Author Topic: Discussion/Comparison of the new generation of American heavy lift launchers  (Read 9359 times)

Offline joek

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Some numbers seem off; not sure about Block 5, but some estimates seem optimistic for F9v1.2/FT.
The numbers for C3=0, from NASA Launch Services Program shown in attached figure.


Note: The data for F9/FH appears to be discrete; if you attempt to inquire about any data point (regardless of type of orbit), you won't get any data for F9/FH unless data for that specific data point has been entered.  E.g., if you want LEO numbers, use 400km; anything else is unlikely to return a result for any SpaceX vehicle; want C3 numbers, use C3=0; etc.
« Last Edit: 06/07/2017 02:00 AM by joek »

Offline envy887

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The LSP data hasn't been updated in a while. It doesn't match the data SpaceX has on their website, which is presumably for Block 5. They don't have any data at all on New Glenn or any other vehicle bigger than DIVH.

Offline joek

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The LSP data hasn't been updated in a while. It doesn't match the data SpaceX has on their website, which is presumably for Block 5. They don't have any data at all on New Glenn or any other vehicle bigger than DIVH.

Correct, thus my caution about "Block 5" vs. the data on the LSP site.  However, some of the numbers being thrown around in this discussion appear to be more optimistic (or pessimistic) than the LSP numbers.  Pick your poison and stick with it.

Offline envy887

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Which numbers are you referring to?

My estimates are based on the values provided by the launch service providers themselves, not NASA's LSP program. I'm not sure where Ed's numbers are from.

Offline joek

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Which numbers are you referring to?

Numbers quoted by LSP or the provider.  Any other numbers are, AFAICT, estimates by forum members--which do not appear to be consistent with other "official" numbers.

Offline envy887

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Which numbers are you referring to?

Numbers quoted by LSP or the provider.  Any other numbers are, AFAICT, estimates by forum members--which do not appear to be consistent with other "official" numbers.
I was asking which ones specifically you find inconsistent.

Offline Dante80

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For that matter, why not just launch a complete FH upper stage fully fueled or a stretched upper stage no payload.  Dock Orion to it, then proceed to cis-lunar.  No need for refueling.  Just separate the booster upper stage, and redock with a new upper stage either sent on a F9 or another FH.  Two FH launches are still cheaper than one SLS launch.

You cannot insert a fueled Falcon upper stage to Orbit. It weighs something like 120 tons (this regularly gets missed, for some reason) . And has a length of 12m+ thus making fairing encapsulation impossible. 
« Last Edit: 06/07/2017 05:02 AM by Dante80 »

Offline QuantumG

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You cannot insert a fueled Falcon upper stage to Orbit. It weighs something like 120 tons (this regularly gets missed, for some reason) . And has a length of 12m+ thus making fairing encapsulation impossible.

I'm just gunna leave the second part of this alone :)

We don't know much about the Falcon Heavy second stage mass figures. Some reasonable estimates are:

Length: 13.8 m
Diameter: 3.7 m
Empty mass: 3,900 kg
Propellant mass: 92,670 kg
Thrust: 934 kN
ISP: 348 s
Payload to LEO: 63,800 kg

These come from here and here and of course here.

If you apply the rocket equation to these numbers you find that the second stage is only providing about 3 km/s of delta-v to the payload to get it to orbit. That's the idea of the Falcon heavy, the boosters push the core stages hard and it's also why recovering the first stage is so much more difficult than Falcon 9.

Say you just launch an empty fairing, how much fuel will be left in the second stage? Answer: about 39% What does that mean? It means you can throw about 19 tons through TLI.

The dry mass of a Merlin 1D is about 630 kg. I don't know how much the mass the extended nozzle is, and I also haven't tried to account for the fairing mass, which we don't need any more... but whatever. Say the dry mass per meter of the tank is about 234 kg and the propellant per meter of tank is about 6715 kg. Let's stretch the tank by 13.1 meters (the length of the fairing), what's this give us? It gives us about 35 tons through TLI.

Here is my math.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? The slowest possible.

Offline QuantumG

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Oh, and honestly that's the hard way. If you just replace the fairing with a third stage that is identical to the second stage, you'll get 39 tons through TLI. The second stage does 2,230 m/s of the burn to orbit, the third stage does the rest and is 73.4% full when you come to do your TLI burn. Of course, you have to throw away another Merlin, so it's not free, and who knows if the fineness ratio is getting too high here.


Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? The slowest possible.

Offline Dante80

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You cannot insert a fueled Falcon upper stage to Orbit. It weighs something like 120 tons (this regularly gets missed, for some reason) . And has a length of 12m+ thus making fairing encapsulation impossible.

I'm just gunna leave the second part of this alone :)

We don't know much about the Falcon Heavy second stage mass figures. Some reasonable estimates are:

Length: 13.8 m
Diameter: 3.7 m
Empty mass: 3,900 kg
Propellant mass: 92,670 kg
Thrust: 934 kN
ISP: 348 s


The sources I used for F9 S2 weight are this and this. I imagine the FH S2 may be a little heavier when realized, if only for structural support reasons.

The quoted numbers from SFI are a little weird though. Without a PAF, fairings and payload the number they give comes short (549,054 kg vs 517,800 kg). Also ,the numbers they give for S2 are exactly the same as those listed here for v1.1. I think that the article was simply not updated properly.

I agree that it is not that easy to ascertain S2 weight, since the public information we have is lacking (and FH has not even flown yet, of course).
« Last Edit: 06/07/2017 08:35 PM by Dante80 »

Offline hkultala

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SLS Blk 1          2019?    24,500 kg    19,500 kg      N/A

Where are these SLS block 1 numbers from?

They seem suspiciously low, I think the payload for these trajectories should be higher

« Last Edit: 06/07/2017 08:36 PM by hkultala »

Offline alexterrell

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Oh, and honestly that's the hard way. If you just replace the fairing with a third stage that is identical to the second stage, you'll get 39 tons through TLI. The second stage does 2,230 m/s of the burn to orbit, the third stage does the rest and is 73.4% full when you come to do your TLI burn. Of course, you have to throw away another Merlin, so it's not free, and who knows if the fineness ratio is getting too high here.

Wouldn't it be easier to use Falcon Heavy (reusable) to launch a number of ~50 ton (fuelled weight) rockets into Low Earth Orbit. Two of these (I can't recall the exact numbers) would dock on to one payload (perhaps 60 tons - expendable Falcon Heavy payload), and launch it through Trans Mars injection.

No fuel transfer needed - just docking.

ACES could be used, but given turn around times, a LOx/Kersone rocket might be better. Given a 2 week turnaround:

Week 0: FH(X) - Launch 1: Launch payload
Week 2: FH - Launch fuel tanker 1
Week 4: FH - Launch fuel tanker 2
Week 6: F9 - Launch crew in Dragon.

Offline Ictogan

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Oh, and honestly that's the hard way. If you just replace the fairing with a third stage that is identical to the second stage, you'll get 39 tons through TLI. The second stage does 2,230 m/s of the burn to orbit, the third stage does the rest and is 73.4% full when you come to do your TLI burn. Of course, you have to throw away another Merlin, so it's not free, and who knows if the fineness ratio is getting too high here.
I'd be surprised if the Falcon 9/heavy upper stage had the structural margins to carry another identical stage and a 39 ton payload.

Offline ncb1397

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Oh, and honestly that's the hard way. If you just replace the fairing with a third stage that is identical to the second stage, you'll get 39 tons through TLI. The second stage does 2,230 m/s of the burn to orbit, the third stage does the rest and is 73.4% full when you come to do your TLI burn. Of course, you have to throw away another Merlin, so it's not free, and who knows if the fineness ratio is getting too high here.
I'd be surprised if the Falcon 9/heavy upper stage had the structural margins to carry another identical stage and a 39 ton payload.

Not to mention that ~6 mT comsats already are almost maxing out the fairing:

« Last Edit: 06/07/2017 09:41 PM by ncb1397 »

Offline spacenut

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So, to get Orion to cis-lunar space with commercial rockets, SpaceX would have to stretch the 2nd stage to accomodate extra fuel, plus have docking ability and launch on FH.  Then launch Orion on FH with rear docking capability.  Then dock, and use the stretched 2nd stage from the first launch to send Orion to cis-lunar space. 

A stretched second stage shouldn't be too hard for SpaceX.  Having the docking capability for both could work out.  This would be similar to the Direct 70 ton craft approach.  Two launches dock and go to moon. 

New Glenn may be able to do the same with two launches. 

Both of these may be more than adequate for a moon program without SLS.  Competition like ISS resupply, with at least two providers.  ULA may get in the game if they can get Vulcan w/ACES. 

Even Mars could be done like NautilusX with several launch providers over time. 

Offline Coastal Ron

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Not to mention that ~6 mT comsats already are almost maxing out the fairing:

That doesn't look like a 5m fairing, and Falcon 9 fairing internal volume looks much bigger (see below with Jason 3 payload):

If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline envy887

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Not to mention that ~6 mT comsats already are almost maxing out the fairing:
That doesn't look like a 5m fairing, and Falcon 9 fairing internal volume looks much bigger (see below with Jason 3 payload):

It is. Jason 3 is just tiny, only 553 kg.

Offline joek

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I was asking which ones specifically you find inconsistent.
All of them.  We have LSP's numbers (pre-Block-5?); then we have SpaceX published estimates (Block-5?); then we have member estimates (all over the map).  Not unexpected that they are inconsistent.

Offline envy887

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SLS Blk 1          2019?    24,500 kg    19,500 kg      N/A

Where are these SLS block 1 numbers from?

They seem suspiciously low, I think the payload for these trajectories should be higher
Ed's numbers for SLS are here: http://www.spacelaunchreport.com/sls0.html

However, you are right that they are a little low. I think Ed calculated the payload that iCPS can push through 3150 m/s TLI from a 200 km staging LEO. However, SLS Block 1 will use a elliptical staging orbit with a 1800 km apogee, which only needs an additional 2725 m/s to reach the same TLI. The additional performance of the core stage gives iCPS a 3 tonne boost.

iCPS can push ~27,500 kg though that TLI, based on the mass numbers published by Boeing (see attached pdf, which cites a 27 tonne payload to TLI).

Gunther has a 28,000 kg payload to escape listed, which I think is out of date: http://space.skyrocket.de/doc_lau/sls.htm

This is the same number that shows up in Wikipedia as the payload mass to EML2, which is even further than escape. https://en.wikipedia.org/wiki/Space_Launch_System#Payload_mass_to_various_orbits

That is sourced from a Boeing PDF, which appears to list the TLI payload as 25 tonnes, then later states payload to EML2 as 28 tonnes http://www.boeing.com/assets/pdf/defense-space/space/sls/docs/sls_mission_booklet_jan_2014.pdf

I think that's a misunderstanding of 28,000 kg to EML2 injection, with the payload doing insertion at EML2, and the actual capacity to TLI is about 28,000 kg.
« Last Edit: 06/08/2017 12:02 AM by envy887 »

Offline envy887

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Working backward from the Trans-Mars values published by SpaceX, I came up
with 5.6 tonnes TLI for F9B5 and 20.9 tonnes TLI for FH.  I'm honestly having
trouble seeing how Falcon Heavy meets its claimed payload goals, let alone the
numbers we've conjured in our guesstimates, unless it incorporates
yet-to-be-revealed improvements.  To be conservative, I'm putting these at
5.5 tonnes and 20.5 tonnes, respectfully.
I'd prefer most accurate estimate over conservative estimate, but those both seem reasonable. Certainly within the margin for error in this exercise.

Quote
I'm certain that New Glenn's TLI number would not be less than its TMI number,
so I'm leaving my original guesses on that rocket unchanged for now.  I'm adding
a GTO column because that is an oft-listed number.

Yes the TMI number would be even lower. Pushing that giant upper stage through 3.8 km/s beyond LEO is not at all efficient. Using the same methods, I get between 3,750 kg and 2,000 kg transMars for 2-stage New Glenn with booster reuse.

If New Glenn is used for these trajectories, I imagine they will use the 3-stage version, which should be substantially better.

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