Author Topic: SpaceX Falcon Heavy Discussion (Thread 6)  (Read 533335 times)

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #600 on: 04/24/2018 06:28 pm »
Since Europa Clipper isn't designed yet, it could still be configured to launch on 2 FHs in 2 parts: probe and propulsion.

It won't be, but i just wanted to point out how poor a solution SLS is for the cost.

No, that does't work.  And it is "designed"

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #601 on: 04/24/2018 07:02 pm »
Since Europa Clipper isn't designed yet, it could still be configured to launch on 2 FHs in 2 parts: probe and propulsion.

It won't be, but i just wanted to point out how poor a solution SLS is for the cost.

No, that does't work.  And it is "designed"

not sure what you mean by "work". If two FHs can't lift an assembled probe with enough dV to get to the mission orbit, then use three, or four. Still cheaper than SLS. Also, Preliminary design is scheduled to be completed in September. That could very well be rescheduled depending on launcher changes.

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #602 on: 04/24/2018 07:11 pm »

not sure what you mean by "work". If two FHs can't lift an assembled probe with enough dV to get to the mission orbit, then use three, or four.

Even more unworkable.  The point of FH is not to get it to LEO but to escape velocity.

And more expensive spacecraft.

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #603 on: 04/24/2018 07:18 pm »
This isn't the "Redesign Europa Clipper for a vehicle it's not going to use" thread. 

Online envy887

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #604 on: 04/24/2018 07:40 pm »
SLS Block 1 is limited by it's small upper stage and the orbit it can leave it in at staging.

For small and medium payloads to very high energy trajectories FH can definitely match or exceed the Block 1 with a small kick stage, and possibly without one. No need for distributed lift for that.

Offline Brovane

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #605 on: 04/24/2018 08:55 pm »

not sure what you mean by "work". If two FHs can't lift an assembled probe with enough dV to get to the mission orbit, then use three, or four.

Even more unworkable.  The point of FH is not to get it to LEO but to escape velocity.

And more expensive spacecraft.

Jim - Isn't the Europa Clipper a Class A payload since it is a flagship project?  Which would mean either SLS or a category 3 certified LV? 
"Look at that! If anybody ever said, "you'll be sitting in a spacecraft naked with a 134-pound backpack on your knees charging it", I'd have said "Aw, get serious". - John Young - Apollo-16

Offline LouScheffer

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #606 on: 04/24/2018 09:52 pm »
The FH alone might do the job for Europa Clipper.  From the Space FH page it can put 63.8t into LEO.   Add in the second stage mass of 5t and that's a stack mass of 68.8t.   From LEO, a direct Jupiter path takes 6300 m/s.  That means a mass ratio of exp(6300/348/9.8 ) or 6.342, at the known ISP of 348.  So the ending stack mass is about 10.8t.  Subtract the 5t of the second stage to get a direct-to-Jupiter payload of 5.8t.  If the second stage is somewhat lighter, at 4.7t, as has been speculated, then the injected mass could well be 6.1t, the same as SLS (See This europa clipper presentation, page 31.), and exactly what Europa Clipper is designed for, so no spacecraft changes.

Sure, that's a completely expendable FH.  But it's still much cheaper than SLS, and much more capable than ATLAS. 

EDIT:  Fix stupid conversion of "8 )" to smiley "8)"

« Last Edit: 04/24/2018 09:54 pm by LouScheffer »

Offline speedevil

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #607 on: 04/24/2018 10:44 pm »
If the second stage is somewhat lighter, at 4.7t, as has been speculated, then the injected mass could well be 6.1t, the same as SLS (See This europa clipper presentation, page 31.), and exactly what Europa Clipper is designed for, so no spacecraft changes.

Sure, that's a completely expendable FH.  But it's still much cheaper than SLS, and much more capable than ATLAS. 


https://twitter.com/elonmusk/status/963095860060934144
Quote
Scott Manley: I’m also curious as to whether SpaceX would consider stretching Stage 2 if there was a market that made sense.
Elon Musk:
Under consideration. We’ve already stretched the upper stage once. Easiest part of the rocket to change. Fairing 2, flying soon, also has a slightly larger diameter. Could make fairing much longer if need be & will if BFR takes longer than expected.

A moderate S2 stretch would help a lot indeed with higher energy payloads.
« Last Edit: 04/24/2018 10:46 pm by speedevil »

Offline woods170

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #608 on: 04/25/2018 10:07 am »

not sure what you mean by "work". If two FHs can't lift an assembled probe with enough dV to get to the mission orbit, then use three, or four.

Even more unworkable.  The point of FH is not to get it to LEO but to escape velocity.

And more expensive spacecraft.

Jim - Isn't the Europa Clipper a Class A payload since it is a flagship project?  Which would mean either SLS or a category 3 certified LV? 

That is correct. And FH is still a long way from Category 3 certification.
Generally, scientific spacecraft, such as Europa Clipper, are appointed to launch vehicles early in their design process. Which is exactly where Europa Clipper is today. The available performance from the launch vehicle is an integrated part of both the mission- and spacecraft design.
Therefore, it is important that the final choice of launch vehicle (SLS block 1 vs SLS block 1B) is made as soon as possible.

Offline JamesH65

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #609 on: 04/25/2018 11:47 am »

not sure what you mean by "work". If two FHs can't lift an assembled probe with enough dV to get to the mission orbit, then use three, or four.

Even more unworkable.  The point of FH is not to get it to LEO but to escape velocity.

And more expensive spacecraft.

Jim - Isn't the Europa Clipper a Class A payload since it is a flagship project?  Which would mean either SLS or a category 3 certified LV? 

That is correct. And FH is still a long way from Category 3 certification.
Generally, scientific spacecraft, such as Europa Clipper, are appointed to launch vehicles early in their design process. Which is exactly where Europa Clipper is today. The available performance from the launch vehicle is an integrated part of both the mission- and spacecraft design.
Therefore, it is important that the final choice of launch vehicle (SLS block 1 vs SLS block 1B) is made as soon as possible.

I do wonder whether craft like the BFS will change this decision making process. Once you have 'huge' lifters with a massive chomper door like the proposed BFS, will it be necessary any longer to make the choice of LV so early?

Offline clongton

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #610 on: 04/25/2018 11:57 am »
I do wonder whether craft like the BFS will change this decision making process. Once you have 'huge' lifters with a massive chomper door like the proposed BFS, will it be necessary any longer to make the choice of LV so early?

Flagship mission hardware is designed very early in the process to take maximum advantage of a specific Launch Vehicle. Change the LV and you have to go back to the beginning and start again. That's not going to happen with Europa Clipper. SLS has already been designated as the LV and that is extremely unlikely to change. The only real decision yet to be made is whether the SLS LV will be Block 1 or 1B.
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Online envy887

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #611 on: 04/25/2018 12:40 pm »
I do wonder whether craft like the BFS will change this decision making process. Once you have 'huge' lifters with a massive chomper door like the proposed BFS, will it be necessary any longer to make the choice of LV so early?

Flagship mission hardware is designed very early in the process to take maximum advantage of a specific Launch Vehicle. Change the LV and you have to go back to the beginning and start again. That's not going to happen with Europa Clipper. SLS has already been designated as the LV and that is extremely unlikely to change. The only real decision yet to be made is whether the SLS LV will be Block 1 or 1B.

The fact that SLS Block 1 and Block 1B have very different capabilities belies your point...

As long as a replacement vehicle meets or exceeds the necessary capabilities the first vehicle, there is no need to redesign the spacecraft. For example, a SC designed for Falcon 9 could fly on Falcon Heavy without redesign, regardless of whether is was a flagship mission or not.

BFR is rather off topic, but Falcon Heavy could potentially match SLS Block 1 in terms of the required capabilities. Clipper does not need SLS's fairing volume, so only launch environment, injection energy, and potentially integration orientation are relevant.

I agree that the EC LV is highly unlikely to change from SLS, but that is largely due to political and less due to technical reasons.

Offline AncientU

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #612 on: 04/25/2018 01:53 pm »

not sure what you mean by "work". If two FHs can't lift an assembled probe with enough dV to get to the mission orbit, then use three, or four.

Even more unworkable.  The point of FH is not to get it to LEO but to escape velocity.

And more expensive spacecraft.

Jim - Isn't the Europa Clipper a Class A payload since it is a flagship project?  Which would mean either SLS or a category 3 certified LV? 

That is correct. And FH is still a long way from Category 3 certification.
Generally, scientific spacecraft, such as Europa Clipper, are appointed to launch vehicles early in their design process. Which is exactly where Europa Clipper is today. The available performance from the launch vehicle is an integrated part of both the mission- and spacecraft design.
Therefore, it is important that the final choice of launch vehicle (SLS block 1 vs SLS block 1B) is made as soon as possible.

And SLS, which hasn't flown yet, gets a pass.
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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #613 on: 04/25/2018 02:16 pm »
Looks folks, NASA picked the home team.

It's fun to compare them on a spreadsheet, but nothing is going to change at this point. 

Remember, Europa Clipper wouldn't exist without political backing and that same backing wants SLS.

Maybe on the next one.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #614 on: 04/25/2018 02:22 pm »
I do wonder whether craft like the BFS will change this decision making process. Once you have 'huge' lifters with a massive chomper door like the proposed BFS, will it be necessary any longer to make the choice of LV so early?


Yes, because of the design considerations. 

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #615 on: 04/25/2018 02:23 pm »

I agree that the EC LV is highly unlikely to change from SLS, but that is largely due to political and less due to technical reasons.

Don't count your chickens...

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #616 on: 04/25/2018 02:31 pm »

not sure what you mean by "work". If two FHs can't lift an assembled probe with enough dV to get to the mission orbit, then use three, or four.

Even more unworkable.  The point of FH is not to get it to LEO but to escape velocity.

And more expensive spacecraft.

Jim - Isn't the Europa Clipper a Class A payload since it is a flagship project?  Which would mean either SLS or a category 3 certified LV? 

That is correct. And FH is still a long way from Category 3 certification.
Generally, scientific spacecraft, such as Europa Clipper, are appointed to launch vehicles early in their design process. Which is exactly where Europa Clipper is today. The available performance from the launch vehicle is an integrated part of both the mission- and spacecraft design.
Therefore, it is important that the final choice of launch vehicle (SLS block 1 vs SLS block 1B) is made as soon as possible.

And SLS, which hasn't flown yet, gets a pass.


You still don't understand.  It isn't a "pass".  Certification only applies to non NASA managed vehicles.  Certification didn't apply to Titan IIIE for Viking and Voyager because NASA was intimately involved in the design and development.  NASA didn't certify Delta II because it had enough successful launches.   NASA had to certify Atlas V for MRO and Pluto New Horizons because it didn't have enough flights.  Delta IV Heavy for PSP is going through cert because it doesn't have enough flights.

Online envy887

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #617 on: 04/25/2018 03:02 pm »
[edit/gongora: trimmed out JWST stuff]

Don't count your chickens...

You think there is a reasonably high chance EC is moved off SLS?
« Last Edit: 04/25/2018 04:32 pm by gongora »

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #618 on: 04/25/2018 03:23 pm »

So, why do you hate the idea of Clipper flying on SLS?

Just because I know the rules doesn't mean I have to like the players. 

Certification is just a way of obtaining the same data as when if NASA was managing the project.  Certification is not guarantee of success.

Online rockets4life97

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #619 on: 04/25/2018 03:51 pm »
What is the earliest FH could be certified for Air Force and NASA missions?

 

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