Author Topic: ULA Vulcan Rocket Q&A with ULA's Dr. George Sowers - April 14, 2015  (Read 68525 times)

Offline georgesowers

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Dr Sowers,

If follow-up questions are allowed (thanks for answering my first one!), can you talk about other items in the trade space that were examined but maybe rejected? I'm sure you looked at full-stage reuse, multiple engines, that sort of thing, but anything more fanciful like 4+ core vehicles, flyback/flythrough boosters, SSTO etc? Not sure how much you can talk about it, but your title *is* Chief Mad Scientist, so hopefully there's some real mad science stuff that you can talk about. I totally understand if none of that can be public until much later when a history of the development program can be written.

Thank you again!

Not a lot of far out stuff was seriously looked at in the first two steps.  The prime considerations were getting off the RD-180 (step 1 and the BE-4) and replicating DIV heavy performance to GSO (ACES).  The reusable BE-4 opens up engine reuse (step 3).  We have ideas for stage reuse that are further down the road. The capabilities we introduce into ACES enable all sorts of future applications (including distributed lift, step 4) and dramatically lower the cost of BEO missions.

I'm a firm believer in the evolutionary approach to development.  The key is to look several steps ahead, each step building upon the one before and enabling the next.  The end result is revolutionary.

Offline georgesowers

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Thank you for answering my earlier question Dr. Sowers.

You've talked about reusing an upper stage. After payload separation, you've got a free US - to reuse it would need to acquire orbit for new payload, prox ops, attach, execute a series of timed burns, and separate again.

ACES/Centaur don't appear to be anything more than typical, autonomous US at the moment. Even Agena, which was more of a spacecraft than just an US, didn't have all of that to do the above. Nor are payloads attached to US without significant ground prep, spin table, etc. Had not heard Astrotech making on-orbit house calls yet ;)

Where's the extra SC part coming from that can "command" / "manage" / "handle" ACES/Centaur?

Again, thank you from the NSF community here. We really appreciate it when you communicate with us like this.

ACES will start out as a typical autonomous upper stage, but we hope to evolve it to much more.  For example, the simplest reuse is to refuel the stage in the course of executing a single mission.  This could be to deliver cargo to a station at L1.  An ACES derived tanker is launched to LEO.  The cargo module is launched to LEO using ACES.  ACES rendezvous' with the tanker.  ARPO avionics and SW is available commercially, or the cargo module is equipped with it.  ACES is refueled and burns to L1 delivering the cargo.

A more complex example is ACES equipped in XEUS mode as a lander.  Then it can cycle back and forth from an L1 station to the lunar surface, refueling at each place, delivering cargo or crew.  Or simply refuel on the lunar surface with hydrogen and oxygen mined from water in craters at the poles, as detected by LCROSS.

The long duration, unlimited burn, refueling capability built into ACES allows the high ISP and thrust of cryogenic fuels to be applied to any BEO mission. 

Offline georgesowers

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I'll avoid a Reddit-style question about if you prefer cakes or pies, and ask evolvability. Just how much can you upgrade this specific system by way of upmass, and where do you think is the top line for upmass? (say versus mulitple launches) in the future customer requirement market.

Multiple cores is the standard upgrade path to super heavy capability, but I've become convinced that distributed lift is the way to go.  It all comes back to $/kg.

Offline georgesowers

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Hi Dr Sowers,

Regarding aerocapture of the parachuting engine by helicopter, will it necessarily be a manned helicopter, or is there a possibility of an unmanned drone helicopter being used to reduce risk?

Thanks for your time, sir.

Given the mass of the engines, it needs to be a big helicopter.  Hadn't though about unmanned.  What risk are you trying to mitigate?

Offline georgesowers

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Thanks Dr Sowers for all the great answers.

Could the SMART system be applied to upper stage? Tory hinted at using it elsewhere.

I'll leave you with Tory's hints...     :)

Offline georgesowers

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Dr Sowers; you mentioned earlier in the thread that you would not rule out a future 'triple core' heavy version of Vulcan. Has ULA also looked at versions with 8 or even 10x solid boosters on a single corestage? It appears that many boosters might fit on a 5 meter stage. It would seem to me that such a launcher with an ACES upper stage would have a lot of capability!!

Yes it would.  For now, we've limited it to 6 due to the size of the opening in the flame duct. 

Offline georgesowers

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Dr Sowers,

When eliminating turbine based units from the IVF system design, were sub-atmospheric 'inverted brayton cycles' such as outlined in the linked pdf, considered.  This is a scheme for a residential scale CHP (high enthalpy) micro-turbine system, that reverses compressor and turbine sequence to  produce very-low-power turbo-generators.

Or would continuous combustion require too high a fuel flow to keep combustion temperatures sensible, (what is the peak combustion temperature in the IC engine anyway)?

http://www.agileturbine.com/publications/Small%20Scale%20Combined%20Heat%20and%20Power.pdf 

thanks
Toby

Post this question on the IVF thread.  I'll get Frank Zegler, the inventor, to answer.  (Another way of saying: I haven't the foggiest...)

Offline georgesowers

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Dr. Sowers;

 Is the new upper stage planned to be referred to as ACES indefinitely, or will there be a name selection/competition as there was for Vulcan?

TBD.  Someone one my reddit AMA last week suggested Romulan, I countered with Klingon.  My main criteria is it has to sound dramatic during terminal count when the launch control team declares "go Vulcan!, go XXX!"  Gives me chill every time.

Offline gin455res

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Cool thanks.
(it's already up, maybe i'll link to the post on this thread, as I think I was a bit too succinct in the other thread)

Offline georgesowers

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Dr. Sowers, reading your response on the possibility of a three core Vulcan made me think a little. For what practical purposes does the first stage of the Vulcan inherit characteristics from the Common Core Boosters/Common Booster Cores of today, given that it will use entirely new engines and propellant?

-

Also (apologies for the sneaky two part question, feel free to ignore this part at your discretion) - will the stars and stripes paint job on the first stage make its way onto the final LV?

Thank you so much for spending your time with us Doctor.  :D It's exciting work you guys n' gals are doing.

The design philosophy is the same.  Same hardware flies all configurations.  And built in the same factory with very similar processes.

TBD on the paint job.

Offline georgesowers

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Hi Dr. Sowers,

Two quick questions if I may:

1) Will ACES upper stage cost more or less than Centaur (actual cost not performance based)?

2) What is the cost of the second stage relative to the first? I believe current ratio is ~40/60 for Atlas, will this ratio go up or down for Vulcan?

Thanks again for answering our questions!

ACES cost will be less than Centaur for equivalent number of engines.  Cost ratio of the stages will be similar to today.

Offline Damon Hill

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Dr. Sowers:

I'm extremely fascinated and impressed with the IVF design (why wasn't this addressed decades ago?) and the very smart implementation of an internal combustion engine, counter-intuitive as it may first appear.  (And it's blowing a lot of minds in this forum, even though online documentation explains it all.)

So, a question:  How is the torque of such a rotating engine in microgravity compensated?  That's the one detail I don't recall being explained.  Two such engines, mounted in opposite directions might do it, but single-engine mode if one is shut down might require considerable thruster firing to maintain a stable vehicle attitude.  But I'd like to think a simple solution is available.

(edit: as pointed out in the specific IVF thread, there IS a simple solution, and it's just a matter of rotating the equipment PTO shaft in the opposite direction, rather than an inline coupling to the crankshaft.  I shoulda realized that.)

--Damon
« Last Edit: 04/20/2015 12:51 AM by Damon Hill »

Offline georgesowers

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Dr. Sowers,

Thanks for answering my earlier question on why Stainless for ACES tank. May I take a follow-up one step further?

You indicated that Stainless Balloon tanks had the cost / mass fraction advantage for the upper stage. So what tips the balance towards conventional Al tanks for the first stage? Cost? Ease of handling? Tooling? or will we see a return of a Stainless Balloon tank on the first stage?

Thanks again for taking the time.

I really like the special anodize job in the Vulcan videos and images. Any chance we will see that on the real Vulcan? Or will be the same boring copper coat we see on current Atlas's?

The trade of steel vs Al on the first stage was very close.  Mass fraction is not as important on the booster as it is on the upper stage.  a lot of passionate debate.  But we are staying with Al for Vulcan step 1.

Offline georgesowers

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Dr. Sowers,
Any chance the SRB's will be called Klingons?  ;)

Who knows?  But we have to be mindful of the heirs of Gene Roddenberry.  ;)

Offline georgesowers

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Hello Dr Sowers. My questions are about IVF.

IVF seems like such a win/win for both ULA and its customers I don't understand why it's been so difficult to find missions it can be tested on.  :(

Could it be tested in smaller parts (like thrusters, battery and engine for example) on different flights so your customers are more relaxed about having the whole package on a single flight?

Due to its size does it need a mission with a lot of excess capacity for it to be fitted in addition to the standard flight systems, just in case, or is it primarily customer nerves ?

All about money.  That being said, we are entering into flight qual of the thrusters and will fly them soon.  They have great utility by themselves allowing low cost upper stage disposal.  Also, we have a wide range of customers beginning to realize the benefits of IVF.  I'm optimistic we can get it deployed before ACES.

Offline georgesowers

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Thank you for answering all these questions.

I'm very impressed by your showing here.  I'm impressed that you were willing to come on here and answer every single question.  I'm impressed that the answers are thoughtful and substantive and not just marketing fluff.  And this is coming from a SpaceX fan.

I hope ULA appreciates what you're doing here.  I suspect I'm not the only one whose opinion of ULA has been raised.

Thanks!  It's great fun to talk about what I love with folks who are equally passionate. 

Offline georgesowers

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Dr. Sowers:

I'm extremely fascinated and impressed with the IVF design (why wasn't this addressed decades ago?) and the very smart implementation of an internal combustion engine, counter-intuitive as it may first appear.  (And it's blowing a lot of minds in this forum, even though online documentation explains it all.)

So, a question:  How is the torque of such a rotating engine in microgravity compensated?  That's the one detail I don't recall being explained.  Two such engines, mounted in opposite directions might do it, but single-engine mode if one is shut down might require considerable thruster firing to maintain a stable vehicle attitude.  But I'd like to think a simple solution is available.


--Damon

We haven't done a detailed analysis of disturbance forces and torques induced on the stage by the operation of IVF, but my gut is that they will be pretty small and easily compensated.  There aren't that many moving parts.

Offline georgesowers

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Ha!  I finally got ahead of you.  Helps to work on a weekend with access to beer!  OBTW, though the Dr. title is good for my ego, my name is George, or just G.

Online jg

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George,

There is a lot of interest in the IVF work; a q/a like this one with answers from Frank Zegler would be great if it can be arranged.  Having had the chance to talk to him about it last week, I'm extremely impressed and think that it would be great if up to date information can be shared, to the extent possible.  IVF is a game changer, as reusability will be (presuming SpaceX and/or you succeed).


Offline skater

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There was a mention of selecting the AR1 engine in 18 months if the Blue Origin engine isn't coming along as expected.  What impact would that have on first stage design?  Thanks!

Since AR-1 uses RP fuel, the first stage design would look a lot like Atlas V.

Thanks, Dr. Sowers.  I expected it would have some impact on tankage (although it sounds like it's rather likely you'll end up with the BE-4 Methane/LOX engine).  Thank you for being so open to a public forum like this - it's great to have the kind of access to the decision makers in this industry.

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