United Launch Alliance (ULA) Vulcan Next Generation Launch System (NGLS)

Slightly off topic question - what is the advantage of using CH4 as a fuel vice say RP-1? I understand that hydrogen is particularly hard to contain and keep cool, and so there is advantages there, but what else? I assume cost is a little lower since some kind of purified natural gas could be used? Also if CH4 is desirable, what prevented its use up until very recently?
 
Josh_TN said:
Slightly off topic question - what is the advantage of using CH4 as a fuel vice say RP-1? I understand that hydrogen is particularly hard to contain and keep cool, and so there is advantages there, but what else? I assume cost is a little lower since some kind of purified natural gas could be used? Also if CH4 is desirable, what prevented its use up until very recently?
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Autogenous pressurization of propellant tank. Cleaner than Kerosene for reuse (less soot)
 
Byeman said:
Autogenous pressurization of propellant tank. Cleaner than Kerosene for reuse (less soot)
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Fair enough. What has prevented people from using liquid methane before? If it can be contained on an LNG carrier, I would have thought hydrogen not particular worth the effort, despite its superior performance. Is hydrogen that more energetic per volume/mass that it makes a huge difference in structural size/mass? And if so, what has changed? It seems like all the popular kids on the space playground are making the switch to methane based fuel now (Landspace, Vulcan, Starship)
 
Josh_TN said:
Fair enough. What has prevented people from using liquid methane before? If it can be contained on an LNG carrier, I would have thought hydrogen not particular worth the effort, despite its superior performance. Is hydrogen that more energetic per volume/mass that it makes a huge difference in structural size/mass? And if so, what has changed? It seems like all the popular kids on the space playground are making the switch to methane based fuel now (Landspace, Vulcan, Starship)
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Methane replaced kerosene and not hydrogen. Nothing prevented it. Kerosene requires helium for pressurization and is messy for reuse.
 
Byeman said:
Methane replaced kerosene and not hydrogen. Nothing prevented it. Kerosene requires helium for pressurization and is messy for reuse.
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Were there previous issues with achieving the property purity of methane? I cannot imagine liquifying it has been a problem for many decades.
 
Josh_TN said:
What prevented CH4 from replacing RP1 then?
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Requirements

RP-1 is really good as a first stage propellent, it's relatively easy to make, handle, store, and energy dense. It's not anywhere near as efficient as LH2, but it's really good for overcoming gravity and aerodynamic drag in the atmosphere. LH2 is a really good fuel once gravity is overcome and there's no atmosphere. That's why a lot of rockets were RP1 first stage and LH2 upper stage. The downside is LH2 is not an easy fuel to deal with.

CH4 has some of the benefits of both LH2 and RP-1, with fewer of the drawbacks being less cryogenic than LH2 and easier to handle. Also, it's pretty easy to get (and can even be "green"). The main two requirements that now make it preferred are reusability (already discussed) and it can be made on Mars. Take those away, and RP-1 would still be a good first stage propellent.

It's insightful to look at the EELV program to see the tradeoffs.

Atlas V RD-180 860,000 lbs. thrust (SL) 311 SL ISP 12,000 lb. engine weight 12.5 ft diameter
Delta IV RS-68 660,000 lbs. thrust (SL) 365 SL ISP 14,500 lb. engine weight 16 ft diameter
SpaceX Raptor 2 507,000 lbs. thrust (SL) 327 SL ISP 3,500 lb. engine weight

If I had the BE-4 info, I'd post it. The Delta had a more efficient engine but gave it all up with a bigger heavier structure (also wasn't very good on the amount of thrust, RS-68A, cough). The RD-180 put out a lot more thrust, through a lighter engine with a lighter first stage structure (the insulation didn't catch fire either ;)) . When I worked EELV no one wanted to launch on a Delta unless they had no choice.

Now, Vulcan, SS/SH aren't in the comparison since they have pretty different requirements. Atlas V/Delta IV both were built for the same set of requirements and make the trade space closer to an apples-to-apples comparison.
 
Bloomberg is now reporting that the US Air Force has imposed unspecified fines on ULA for launch delays. This is concerning the Vulcan launcher.

 
https://twitter.com/x/status/1792571439880831014
View: https://twitter.com/torybruno/status/1792571439880831014


Over the last couple of days, I’ve shared a flock of Centaur IIIs and a herd of Atlas’. Here’s a crowd of Centaur Vs. #CrowdedFactory
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cool!!
Any update on the Vulcan rocket? Have the engines finished their installation?
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https://twitter.com/x/status/1792575575862792535
View: https://twitter.com/torybruno/status/1792575575862792535


CERT2 engines have been installed for a while. Working the third Vulcan now. 1 of 2 in hand. Second one on its way
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https://twitter.com/x/status/1792633951414046805
View: https://twitter.com/torybruno/status/1792633951414046805


It may not look like it now, but this will very soon be VLP-2! The SECOND #VulcanRocket mobile launch platform is making excellent progress and will soon be arriving at the Cape! This opens up parallel processing of rockets feeding the SLC41 pad
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https://twitter.com/x/status/1792636845794140642
View: https://twitter.com/ulalaunch/status/1792636845794140642


The addition of Vulcan Launch Platform-2, or VLP-2, will help establish Lane 2, a second launch processing capability for #VulcanRocket to meet demand for higher launch rate cadence from Amazon’s @ProjectKuiper and other customers.
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https://twitter.com/x/status/1790349365195821379
View: https://twitter.com/torybruno/status/1790349365195821379

Tory Bruno tweet said:
Cool angle of Vulcan CERT2 booster. (ITAR team is feeling generous today… ;)
#VulcanRocket #Cert2
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https://twitter.com/x/status/1791196241851777522
View: https://twitter.com/torybruno/status/1791196241851777522

The pic is a little blurry. Is it possible to get a clear picture? I really like this one.
Sorry to trouble you.
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Tory Bruno tweet said:
Sorry no, blurriness is one of the tools that allows me to show these to you.
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https://twitter.com/x/status/1793590820286951900
View: https://twitter.com/torybruno/status/1793590820286951900


I've shown you a flock of Centaur IIIs, a crowd of Atlases, and a thunder of Centaur V's. It's time for a gang of Vulcans. #CrowdedFactory.
#VulcanRocket #Cert2
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https://twitter.com/x/status/1796268418187833706
View: https://twitter.com/torybruno/status/1796268418187833706


Raising the Roof!!

The SPOC is becoming a new VIF-2. Construction is underway and being accelerated. We'll be vertically assembling two #VulcanRocket 's simultaneously in VIF-1 & VIF-2. And rapid firing them at the pad for a high launch tempo next year
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https://twitter.com/x/status/1796278621914476595
View: https://twitter.com/torybruno/status/1796278621914476595


We'll move to flying every 2 weeks next year
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Josh_TN said:
Were there not like a half dozen launches scheduled for this year?
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There four launches planned
the first was 8 January with The Peregrine Moon lander
next had be First flight of Dream Chaser, but there delays
follow two Classified launches for USSF

however ULA need the second launch to qualification of Vulcan to the DoD
to launch the two USSF missions
 
The seventh and eighth satellites in the GSSAP series appear to be the payload for the fourth launch of Vulcan currently planned for the second half of the year. But being as the third launch could now be in March 2025, who knows.
 
Vulcan to launch two national security missions this year, that is good news for United Launch Alliance. Looks like the future is secure for Vulcan then.
 
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Will Vulcan/Centaur have to get a special adaptor to attach Dreamchaser? Or will it attach to the rocket without a problem?
 
FighterJock said:
Will Vulcan/Centaur have to get a special adaptor to attach Dreamchaser? Or will it attach to the rocket without a problem?
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Dreamchaser rides in a shroud, so no special adaptor needed beyond the usual to adapt any payload to the shroud.
 
Thanks TomS, I did not know that Dreamchaser had to be launched in a shroud. So opposite of what ESA were plannning to do for Hermes Europe's own attempt at a shuttle but was cancled much to my annoyance.
 
So there will be two variants of the Dreamchaser one unmanned and one with crew. Thanks for that news NMaude.
 
So I take it that there will only be one variant being optionaly manned where it does not require astronauts for certain missions.
 
FighterJock said:
So I take it that there will only be one variant being optionaly manned where it does not require astronauts for certain missions.
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No. the manned and unmanned versions would be significantly different. However, it isn't certain that the manned version will actually be built. It's tied to the Orbital Reef space station being developed by Blue Origin and there were reports last year that the relationship between Sierra Space and Blue Origin was not good. However, it seems to have survived into 2024. Given that the other crew option for Orbital Reef is supposed to be Starliner, I think keeping Sierra Space on the team is going to be an important goal for BO.
 

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