

Because making the upper stage reusable will eat into your payload to such an extent that it could not lift many of its payloads. They will require a larger booster.

John
Title: Re: Raptor Upper Stage consolidated thread
Post by: TrevorMonty on 06/24/2017 06:58 PM


All true - F9 will be replaced eventually.

But why not start with RUS?  Get some benefits early with a much smaller redesign effort, and be smarter when you decide to completely move away from F9?

Because making the upper stage reusable will eat into your payload to such an extent that it could not lift many of its payloads. They will require a larger booster.

John

Design F9 so can fly RUS or current EUS.

If they do develop a reuseable US there are some design options.
1) Use with existing fairing, allows for bulky payloads.
2) Add cargo bay with robotic arm . If made long life they end up with something like Shuttle/ X37 cross.
No fairing to recover, potential return of satellites. Delivery and return of bulky ISS cargo, by using a pressurized container eg Cygnus without SM.
Ideal for LEO satellite constellation deployment and disposal. For disposal just grap satellite and tow it to lower orbit eg 180km.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/24/2017 07:28 PM
Unlikely. Boosters and first stages will need to be recovered. Which cannot be done when they are sporting Raptors. Raptor will likely be on upper stage only simply because only the upper stage really in need of the improved performance.

Recovery is fine if they use the development 1,000 kN Raptor and do a 1 to 1 swap with Merlin. Remove the helium, move the common bulkhead a little, and off they go.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/25/2017 01:05 AM
Still, methane is less dense than kerosene.  Raptor would burn up the fuel in a standard diameter Falcon faster, even if subscale, so it requires a larger diameter to make up for the less dense fuel. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/25/2017 02:27 AM
Still, methane is less dense than kerosene.  Raptor would burn up the fuel in a standard diameter Falcon faster, even if subscale, so it requires a larger diameter to make up for the less dense fuel.

Nope.

Raptor's goal specs are so much better than Merlin that it would get similar delta-v out of an equal volume of fuel, despite the lower fuel density and mass.

Burning up the fuel faster isn't a problem, since its also accelerating faster due to the higher thrust.
Title: Re: Raptor Upper Stage consolidated thread
Post by: livingjw on 06/25/2017 12:14 PM


All true - F9 will be replaced eventually.

But why not start with RUS?  Get some benefits early with a much smaller redesign effort, and be smarter when you decide to completely move away from F9?

Because making the upper stage reusable will eat into your payload to such an extent that it could not lift many of its payloads. They will require a larger booster.

John

Design F9 so can fly RUS or current EUS.

If they do develop a reuseable US there are some design options.
1) Use with existing fairing, allows for bulky payloads.
2) Add cargo bay with robotic arm . If made long life they end up with something like Shuttle/ X37 cross.
No fairing to recover, potential return of satellites. Delivery and return of bulky ISS cargo, by using a pressurized container eg Cygnus without SM.
Ideal for LEO satellite constellation deployment and disposal. For disposal just grap satellite and tow it to lower orbit eg 180km.

All of those things are doable, but not without a major reduction in payload capacity. I think they will opt for a bigger booster with an scaled down BFS OML S2.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 06/25/2017 04:21 PM
All true - F9 will be replaced eventually.

But why not start with RUS?  Get some benefits early with a much smaller redesign effort, and be smarter when you decide to completely move away from F9?

Because making the upper stage reusable will eat into your payload to such an extent that it could not lift many of its payloads. They will require a larger booster.

John
That is precisely why I think that the RUS will be for FH only.

I think all the arguments about different fuels required is a non-starter. RP-1 fueling support is already there. If they have any intention of a sub-scale (less than ITS) will be done on an existing pad like LC39A, so they will add capability for CH4. This is true if they build an all methane rocket or mixed. Since they are committed to CH4 as a fuel in the near future there would be almost no cost difference between supporting an RP-1/CH4 rocket than only CH4. Elon's argument about single fuel applied to initial setup of starting a rocket business and is no longer applicable.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/25/2017 05:08 PM
Wrong, Elon's comment was a rocket in general and one that will be low cost.  It has nothing to do with being a startup.

And the comment about no cost difference is blatantly wrong.  There are big costs.  And RP-1 would be removed.  The non starter is the fanasty called RUS.  It is an internet myth.  It exists no where else.  Spacex has never said they were developing one or mention one. The Air Force contract is only for engine and is a dead end.
Title: Re: Raptor Upper Stage consolidated thread
Post by: M.E.T. on 06/25/2017 05:51 PM
Wrong, Elon's comment was a rocket in general and one that will be low cost.  It has nothing to do with being a startup.

And the comment about no cost difference is blatantly wrong.  There are big costs.  And RP-1 would be removed.  The non starter is the fanasty called RUS.  It is an internet myth.  It exists no where else.  Spacex has never said they were developing one or mention one. The Air Force contract is only for engine and is a dead end.

Jim, just to clarify, when you say RP-1 will be removed, do you mean that the capability to fuel rockets with RP-1 will be removed completely from the pad? If so, does that mean that a new fully methane based mini-ITS will not be able to launch from the same pad as a Falcon 9 in future?
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/25/2017 06:01 PM
This is veering off topic.

There isn't a single reader here who doesn't want to see an all-methane architecture.  Opinions may vary on whether a 3.6 m F9-based rocket is a good idea, but neither that or a mini-ITS are the topics here.

This thread is about a RUS for F9/FH, and again everyone knows that this entails development work, and changes to the fuel supply to the upper stage.  Everyone can also count the benefits.

Contrary to the assertion upthread, this is not rocket science.

This is watching the CTO juggling the introduction of new technology while maintaining operations and keeping an eye on profitability - that same skill RobotBeat was highlighting earlier.

 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/25/2017 07:29 PM
The issue are the drawbacks that are conveniently overlooked.  And those who are blinded by the cult of personality and accept everything fed to them.
Title: Re: Raptor Upper Stage consolidated thread
Post by: M.E.T. on 06/25/2017 07:42 PM
This is veering off topic.

There isn't a single reader here who doesn't want to see an all-methane architecture.  Opinions may vary on whether a 3.6 m F9-based rocket is a good idea, but neither that or a mini-ITS are the topics here.

This thread is about a RUS for F9/FH, and again everyone knows that this entails development work, and changes to the fuel supply to the upper stage.  Everyone can also count the benefits.

Contrary to the assertion upthread, this is not rocket science.

This is watching the CTO juggling the introduction of new technology while maintaining operations and keeping an eye on profitability - that same skill RobotBeat was highlighting earlier.

What I am trying to understand, hence my question to Jim, is whether the challenges of fueling one rocket with two different fuel types are significantly different to alternately flying a fully methane based rocket - whatever it ends up being - and the current F9 from the same pad in a few years time. Because that would also require the pad to be capable of handling two different fuel types. One week the new methane based rocket might be launching from it, and the next week the RP-1 based Falcon 9 could be launching from it.

So what I am trying to grasp is whether having the capacity to use both the fuel types on the same rocket is significantly more complicated than being able to alternate between a methane and RP-1 based rocket from one week to the next, which would be required in any case once a future Raptor based rocket operates concurrently with the F9 Block V.
 
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/25/2017 07:50 PM
This is veering off topic.

There isn't a single reader here who doesn't want to see an all-methane architecture.  Opinions may vary on whether a 3.6 m F9-based rocket is a good idea, but neither that or a mini-ITS are the topics here.

This thread is about a RUS for F9/FH, and again everyone knows that this entails development work, and changes to the fuel supply to the upper stage.  Everyone can also count the benefits.

Contrary to the assertion upthread, this is not rocket science.

This is watching the CTO juggling the introduction of new technology while maintaining operations and keeping an eye on profitability - that same skill RobotBeat was highlighting earlier.

What I am trying to understand, hence my question to Jim, is whether the challenges of fueling one rocket with two different fuel types are significantly different to alternately flying a fully methane based rocket - whatever it ends up being - and the current F9 from the same pad in a few years time. Because that would also require the pad to be capable of handling two different fuel types. One week the new methane based rocket might be launching from it, and the next week the RP-1 based Falcon 9 could be launching from it.

So what I am trying to grasp is whether having the capacity to use both the fuel types on the same rocket is significantly more complicated than being able to alternate between a methane and RP-1 based rocket from one week to the next, which would be required in any case once a future Raptor based rocket operates concurrently with the F9 Block V.
For a company that has innovation in its blood, running another fuel up the T/E is peanuts. It's not even a deep cryogen and if the US has no Helium tanks, even better.

For a (hypothetical) company that is used to think in terms of "minimizing change to existing assets/technology" - yeah, it's a high visibility issue.

SpaceX was never shy about changing things.  See the F9 1.1 and 1.2 arguments...
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 06/25/2017 07:57 PM
Still, methane is less dense than kerosene.  Raptor would burn up the fuel in a standard diameter Falcon faster, even if subscale, so it requires a larger diameter to make up for the less dense fuel.

Nope.

Raptor's goal specs are so much better than Merlin that it would get similar delta-v out of an equal volume of fuel, despite the lower fuel density and mass.

Burning up the fuel faster isn't a problem, since its also accelerating faster due to the higher thrust.

... and when the RUS gives about the same impulse as current falcon upper stage but weights about 15 tonnes less, the first stage can give it higher initial speed, staging later, increasing the capacity.


And, if they stretch the upper stage by something like 3-4 meters, then the propellant weight or initial stage weight is about the same as current falcon upper stage, but the impulse from the second stage is considerably better due the 380s vs 347s impulse. (the stage empty weight will also increase, but not too much)

Title: Re: Raptor Upper Stage consolidated thread
Post by: IainMcClatchie on 06/25/2017 10:09 PM
It seems to me the only way SpaceX is going to develop a Raptor upper stage is if they get something for it.  The trouble is, Raptor on top of one or three Falcon 9 cores would deliver an upper stage midway between two useful points, but not actually give them any new capability.

RUS would give them a little more payload.  Falcon 9 doesn't need more payload... Falcon Heavy will take care of any occasional needs for more payload.  Falcon Heavy doesn't need more payload, nobody is building anything that big (that pays).

If the RUS gave them twice as much payload, that would be interesting, but it doesn't.  2x the payload would be interesting because a reusable upper stage is going to deliver something like half the payload of the same stage expended.  Reusability is definitely something they'd like, but reusability with a substantial reduction in payload to GTO isn't going to be acceptable.

If I'm not mistaken, making a larger diameter upper stage that more fully utilizes the potential of a Raptor doesn't change this analysis.  It's still not going to deliver enough payload.

The potentially interesting case is, would a reusable Raptor upper stage on a Falcon Heavy throw as much and cost less than the existing Falcon 9?  I can't see how this is possible.  Consider just the engines.  If the two boosters were run for 18 missions before retirement, they'd use an average of one M1D per mission.  18 F9 missions would use 18 MVacs.  Even if the MVac costs twice what an M1D costs, you'd need the boosters run for nine missions before it breaks even.

So it seems to me that before they have a reusable upper stage, SpaceX will need the infrastructure for larger diameter stages.  It will no longer be possible to truck the stages around, so final assembly, testing, launch, and landing will all happen in one place.  This will be either Florida or Texas.  My guess is that SpaceX will not commit to a place until they have permits for all that activity, in particular the testing.  They probably don't know yet if they'll get all that in Boca Chica.

I'm surprised they are building the Boca Chica launch pad on land.  I'd think a pad five miles out to sea would have far fewer constraints on testing, launches, and landings.  And I'd think they are already committed to the infrastructure for landing and then moving whatever this new, bigger first stage would be on a barge.

Also, I think the business case for a reusable upper stage will not close until CommX or OneWeb is fully committed to at least many hundreds of launches.  Falcon works too well right now.  It will be a couple years at least to shake out the myriad business issues.

We will see an announcement of a reusable upper stage from SpaceX some day.  I'd guess years from now, and when we see it, it'll be part of a new rocket, designed for lifting large satellite constellations.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 06/25/2017 10:46 PM
Falcon Heavy doesn't need more payload, nobody is building anything that big (that pays).

If FH+RUS can lift circa 90 tons to LEO, then it can compete with whatever NASA wants SLS for.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 06/25/2017 10:48 PM
RUS would give them a little more payload.  Falcon 9 doesn't need more payload... Falcon Heavy will take care of any occasional needs for more payload.

This assumes that for SpaceX, FH launch costs about as much as F9 launch. What is your basis to assume that?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 06/26/2017 12:41 AM
Wrong, Elon's comment was a rocket in general and one that will be low cost.  It has nothing to do with being a startup.

And the comment about no cost difference is blatantly wrong.  There are big costs. And RP-1 would be removed. The non starter is the fanasty called RUS.  It is an internet myth.  It exists no where else.  Spacex has never said they were developing one or mention one. The Air Force contract is only for engine and is a dead end.

Why would RP-1 be removed? There are other rockets with RP-1 and H2.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/26/2017 01:36 AM
Like someone said, IF they are going to launch F9, FH, and an ITS from the cape, they are going to have to have methane capabilities to go along with lox and kerosene.  So, that money and infrastructure is going to have to be built anyway. 

The Raptor would have greater capabilities, so it would be able to be made into a reusable stage that would match the existing expendable upper stage also.  OR, removing the reusable material and legs, could launch a heavier payload in expendable mode to almost match SLS. 

On the other side, when they get ITS going, it will probably make all other rockets obsolete, especially with in space refueling for deep space missions of all types.  This would thus make possible Raptor upper stage either not developed or delayed.   
Title: Re: Raptor Upper Stage consolidated thread
Post by: Robotbeat on 06/26/2017 01:50 AM
The only point I can see them doing a Raptor upper stage is if:
1) they think they could fly the same stage on a Raptor first stage in the future
Or
2) they want a subscale BFS sent to Mars in 2020 and think this is the fastest/cheapest way to do it.
Title: Re: Raptor Upper Stage consolidated thread
Post by: CuddlyRocket on 06/26/2017 02:53 AM
Falcon Heavy doesn't need more payload, nobody is building anything that big (that pays).

If FH+RUS can lift circa 90 tons to LEO, then it can compete with whatever NASA wants SLS for.

I'm not sure that NASA wants SLS for anything - they're building it because Congress mandates it and are struggling to find any missions for it that the same Congress is willing to find even more cash for!
Title: Re: Raptor Upper Stage consolidated thread
Post by: WindnWar on 06/26/2017 05:22 AM
A question, how much mass and volume consumed do you eliminate in the second stage by getting rid of the copv's for the helium and all the struts that hold them?

Does removing those tanks get your volume for methane closer to the current fuel/oxygen volumes, or close enough that you might need even less of a tank stretch to equal the same upper stage mass?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 06/26/2017 05:22 AM
Does anyone know where the RP-1 tanks are on Pad LC39A? Have I correctly identified the LOX and H2 tanks? Has the H2 been converted to RP-1? What are the tanks just below the H2? What is the building for with the pipes going to the pad in the lower left? Where and how are the LOX and RP-1 chilled?
Title: Re: Raptor Upper Stage consolidated thread
Post by: intrepidpursuit on 06/26/2017 05:35 AM
Calculations seem to have proven that Raptor with existing S2 tankage would be net zero performance gain.

If they changed to Raptor for S2, they would have to shut down pads for months at a time to do the upgrade (fuel farms could maybe be worked on between launches, but plumbing in the TEL would be no small task and would require shutdown). It would ask risk to a rocket that SpaceX is already struggling to claim is reliable (getting there if there are no more failures). It would reduce their launch capacity while upgrading. It would increase the cost of S2.

So, tons of downsides and only potential upside is if they make it bigger and big enough that they could make S2 reusable.

If they made S2 reusable it would save roughly 15% of current launch costs (70% is S1, been implied the rest is ~60/40 S2 and fairing, plus refurb costs, educated guess). That would allow them to push their launch costs down after they recouped the costs of the upgrade. Their costs are already lower than anyone else when the whole rocket is expendable. So the only place these costs even matter is to launch constellation.

If they are already building a giant, fully reusable raptor based rocket, why not build an S2 for that which is customized for constellation deployment? It would be fully reusable, have its own pad and infrastructure and be purpose built from the beginning. It wouldn't interfere with current cash flow and would almost certainly be cheaper to launch per/kg due to reduced refurbishment and cheaper fuel. More investment, but more reward.

Therefore, I can't see any reason why shoehorning an entirely new S2 on an incredible rocket that is just hitting its stride makes sense in any scenario.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 06/26/2017 07:06 AM
Calculations seem to have proven that Raptor with existing S2 tankage would be net zero performance gain.

Those calculations that totally ignore the fact that when L1 has to lift lighter stage2 to the staging point, the staging happens at higher speed?

When the second stage weights almost 15% less , the staging can happen at about 0.3 km/s higher speed (when landing on barge, with RTLS this difference is less), so the second stage has about 0.3 km/s less work to do.

Assuming the current second stage gives something like 8.3 km/s impulse to 6 tonne satellite, the same volume of methalox can give 8km/s impulse to about 7.75 tonne satellite. This gives nice 29% increase to GTO payload. Or, for same payload, it gives 1.75 tonnes extra capacity that can be used for recovery hardware of the second stage.

But if the raptor engine is heavier than merlin 1dvac engine, then of course the engine weight difference has to be subtracted from this number, my calculations were based on the "mini-raptor" which has about same size as merlin 1dvac, and which has nozzle that can fit inside the 3.66 meters.


Title: Re: Raptor Upper Stage consolidated thread
Post by: MikeAtkinson on 06/26/2017 07:16 AM
Falcon Heavy doesn't need more payload, nobody is building anything that big (that pays).

If FH+RUS can lift circa 90 tons to LEO, then it can compete with whatever NASA wants SLS for.

FH fairing is too small to replace SLS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 06/26/2017 07:27 AM
Falcon Heavy doesn't need more payload, nobody is building anything that big (that pays).

If FH+RUS can lift circa 90 tons to LEO, then it can compete with whatever NASA wants SLS for.

I'm not sure that NASA wants SLS for anything - they're building it because Congress mandates it and are struggling to find any missions for it that the same Congress is willing to find even more cash for!

As history teaches us, when there is a risk of unpleasant questions being asked ala "why the heck do we build this thing, it does not make economic sense?", the reason for it existence will be created. In the case of SLS:

https://en.wikipedia.org/wiki/Europa_Clipper

Captain Obvious tells me that it will be designed so that it can only be lifted by SLS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/26/2017 12:51 PM
Calculations seem to have proven that Raptor with existing S2 tankage would be net zero performance gain.

Those calculations that totally ignore the fact that when L1 has to lift lighter stage2 to the staging point, the staging happens at higher speed?

When the second stage weights almost 15% less , the staging can happen at about 0.3 km/s higher speed (when landing on barge, with RTLS this difference is less), so the second stage has about 0.3 km/s less work to do.

Assuming the current second stage gives something like 8.3 km/s impulse to 6 tonne satellite, the same volume of methalox can give 8km/s impulse to about 7.75 tonne satellite. This gives nice 29% increase to GTO payload. Or, for same payload, it gives 1.75 tonnes extra capacity that can be used for recovery hardware of the second stage.

But if the raptor engine is heavier than merlin 1dvac engine, then of course the engine weight difference has to be subtracted from this number, my calculations were based on the "mini-raptor" which has about same size as merlin 1dvac, and which has nozzle that can fit inside the 3.66 meters.

With a full model including this effect, the difference is about 24% improvement to GTO and 12% to LEO with ASDS booster landing. While a solid improvement, it's likely not enough to enable reuse or make it worthwhile to SpaceX.

A RUS isn't really worthwhile unless it enables reuse and other BFS-like capabilities (IMO). That means a 3,000 kN Raptor, or at least 2 of the 1,000 kN versions, which means at least a 200-tonne upper stage, which means uprating Merlin 1D (or 1E?) to at least 1000 kN (225 klbf), if they want to launch it on F9.

Shotwell said they have run Merlin up to 240 klbf (1070 kN), so maybe that's possible, but IMO it means a methane booster (hi Jim) with 9x 1000 kN Raptors.

OR, it means a mini BFS that masses over 300 tonnes wet, adds a lot of the capabilities of the BFS (refueling, side entry, internal cargo space, etc) and only launches on FH at first. And maybe later on a large (~NG-sized) methane single stick.

Basically, what Chris said here:
The only point I can see them doing a Raptor upper stage is if:
1) they think they could fly the same stage on a Raptor first stage in the future
Or
2) they want a subscale BFS sent to Mars in 2020 and think this is the fastest/cheapest way to do it.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/26/2017 01:36 PM

https://en.wikipedia.org/wiki/Europa_Clipper

Captain Obvious tells me that it will be designed so that it can only be lifted by SLS.

Your Captain Obvious is wrong and his intuition needs calibration as shown times before.

 Captain Obvious needs to stick to topics that he knows something about.

Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 06/26/2017 01:40 PM
I am still convinced that a upper stage with ~4m diameter is the most versatile solution.

It would be usable on both F9 and FH. It could be launched using the existing TEL, upgraded for methane. That TEL would allow for using both kerolox and methalox upper stages. It would improve payload beyond a stage with constant Falcon upper stage volume. Enough to maintain payload and gain reusablility. Enough to be a Mars lander with some payload but probably not for manned missions.

It would not optimize for Mars performance. But that woud be served by a future full methalox launch vehicle. Assuming in orbit refuelling it would still land an astounding amount of payload on Mars compared to everything else on the drawing board.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/26/2017 01:44 PM
I am still convinced that a upper stage with ~4m diameter is the most versatile solution.
 

Based on flawed thinking.

It is incapable with existing production line, launch site GSE, current TELs, transport hardware, etc.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Eerie on 06/26/2017 01:51 PM
Can Falcon 9 fly with a longer S2 of the same radius?
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 06/26/2017 02:27 PM
I am still convinced that a upper stage with ~4m diameter is the most versatile solution.
 

Based on flawed thinking.

It is incapable with existing production line, launch site GSE, current TELs, transport hardware, etc.

We know that. So why repeat it?

A Raptor upper stage will not come from an existing production line. The TEL will need to be modified.

Edit: Because we know it my suggestion is not based on flawed thinking.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/26/2017 02:32 PM
I am still convinced that a upper stage with ~4m diameter is the most versatile solution.
 

Based on flawed thinking.

It is incapable with existing production line, launch site GSE, current TELs, transport hardware, etc.

We know that. So why repeat it?

A Raptor upper stage will not come from an existing production line. The TEL will need to be modified.

Edit: Because we know it my suggestion is not based on flawed thinking.

It is flawed because it would be too disruptive for the existing FH and it would interfere with manned Dragon 2 flights.  Both these are priorities for Spacex. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/26/2017 02:39 PM
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 06/26/2017 02:58 PM

A RUS isn't really worthwhile unless it enables reuse and other BFS-like capabilities (IMO). That means a 3,000 kN Raptor, or at least 2 of the 1,000 kN versions, which means at least a 200-tonne upper stage, which means uprating Merlin 1D (or 1E?) to at least 1000 kN (225 klbf), if they want to launch it on F9.

Lots of claims without any basis.

 1 MN is plenty of thrust for upper stage, no need for more thrust, and this is easily enough even for some ~20-meter long 140-tonne upper stage. And this upper stage could be easily lifted even with current F9 first stage, though with more gravity losses, but the thrust improvements coming in block 5 mean that block 5 first stage might lift this 140-tonne upper stage with less gravity losses than the current block 3 has.

Quote
Shotwell said they have run Merlin up to 240 klbf (1070 kN), so maybe that's possible, but IMO it means a methane booster (hi Jim) with 9x 1000 kN Raptors.

No need, there is plenty of thrust and good enough T/W even with current engines.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/26/2017 03:02 PM
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

Not a question of capacity (i.e. more of the same) but of capability (i.e. able to do new things). Current US does not have capabilities SpaceX needs for Mars, and they cannot be added: orbital/Mars refueling, lifting entry, "easy" reuse. A Raptor stage can have those capabilities.

Quote
LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.

Can't D2 cargo and other NASA payloads fly from 40?

They have a number of options:
1) add a second HIF and TEL with a rail switcher at 39A
2) dedicate the Boca Chica facility to methane or mixed vehicles
3) build an additional HIF and TEL at Boca Chica
4) add a FSS to 40 to support crew and VI
5) basically rebuild 40 with a 2nd HIF and TEL to the west and use the current flame trench, enlarged if needed.
6) add a separate pad and flame trench to 40 for FH, like the old plan

None are without drawbacks, but all would solve the major issues.
Title: Re: Raptor Upper Stage consolidated thread
Post by: tater on 06/26/2017 03:44 PM
If they were to experiment with a BFS-like US for F9 (for testing, if nothing else), it seems like the infrastructure would be best installed at the TX launch site, as making changes there disrupts none of their priority 1 operations, and Musk has said a few times that BFR/BFS would fly from there, anyway (with requires the methlox infrastructure, so such additions would not be wasted).
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 06/26/2017 03:48 PM
For a company that has innovation in its blood, running another fuel up the T/E is peanuts. It's not even a deep cryogen and if the US has no Helium tanks, even better.

For a (hypothetical) company that is used to think in terms of "minimizing change to existing assets/technology" - yeah, it's a high visibility issue.

SpaceX was never shy about changing things.  See the F9 1.1 and 1.2 arguments...

This kind of rhetoric is used a lot to justify any pet idea of a poster; "SpaceX will do this because it's the New Space way!"
So I might as well use it too:
To me, postponing ITS in order to make incremental improvements to Falcon, which a RUS would do, is less 'SpaceX-y' than just going full bore straight to ITS asap.  They'll learn more from ITS failures than RUS failures.
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/26/2017 04:10 PM
For a company that has innovation in its blood, running another fuel up the T/E is peanuts. It's not even a deep cryogen and if the US has no Helium tanks, even better.

For a (hypothetical) company that is used to think in terms of "minimizing change to existing assets/technology" - yeah, it's a high visibility issue.

SpaceX was never shy about changing things.  See the F9 1.1 and 1.2 arguments...

This kind of rhetoric is used a lot to justify any pet idea of a poster; "SpaceX will do this because it's the New Space way!"
So I might as well use it too:
To me, postponing ITS in order to make incremental improvements to Falcon, which a RUS would do, is less 'SpaceX-y' than just going full bore straight to ITS asap.  They'll learn more from ITS failures than RUS failures.

Replied here:
http://forum.nasaspaceflight.com/index.php?topic=43219.msg1695346#msg1695346
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/26/2017 04:26 PM

A RUS isn't really worthwhile unless it enables reuse and other BFS-like capabilities (IMO). That means a 3,000 kN Raptor, or at least 2 of the 1,000 kN versions, which means at least a 200-tonne upper stage, which means uprating Merlin 1D (or 1E?) to at least 1000 kN (225 klbf), if they want to launch it on F9.

Lots of claims without any basis.

 1 MN is plenty of thrust for upper stage, no need for more thrust, and this is easily enough even for some ~20-meter long 140-tonne upper stage. And this upper stage could be easily lifted even with current F9 first stage, though with more gravity losses, but the thrust improvements coming in block 5 mean that block 5 first stage might lift this 140-tonne upper stage with less gravity losses than the current block 3 has.

Quote
Shotwell said they have run Merlin up to 240 klbf (1070 kN), so maybe that's possible, but IMO it means a methane booster (hi Jim) with 9x 1000 kN Raptors.

No need, there is plenty of thrust and good enough T/W even with current engines.

All of this is true, but pointless as it doesn't enable any of the BFS capabilities.

However, I think I'm off topic here. Jim as OP stated this thread only refers to a methane stage operating as the current stage.

Discussion of a BFS-like upper stage for F9 and (or?) FH is here: http://forum.nasaspaceflight.com/index.php?topic=43219.msg1695346#msg1695346
Title: Re: Raptor Upper Stage consolidated thread
Post by: woods170 on 06/26/2017 07:14 PM
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.
Your line of reasoning is flawed Jim.

Why is there a Falcon Heavy? There was no need for it given that the heavy payloads could/can be lofted by Delta IV Heavy.

Yet, Falcon Heavy exists.

Why is SpaceX reusing rockets? There was no need for it given that the world did just fine for the past 5+ decades launching on expendable rockets only.

Yet, reusable Falcon exists.

Why is SpaceX working on recovering the fairings? There is no need for it given that they are able of meeting their launch schedule even without reusing the fairing.

Yet, fairing recovering is being worked on and tested in practice.

Why is there a SpaceX? There was no need for it given that there were enough launch service providers to cater for the worlds launch needs.

Yet, SpaceX exists.

And in case you had forgotten: SpaceX was already working on improved Falcon 9, aka v1.1, when Falcon 9 v1.0 had yet to fly. Much like SpaceX was already working on an improved launcher (aka Falcon 5) while Falcon 1 had yet to fly.

The more your repeat your mantra of "Why?", "What's the reason?" the more you confirm the fact that your really don't "get" SpaceX.
That company is not run by logical reasoning alone. It is run by passion as well. And the latter makes for seemingly irrational or illogical decision making.

And I for one am glad it happens. Had it not been for seemingly irrational and/or illogical decision making than mankind never would have sent anything into space. After all, mankind did just fine without spaceflight for the better part of 500,000 years.

Yet, spaceflight exists.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 06/26/2017 07:33 PM
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.
Your line of reasoning is flawed Jim.

Why is there a Falcon Heavy? There was no need for it given that the heavy payloads could/can be lofted by Delta IV Heavy.

Yet, Falcon Heavy exists.

Why is SpaceX reusing rockets? There was no need for it given that the world did just fine for the past 5+ decades launching on expendable rockets only.

Yet, reusable Falcon exists.

Why is SpaceX working on recovering the fairings? There is no need for it given that they are able of meeting their launch schedule even without reusing the fairing.

Yet, fairing recovering is being worked on and tested in practice.

Why is there a SpaceX? There was no need for it given that there were enough launch service providers to cater for the worlds launch needs.

Yet, SpaceX exists.

And in case you had forgotten: SpaceX was already working on improved Falcon 9, aka v1.1, when Falcon 9 v1.0 had yet to fly. Much like SpaceX was already working on an improved launcher (aka Falcon 5) while Falcon 1 had yet to fly.

The more your repeat your mantra of "Why?", "What's the reason?" the more you confirm the fact that your really don't "get" SpaceX.
That company is not run by logical reasoning alone. It is run by passion as well. And the latter makes for seemingly irrational or illogical decision making.

And I for one am glad it happens. Had it not been for seemingly irrational and/or illogical decision making than mankind never would have sent anything into space. After all, mankind did just fine without spaceflight for the better part of 500,000 years.

Yet, spaceflight exists.

and so... that necessitates a RUS? i'm not following...
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 06/26/2017 07:42 PM
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.
Your line of reasoning is flawed Jim.

Why is there a Falcon Heavy? There was no need for it given that the heavy payloads could/can be lofted by Delta IV Heavy.

Yet, Falcon Heavy exists.

FH is made by SpaceX. It is to create money to SpaceX, DIVH cannot do that.

Quote
Why is SpaceX reusing rockets? There was no need for it given that the world did just fine for the past 5+ decades launching on expendable rockets only.

Yet, reusable Falcon exists.

SpaceX is reusing rockets because it makes launches cheaper.

Quote
Why is SpaceX working on recovering the fairings? There is no need for it given that they are able of meeting their launch schedule even without reusing the fairing.

Yet, fairing recovering is being worked on and tested in practice.

Fairing recovery has nothing to do with launch schedule. It's all about cost.

Quote
Why is there a SpaceX? There was no need for it given that there were enough launch service providers to cater for the worlds launch needs.

Yet, SpaceX exists.


All of the previous launch providers were too expensive. There was need for cheaper rockets.

Quote
And in case you had forgotten: SpaceX was already working on improved Falcon 9, aka v1.1, when Falcon 9 v1.0 had yet to fly. Much like SpaceX was already working on an improved launcher (aka Falcon 5) while Falcon 1 had yet to fly.

Actually no. They were working on different version of F9 than the v1.1. THis version was to have "merlin 1c+" engines and have much less capacity than v1.1 has. They canned it when they jumped to much more powerful merlin 1d instead.

Quote
The more your repeat your mantra of "Why?", "What's the reason?" the more you confirm the fact that your really don't "get" SpaceX.
That company is not run by logical reasoning alone. It is run by passion as well. And the latter makes for seemingly irrational or illogical decision making.

Wrong. All the engineering decisions are done by numbers and logic, not passion.

The passion is only about getting to Mars.

It's YOU who do not understand spaceX, and it's YOU whose logic is flawed.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 06/26/2017 07:51 PM
Well seems the idea of a Raptor S2 gets boost.

Interview with Gwynne Shotwell On the Space Show

from notes on reddit:

https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/ (https://www.reddit.com/r/spacex/comments/6ix76m/interview_with_gwynne_shotwell_on_the_space_show/)

Quote
There have been dozens of Raptor tests(!) Initially intended for Mars, we are also looking at Raptor's utility for the Falcon program.


Wrong.  Where is does she says just second stage? 
It be more likely both stages using Raptor.
Unlikely. Boosters and first stages will need to be recovered. Which cannot be done when they are sporting Raptors.

Based on what?

There is nothing preventing boosters and first stages being recovered even if they would have Raptor engines, as long as the engines are spaced inline and not in a triangle, to have one engine in the middle for the landing.

Higher minimum T/W makes the landing a bit riskier, but SpaceX just succesfully landed a first stage using 3 M1D engines. Those together have about the same maximum thrust as one "full" Raptor, but Raptor is expected to throttle down deeper than M1D, giving lower minimum T/W than what they already have used for landing.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/26/2017 08:03 PM

Your line of reasoning is flawed Jim.

Why is there a Falcon Heavy? There was no need for it given that the heavy payloads could/can be lofted by Delta IV Heavy.

Yet, Falcon Heavy exists.


No.  Falcon Heavy exist because:
 a. it is a competitor to Delta IV
b.  it enables some of Spacex's plans
3.7 m dia RUS does neither. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Space Ghost 1962 on 06/26/2017 08:39 PM
Delta IVH was done "top down" as a means to address NSS Titan IV A/B payloads without its hideous cost structure. Three similar cores of a liquid.

FH similarly attempts to serve the same market, the same way ... using a lower cost platform.

SX unlike ULA does "bottom up" developments to use excess booster performance to attempt to advance LV capabilities, such as reuse of stages.

FH continues to project excessive performance beyond Delta IV-HU, which defines the top of this market.

They can use this *any way* they'd like to attempt to further advance LV. Perhaps excess performance to experiment with US recovery and/or higher performance US (ala ACES)?

They have an asset in a subscale Raptor, build for an AF US engine program.

Musk says he's tempted, on/off about this.

Jim you are absolutely right about the loss of the cost structure for an all kerolox F9/FH.

But haven't you long discounted SX attempts to advance LV, and the benefits those might return?

Is your objection any different among these?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Joel on 06/27/2017 03:05 AM
It be more likely both stages using Raptor.
And the retirement of Merlin?
Title: Re: Raptor Upper Stage consolidated thread
Post by: darkenfast on 06/27/2017 04:34 AM
Falcon 9 and Falcon Heavy exist for one main reason: to make a ton of money in order to further SpaceX's main goal: the expansion of humanity off of the planet.  They cannot make that ton of money if they go down the path of keeping the Falcon family in an experimental mode, making MAJOR changes that aren't justified by the market and add a lot of cost.  An example: if it costs $6 million to make a fairing set and they can make the recovery (plus recouping R&D costs) without risk to the customer and for, say $1 million, then it's a good rational decision.  Crossfeed is an example of a fascinating idea that they finally decided to shelve (for now), because the complexity and cost did not justify it.  All of this has to be considered in light of the revenue that they bring in.  If they make the upper stage too big to routinely transport over roads, how will that affect the price, demand and profit?  If they have to start adding Methane to the pad structure to use a Raptor before the BFR, same thing.

IMHO, Falcon needs to the R-7 of the rocket world for a decade or two.  After the mishaps, they are finally starting to hit their stride and deliver the service that their paying customers need.  Will product improvement along the line happen?  Probably.  Do they need to risk their bread-and-butter business to try out new stages in place of what is finally working?  Probably not.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 06/27/2017 05:51 AM
If they have to start adding Methane to the pad structure to use a Raptor before the BFR, same thing.

Can this scaremongering about "adding methane" stop? Gosh, these guys not only built a new rocket, new capsule, and new (and amazing) engines, they managed to land a rocket! On a ship!! And somehow adding some LNG tanks, pumps and pipes, *which is COTS tech*, is a big problem? Really?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Varn on 06/27/2017 06:29 AM
Been watching this, thus far undecided.

Running up another fuel should almost be a non-issue IMO, plumbing wise up the erector.  Running that up within the next 12 months?  That is another unneeded issue.  F9 doesn't seem to need a new US. I am only a layman, but it seems that FH might need a better US. Not adding that for F9 means LC-40 has no need, only SLC-39 would need the mod.

Something that I saw asked at least twice, can the current US get stretched to about 2x the current F9 config?  FH may need something with more push. I just don't see Merlin needed for this at this time...

I know this is off topic for this thread. but can the current F9 US get more or less doubled in capacity, and taps added to fuel a larger US without *too significant* modifications to the current erector to give the FH better capability?
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/27/2017 06:41 AM
Been watching this, thus far undecided.

Running up another fuel should almost be a non-issue IMO, plumbing wise up the erector.  Running that up within the next 12 months?  That is another unneeded issue.  F9 doesn't seem to need a new US. I am only a layman, but it seems that FH might need a better US. Not adding that for F9 means LC-40 has no need, only SLC-39 would need the mod.

Something that I saw asked at least twice, can the current US get stretched to about 2x the current F9 config?  FH may need something with more push. I just don't see Merlin needed for this at this time...

I know this is off topic for this thread. but can the current F9 US get more or less doubled in capacity, and taps added to fuel a larger US without *too significant* modifications to the current erector to give the FH better capability?

F9 doesn't NEED a better US, but remember that many people have pointed out that F9's cost reductions are limited by the fact that the US is not reusable, and that the F9 system is only "partially reusable" and so on and so forth.

But the more you point out the deficiencies of a non-reusable US, the more you should support doing something about it, right?
Title: Re: Raptor Upper Stage consolidated thread
Post by: RDMM2081 on 06/27/2017 07:08 AM
In my mind, the answer to Jim's question of "why" has nothing to do with the business case of the Falcon family and adding or enhancing their capability. I agree, that's a non starter at this point in time.

What DOES make sense to me is using F9 S1 as a test bed to launch an experimental S2 to test Raptor in vacuum, CF OML, CF tankage, lifting body re-entry, long duration coast, ZBO on orbit methalox management, on orbit methalox tranfer, and on orbit space tug practice.

Fine. Working with two fuels on a pad is hard and expensive(Jim, I am speaking directly to you here) BUT, getting to practice these additional techs as a PAYLOAD, is worth the effort of bringing LNG to the launch pad(could it literally be as basic as pumping from a tanker truck parked onsite, assuming the plumbing existed in the TEL?) and launching a RUS as a technology demonstrator payload. Not as an operational capability.  I think this is the crux of the disagreement between Jim and so many.

Of course, some day, there will be full methalox pads for booster and S2(ITS/BFR) but that is another topic for another thread.
Title: Re: Raptor Upper Stage consolidated thread
Post by: woods170 on 06/27/2017 08:43 AM
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.
Your line of reasoning is flawed Jim.

Why is there a Falcon Heavy? There was no need for it given that the heavy payloads could/can be lofted by Delta IV Heavy.

Yet, Falcon Heavy exists.

Why is SpaceX reusing rockets? There was no need for it given that the world did just fine for the past 5+ decades launching on expendable rockets only.

Yet, reusable Falcon exists.

Why is SpaceX working on recovering the fairings? There is no need for it given that they are able of meeting their launch schedule even without reusing the fairing.

Yet, fairing recovering is being worked on and tested in practice.

Why is there a SpaceX? There was no need for it given that there were enough launch service providers to cater for the worlds launch needs.

Yet, SpaceX exists.

And in case you had forgotten: SpaceX was already working on improved Falcon 9, aka v1.1, when Falcon 9 v1.0 had yet to fly. Much like SpaceX was already working on an improved launcher (aka Falcon 5) while Falcon 1 had yet to fly.

The more your repeat your mantra of "Why?", "What's the reason?" the more you confirm the fact that your really don't "get" SpaceX.
That company is not run by logical reasoning alone. It is run by passion as well. And the latter makes for seemingly irrational or illogical decision making.

And I for one am glad it happens. Had it not been for seemingly irrational and/or illogical decision making than mankind never would have sent anything into space. After all, mankind did just fine without spaceflight for the better part of 500,000 years.

Yet, spaceflight exists.

and so... that necessitates a RUS? i'm not following...
None of the items listed by me in my previous post were necessary. Yet they exist anyway.
There is no apparent need for a RUS. But SpaceX is looking into Raptor on FH anyway.

Now you follow?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Joel on 06/27/2017 12:42 PM
Would a suborbital Grasshopper-like reusable upper stage make sense? Launched on a F9 first stage, it would fly to 4 km/s, then to 5 km/s, then to 6 km/s, then to 7 km/s before reaching orbital speeds. That would allow them to step-by-step work out all the issues.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/27/2017 01:22 PM
It is perplexing trying to figure out whether a Raptor upper stage is worth it.  Some things stuck out to me.

A 5.2m upper stage is the same diameter as the fairing, and one person said it would not affect the aerodynamic loads.

A 5.2m upper stage with a full size Raptor vacuum would give F9 28 tons to LEO in fully expendable mode.  This matches Delta IV heavy in a single stick rocket.  Far cheaper.  However, there aren't many Delta IV heavy loads. 

This same 5.2m upper stage would give FH about 85-90 tons to LEO in fully expendable mode.  SLS territory.  Even 5.2m diameter could be a problem with very large payloads. 

A Raptor upper stage could be developed into a reusable stage with about the same capabilities they now have, thus saving that extra 15-20% of costs.  What would the costs be to refurbish a second stage that has a lot more heating and pressure loads than the booster?  Would the savings offset the costs of pad modifications for methalox and the costs of refurbishment?  Is it worth it if ITS comes on line in 3 years?  ITS would probably put FH to rest. 

If someone could be realistic and answer these costs paybacks, that would be the determining factors. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 06/27/2017 02:42 PM
Is it worth it if ITS comes on line in 3 years?

How? I'm a "SpaceX fanboi" and I don't see it happening that fast. No engine yet, no pad yet, no fiber-wound tanks yet. No new factory for large tanks yet.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Roy_H on 06/27/2017 04:16 PM
Why do it?

I do not believe there is a value case for a Raptor on a standard F9 and even for FH there is no obvious need for the extra performance. However I think there is value in gaining flight experience with Raptor at relatively low cost (instead of 17 - 42 Raptors on a booster!) Methane is not optimal for a booster, but is ideal for space. Long loiter times (days not hours) with RP-1 are near impossible as it will freeze but keeping CH4 and LOX at same temperature both in liquid form at atmospheric pressure is fairly easy, much easier than keeping H2 liquid. This makes CH4/LOX ideal for space tug and beyond low orbit applications. SpaceX could also work out space refueling, again on a small scale before going with ITS.

And Jim, I would really appreciate an explanation why it is near impossible to provide GSE for RP-1 or CH4 upper stages as required. Is it not possible to add another fuel line to the TE? No room?

edit: temperature above means about 60°K
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/27/2017 04:32 PM
However I think there is value in gaining flight experience with Raptor at relatively low cost

There is no value in just flying an engine for experience
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 06/27/2017 04:36 PM
... I think there is value in gaining flight experience with Raptor at relatively low cost ...

Isn't this pre-1990's thinking, or whenever computer modeling advanced sufficiently, maybe 2005? They have test stands, they have computer modeling; testing on the rocket is only useful to verify the models, and even then it's only really useful when you build the hardware to match the model. i.e. launching a raptor on a frankenstein US wouldn't help to validate ITS modeling.

by your same logic, they'll have to send a precursor raptor to mars in order to test it there before they send ITS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 06/27/2017 04:53 PM
by your same logic, they'll have to send a precursor raptor to mars in order to test it there before they send ITS.

Maybe not "have to". But don't be surprised if they do.
Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 06/27/2017 04:58 PM
However I think there is value in gaining flight experience with Raptor at relatively low cost

There is no value in just flying an engine for experience
Grasshopper?

Yes, that's more than just the engine, but how close can you mimic the aerodynamics of a huge ultra low mass reentry vehical with a smaller but more dense (same aerodynamic loading per square meter) test craft?

Wouldnt even be a commercial vehical, just a 1-off testbed like Grasshopper.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/27/2017 05:47 PM
What does a Raptor upper stage that operates like the current Merlin upper stage enable?

It could be flight testing Raptor, maybe, but like Jim says that's not really useful.

Or it could be upper stage reuse, similar to this: http://selenianboondocks.com/2008/12/falcon-ix-upper-stage-recovery-kremlinology/

But is there a pressing need for upper stage reuse? At this point the only reason for it would be enabling cheaper deployment of the constellation. GTO launches do require the extra performance, but probably are not frequent enough to justify the investment of themselves.

But a small incremental payload like constellation sats are amenable to perfecting this style reuse with the current upper stage. Even if it takes 2x as many launches as a fully reuseable Raptor system, the development costs are much smaller.

A BFS-style upper stage appears to be SpaceX's chosen direction for the future, so they will minimize development expenses that don't go in that direction.

So perhaps the question should be, how much more is a reuseable Raptor stage worth, compared to a reuseable Merlin stage?
Title: Re: Raptor Upper Stage consolidated thread
Post by: woods170 on 06/27/2017 08:09 PM
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.
Your line of reasoning is flawed Jim.

Why is there a Falcon Heavy? There was no need for it given that the heavy payloads could/can be lofted by Delta IV Heavy.

Yet, Falcon Heavy exists.

FH is made by SpaceX. It is to create money to SpaceX, DIVH cannot do that.
The money making machine for SpaceX is Falcon 9, not Falcon Heavy. Haven't you noticed how empty the manifest for FH is and how full it is for F9?
Falcon Heavy serves only a very limited market. A substantial part of that market will be NSS launches. And frankly, USAF and NRO couldn't care less if FH flies or not. They already have Delta IV Heavy. Having a second heavy lifter at their disposal is merely a "nice to have". You don't believe me? Then explain why USAF never pushed LockMart for Atlas V Heavy. I'll tell you why USAF never did. Because redundancy in heavy lift for NSS is not needed. And that brings us back to my original point. From a standpoint of heavy lifters Falcon Heavy isn't needed. That was the point I was trying to make to Jim: There is no apparent logical reason for FH to exist. Yet SpaceX built it anyway. Which is a clear indicator that SpaceX decision making is not always logical. Something that Jim IMO fails to see.

Why is SpaceX reusing rockets? There was no need for it given that the world did just fine for the past 5+ decades launching on expendable rockets only.

Yet, reusable Falcon exists.
SpaceX is reusing rockets because it makes launches cheaper.
Yeah, that's the SpaceX reason. However, none of the other launch providers ever found it necessary to make their launches cheaper. You wanna know why? Because prior to SpaceX their was no disruptive force acting on the market. The parties in need of launch services gladly paid for the higher priced launches. They had no choice for lack of a disruptive force. And was the point I was making to Jim: Logically speaking there was no reason for reusable launch vehicles. The launch market did not require it. Yet SpaceX went for reusability anyway. So, another fine example of SpaceX making a seemingly illogical decision without a clear why.

Why is SpaceX working on recovering the fairings? There is no need for it given that they are able of meeting their launch schedule even without reusing the fairing.

Yet, fairing recovering is being worked on and tested in practice.

Fairing recovery has nothing to do with launch schedule. It's all about cost.
It is not all about cost. It is about being able to increase the launch cadence. Elon himself pointed out in 2015 that fairing production is labor intensive and takes a lot of time. So much time in fact that fairing production becomes a limiting factor once the launch tempo increases beyond a certain limit. That was, and according to my sources, still is the main driver behind fairing recovery. The improved cost aspect is merely a nice side-effect.

Why is there a SpaceX? There was no need for it given that there were enough launch service providers to cater for the worlds launch needs.

Yet, SpaceX exists.


All of the previous launch providers were too expensive. There was need for cheaper rockets.
Then why is it that prior to Elon having a space-themed brainwave nobody ever bothered to succesfully market a cheaper rocket?
The answer is that there was no need for cheaper rockets. Despite the other launch service providers supposedly being "too expensive" their launch manifests were pretty full. What you don't understand is that launch service providers are interested in reliability first, and cost second. That's why one of the most expensive launch service providers -Arianespace - was capable of catching a full half of the commercial launch market: they were (and still are btw.) the worlds most reliable launch services provider.

And in case you had forgotten: SpaceX was already working on improved Falcon 9, aka v1.1, when Falcon 9 v1.0 had yet to fly. Much like SpaceX was already working on an improved launcher (aka Falcon 5) while Falcon 1 had yet to fly.

Actually no. They were working on different version of F9 than the v1.1. THis version was to have "merlin 1c+" engines and have much less capacity than v1.1 has. They canned it when they jumped to much more powerful merlin 1d instead.
Incorrect. That particular upgrade of Falcon 9 v1.0 was exactly what Falcon 9 v1.1 also is: a more powerfull version of the basic rocket.

The more your repeat your mantra of "Why?", "What's the reason?" the more you confirm the fact that your really don't "get" SpaceX.
That company is not run by logical reasoning alone. It is run by passion as well. And the latter makes for seemingly irrational or illogical decision making.

Wrong. All the engineering decisions are done by numbers and logic, not passion.
You confuse engineering decisions for business decisions. The decisions to develop a reusable launcher is a business decision, not an engineering decision. Same for the decision to do fairing recovery or develop FH.
Those business decisions come from both logical reasoning and passion for doing thing differently (like going to Mars without waiting another 4 decades for NASA to do so).
Make no mistake. SpaceX engineering is among the best there is. And engineering decisions are indeed based on logic. But the business decisions come long before those and are very much a passion-thing, courtesy of Elon's personality.

The passion is only about getting to Mars.
Disagree. SpaceX has passion for many more things than "just" Mars.

It's YOU who do not understand spaceX, and it's YOU whose logic is flawed.
I don't think Jim needs you to defend his argument. He is perfectly capable of doing so himself.


Edit: removed the snark, per Lar's suggestion.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Lar on 06/27/2017 08:13 PM
Let's keep the snark to a reasonable level. This topic has passionate participants on both sides. Passion is fine but be excellent to each other. Not quoting any one post because I saw a lot of it.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RotoSequence on 06/27/2017 08:17 PM
It's entirely wrong to construe the Falcon Heavy as an illogical choice. The Falcon 9's performance has increased far above and beyond the original baseline specification that existed when Falcon Heavy was conceived to meet the heavy lift requirements of satellites on SpaceX's launch manifest. SpaceX Marginalized the Falcon Heavy by making Falcon 9 good enough for most of the Falcon Heavy's original manifest.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Chris Bergin on 06/27/2017 08:21 PM
There's people in Syria saying "I know we think we have it bad, but I've just read the "Raptor Upper Stage consolidated thread" on NSF and I'm praying for the folk posting on there". ;)

Keep. It. Civil.

Oh, Lar already beat me. Well, perhaps the thread needs double-teaming.
Title: Re: Raptor Upper Stage consolidated thread
Post by: abaddon on 06/27/2017 10:16 PM
The money making machine for SpaceX is Falcon 9, not Falcon Heavy. Haven't you noticed how empty the manifest for FH is and how full it is for F9?
Falcon Heavy serves only a very limited market.
Well... maybe, maybe not.

FH is late.  FH has lost payloads (two?) because of that, and also has not signed payloads (unknown) because of that.  F9 has several launches (three+?) that are expendable that would be candidates for FH if it were available.  At least one of those was signed as an FH payload.

6+ metric ton satellites are not that uncommon.  Chances are SpaceX will be able to win a larger share of that market with FH operational, eating into Proton and Ariane 5 market - as long as FH proves to be successful.

Even with Block 5 upgrades, it seems unlikely a regular F9 will be able to launch these birds and recover the first stage.  So I think FH could have a bigger role to play moving forward than you are thinking here.
Title: Re: Raptor Upper Stage consolidated thread
Post by: docmordrid on 06/27/2017 11:36 PM
The USAF is planning on DIVH going away by 2023 and choosing a replacement, and only Falcon Heavy, New Glenn, and maybe Vulcan ACES look to be in the hunt.

Add a backup launcher and the notion that the USAF has no interest in FH seems quite unlikely.

http://spacenews.com/delta-4-replacement-ready-by-2023-top-general-says/

Quote
Delta 4 replacement ready by 2023, top general says

Testifying before the House Armed Services Committee’s strategic forces subcommittee, Raymond said that the Air Force expects to have uninterrupted access to heavy launch for national security missions.

Several companies have heavy-lift vehicles in development, including SpaceX’s Falcon Heavy and Blue Origin’s New Glenn, that could replace the Delta 4 Heavy built by United Launch Alliance.

The Air Force has purchased launches on seven more Delta 4 Heavy rockets, Raymond said, though one launch will be a NASA mission. The final launch is scheduled for 2023.
>
Title: Re: Raptor Upper Stage consolidated thread
Post by: Space Ghost 1962 on 06/27/2017 11:40 PM
One of the best posts this year.
Here is what it all boils down to.

Why?

There has yet to be a good or marginal reason for Spacex to make a RUS for FH.  Nobody has on this forum has yet to come forth with a reason.

FH hasn't flown.  FH has yet to book a payload that needs its whole capability.  So why would they be looking at improvements.

LC-39A is going to be busy with Dragon 2 (cargo and crew), DOD vertical integrated payloads, NASA payloads, FH missions, etc.  So when and how is Spacex going to add a new upper stage that uses a new TEL and still service the existing upper stage.
Your line of reasoning is flawed Jim.

Why is there a Falcon Heavy? There was no need for it given that the heavy payloads could/can be lofted by Delta IV Heavy.

Yet, Falcon Heavy exists.

FH is made by SpaceX. It is to create money to SpaceX, DIVH cannot do that.
The money making machine for SpaceX is Falcon 9, not Falcon Heavy. Haven't you noticed how empty the manifest for FH is and how full it is for F9?
Cannot get why this is so hard for many here to grasp. F9 is "bread and butter". It is an excellent design for exactly what it's supposed to do.

But it is not Atlas-V. Nor any of the other vehicles. IMHO, Musk is pivoting the entire launch service provider business around F9. And "they" collectively ... don't like it. Too bad.

Quote
Falcon Heavy serves only a very limited market. A substantial part of that market will be NSS launches. And frankly, USAF and NRO couldn't care less if FH flies or not. They already have Delta IV Heavy. Having a second heavy lifter at their disposal is merely a "nice to have". You don't believe me? Then explain why USAF never pushed LockMart for Atlas V Heavy. I'll tell you why USAF never did. Because redundancy in heavy lift for NSS is not needed. And that brings us back to my original point. From a standpoint of heavy lifters Falcon Heavy isn't needed. That was the point I was trying to make to Jim: There is no apparent logical reason for FH to exist. Yet SpaceX built it anyway. Which is a clear indicator that SpaceX decision making is not always logical. Something that Jim IMO fails to see.
Agreed.

The biggest benefactor after SX of FH flying 3+ times successfully is likely ULA! Advancing the EOL clock on DIVH likely allows a more nimble ULA. Not because DIVH doesn't ... but because it takes to much, to do it.

FH is a useful luxury. Affordable because of F9 leverage/commonality.

But FH payloads won't be a major increment to SX annual revenue yield, nor net profit. (Not much of a burden either, so by not flying it much won't require as much overhead as other rivals.)

Quote
Why is SpaceX reusing rockets? There was no need for it given that the world did just fine for the past 5+ decades launching on expendable rockets only.

Yet, reusable Falcon exists.
SpaceX is reusing rockets because it makes launches cheaper.
Yeah, that's the SpaceX reason. However, none of the other launch providers ever found it necessary to make their launches cheaper. You wanna know why? Because prior to SpaceX their was no disruptive force acting on the market. The parties in need of launch services gladly paid for the higher priced launches. They had no choice for lack of a disruptive force. And was the point I was making to Jim: Logically speaking there was no reason for reusable launch vehicles. The launch market did not require it. Yet SpaceX went for reusability anyway. So, another fine example of SpaceX making a seemingly illogical decision without a clear why.
Well put.

Space launch has been long overdue for disruption. "They've" fought against it bitterly and are losing that battle.

So "they'll" either have to get good at competing on the edge of the wave of disruption, or fade away.

It has been mostly good our heritage. We shall build upon it, respect it, and take it to the next level as a new heritage.

Disruption means you can get access to business structural problems inside a market. In doing so, you rip it apart, make it work by means that address the structural issue, then put it back together.

To address unserved market that will not accept prior launch service provider offerings, you cannot simply address customers where price is no object. Because those simply raise the cost level when they need something, anything. This is the structural problem.

Quote
Why is SpaceX working on recovering the fairings? There is no need for it given that they are able of meeting their launch schedule even without reusing the fairing.

Yet, fairing recovering is being worked on and tested in practice.

Fairing recovery has nothing to do with launch schedule. It's all about cost.
It is not all about cost. It is about being able to increase the launch cadence. Elon himself pointed out in 2015 that fairing production is labor intensive and takes a lot of time. So much time in fact that fairing production becomes a limiting factor once the launch tempo increases beyond a certain limit. That was, and according to my sources, still is the main driver behind fairing recovery. The improved cost aspect is merely a nice side-effect.
Indeed.

Booster reuse already is speeding up manifest consumption.

Quote
Why is there a SpaceX? There was no need for it given that there were enough launch service providers to cater for the worlds launch needs.

Yet, SpaceX exists.


All of the previous launch providers were too expensive. There was need for cheaper rockets.
Then why is it that prior to Elon having a space-themed brainwave nobody ever bothered to succesfully market a cheaper rocket?
The answer is that there was no need for cheaper rockets. Despite the other launch service providers supposedly being "too expensive" their launch manifests were pretty full. What you don't understand is that launch service providers are interested in reliability first, and cost second. That's why one of the most expensive launch service providers -Arianespace - was capable of catching a full half of the commercial launch market: they were (and still are btw.) the worlds most reliable launch services provider.
Arianespace is also the leader in selling additional launch services to a cautious customer base.

This is the "top of the pyramid" of launch service sales. The most valuable component.

But also the slowest growth rate. The only ones slower are institutional/NSS. Which also have "special needs".

The high growth rate is at the bottom of the pyramid. The business has yet to really reach the level to access it.

And until now, no one has attempting to reach for it. It has been considered "foolish" to do so. Why risk so much for such a difficult opportunity.

Thank you woods170 for saying what needed to be said.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 06/28/2017 01:25 AM
...

Neither you nor woods170 mentioned a raptor upper stage in your long posts.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Space Ghost 1962 on 06/28/2017 01:49 AM
...

Neither you nor woods170 mentioned a raptor upper stage in your long posts.

Sometimes you have to correct a mis-impression, of the kind Jim (and a few others) brought in.

Otherwise one does not get the point.

I'd stopped posting about Raptor til it became better understood of the difference in strategy, operations, business intent, and the function of disruption. (Most of the money made in the past two decades has been due to disruption, that's why its so important.)

Some don't get what's going on. Largely because ... they don't want to.

How can you get inside the head of Musk unless you at least accept some of his perspective. Especially when its on the cusp, like here with the "on again, off again" Falcon + Raptor.

I disagree about testing a RVac stage:
 1. They don't have a vaccuum test stand.
 2. One for RVac would be enormously expensive, more than a F9R launch.
 3. What would you test? In flight chill down, pressurization, ignition, throttle up, shutdown, coast, re-ignition, and burn to depletion.
 4. Benefit would be a competitive to ACES stage
 5. Alongside recovery of a F9US, might turn a limited concept into a 100% reusable vehicle in 1-2 years.
 6. Which might make cost recovery of the LV 3x more aggressive

Musk would not do it for immediate revenue or cost recovery. He'd do it to disrupt with a vehicle that could do what others could not. As before.

Such would be more effective than FH, because we already have a DIVH. "Good enough".

We don't have an ACES class reusable US.

What might the effect look like - alongside a consistent cadence of F9, an occasional experimental RUS launch. (I'll explain in another post later.) So like the march for booster reuse we watched, a similar for RUS.

Won't bring in much revenue. Will up the competitive ante. Perhaps the springboard for more C3 and Raptor adventures.

Please continue to push back as you did.
Title: Re: Raptor Upper Stage consolidated thread
Post by: BobHk on 06/28/2017 03:41 AM
"Despite describing the Block 5 as the final version of the Falcon 9, Shotwell hinted at the possibility of a future version of the rocket that could use the Raptor engines designed for transportation to Mars. Shotwell said Raptor, a liquid methane and oxygen engine for SpaceX’s interplanetary spaceship, has undergone “many dozens of tests” and is progressing well.

“The original idea for those engines were to serve as a propulsion system for the big Mars system, but we are looking at the utility of it on the Falcon program,” she said."

Yeah.  Can we be released from this single thread now that the Raptor on F9 is no longer speculative?

FROM HERE:  http://spacenews.com/spacexs-final-falcon-9-design-coming-this-year-two-falcon-heavy-launches-next-year/

Title: Re: Raptor Upper Stage consolidated thread
Post by: rakaydos on 06/28/2017 04:36 AM
"Despite describing the Block 5 as the final version of the Falcon 9, Shotwell hinted at the possibility of a future version of the rocket that could use the Raptor engines designed for transportation to Mars. Shotwell said Raptor, a liquid methane and oxygen engine for SpaceX’s interplanetary spaceship, has undergone “many dozens of tests” and is progressing well.

“The original idea for those engines were to serve as a propulsion system for the big Mars system, but we are looking at the utility of it on the Falcon program,” she said."

Yeah.  Can we be released from this single thread now that the Raptor on F9 is no longer speculative?

FROM HERE:  http://spacenews.com/spacexs-final-falcon-9-design-coming-this-year-two-falcon-heavy-launches-next-year/

It's just as speculative as ever. Listen to the actual interview, GS was trying to navigate around a leading question and give a noncomittal answer.
Title: Re: Raptor Upper Stage consolidated thread
Post by: hkultala on 06/28/2017 08:04 AM
"Despite describing the Block 5 as the final version of the Falcon 9, Shotwell hinted at the possibility of a future version of the rocket that could use the Raptor engines designed for transportation to Mars. Shotwell said Raptor, a liquid methane and oxygen engine for SpaceX’s interplanetary spaceship, has undergone “many dozens of tests” and is progressing well.

“The original idea for those engines were to serve as a propulsion system for the big Mars system, but we are looking at the utility of it on the Falcon program,” she said."

I think of of the reasons why they are changing their mind about using raptor in falcon rocket is that originally they thought they cannot land raptor-based falcon first stage because of too high minimum T/W, but now they are getting confident that they can do it, and they already proved the minimum T/W is not too high by landing the bulgariasat booster with 3 merlin 1d engines.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/28/2017 11:55 AM
"Despite describing the Block 5 as the final version of the Falcon 9, Shotwell hinted at the possibility of a future version of the rocket that could use the Raptor engines designed for transportation to Mars. Shotwell said Raptor, a liquid methane and oxygen engine for SpaceX’s interplanetary spaceship, has undergone “many dozens of tests” and is progressing well.

“The original idea for those engines were to serve as a propulsion system for the big Mars system, but we are looking at the utility of it on the Falcon program,” she said."

I think of of the reasons why they are changing their mind about using raptor in falcon rocket is that originally they thought they cannot land raptor-based falcon first stage because of too high minimum T/W, but now they are getting confident that they can do it, and they already proved the minimum T/W is not too high by landing the bulgariasat booster with 3 merlin 1d engines.

Or maybe they are considering a actual production run of the 1,000 kN version of Raptor which they already have, which would be a lot closer to a drop-in replacement for Merlin.

Past 3-engine landing burns have gone from 100% on three engines to 40% on just one engine, according to Musk. That's equivalent to a 13% throttle, which I doubt a 3 MN Raptor could do. 25% on a 2 MN version might be possible. But they would have to rework the octaweb for 4 bigger engines.
Title: Re: Raptor Upper Stage consolidated thread
Post by: JamesH65 on 06/28/2017 11:58 AM
"Despite describing the Block 5 as the final version of the Falcon 9, Shotwell hinted at the possibility of a future version of the rocket that could use the Raptor engines designed for transportation to Mars. Shotwell said Raptor, a liquid methane and oxygen engine for SpaceX’s interplanetary spaceship, has undergone “many dozens of tests” and is progressing well.

“The original idea for those engines were to serve as a propulsion system for the big Mars system, but we are looking at the utility of it on the Falcon program,” she said."

I think of of the reasons why they are changing their mind about using raptor in falcon rocket is that originally they thought they cannot land raptor-based falcon first stage because of too high minimum T/W, but now they are getting confident that they can do it, and they already proved the minimum T/W is not too high by landing the bulgariasat booster with 3 merlin 1d engines.

We have not had any evidence to show they are chaining their mind about a Raptor US. We have one off the cuff comment that they might take a look at it. That's all. Their investigation may be as simple as "We reckon this is a stupid idea, just go and confirm it is"

I've with Jim on this one, it just doesn't seem to have any real reason for existence. Test bed for Raptor? Nah. Not needed. Makes the stage reusable? Nah, too expensive to implement and would never make the cash back. Need for bigger payloads? Nah, not enough payloads to make it pay.

The only thing I can think of that might make a Raptor engined stage on top of an F9 even vaguely useful would be a custom combined stage/satellite dispenser for the constellation. That might be cost effective if they are able to make it reusable.

Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/28/2017 12:41 PM
...
The only thing I can think of that might make a Raptor engined stage on top of an F9 even vaguely useful would be a custom combined stage/satellite dispenser for the constellation. That might be cost effective if they are able to make it reusable.

Agree with this, but it would need an integrated fairing with TPS, which starts looking an awful lot like a mini-BFS, which isn't what this thread is about.

Thread for mini-BFS type vehicles is here:
https://forum.nasaspaceflight.com/index.php?topic=43219.0
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/28/2017 12:53 PM
Since F9 is their bread and butter, and FH will not launch that much.  FH with a Raptor upper stage could become the Mars prep rocket.  They are going to have to install communication satellites in orbit around Mars and some satellites in an orbit between earth and Mars if they want continuous communication with a Martian colony.  This means also if Mars is on the other side of the sun from earth.  FH with a high ISP Raptor upper stage can deploy these satellites.  Also, a colony site that is flat for landings yet close to a large water supply will have to be found.  More drilling will need to be done on Mars to find suitable sites.

This is where a reusable Raptor upper stage comes in.  For deep space use, Mars landings, and Mars satellite deployments. 

They can develop a refuelable upper stage, and use it for Mars deployments.  All of this to test the BFS/ITS equipment. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/28/2017 01:02 PM
Since F9 is their bread and butter, and FH will not launch that much.  FH with a Raptor upper stage could become the Mars prep rocket.  They are going to have to install communication satellites in orbit around Mars and some satellites in an orbit between earth and Mars if they want continuous communication with a Martian colony.  This means also if Mars is on the other side of the sun from earth.  FH with a high ISP Raptor upper stage can deploy these satellites.  Also, a colony site that is flat for landings yet close to a large water supply will have to be found.  More drilling will need to be done on Mars to find suitable sites.

This is where a reusable Raptor upper stage comes in.  For deep space use, Mars landings, and Mars satellite deployments. 

They can develop a refuelable upper stage, and use it for Mars deployments.  All of this to test the BFS/ITS equipment.

The current upper stage can do everything that a Raptor stage operating the same way could. Neither would be able to land on Mars.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 06/28/2017 01:21 PM
If the stage is reusable, it could land on Mars if it is refueled in orbit with enough fuel to get there and land.  A reusable stage would have a deep throttling Raptor to land back on earth, so it could land on Mars.   Again, pre testing ITS equipment on a smaller scale.   

The Kerolox upper stage doesn't have the ISP for deep space work and fuel is heavier.  Raptor is going to be able to deep throttle, Merlin can't. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Ictogan on 06/28/2017 01:42 PM
If the stage is reusable, it could land on Mars if it is refueled in orbit with enough fuel to get there and land.  A reusable stage would have a deep throttling Raptor to land back on earth, so it could land on Mars.   Again, pre testing ITS equipment on a smaller scale.   

The Kerolox upper stage doesn't have the ISP for deep space work and fuel is heavier.  Raptor is going to be able to deep throttle, Merlin can't.
Landing on Mars is much more complicated than landing on earth. You need much more powerful communication equipment, different guidance, very low boiloff and solar panels(or some other way of generating power or very large batteries).
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 06/28/2017 01:58 PM
Need for bigger payloads? Nah, not enough payloads to make it pay.

Sure about that? Just one DIVH launch costs $400m, and that is "merely" for 29ton to LEO.
You can ask for a lot more $$$ when you are the only rocket with capability.
Title: Re: Raptor Upper Stage consolidated thread
Post by: RoboGoofers on 06/28/2017 02:08 PM
If the stage is reusable, it could land on Mars if it is refueled in orbit with enough fuel to get there and land.  A reusable stage would have a deep throttling Raptor to land back on earth, so it could land on Mars.   Again, pre testing ITS equipment on a smaller scale.   

The Kerolox upper stage doesn't have the ISP for deep space work and fuel is heavier.  Raptor is going to be able to deep throttle, Merlin can't.

This idea is way beyond the scope of the original proposed idea, a stopgap minimal RUS to replace the Merlin US until ITS.

Go here, as envy887 sugested:
https://forum.nasaspaceflight.com/index.php?topic=43219.0 (https://forum.nasaspaceflight.com/index.php?topic=43219.0)
Title: Re: Raptor Upper Stage consolidated thread
Post by: meekGee on 06/28/2017 02:16 PM
RUS remains speculative even after that interview, but nobody is claiming otherwise.

The debate is whether it's a good idea, irrespective of what SpaceX eventually decides to do.
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 06/28/2017 03:24 PM
If the stage is reusable, it could land on Mars if it is refueled in orbit with enough fuel to get there and land.  A reusable stage would have a deep throttling Raptor to land back on earth, so it could land on Mars.   Again, pre testing ITS equipment on a smaller scale.   

The Kerolox upper stage doesn't have the ISP for deep space work and fuel is heavier.  Raptor is going to be able to deep throttle, Merlin can't.

The problem is not landing but entry.

The current stage (or a Raptor stage operating on the same principles) can't be modified to land on Mars with cargo, as it doesn't have a cargo area protected by TPS and it cannot generate enough lift to do Mars EDL. Even if they put a heatshield on the front, it will go splat.

If they modify it enough to do a lifting entry and have a TPS protected cargo bay, it's basically a mini-BFS.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Rummy on 06/30/2017 07:20 PM
One reason against RUS that I haven't seen mentioned (apologies if I missed it) is the impact on focus. SpaceX is not a small company anymore, but I'm sure they are resource constrained when it comes to major design efforts. Putting the A team on RUS means they can't work BFR. I wouldn't underestimate the impact of this constraint.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Lar on 06/30/2017 07:27 PM
Yeah.  Can we be released from this single thread now that the Raptor on F9 is no longer speculative?

No, I feel this is working well... and I bet my post gets more likes than yours :) (not that likes mean anything)
Title: Re: Raptor Upper Stage consolidated thread
Post by: Rummy on 06/30/2017 07:29 PM
Although I agree with Jim wrt the likelihood of seeing a RUS on a Falcon, I strongly object to his characterization of the USAF contract as a dead end. That misses the point of early development contracts. An effort that ends up as non-viable but assists an adjacent technology should not be called a dead end. Perhaps a forking road and a cul-de-sac?
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 06/30/2017 07:33 PM
It is a dead end, the USAF was never going to take it to full development
Title: Re: Raptor Upper Stage consolidated thread
Post by: Joris on 06/30/2017 08:33 PM
It is a dead end, the USAF was never going to take it to full development

Because they have a rocket that does what they need and the only improvement is reliability I assume?
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 07/01/2017 12:17 AM
Unless the Air Force wanted a Raptor upper stage to improve F9 for GSO satellites.  Or FH.  Even if a Raptor upper state is expendable, it would still be cheaper than Delta IV heavy for big birds, and F9 may be able to launch them without FH. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 07/01/2017 02:33 AM
Unless the Air Force wanted a Raptor upper stage to improve F9 for GSO satellites.  Or FH.  Even if a Raptor upper state is expendable, it would still be cheaper than Delta IV heavy for big birds, and F9 may be able to launch them without FH.

Just stop.  They don't
Title: Re: Raptor Upper Stage consolidated thread
Post by: philw1776 on 07/01/2017 03:32 PM
This article...

http://spacenews.com/blue-origin-retains-engine-lead-as-house-considers-limitations-on-launch-system-funding/

confirms that the AF cannot pay SpaceX to develop a raptor upper stage for F9 or FH.

"a specific prohibition against funding “the development of new launch vehicles under such program.” It also specifically defines a “rocket propulsion system” that can be funded as a first-stage rocket engine or motor. “The term does not include a launch vehicle, an upper stage, a strap-on motor, or related infrastructure,”
Title: Re: Raptor Upper Stage consolidated thread
Post by: Nathan2go on 07/01/2017 08:48 PM
...  F9 doesn't seem to need a new US. I am only a layman, but it seems that FH might need a better US. Not adding that for F9 means LC-40 has no need, only SLC-39 would need the mod....

Something that I saw asked at least twice, can the current US get stretched to about 2x the current F9 config?  FH may need something with more push...

Yes, I think the FH needs a heavier upper stage, because the payload capability with 3-core reuse is too low, probably only 8 tons to GTO.  Which is less than Ariane V at 10t, and Delt 4H at 13t.

Quote from: Spacenut
A 5.2m upper stage is the same diameter as the fairing, ...
While going to a 5.2m diameter would be the most aesthetically pleasing way to add more propellant, I suspect that 3.4m would be structurally doable, and much less problematic (i.e. road transportable, factory tooling, etc).  It would mean strengthening the core stage and interstage (which they are doing).  Perhaps 3x the tank volume is going too far, but a 50-100% stretch would still be helpful.


[Raptor US] ... it just doesn't seem to have any real reason for existence. Test bed for Raptor? Nah. Not needed. Makes the stage reusable? Nah, too expensive to implement and would never make the cash back.
SpaceX does not have $10B to develop ITS.  Demonstrating S2 reuse on a Falcon family rocket, and flying Raptor are both extremely valuable ways to help persuade the general public that ITS might be doable.  This will help bring in other people's money (whether thru governments or private investment).  It will serve to make SLS look obsolete, and will generate pressure for NASA to modernize their thinking (e.g. maybe help fund private companies to build SLS replacement, to duplicate the space station commercial cargo COTS program).

But S2 reuse is a different question than engine-swap/tank-stretch.   As a business, it really depends on finding sufficient LEO payloads, since reuse for GTO will be much harder (will likely require on-orbit refueling).  Perhaps the SpaceX LEO sat constellation will happen, and be a driver for S2 reuse.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Robotbeat on 07/01/2017 09:13 PM
But SpaceX does have access to some money to build a smaller ITS. That is a more logical approach. Jim is probably right.
Title: Re: Raptor Upper Stage consolidated thread
Post by: gospacex on 07/02/2017 12:49 AM
Quote from: Spacenut
A 5.2m upper stage is the same diameter as the fairing, ...
While going to a 5.2m diameter would be the most aesthetically pleasing way to add more propellant, I suspect that 3.4m would be structurally doable, and much less problematic (i.e. road transportable, factory tooling, etc).

SpaceX wants to start building wider rockets anyway. Ergo, it will need a new factory with new tooling and with access for waterway transportation, regardless of RUS materializing or not.
Title: Re: Raptor Upper Stage consolidated thread
Post by: MATTBLAK on 07/02/2017 01:41 AM
What if Elon leased part of Michoud for 20 years or so? And the associated barges etc. Must be plenty of room in there even with the SLS activities. And if SLS gets canned - Elon might look like a prescient hero; saving jobs and infrastructure etc.

Or how feasible would it be to establish factory facilities eventually at Mcgregor, Texas?
Title: Re: Raptor Upper Stage consolidated thread
Post by: envy887 on 07/02/2017 02:20 AM
What if Elon leased part of Michoud for 20 years or so? And the associated barges etc. Must be plenty of room in there even with the SLS activities. And if SLS gets canned - Elon might look like a prescient hero; saving jobs and infrastructure etc.

Or how feasible would it be to establish factory facilities eventually at Mcgregor, Texas?
Even Hawthorne is better than McGregor for building large rocket stages. Much closer to barge transport.

Iirc Elon did say they looked at Michoud though.
Title: Re: Raptor Upper Stage consolidated thread
Post by: alang on 07/02/2017 02:31 PM
But SpaceX does have access to some money to build a smaller ITS. That is a more logical approach. Jim is probably right.

If Mr Musk makes a lot of money from his other business interests then the game will be very different as I am confident he would spend it on rockets.
This coming year will therefore be very important for SpaceX but in ways we're not allowed to discuss on this site.
If it all goes wrong for him financially elsewhere then some of these dreams could come to nothing.
Most likely outcome is moderate success and slow implementation of a Mars architecture, but it could be a lot better or a lot worse.
Title: Re: Raptor Upper Stage consolidated thread
Post by: spacenut on 07/02/2017 07:28 PM
Raptor upper stage could very well be a dead end.  Remember NASA developed the J2X and shelved it.  They also shelved the RL-60.  They spent a lot of time trying to figure out how to make SSME air startable for Aries I.  They also used the J2 turbopump system and developed a plug nozzle engine that was tested but never used.  They developed a NERVA nuclear engine and tested it, but never used it in space. 

SpaceX did use the money wisely and developed the sub scale Raptor.  SpaceX also used money to help develop the F9 and the Dragon.  Others who got money never made it as far as SpaceX has come. 
Title: Re: Raptor Upper Stage consolidated thread
Post by: Robotbeat on 07/02/2017 08:07 PM
I don't know that SpaceX has done really any work on a Raptor upperstage other than like an afternoon's worth of graphics for a PowerPoint somewhere. Raptor, though? Absolutely. They've definitely invested in that, and continue to. Not at all a dead end.
Title: Re: Raptor Upper Stage consolidated thread
Post by: punder on 07/02/2017 08:15 PM

Yes, I think the FH needs a heavier upper stage, because the payload capability with 3-core reuse is too low, probably only 8 tons to GTO.  Which is less than Ariane V at 10t, and Delt 4H at 13t.

Of course 3-core reuse is ideal, but what is the payload with full expendable? That is the valid comparison.
Title: Re: Raptor Upper Stage consolidated thread
Post by: AncientU on 07/02/2017 08:23 PM

Yes, I think the FH needs a heavier upper stage, because the payload capability with 3-core reuse is too low, probably only 8 tons to GTO.  Which is less than Ariane V at 10t, and Delt 4H at 13t.

Of course 3-core reuse is ideal, but what is the payload with full expendable? That is the valid comparison.

26.7 tonnes per SpaceX site, or a bit over 3x F9 expendable (8.3t) which makes sense.
F9 reusable with ASDS landing is around 5.5-6.0t, so FH should get 16-18t with boosters RTLS and core downrange recovery.  Definitely will outperform Ariane 5 and Delta Heavy.
Title: Re: Raptor Upper Stage consolidated thread
Post by: MATTBLAK on 07/02/2017 10:17 PM
There is actually little need for a Raptor powered upper stage for Falcon Heavy - though obviously that would be 'cool' in terms of performance etc. If they just stretched the upper stage propellant tanks a bit more and upgraded the Merlin vacuum engine again - most of the same benefits could be achieved. In fully expendable mode; FH could then get almost 70 metric tons into low Earth orbit, nearly 20 tons on Trans-Mars Injection and nearly 30 tons to GTO. Pretty darn good.

But this would probably be the best, 'bleeding edge' of FH performance. Anything more would likely require major redesign or a whole new design.
Title: Re: Raptor Upper Stage consolidated thread
Post by: TomH on 07/02/2017 11:37 PM
If they just stretched the upper stage propellant tanks a bit more and upgraded the Merlin vacuum engine again - most of the same benefits could be achieved. In fully expendable mode; FH could then get almost 70 metric tons into low Earth orbit, nearly 20 tons on Trans-Mars Injection and nearly 30 tons to GTO. Pretty darn good.

And a dual launch architecture of that could make a very robust and economic manned lunar program.
Title: Re: Raptor Upper Stage consolidated thread
Post by: MATTBLAK on 07/03/2017 12:05 AM
If they just stretched the upper stage propellant tanks a bit more and upgraded the Merlin vacuum engine again - most of the same benefits could be achieved. In fully expendable mode; FH could then get almost 70 metric tons into low Earth orbit, nearly 20 tons on Trans-Mars Injection and nearly 30 tons to GTO. Pretty darn good.

And a dual launch architecture of that could make a very robust and economic manned lunar program.
Oh yes! We have a good thread about that somewhere round here - Dragon derivatives as the Command Module and Descent/Ascent vehicles etc ;)
Title: Re: Raptor Upper Stage consolidated thread
Post by: Nathan2go on 07/03/2017 09:31 PM

Yes, I think the FH needs a heavier upper stage, because the payload capability with 3-core reuse is too low, probably only 8 tons to GTO.  Which is less than Ariane V at 10t, and Delt 4H at 13t.

Of course 3-core reuse is ideal, but what is the payload with full expendable? That is the valid comparison.

26.7 tonnes per SpaceX site, or a bit over 3x F9 expendable (8.3t) which makes sense.
F9 reusable with ASDS landing is around 5.5-6.0t, so FH should get 16-18t with boosters RTLS and core downrange recovery.  Definitely will outperform Ariane 5 and Delta Heavy.
That calculation ignores the fact that you tripled the first stage, but are keeping the second stage the same.  Bringing back the first stage while maintaining good payload capability depends on keeping the staging velocity low, under Mach 7 for Falcon 9.  Landing a core downrange helps a bit, say Mach 9 single-core. 

Carrying a payload of 16t and a 4t vehicle to GTO, using 120t of propellant gives a Mr of  7.  This means that you have to stage at Mach 12...

Ok, I ran the calculations again, and I think you are correct.  With 3 core re-use, and the existing Falcon upper stage, I think the GTO payload will be about 15 tons.  For LEO, staging is around Mach 13, and payload will be about 40t.  These are rough calculations.

So there is still a significant benefit to payload capacity with upsizing the 2nd stage, but the existing stage is useful for FH.  I'm not sure why the SpaceX pricing table calls out 8t to GTO.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Robotbeat on 07/03/2017 10:16 PM
...market segmentation. Also allows them to perform upper stage reuse experiments, allow more margin for stage recovery, and maybe even secondary payloads.

Additionally, there's a good chance they think block 5 can do 8t, so that gives them the flexibility of two different configurations for launch.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 07/03/2017 10:27 PM

Additionally, there's a good chance they think block 5 can do 8t, so that gives them the flexibility of two different configurations for launch.

that exactly opposite of what Spacex does
Title: Re: Raptor Upper Stage consolidated thread
Post by: Robotbeat on 07/03/2017 11:37 PM

Additionally, there's a good chance they think block 5 can do 8t, so that gives them the flexibility of two different configurations for launch.

that exactly opposite of what Spacex does
If FH is unavailable for whatever reason, they could launch reusable FH payloads on expendable F9.

For instance, if LC39a is booked, they could launch from LC40 (which can only handle single stick) instead.

Intelsat 35e was originally FH, wasn't it?
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 07/06/2017 07:23 AM
...market segmentation.

Been thinking about this. One thing you could do as a novel market segment might be effectively an ACES like concept as an unmanned high C3 missions "tug".

IMO ability to land a stage and lower cost of launch make an ACES like concept obsolete.
Title: Re: Raptor Upper Stage consolidated thread
Post by: R.Simko on 07/25/2017 02:58 PM
I had an idea of how SpaceX can increase the wt of a payload a Falcon rocket can launch, or save fuel for second stage recovery.  My idea is to put springs on the second stage, that would launch the payload, like the shuttle use to do when launching satellites. 

The spring could give the payload extra delta-v, while acting to slow the second stage at the same time, thereby saving fuel for recovery.  I don't know if this is practical because of the extra wt of the springs or other considerations.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Bynaus on 07/25/2017 03:02 PM
I had an idea of how SpaceX can increase the wt of a payload a Falcon rocket can launch, or save fuel for second stage recovery.  My idea is to put springs on the second stage, that would launch the payload, like the shuttle use to do when launching satellites. 

The spring could give the payload extra delta-v, while acting to slow the second stage at the same time, thereby saving fuel for recovery.  I don't know if this is practical because of the extra wt of the springs or other considerations.

The energy density of a spring is very low compared to the fuel it would replace. So as you suspect, its not practical.
Title: Re: Raptor Upper Stage consolidated thread
Post by: R.Simko on 07/25/2017 03:10 PM
I had an idea of how SpaceX can increase the wt of a payload a Falcon rocket can launch, or save fuel for second stage recovery.  My idea is to put springs on the second stage, that would launch the payload, like the shuttle use to do when launching satellites. 

The spring could give the payload extra delta-v, while acting to slow the second stage at the same time, thereby saving fuel for recovery.  I don't know if this is practical because of the extra wt of the springs or other considerations.

The energy density of a spring is very low compared to the fuel it would replace. So as you suspect, its not practical.

Thanks Bynaus, I thought that might be the case.
Title: Re: Raptor Upper Stage consolidated thread
Post by: ZachF on 09/11/2017 12:31 PM
"Despite describing the Block 5 as the final version of the Falcon 9, Shotwell hinted at the possibility of a future version of the rocket that could use the Raptor engines designed for transportation to Mars. Shotwell said Raptor, a liquid methane and oxygen engine for SpaceX’s interplanetary spaceship, has undergone “many dozens of tests” and is progressing well.

“The original idea for those engines were to serve as a propulsion system for the big Mars system, but we are looking at the utility of it on the Falcon program,” she said."

I think of of the reasons why they are changing their mind about using raptor in falcon rocket is that originally they thought they cannot land raptor-based falcon first stage because of too high minimum T/W, but now they are getting confident that they can do it, and they already proved the minimum T/W is not too high by landing the bulgariasat booster with 3 merlin 1d engines.

We have not had any evidence to show they are chaining their mind about a Raptor US. We have one off the cuff comment that they might take a look at it. That's all. Their investigation may be as simple as "We reckon this is a stupid idea, just go and confirm it is"

I've with Jim on this one, it just doesn't seem to have any real reason for existence. Test bed for Raptor? Nah. Not needed. Makes the stage reusable? Nah, too expensive to implement and would never make the cash back. Need for bigger payloads? Nah, not enough payloads to make it pay.

The only thing I can think of that might make a Raptor engined stage on top of an F9 even vaguely useful would be a custom combined stage/satellite dispenser for the constellation. That might be cost effective if they are able to make it reusable.

What a Raptor US +B5 would allow, is launching the average sized GEO satellite to GTO and having the booster RTLS. 

It's not hard, with a faster launch cadence, to see the slow-moving ASDS ship as a potential bottleneck. Raptor US may be unlikely, but this fact with the fact that they have been testing MiniRaptor probably makes this less unlikely than some think.

I personally think they are going to develop 2 Raptors, one 3MN sea level version and a ~1.4MN vac verson based off the ~1MN test version. 18 Raptor3Ss fit perfectly in a 9m frame for the first stage, and 6 ~1.4MN vacuums with one SL in the middle fit well enough to even increase the vacuum version's expansion ratio slighty and perhaps get a few more seconds of ISP. 18 3MN Raptors would also give a BFR 42% of the GTOW of ITS2016 a slightly better liftoff TWR (1.47vs1.38). With a slighty higher liftoff TWR and slightly higher second stage ISp, SpaceX might be able to meet their performance goals with less aggressive materials development.
Title: Re: Raptor Upper Stage consolidated thread
Post by: MikeAtkinson on 09/11/2017 01:47 PM
What a Raptor US +B5 would allow, is launching the average sized GEO satellite to GTO and having the booster RTLS. 

It's not hard, with a faster launch cadence, to see the slow-moving ASDS ship as a potential bottleneck. Raptor US may be unlikely, but this fact with the fact that they have been testing MiniRaptor probably makes this less unlikely than some think.

There are only about 20 GEO satellites a year maximum that SpaceX could launch, that is not enough for launch cadence with ASDS return to be a limiting factor.

There are perhaps good reasons for Raptor US + B5 but launch cadence for GEO sats is not one of them.
Title: Re: Raptor Upper Stage consolidated thread
Post by: wannamoonbase on 09/11/2017 03:02 PM
There are perhaps good reasons for Raptor US + B5 but launch cadence for GEO sats is not one of them.

Enabling US recovery is about the most powerful reason I can think of, but is it needed or can it wait for ITSy?

The Block 5 F9 could easily dominate the global launch market with disposable US. 

A change in the launch market is needed to justify further development.
Title: Re: Raptor Upper Stage consolidated thread
Post by: Nomadd on 09/11/2017 04:40 PM
What a Raptor US +B5 would allow, is launching the average sized GEO satellite to GTO and having the booster RTLS. 

It's not hard, with a faster launch cadence, to see the slow-moving ASDS ship as a potential bottleneck. Raptor US may be unlikely, but this fact with the fact that they have been testing MiniRaptor probably makes this less unlikely than some think.

There are only about 20 GEO satellites a year maximum that SpaceX could launch, that is not enough for launch cadence with ASDS return to be a limiting factor.

There are perhaps good reasons for Raptor US + B5 but launch cadence for GEO sats is not one of them.
ASDS can be a limiting factor no matter what. It can break, need upgrades, spend two months getting through an ABS inspection for stupid reasons or be unavailable for lots of reasons. Any one of which could wind up putting $30 million in 1st stage hardware on the bottom.
Title: Re: Raptor Upper Stage consolidated thread
Post by: guckyfan on 09/11/2017 04:51 PM
What a Raptor US +B5 would allow, is launching the average sized GEO satellite to GTO and having the booster RTLS. 

It's not hard, with a faster launch cadence, to see the slow-moving ASDS ship as a potential bottleneck. Raptor US may be unlikely, but this fact with the fact that they have been testing MiniRaptor probably makes this less unlikely than some think.

A Raptor upper stage would be more expensive than a Merlin upper stage. Not worth it unless it is reusable. First stage RTLS is desirable but not nearly enough to justify expending a Raptor upper stage.
Title: Re: Raptor Upper Stage consolidated thread
Post by: titusou on 09/30/2017 01:50 AM
Based on IAC 2017 info on BFR, Raptor now seems down-sized from 3000kN class to 1700kN class.
That's closer to Merline1D(Vac)'s 900kN class.

Maybe that make the Falcon9 with Raptor upper more likely to happen?

Titus
Title: Re: Raptor Upper Stage consolidated thread
Post by: octavo on 09/30/2017 06:43 AM


Based on IAC 2017 info on BFR, Raptor now seems down-sized from 3000kN class to 1700kN class.
That's closer to Merline1D(Vac)'s 900kN class.

Maybe that make the Falcon9 with Raptor upper more likely to happen?

Titus

Since Musk explicitly said that they're trying to make f9 and FH redundant, I think if anything we can now categorically put this to bed. There will be no raptor US for any Falcon rocket. Their focus now is FH and dragon 2, then straight on to BFR/BFS
Title: Re: Raptor Upper Stage consolidated thread
Post by: Jim on 10/02/2017 12:19 AM

Since Musk explicitly said that they're trying to make f9 and FH redundant, I think if anything we can now categorically put this to bed. There will be no raptor US for any Falcon rocket. Their focus now is FH and dragon 2, then straight on to BFR/BFS

thank you
Title: Re: Raptor Upper Stage consolidated thread
Post by: IanThePineapple on 10/02/2017 12:23 AM
Since Musk explicitly said that they're trying to make f9 and FH redundant, I think if anything we can now categorically put this to bed. There will be no raptor US for any Falcon rocket. Their focus now is FH and dragon 2, then straight on to BFR/BFS

Oh thank goodness, the amount of people still insisting Raptor S2 is happening is crazy
Title: Re: Raptor Upper Stage consolidated thread
Post by: philw1776 on 10/02/2017 05:07 PM
For reference:

Gwynne Shotwell said at MIT SpaceX will not make the F9 second stage reusable.
https://www.reddit.com/r/spacex/comments/72vluq/gwynne_shotwell_speaking_at_mit_road_to_mars/

so Raptor enabling 2nd stage F9/FH re-usability is a dead argument.