ULA Vulcan Launch Vehicle - General Discussion Thread 2

[PahTo]

Vulcan isn't using Delta 4 tooling, as I understand things.  It is a new rocket.  Vulcan is going to be 5.4 meters diameter, wider than Delta 4 CBC's 5.08 meters (200 inches).  Vulcan tank panels are orthogrid, four to make a cylinder.  Delta 4 panels are isogrid, five to make a cylinder.  Etc.

 - Ed Kyle

Is the reason for the (expensive) change in tooling to go with a 5.4 meter stage due to the change in fuel?  That is, with methane being more dense, and the desire the make stages as short/squat as possible, is that enough reason to change things so dramatically?

[envy887]

Vulcan isn't using Delta 4 tooling, as I understand things.  It is a new rocket.  Vulcan is going to be 5.4 meters diameter, wider than Delta 4 CBC's 5.08 meters (200 inches).  Vulcan tank panels are orthogrid, four to make a cylinder.  Delta 4 panels are isogrid, five to make a cylinder.  Etc.

 - Ed Kyle

Is the reason for the (expensive) change in tooling to go with a 5.4 meter stage due to the change in fuel?  That is, with methane being more dense, and the desire the make stages as short/squat as possible, is that enough reason to change things so dramatically?

Vulcan tankage is easier and cheaper to make than Delta IV, so adding tooling cost is worthwhile when spread across the large number of tanks that will be built.

[Jim]

Triple-core rockets are evolutions from existing single-core rockets, which means they can use most of the existing manufacturing and support systems. That means triple-core rockets are the logical and least expensive way to increase payload beyond single-core launchers.

Cost is a very important factor since as of today there is only a need for flying Delta IV Heavy just once a year or less (9 flights in 13 years). That amount of demand does not merit a completely new design.

SpaceX has the forecasted demand for more lift to space, which means they can afford to go with a revolutionary design, one that requires new manufacturing and support systems. So it's not because of any challenges that Falcon Heavy presents per se, just that Falcon Heavy was only meant to be an interim solution from the start.

Even if Falcon Heavy had flown years ago and had not had any triple-core related issues SpaceX would still be replacing it with the BFR and BFS, so the challenges that triple-core launch systems present was never a factor in moving to the BFR and BFS.

Not true.  There are conflicting and incorrect statements in the above starting with the first sentence

[envy887]

Ariane 4 had both solid and liquid rocket booster options.  It was a dominant commercial player in its time.

I stand corrected.

IIRC a lot of the stages on A4 were liquid hypergols. I have a vague thought the LRB's were also storable. I don't think that's a viable option today. 

Ah, ok.

A single BE-4 has about 25% more thrust than a GEM-63XL. The thrust and ISP increase would help with margins for recovery, but I don't think BE-4 can throttle enough for a single-engine booster to do VTVL. Maybe they could use vernier engines for landing (methalox RL-10 or Broadsword?) or convert BE-3 to run methalox and use three of those.

The engine is the joker in the pack. I think that's the challenge, but I wasn't thinking about them being recoverable or reusable. Just bringing more of Vulcan's structure in house. I will note that in principal any LRB is more easy to throttle than an SRB, which would allow a more flexible range of flight profiles. How useful it would be to do so is another matter.

The simplest (cheapest) option would be a  fixed thrust, fixed nozzle LRB with about the same thrust as an SRB and a bit better Isp. Beyond that you get throttleable  then throttleable with TVC

An interesting question would be if you could control the thrust profiles of all the LRBs (from Vulcan's GNC) could you use that to reduce the number needed to fly a mission?

I'm not sure developing another LRE is the cheapest option. A BE-4 is about $8M, while a GEM-63XL is roughly $10. Can ULA build a set of flight tanks roughly the size of Falcon 1-e and integrate the BE-4 for $2M?

[lrk]

One option under discussion for adding reusability is moving the engines to recoverable side-mounted pods.  What if a varying number of these pods could be used, potentially in addition to the engines built in to the core?  This would serve to increase the TWR early in flight, but some the pods could be jettisoned as propellant is depleted, somewhat like the original Atlas. 
This seems like it might add less complexity than using complete cores as LRBs, especially if a similar redesign was to be happening anyway in order to implement engine recovery.  This approach would also retain the gradual scalability of adding SRBs, but would be cheaper assuming the engine pods could be easily refurbished. 
Thoughts? 

[john smith 19]

I'm not sure developing another LRE is the cheapest option. A BE-4 is about $8M, while a GEM-63XL is roughly $10. Can ULA build a set of flight tanks roughly the size of Falcon 1-e and integrate the BE-4 for $2M?

That's the tricky bit with LRB's. Doing a "good enough" engine at a reasonable price. I guess Microcosm was the classic in pressure fed all composite LOX/RP1 designs.

TBH I keep thinking of the "Flomerics" concept using a small high pressure inert gas tank to drive a simple pressure system and low pressure (light) main tanks.

Inert gas drive would likely be heavier than an expander cycle but mechanically and thermodynamicaly simpler.

[Zed_Noir]

I'm not sure developing another LRE is the cheapest option. A BE-4 is about $8M, while a GEM-63XL is roughly $10. Can ULA build a set of flight tanks roughly the size of Falcon 1-e and integrate the BE-4 for $2M?

That's the tricky bit with LRB's. Doing a "good enough" engine at a reasonable price. I guess Microcosm was the classic in pressure fed all composite LOX/RP1 designs.

TBH I keep thinking of the "Flomerics" concept using a small high pressure inert gas tank to drive a simple pressure system and low pressure (light) main tanks.

Inert gas drive would likely be heavier than an expander cycle but mechanically and thermodynamicaly simpler.

Well somewhat in jest. If the AR-1 is somehow selected for the Vulcan. Then the obvious LRE choice for strapped-on booster is the unmentionable one from Hawthorne. Which is cheap and in mass production along with a lot flight time. 

[brickmack]

while a GEM-63XL is roughly $10 [million]

Source? From RocketBuilder, AJ60A is like 6-7 million (in terms of price increase to customer. Cost to ULA is likely lower). ULA has said the standard GEM-63 will be slightly cheaper than that. The XL version is bigger, but doubtful by enough to increase cost by ~4-5 million (Its not gonna be ~twice the size, and much of that cost is in things like the electronics that don't increase with booster stage anyway)

[Jim]

Vulcan isn't using Delta 4 tooling, as I understand things.  It is a new rocket.  Vulcan is going to be 5.4 meters diameter, wider than Delta 4 CBC's 5.08 meters (200 inches).  Vulcan tank panels are orthogrid, four to make a cylinder.  Delta 4 panels are isogrid, five to make a cylinder.  Etc.

 - Ed Kyle

Is the reason for the (expensive) change in tooling to go with a 5.4 meter stage due to the change in fuel?  That is, with methane being more dense, and the desire the make stages as short/squat as possible, is that enough reason to change things so dramatically?

Also, to maintain a constant diameter from core to upper stage to fairing

[Jim]

The 5.08 meter to 5.4 meter diameter change represents a shift away from MDAC/Boeing's 1990s relationships with Japan's Mitsubishi

No, the 5.08 meter diameter was from the Titan IV fairing.  Everything on Delta IV flowed down from that, just as Vulcan will.

[PahTo]

Thanks for the informed responses.  So even with the 5.4m diameter, it sounds like the stage length (at least for S1) will still be similar to the DIV [EDIT:  or perhaps more accurately, the Atlas V] core.  S2 will be interesting (post Centaur)--perhaps the 5.4 diameter will be the template for the long-awaited ACES...

[envy887]

while a GEM-63XL is roughly $10 [million]

Source? From RocketBuilder, AJ60A is like 6-7 million (in terms of price increase to customer. Cost to ULA is likely lower). ULA has said the standard GEM-63 will be slightly cheaper than that. The XL version is bigger, but doubtful by enough to increase cost by ~4-5 million (Its not gonna be ~twice the size, and much of that cost is in things like the electronics that don't increase with booster stage anyway)

From the BE-4 page: https://www.blueorigin.com/be4

The BE-4 saves taxpayers an additional $3 billion in national security launch costs over 20 years by providing higher thrust – 1.1 million pounds versus 860,000 pounds for the RD-180 – which enables a greater payload capability and allows for the removal of a solid rocket motor at more than $10 million per flight for comparable missions.

[russianhalo117]

Thanks for the informed responses.  So even with the 5.4m diameter, it sounds like the stage length (at least for S1) will still be similar to the DIV [EDIT:  or perhaps more accurately, the Atlas V] core.  S2 will be interesting (post Centaur)--perhaps the 5.4 diameter will be the template for the long-awaited ACES...

After Centaur-3 SEC and DEC is retired from Vulcan Family. Centaur-5 will serve as the interim stage until ACES is ready and Centaur-5 may even co exist with ACES for a while before it gets the boot.

[brickmack]

After Centaur-3 SEC and DEC is retired from Vulcan Family. Centaur-5 will serve as the interim stage until ACES is ready and Centaur-5 may even co exist with ACES for a while before it gets the boot.

When the B330 lunar mission was first announced, I made a reddit comment which Tory Bruno replied to https://www.reddit.com/r/ula/comments/76ysr9/bigelow_aerospace_and_united_launch_alliance/dojavha/?context=3 . His response is kinda vague, but "A little bit of all of that" would include my hypothesis about inherent optimization differences between upper stages and tugs. Implying that Centaur V may remain in service through the whole duration of the Vulcan program to support heavy payload launches to LEO

[jongoff]

With the staging velocity of a typical strapon, it would be interesting if you could replace the SRBs down the road with LOX/Methane boostback LRBs.

Interesting suggestion. (Had made a related suggestion for a euorpean launcher that wasn't well received for its larger boosters.)

You could have the benefit of a optimize ELV with maximum payload/discard (no reuse), ELV with partial assist (some booster propellant for strapon recovery/reuse, recoverable first stage landed with considerable booster props dedicated for stage recovery.

Possibly use a subscale test version of a BE4?

So you'd develop/fly the core vehicle no strap-ons, then thrust augment strap-ons/jettison, then test recovery/land jettisoned strap-ons,  then land stage with strap-ons left attached. You might learn enough to get landings right on the first attempt.

Perhaps you could even attach a landing leg the the outboard of the strapon? The load paths would work.

I had blogged about the idea of using a Masten XS-1 derived stage as a boostback strapon about six months ago, but hadn't had a chance to blog about the idea you mention in your last two paragraphs. But yeah, if you can make the sizing work, you could feasibly use the strapons to enable a full-stage recovery for low-performance missions, and do strapon boostback RTLS plus SMART engine recovery for higher-performance missions (maybe with strapon full-stage barge recovery for intermediate performance missions). The aerodynamics, performance, and landing reliability likely wouldn't be as good as for a purpose-designed system like F9R, but it wouldn't require much if any changes to the core stage to make it happen, which means it could be added on down the road.

As for the engine, both Masten and Ursa Major are planning high-performance LOX/Methane engines in the right size range, depending on how much thrust you want with an LRB, and how much clustering you want to do...

The form factor would be weird, but if done right they could double as a boost back first stage for a reusable or semi-reusable smallsat launcher.

They don't have to just be cylinders - you could do radial "wedge" space filling design too. Bit of a challenge to stabalize for independent landing though.

Not necessarily that hard though. It's probably a suboptimal *technical* concept, but possibly a decent business/technical concept.

~Jon

[jongoff]

...
Possibly use a subscale test version of a BE4?
...

And where would one get that?

I'd go with Masten or Ursa Major--both are developing 25-65klbf LOX/Methane engines (Ursa using staged combustion, Masten using dual expander), with both targeting Merlin-class T/W ratios and Masten's being designed from the start for throttleability (for VTVL operations).

~Jon

[envy887]

...
Possibly use a subscale test version of a BE4?
...

And where would one get that?

I'd go with Masten or Ursa Major--both are developing 25-65klbf LOX/Methane engines (Ursa using staged combustion, Masten using dual expander), with both targeting Merlin-class T/W ratios and Masten's being designed from the start for throttleability (for VTVL operations).

~Jon

What diameter booster would they need to fit 3 engines across? They would need 5-7 of those engines clustered on each LRB to replace the thrust of a single GEM. That would make VTVL recovery simple.

And with a single engine upper stage that would make a nice small sat launcher.

[woods170]

Yes.  The 5.4 meter diameter is shared by Ariane 5 and 6, which will also share some or most aspects of the Vulcan payload fairing.  One wonders what other bits Vulcan and Ariane might end up sharing.

Other than the fairings being produced by RUAG the two vehicles will share nothing.

[john smith 19]

Not necessarily that hard though. It's probably a suboptimal *technical* concept, but possibly a decent business/technical concept.

Given ULA's complex relationship with it's parents that sounds like the right direction for them to go in.

What diameter booster would they need to fit 3 engines across? They would need 5-7 of those engines clustered on each LRB to replace the thrust of a single GEM. That would make VTVL recovery simple.

And with a single engine upper stage that would make a nice small sat launcher.

Wikipedia says the the GEM 60 motors are 60" in diam and 197.5 Klb thrust.

https://en.wikipedia.org/wiki/Graphite-Epoxy_Motor

That's 3-4 of the largest engines, assuming the Vulcan GEMS have no higher thrust. They have carried provision for TVC if needed.

[Ictogan]

Not necessarily that hard though. It's probably a suboptimal *technical* concept, but possibly a decent business/technical concept.

Given ULA's complex relationship with it's parents that sounds like the right direction for them to go in.

What diameter booster would they need to fit 3 engines across? They would need 5-7 of those engines clustered on each LRB to replace the thrust of a single GEM. That would make VTVL recovery simple.

And with a single engine upper stage that would make a nice small sat launcher.

Wikipedia says the the GEM 60 motors are 60" in diam and 197.5 Klb thrust.

https://en.wikipedia.org/wiki/Graphite-Epoxy_Motor

That's 3-4 of the largest engines, assuming the Vulcan GEMS have no higher thrust. They have carried provision for TVC if needed.

Vulcan is using the GEM 63 XL. Can't find any thrust numbers on those, but with the naive assumption that thrust should scale with total mass(listed here),  it should be around 300klbf.