Author Topic: Raptor Upper Stage consolidated thread  (Read 124091 times)

Online RoboGoofers

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Re: Raptor Upper Stage consolidated thread
« Reply #280 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...

Offline hkultala

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Re: Raptor Upper Stage consolidated thread
« Reply #281 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.
« Last Edit: 06/26/2017 07:46 pm by hkultala »

Offline hkultala

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Re: Raptor Upper Stage consolidated thread
« Reply #282 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/

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.
« Last Edit: 06/26/2017 08:08 pm by hkultala »

Offline Jim

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Re: Raptor Upper Stage consolidated thread
« Reply #283 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. 
« Last Edit: 06/26/2017 08:04 pm by Jim »

Offline Space Ghost 1962

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Re: Raptor Upper Stage consolidated thread
« Reply #284 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?

Offline Joel

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Re: Raptor Upper Stage consolidated thread
« Reply #285 on: 06/27/2017 03:05 am »
It be more likely both stages using Raptor.
And the retirement of Merlin?

Offline darkenfast

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Re: Raptor Upper Stage consolidated thread
« Reply #286 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.
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Offline gospacex

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Re: Raptor Upper Stage consolidated thread
« Reply #287 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?

Offline Varn

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Re: Raptor Upper Stage consolidated thread
« Reply #288 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?

Offline meekGee

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Re: Raptor Upper Stage consolidated thread
« Reply #289 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?
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Offline RDMM2081

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Re: Raptor Upper Stage consolidated thread
« Reply #290 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.

Offline woods170

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Re: Raptor Upper Stage consolidated thread
« Reply #291 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?

Offline Joel

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Re: Raptor Upper Stage consolidated thread
« Reply #292 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.

Offline spacenut

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Re: Raptor Upper Stage consolidated thread
« Reply #293 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. 

Offline gospacex

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Re: Raptor Upper Stage consolidated thread
« Reply #294 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.
« Last Edit: 06/27/2017 02:43 pm by gospacex »

Offline Roy_H

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Re: Raptor Upper Stage consolidated thread
« Reply #295 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
« Last Edit: 06/27/2017 05:23 pm by Roy_H »
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Offline Jim

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Re: Raptor Upper Stage consolidated thread
« Reply #296 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
« Last Edit: 06/27/2017 04:32 pm by Jim »

Online RoboGoofers

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Re: Raptor Upper Stage consolidated thread
« Reply #297 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.
« Last Edit: 06/27/2017 04:38 pm by RoboGoofers »

Offline guckyfan

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Re: Raptor Upper Stage consolidated thread
« Reply #298 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.

Online rakaydos

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Re: Raptor Upper Stage consolidated thread
« Reply #299 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.

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