ULA Vulcan Launch Vehicle (as announced/built) - General Discussion Thread 3

[FutureSpaceTourist]

Cross-post from Blue BE-4 thread:

I got these response from Tory Bruno:
1. Flight engines very nearly finished....end of July?
2. Acceptance testing will be done in Texas... complete by end of August-mid september?
3. For rate testing [testing for full rate production engines] will occur at Test Stand 4670 at Huntsville ...

https://twitter.com/torybruno/status/1552238343932596224

And....

https://twitter.com/torybruno/status/1552681239404056576

Coupled with the latest Blue BE-4 video, it does look like first flight BE-4s will be with ULA in the next few weeks. So I’d guess Q1 2023 for first Vulcan flight.

[FutureSpaceTourist]

Apologies if this has been discussed up thread, I have a question about how late fairing separation is for Vulcan.

ULA’s video shows fairing separation from the Centaur upper stage some time after booster separation:



and we know Vulcan booster separation comes much later than F9 booster separation:

https://twitter.com/free_space/status/1549936849698816000

As a result, Vulcan 1st stage flies about twice as fast & twice as high as @SpaceX’s Falcon 9 and is much farther downrange than a Falcon 9 when it separates from the upper stage.BE-4 engine splashdown will take place some 1,300 mi. from launch site, depending on trajectory.
 6/6

So doesn’t that mean Vulcan is carrying the fairing much longer than it needs to purely to protect the payload from atmospheric forces? Does that make much difference to the payload Vulcan can lift to orbit?

[FutureSpaceTourist]

Interesting quote from the end of the recent Aviation Week article on SMART engine reuse:

“Our team also is building a list of everything else on the rocket, in kind of descending order, of how much it costs versus how easy it is to get it back,” Bruno adds. “Once we get the hang of this [SMART engine reuse], we’re going to start moving down that list.”

May be fairings are on the list (although see previous post), not sure what else on the list would be practical to recover?

[Jim]

Apologies if this has been discussed up thread, I have a question about how late fairing separation is for Vulcan.

ULA’s video shows fairing separation from the Centaur upper stage some time after booster separation:



and we know Vulcan booster separation comes much later than F9 booster separation:

https://twitter.com/free_space/status/1549936849698816000

As a result, Vulcan 1st stage flies about twice as fast & twice as high as @SpaceX’s Falcon 9 and is much farther downrange than a Falcon 9 when it separates from the upper stage.BE-4 engine splashdown will take place some 1,300 mi. from launch site, depending on trajectory.
 6/6

So doesn’t that mean Vulcan is carrying the fairing much longer than it needs to purely to protect the payload from atmospheric forces? Does that make much difference to the payload Vulcan can lift to orbit?

Fairings are released when aerodynamic heating goes below a certain level and not forces.

[ZachS09]

The RL-10C-1-1 that’ll fly on SBIRS-GEO 6 tomorrow has a 22-inch nozzle extension instead of the regular 33-inch extension.

For Vulcan, will the same 22-inch extension be used too? Or will ULA eventually revert to the 33-inch version?

[russianhalo117]

The RL-10C-1-1 that’ll fly on SBIRS-GEO 6 tomorrow has a 22-inch nozzle extension instead if the regular 33-inch extension.

For Vulcan, will the same 22-inch extension be used too? Or will ULA eventually revert to the 33-inch version?

Other incremental nozzle length revisions are in the works for upcoming minor/moderate RL10C-X upgrades. The maximum constraint for the two RL10C-1-x's is the interstages' outside diameter of 5.54m (since internal diameter is unknown for the interstage). The RL10 to RL10 nozzle clearance spacing from each other at the center of the stage is defined by the current spacing on Centaur-III (DEC) version for the gap between the end of each nozzle extension.

[ZachS09]

The RL-10C-1-1 that’ll fly on SBIRS-GEO 6 tomorrow has a 22-inch nozzle extension instead of the regular 33-inch extension.

For Vulcan, will the same 22-inch extension be used too? Or will ULA eventually revert to the 33-inch version?

Other incremental nozzle length revisions are in the works for upcoming minor/moderate RL10C-X upgrades. The maximum constraint for the two RL10C-1-x's is the interstages' outside diameter of 5.54m (since internal diameter is unknown for the interstage). The RL10 to RL10 nozzle clearance spacing from each other at the center of the stage is defined by the current spacing on Centaur-III (DEC) version for the gap between the end of each nozzle extension.

I asked my question in regards to the vibration problems seen during SBIRS-GEO 5.

If ULA goes back to the 33-inch extension, how would they mitigate the vibration?

[edkyle99]

The RL-10C-1-1 that’ll fly on SBIRS-GEO 6 tomorrow has a 22-inch nozzle extension instead of the regular 33-inch extension.

For Vulcan, will the same 22-inch extension be used too? Or will ULA eventually revert to the 33-inch version?

Other incremental nozzle length revisions are in the works for upcoming minor/moderate RL10C-X upgrades. The maximum constraint for the two RL10C-1-x's is the interstages' outside diameter of 5.54m (since internal diameter is unknown for the interstage). The RL10 to RL10 nozzle clearance spacing from each other at the center of the stage is defined by the current spacing on Centaur-III (DEC) version for the gap between the end of each nozzle extension.

I asked my question in regards to the vibration problems seen during SBIRS-GEO 5.

If ULA goes back to the 33-inch extension, how would they mitigate the vibration?

They (Aerojet Rocketdyne) will have to stiffen it to prevent the 23 Hz-ish resonance that was seen during AV-091.  Perhaps a thrust adjustment could also help.

 - Ed Kyle

[sdsds]

They (Aerojet Rocketdyne) will have to stiffen it to prevent the 23 Hz-ish resonance

So yes, mechanical-engineering-wise adding stiffening mass makes sense. But hey! Conceivably a clever engineer could shift the harmonic resonance characteristics of the nozzle by removing mass rather than adding it, softening rather than stiffening the nozzle. Or no?

[DanClemmensen]

They (Aerojet Rocketdyne) will have to stiffen it to prevent the 23 Hz-ish resonance

So yes, mechanical-engineering-wise adding stiffening mass makes sense. But hey! Conceivably a clever engineer could shift the harmonic resonance characteristics of the nozzle by removing mass rather than adding it, softening rather than stiffening the nozzle. Or no?

Since the RL-10 can be throttled, the designer must somehow avoid resonances across the entire range of thrust values. Do any rocket engines use some sort of dynamically-tuned damper?

[Jim]

They (Aerojet Rocketdyne) will have to stiffen it to prevent the 23 Hz-ish resonance

So yes, mechanical-engineering-wise adding stiffening mass makes sense. But hey! Conceivably a clever engineer could shift the harmonic resonance characteristics of the nozzle by removing mass rather than adding it, softening rather than stiffening the nozzle. Or no?

Since the RL-10 can be throttled, the designer must somehow avoid resonances across the entire range of thrust values. Do any rocket engines use some sort of dynamically-tuned damper?

Not throttled.

[DanClemmensen]

They (Aerojet Rocketdyne) will have to stiffen it to prevent the 23 Hz-ish resonance

So yes, mechanical-engineering-wise adding stiffening mass makes sense. But hey! Conceivably a clever engineer could shift the harmonic resonance characteristics of the nozzle by removing mass rather than adding it, softening rather than stiffening the nozzle. Or no?

Since the RL-10 can be throttled, the designer must somehow avoid resonances across the entire range of thrust values. Do any rocket engines use some sort of dynamically-tuned damper?

Not throttled.

Thanks, Jim. All I knew was that Wikipedia says that it can be throttled. I did not know that this capability is not in use.

[sdsds]

Since the RL-10 can be throttled, the designer must somehow avoid resonances across the entire range of thrust values. Do any rocket engines use some sort of dynamically-tuned damper?

Not throttled.

Rule #1 of NSF Forums: Do Not Argue With Jim.
Rule #2 of NSF Forums: Do Not Argue With Jim.
Rule #3 of NSF Forums: It's the same rule, all the way down the list.
...

Centaur is an amazing vehicle. There are highly accurate sensors measuring the remaining mass of each propellant. A servopositioner adjusts the LOX flow rate to control the mixture ratio and thus optimize propellant utilization. That's bound to at least slightly modify combustion and thus thrust. It seems unlikely those small variations in combustion dynamics and/or thrust would change how the nozzle gets mechanically excited, and thus shouldn't impact resonant "ringing" of the nozzle.

I can't understand how an RL-10C-1-1 33 inch nozzle extension could get onto a flight stage with a resonant frequency that could be excited by anything happening on the vehicle. So I question whether it was really resonance at all, as opposed to motion being caused by an external force at that frequency.... Was the TVC algorithm imparting forces at that frequency on prior flights, and it only became noticeable with the larger nozzle extension?

[FutureSpaceTourist]

https://twitter.com/ulalaunch/status/1558165473757470723

We have made various upgrades at SLC-41 to transform it into a two-rocket launch pad! #VulcanRocket #CountdownToVulcan

twitter.com/torybruno/status/1558164373742518274

What’s going on at the pad? Is that a tanking crew delivering methane for the #VulcanRocket ?  SLC-41 transformed into a Two rocket launch pad!!! #CountdownToVulcan

[Robert_the_Doll]

https://twitter.com/ulalaunch/status/1558165473757470723

We have made various upgrades at SLC-41 to transform it into a two-rocket launch pad! #VulcanRocket #CountdownToVulcan

twitter.com/torybruno/status/1558164373742518274

What’s going on at the pad? Is that a tanking crew delivering methane for the #VulcanRocket ?  SLC-41 transformed into a Two rocket launch pad!!! #CountdownToVulcan

Interesting. What is the storage life of methane and how does that translate to a launch in December or early next year for Vulcan? Assuming that is not being stored ahead of a static test fire first, of course.

[russianhalo117]

https://twitter.com/ulalaunch/status/1558165473757470723

We have made various upgrades at SLC-41 to transform it into a two-rocket launch pad! #VulcanRocket #CountdownToVulcan

twitter.com/torybruno/status/1558164373742518274

What’s going on at the pad? Is that a tanking crew delivering methane for the #VulcanRocket ?  SLC-41 transformed into a Two rocket launch pad!!! #CountdownToVulcan

Interesting. What is the storage life of methane and how does that translate to a launch in December or early next year for Vulcan? Assuming that is not being stored ahead of a static test fire first, of course.

Just like LH2 you have to start filling to first cool the tanks down well in advance. They are now begin the filling and storage operations for the initial flight including reserves for scrubs and recycling as ULA uses a flarestack during operations including recycling. I will leave it at that so as to not promote derailing the thread

[[email protected]]

Are they decided to not conduct a static fire?

[russianhalo117]

Are they decided to not conduct a static fire?

I'm not aware of any updates on that.

[Jim]

Interesting. What is the storage life of methane and how does that translate to a launch in December or early next year for Vulcan? Assuming that is not being stored ahead of a static test fire first, of course.

A WDR is a given.

[Robert_the_Doll]

Interesting. What is the storage life of methane and how does that translate to a launch in December or early next year for Vulcan? Assuming that is not being stored ahead of a static test fire first, of course.

A WDR is a given.

A wet dress rehearsal is one thing, a static test firing is another.