Author Topic: ULA and Boeing Unveil the Atlas V Configuration for the CST-100 Starliner  (Read 18359 times)

Online Chris Bergin

https://www.nasaspaceflight.com/2016/10/atlas-v-starliner-mitigate-aerodynamic-issues/

This goes back a while per L2 notes, but finally we have the confirmation and visually:

Presser:

United Launch Alliance and the Boeing Company Unveil the Atlas V Configuration for the CST-100 Starliner Crew Capsule

 

ULA’s Atlas V will Provide Safe and Reliable Transportation for Starliner to the International Space Station

 

 

Cape Canaveral Air Force Station, Fla. (Oct. 13, 2016) – United Launch Alliance (ULA) and The Boeing Company today unveiled an updated aerodynamic configuration of the Atlas V that will launch Boeing’s CST-100 Starliner capsule for NASA after encountering unique challenges with aerodynamic stability and loads.

This new configuration incorporates an aeroskirt aft of the spacecraft, extending the Starliner Service Module cylindrical surface to improve the aerodynamic characteristics of the integrated launch configuration and bring loads margins back to acceptable flight levels.

            “Through incredible coordination and continued innovative thinking, the collective team of NASA, Boeing and United Launch Alliance completed three wind tunnel tests in six months to investigate the aerodynamic stability of various configurations and to anchor our analytical predictions. Based on that information, we updated the configuration for the Atlas V Starliner integrated vehicle stack,” said Gary Wentz, ULA vice president of Human and Commercial Services. “This configuration is unique because it combines the Atlas V launch vehicle without a payload fairing with Boeing’s Starliner capsule, resulting in different aerodynamic interactions.”

The aeroskirt is a metallic orthogrid structure designed to be jettisoned for improved performance. In the unlikely event that an emergency occurs during boost phase of flight, the aeroskirt has venting provisions to control over-pressurization if the Starliner’s abort engines are fired. Fabrication of the aeroskirt is scheduled to begin this month at ULA’s factory in Decatur, Alabama, following completion of a Production Readiness Review.

"Our testing indicates the solution we chose will sufficiently smooth the air flow around the vehicle during ascent, ensuring crew safety and mission success," said John Mulholland, vice president and program manager of Boeing's Commercial Crew Program.

The ULA team completed the aeroskirt Preliminary Design Review earlier this month. The Atlas V with Starliner has a planned uncrewed flight test in 2018 with operational missions to follow.

“We look forward to our continued partnership with Boeing and NASA to ensure mission success and safety for American astronauts flying from U.S. soil on the Atlas V Starliner,” said Wentz.

            With more than a century of combined heritage, United Launch Alliance is the nation’s most experienced and reliable launch service provider. ULA has successfully delivered more than 110 satellites to orbit that provide critical capabilities for troops in the field, aid meteorologists in tracking severe weather, enable personal device-based GPS navigation and unlock the mysteries of our solar system.

            For more information on ULA, visit the ULA website at www.ulalaunch.com, or call the ULA Launch Hotline at 1-877-ULA-4321 (852-4321). Join the conversation at www.facebook.com/ulalaunch, twitter.com/ulalaunch and instagram.com/ulalaunch.

 

Offline Welsh Dragon

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Well, pretty it ain't, but if it does the trick, all is well.

Offline Rocket Science

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Hard to see any taper behind the skirt from the image... Looks a lot like a "pseudo" Apollo CM/SM now! :)
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Offline rocx

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Which Atlas V configuration is this? 411? 412?
Any day with a rocket landing is a fantastic day.

Online whitelancer64

Which Atlas V configuration is this? 411? 412?

422

2 SRBS and the Centaur upper stage will have two RL-10 engines.
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At last!  Time to update the NSF CG "Future Spacecraft Library"!

Offline Newton_V

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Which Atlas V configuration is this? 411? 412?

That is SRB2 you see in the pic, so by definition it has to be a 422 configuration (ant that it's CST).
The SRBs are always attached in their specific locations.  If you only could see SRB1 on the north side, then you wouldn't know if it was a 412, or 422 (for CST), or a 411, 421, or 431 (with the 4-m PLF).

(I realize you didn't know about the SRB locations)

Offline edkyle99

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
« Last Edit: 10/13/2016 03:53 PM by edkyle99 »

Offline Rocket Science

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
I wonder if there is a reverse taper upwards, as a stiffener, to the Centaur...
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Offline edkyle99

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
I wonder if there is a reverse taper upwards, as a stiffener, to the Centaur...
Maybe.  It would have to connect to the Centaur forward skirt where the 500-series Centaur load reactor connects.  There would also have to be provisions for Centaur venting, I think.

It is going to separate after staging, kind of like a payload fairing.  Another separation step added to the design.

 - Ed Kyle
« Last Edit: 10/13/2016 04:20 PM by edkyle99 »

Offline Rocket Science

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
I wonder if there is a reverse taper upwards, as a stiffener, to the Centaur...
Maybe.  It would have to connect to the Centaur forward skirt where the 500-series Centaur load reactor connects.  There would also have to be provisions for Centaur venting, I think.

It is going to separate after staging, kind of like a payload fairing.  Another separation step added to the design.

 - Ed Kyle
Yes, it is a very curious design... If I were the "chief designer" why not make it a trunk for un-pressurized cargo, but hey that's just me... ;D
« Last Edit: 10/13/2016 04:25 PM by Rocket Science »
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Offline woods170

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
The first major delay of CST-100 (of roughly six months), as announced by Boeing last May, was mostly caused by the need to do this "design patch" and fix an overweight problem.

And now, another slip of roughly six months because Boeing screwed up the lower dome of spacecraft number 2. Let's see, in the space of less than six months the first crewed mission of CST-100 has slipped almost a year.

Ouch...

Clearly, the Boeing way of doing things is not as beatific as some had claimed here.

Offline GWH


Offline Rocket Science

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New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488
Thanks for posting the video. It answer's the question about what the bottom of the skirt looks like... I'll quote Mr. Spock "crude but effective"... I guess... ???
« Last Edit: 10/13/2016 08:47 PM by Rocket Science »
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Offline AnimatorRob

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New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488

Wow. Kudos to Boeing for ponying up for top-shelf animation.
« Last Edit: 10/13/2016 09:18 PM by AnimatorRob »

Offline Star One

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
The first major delay of CST-100 (of roughly six months), as announced by Boeing last May, was mostly caused by the need to do this "design patch" and fix an overweight problem.

And now, another slip of roughly six months because Boeing screwed up the lower dome of spacecraft number 2. Let's see, in the space of less than six months the first crewed mission of CST-100 has slipped almost a year.

Ouch...

Clearly, the Boeing way of doing things is not as beatific as some had claimed here.

Nor is cheap points scoring welcome here.

Offline king1999

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New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488
Well, they call it "skirt" for a reason. The question is why didn't they do the same wind tunnel tests a few years earlier to uncover this issue and had time for a better design. This skirt is just dead weight.

Offline mfck

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New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488

Wow. Kudos to Boeing for ponying up for top-shelf animation.
My thoughts exactly. I doubt I've ever seen a render of such quality (judging mostly by the still frame). Moore's law, I guess... but still, somebody really wants it to be real.
« Last Edit: 10/13/2016 11:15 PM by mfck »

Offline mkent

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Ugh.  I can't wait for Vulcan.

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My thoughts exactly. I doubt I've ever seen a render of such quality (judging mostly by the still frame). Moore's law, I guess... but still, somebody really wants it to be real.

This appears to be the same company that did the earlier Starliner CG.  If so, they also did the Crew Dragon, Falcon Heavy, SLS 1B and DreamChaser Cargo animations!  (and years before that, Constellation and the first concepts of what would become F9-R!)

Offline Rocket Science

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New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488

Wow. Kudos to Boeing for ponying up for top-shelf animation.
My thoughts exactly. I doubt I've ever seen a render of such quality (judging mostly by the still frame). Moore's law, I guess... but still, somebody really wants it to be real.
The rendering is great, the subject's appearance now... meah... :o
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Offline GWH

Ugh.  I can't wait for Vulcan.

Might want to wait for Vulcan ACES before the stack looks proper.  This is with the old skirt but still... 
Credit to okan170 for this rendering.

Also won't ULA have switched over to the Orbital ATK solid boosters with the conical noses by the time Starliner flies?
« Last Edit: 10/14/2016 02:46 AM by GWH »

Offline Wolfram66

New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488

Wow. Kudos to Boeing for ponying up for top-shelf animation.
My thoughts exactly. I doubt I've ever seen a render of such quality (judging mostly by the still frame). Moore's law, I guess... but still, somebody really wants it to be real.

There appears that there is no boattail blending into the S2 fairing skirt

Offline woods170

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
The first major delay of CST-100 (of roughly six months), as announced by Boeing last May, was mostly caused by the need to do this "design patch" and fix an overweight problem.

And now, another slip of roughly six months because Boeing screwed up the lower dome of spacecraft number 2. Let's see, in the space of less than six months the first crewed mission of CST-100 has slipped almost a year.

Ouch...

Clearly, the Boeing way of doing things is not as beatific as some had claimed here.

Nor is cheap points scoring welcome here.
I was voicing my opinion. Which, in case you had failed to notice, is not prohibited in a discussion thread. And yeah, I was taking it out on those members here proclaiming "The Boeing way is better than the SpaceX way!". And yeah, you will also find posts here were I'm taking it out on members proclaiming "SpaceX is better than Boeing!" But again: you failed to notice this.

But I digress.
« Last Edit: 10/14/2016 07:06 AM by woods170 »

Offline mfck

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New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488

Wow. Kudos to Boeing for ponying up for top-shelf animation.
My thoughts exactly. I doubt I've ever seen a render of such quality (judging mostly by the still frame). Moore's law, I guess... but still, somebody really wants it to be real.
The rendering is great, the subject's appearance now... meah... :o

Sure. Meah is an understatement. It's ugly to a point where one starts to doubt its flight qualities

Offline SimonFD



New Boeing video, complete with the new skirt:

https://twitter.com/BoeingDefense/status/786643807810879488

Wow. Kudos to Boeing for ponying up for top-shelf animation.
My thoughts exactly. I doubt I've ever seen a render of such quality (judging mostly by the still frame). Moore's law, I guess... but still, somebody really wants it to be real.
The rendering is great, the subject's appearance now... meah... :o

Sure. Meah is an understatement. It's ugly to a point where one starts to doubt its flight qualities

'As long as it flies I don't think it matters what it looks like', I thought.

Then I watched the video...



Space is big! Really big! You just won't believe how vastly, hugely, mind- bogglingly big it is! I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space. Listen............

Offline Star One

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Here is a photo of a wind tunnel model.  You can see two SRMs. 

I can't understand why ULA and NASA refuse to show the base of the aeroskirt.  I doubt it is open, because hydrogen gas might accumulate, but since it extends down the side of the Centaur LH2 tank, I can't see how it could taper or close.

It seems to me an unsettling design patch, late in the game.

 - Ed Kyle
The first major delay of CST-100 (of roughly six months), as announced by Boeing last May, was mostly caused by the need to do this "design patch" and fix an overweight problem.

And now, another slip of roughly six months because Boeing screwed up the lower dome of spacecraft number 2. Let's see, in the space of less than six months the first crewed mission of CST-100 has slipped almost a year.

Ouch...

Clearly, the Boeing way of doing things is not as beatific as some had claimed here.

Nor is cheap points scoring welcome here.
I was voicing my opinion. Which, in case you had failed to notice, is not prohibited in a discussion thread. And yeah, I was taking it out on those members here proclaiming "The Boeing way is better than the SpaceX way!". And yeah, you will also find posts here were I'm taking it out on members proclaiming "SpaceX is better than Boeing!" But again: you failed to notice this.

But I digress.

That seems a rather strawman justification as I haven't noticed that many being that constructive towards Boeing in comparison to some other companies, and certainly not much in the way of baseless cheerleading for them, mostly it seems to slide towards criticism without any overly great attempt at balance.
« Last Edit: 10/14/2016 09:33 AM by Star One »

Offline zodiacchris

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Children, children, be excellent to each other!  ;)

Offline AncientU

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So now that the original engineering has proven so deficient, will there be a required in-flight abort? 
If not, why not.

(And the answer cannot be the same group engineered it away...)

Or maybe it can...
Quote
Even before Tuesday’s announcement, Boeing officials signaled that engineering challenges—particularly the crucial test of the crew emergency escape system—could upset flight schedules. The test escape system is vital for the project, because it is the only way astronauts can survive a rocket failure from before launch all the way to cutoff of the main engine during ascent. NASA has to sign off on the test results before crew transportation can begin.

Chris Ferguson, Boeing’s deputy program manager, told a space conference in Long Beach last month that a so-called emergency pad abort test, which blasts a stationary capsule off the launch pad, was slated for late 2017. But he said Boeing intended to use simulations to demonstrate that the emergency escape system will work later in the mission, when the rocket is climbing toward orbit.

“We’re pedaling as quickly as we can,” Mr, Ferguson told the conference, calling it “a very aggressive schedule.” He also said “we’ll fly when we’re ready.” If it ultimately “takes a couple of extra months” to certify a safe vehicle, he added, “then we’ll do just that” because “that’s what the country wants, and specifically what the astronauts want.”

http://www.wsj.com/articles/boeing-sees-costs-from-delayed-space-taxi-1476204375

Edit: added WSJ reference.
« Last Edit: 10/14/2016 01:31 PM by AncientU »
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Offline AncientU

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In the new configuration, the launch escape thrusters are inside of the skirt, it appears.
How that is going to relieve over-pressure on the Centaur?  Seems like it would amplify it.
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Offline Jim

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So now that the original engineering has proven so deficient, will there be a required in-flight abort? 


How is the "original engineering" been "has proven so deficient"?   


And also, quit with the snipes.
« Last Edit: 10/14/2016 01:54 PM by Jim »

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In the new configuration, the launch escape thrusters are inside of the skirt, it appears.
How that is going to relieve over-pressure on the Centaur?  Seems like it would amplify it.

By the time the launch escape thrusters activate, you would have stopped caring about the performance or survival of the Centaur stage, because the survival of the crew is at stake.
Any day with a rocket landing is a fantastic day.

Offline AncientU

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In the new configuration, the launch escape thrusters are inside of the skirt, it appears.
How that is going to relieve over-pressure on the Centaur?  Seems like it would amplify it.

By the time the launch escape thrusters activate, you would have stopped caring about the performance or survival of the Centaur stage, because the survival of the crew is at stake.

If you crush (detonate) the Centaur when the launch abort thrusters lite off, you could damage the thrusters, nozzles, or the heat shield (as discussed by a former head of engineering at ULA, moments before getting fired).  Maybe escape would still be successful; their in-flight demo will confirm... oh wait, they aren't doing an in-flight demo.
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Offline Hauerg

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So now that the original engineering has proven so deficient, will there be a required in-flight abort? 


How is the "original engineering" been "has proven so deficient"?   

...
Ahem, by redesigning the stack?

Offline muomega0

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In the new configuration, the launch escape thrusters are inside of the skirt, it appears.
How that is going to relieve over-pressure on the Centaur?  Seems like it would amplify it.
By the time the launch escape thrusters activate, you would have stopped caring about the performance or survival of the Centaur stage, because the survival of the crew is at stake.
If you crush (detonate) the Centaur when the launch abort thrusters lite off, you could damage the thrusters, nozzles, or the heat shield (as discussed by a former head of engineering at ULA, moments before getting fired).  Maybe escape would still be successful; their in-flight demo will confirm... oh wait, they aren't doing an in-flight demo.
Timing is everything....hardware in the loop testing?....so now one has to simulate the flight conditions..?

So now that the original engineering has proven so deficient, will there be a required in-flight abort? 
How is the "original engineering" been "has proven so deficient"?   
1) Solids and non common configurations

2) economics "10 flights to achieve 100M/ea"

3) multiple configurations and testing   (expendable and why certify a LV (Atlas with Solids) that will be retired and the new LV  with solids (Vulcan V0) will eventually replace the solids, but cannot be reused to reduce costs?)

Offline edkyle99

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Here's a quick and dirty estimate for the gross dimensions of this thing, derived from the ULA 400 series drawing.  I'm guessing about the aeroskirt interior support.  I'll try to improve this as more information becomes available.

 - Ed Kyle
« Last Edit: 10/14/2016 02:49 PM by edkyle99 »

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In the new configuration, the launch escape thrusters are inside of the skirt, it appears.
How that is going to relieve over-pressure on the Centaur?  Seems like it would amplify it.

By the time the launch escape thrusters activate, you would have stopped caring about the performance or survival of the Centaur stage, because the survival of the crew is at stake.

If you crush (detonate) the Centaur when the launch abort thrusters lite off, you could damage the thrusters, nozzles, or the heat shield (as discussed by a former head of engineering at ULA, moments before getting fired).  Maybe escape would still be successful; their in-flight demo will confirm... oh wait, they aren't doing an in-flight demo.

The escape thrusters were on the inside in the previous design.

Offline edkyle99

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The escape thrusters were on the inside in the previous design.
Yes, and I believe there were blow-out panels, or the suggestion of them, on the tapered adapter section below the thruster nozzles.  The new aeroskirt will likely have to have some type of blow out panels as well, not to mention accommodations for Centaur boil-off venting and for service tower umbilicals, etc..

 - Ed Kyle
« Last Edit: 10/14/2016 02:51 PM by edkyle99 »

Offline vapour_nudge

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket? 

Offline mfck

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
Sure, mini-skirts are a well established safety measure

Online TrevorMonty

In the new configuration, the launch escape thrusters are inside of the skirt, it appears.
How that is going to relieve over-pressure on the Centaur?  Seems like it would amplify it.

By the time the launch escape thrusters activate, you would have stopped caring about the performance or survival of the Centaur stage, because the survival of the crew is at stake.

If you crush (detonate) the Centaur when the launch abort thrusters lite off, you could damage the thrusters, nozzles, or the heat shield (as discussed by a former head of engineering at ULA, moments before getting fired).  Maybe escape would still be successful; their in-flight demo will confirm... oh wait, they aren't doing an in-flight demo.
As Elon pointed out after lastest mishap, any explosion on liquid fuel stage is fast fire not an explosion. By time Centuar fast fire caused by abort engines is a threat to capsule, the capsule would be well clear and accelerating.

For abort to happen, the LV will have detected an problem and signalled capsule. At same time LV would kill thrust, this may involve  blowing feed lines to engines. The NS demo was not totally realistic as the booster should've killed its thrust.

As for no inflight LAS test, the term "Test like you fly" comes to mind. I wondered if Boeing bosses would buy a car that's crash safety systems had never be tested. NB the LAS doesn't need a Atlas booster, can be any booster that will give Max Q.
« Last Edit: 10/14/2016 04:26 PM by TrevorMonty »

Offline Jim

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
Sure, mini-skirts are a well established safety measure

It doesn't doesn't decrease the reliability or safety of the vehicle.

Offline Galactic Penguin SST

That skirt somehow reminded me of the Delta II with the original 10 feet diameter fairing in the 1990s (ROSAT was launched on one of those). Certainly not elegant but I think that's not quite that ugly actually.  :P
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Offline edkyle99

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
Sure, mini-skirts are a well established safety measure

It doesn't doesn't decrease the reliability or safety of the vehicle.
It adds a separation event.  If the skirt doesn't separate, the ascent might have to be aborted (I'm supposing). 

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Offline AncientU

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
Sure, mini-skirts are a well established safety measure

It doesn't doesn't decrease the reliability or safety of the vehicle.

It is installed to increase the vehicle safety to an acceptable level for crew flights.
« Last Edit: 10/14/2016 06:53 PM by AncientU »
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Offline Jim

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
Sure, mini-skirts are a well established safety measure

It doesn't doesn't decrease the reliability or safety of the vehicle.

It is installed to increase the vehicle safety to an acceptable level for crew flights.

The point is that even if the skirt was not needed for aeroloads, it is benign and passive and doesn't detract the vehicle operation.

Offline Rocket Science

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That skirt somehow reminded me of the Delta II with the original 10 feet diameter fairing in the 1990s (ROSAT was launched on one of those). Certainly not elegant but I think that's not quite that ugly actually.  :P
I remember that! :)
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« Last Edit: 10/14/2016 08:29 PM by Rocket Science »
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Offline AncientU

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
Sure, mini-skirts are a well established safety measure

It doesn't doesn't decrease the reliability or safety of the vehicle.

It is installed to increase the vehicle safety to an acceptable level for crew flights.

The point is that even if the skirt was not needed for aeroloads, it is benign and passive and doesn't detract the vehicle operation.

The point is that it is needed to allow the vehicle to meet minimum safety standards
It therefore is an active, safety-related component that the vehicle cannot fly without.

It is not 'making a safe, reliable launch system safer.'
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Offline Khadgars

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
Sure, mini-skirts are a well established safety measure

It doesn't doesn't decrease the reliability or safety of the vehicle.

It is installed to increase the vehicle safety to an acceptable level for crew flights.

The point is that even if the skirt was not needed for aeroloads, it is benign and passive and doesn't detract the vehicle operation.

The point is that it is needed to allow the vehicle to meet minimum safety standards
It therefore is an active, safety-related component that the vehicle cannot fly without.

It is not 'making a safe, reliable launch system safer.'

You are splicing phrases to make your point.  The Atlas V stack is and has been demonstrated to be one of the (if not the most) reliable and safe vehicle flying today. Because they added a unique payload on top of said stack doesn't change that fact, even if it requires some tweaks to adapt to the payload.

Offline Jim

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The point is that it is needed to allow the vehicle to meet minimum safety standards
It therefore is an active, safety-related component that the vehicle cannot fly without.

It is not 'making a safe, reliable launch system safer.'

So what.  Again, what is your point in this whole discussion. 
It is not active and it does not reduce the reliability of the vehicle.  It is a the addition of simple structure. 
Much like the differences in aerodynamics of the SR-71 vs YF-12 which required ventral fins to be mounted under the fuselage and engine nacelles to maintain stability. 

If they added the skirt at the beginning like the 2nd RL10, we wouldn't be having this discussion
« Last Edit: 10/14/2016 10:04 PM by Jim »

Offline mfck

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The point is, it does not improve safty, it restores it. Maybe.
« Last Edit: 10/14/2016 10:24 PM by mfck »

Offline king1999

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At the minimum, with the skirt on, Starliner now no doubt will be referred as a "She" or "Her". Of course unless you are from Scotland.  :P

Offline Unobscured Vision

I think that as time goes on and more data is released we'll get more of an idea of how the changes will benefit the CST-Atlas configuration. ULA has probably made the right call in solving this problem, but it shouldn't have come to this ...

I'd like to see performance and aerodynamic data before giving the changes a Go/No-Go. I've gone on record elsewhere as being quite critical of this whole design, for a lot of reasons, but I'll keep it above-board and remain neutral for now.
Yep ... just ... yep.

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Seems to be a bit more testiness here than I favor. No need for sparring or scoring points. BETEO.
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Online Johnnyhinbos

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I'd just like to point out that this delay is an honest admission that what Boeing/ULA and SpaceX alike are trying to accomplish is amazingly difficult. We, as sideline spectators, tend to get worked up a bit strongly about our team (and come down hard on same said team when they don't meet our expectations).

Perhaps it might be a good time to reflect on the incredible challenges faced by these private entities and marvel at how they are developing solutions to overcome these hurtles.

Personally, I am amazed, impatient, infatuated, enamored, devastated, speechless, irate, and above all, star struck by what is happening  in my adult lifetime and absolutely can't wait to see what happens next.

So, I wish Boeing, ULA, SpaceX, BlueOrigin, Bigelow, Rocket Lab, NASA with SLS, the Chinese space agency, and the Russians all the best with your endeavors. What you're doing is amazing...
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Online Ronsmytheiii

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I think people here are overreacting, its just a simple answer to an engineering issue. No underlying technical issues, aesthetics aren't really that different.The only negative I can see is the schedule slip, but Boeing isn't alone in engineering issues slowing down first flight. This is just good old engineering at its finest.

Offline Jim

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The point is, it does not improve safty, it restores it. Maybe.


There is no maybe

Offline Jim

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I've gone on record elsewhere as being quite critical of this whole design, for a lot of reasons,

What are those reasons and what are they based on?
Please share because I doubt they would stand up
« Last Edit: 10/15/2016 12:26 PM by Jim »

Offline muomega0

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I think people here are overreacting, its just a simple answer to an engineering issue. No underlying technical issues,
Why did the US adopt a space policy to prevent Atlas/Delta from launching crew?  Besides being a convenient way to maintain excess, expensive launch capacity, did anyone think that solids and crew would not be mixed in the future rockets? Since Earth departure is a very small part of LOC....perhaps yes.

1) Solids and non common configurations
2) economics "10 flights to achieve 100M/ea"
3) multiple configurations and testing   (expendable and why certify a LV (Atlas with Solids) that will be retired and the new LV  with solids (Vulcan V0) will eventually replace the solids, but cannot be reused to reduce costs?)
Just stop, this is not a place to preach your crusade.   Those have nothing to do with the addition of the skirt.
On the positive side, it's his shortest post ever.
Links are added to reduce length.  Apologies ahead time... :D
--
The thread title does not contain the word 'skirt'...is there a location that narrowly focusses on this topic?

There are are some who think that LH2 would be the ideal fuel for BEO/abort while others support methane while others support solids from Earth...but it seems counterintuitive to Stifle Dissent, no?

The Atlas V stack is and has been demonstrated to be one of the (if not the most) reliable and safe vehicle flying today.
When was the last time a Centaur second stage with two RL10 engines with two SRBs flew, 5x2, 4x2?
Will a 422 fly cargo in the future and will the skirt remain for cargo as the SRBs burn for 88 seconds? 
Atlas Launches 2010-2019
Atlas Launches 1990-1999
Atlas Launches 2000-2009

USAF 45th Space Wing Study released in 2009 concluded that the Ares I capsule will not survive an abort between MET's of ~30 and 60 seconds.  Another conclusion is that it re-affirmed the predictive codes of the 1980s, where, to increase performance, solids were added to Titan.   Days after ESAS, and confirmed here, for example, about a year later Ares could not do the job because of LAS mass.  What are the range of times being studied for the destruct button in this 422 configuration?

That is why when Musk revisted Titan I with only one engine type, those who, even serendipitously, knew history, understood its merits.

I've gone on record elsewhere as being quite critical of this whole design, for a lot of reasons, but I'll keep it above-board and remain neutral for now.
Many many reasons to be both critical and supportive...
What this comes down to is how the short term certification rules are being met and the implications for long term.

Is the risk guaranteed to be under Y%, or just probably under Y% and what probability?--Note the former costs are humbling at best.   The only real answer is demonstrated reliability which is why cargo (dirt cheap propellant)/test flights really would help or just take the risk without all the costs until the LV is retired.  Will even one flight give any more confidence?

Offline Jim

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USAF 45th Space Wing Study released in 2009 concluded that the Ares I capsule will not survive an abort between MET's of ~30 and 60 seconds.  Another conclusion is that it re-affirmed the predictive codes of the 1980s, where, to increase performance, solids were added to Titan.   Days after ESAS, and confirmed here, for example, about a year later Ares could not do the job because of LAS mass.  What are the range of times being studied for the destruct button in this 422 configuration?

That is why when Musk revisted Titan I with only one engine type, those who, even serendipitously, knew history, understood its merits.



More mumble jumble nonsense and linking to your own posts

The Ares I study has nothing do with this vehicle.


Offline muomega0

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USAF 45th Space Wing Study released in 2009 concluded that the Ares I capsule will not survive an abort between MET's of ~30 and 60 seconds.  Another conclusion is that it re-affirmed the predictive codes of the 1980s, where, to increase performance, solids were added to Titan.   Days after ESAS, and confirmed here, for example, about a year later Ares could not do the job because of LAS mass.  What are the range of times being studied for the destruct button in this 422 configuration?

That is why when Musk revisted Titan I with only one engine type, those who, even serendipitously, knew history, understood its merits.



More mumble jumble nonsense and linking to your own posts

The Ares I study has nothing do with this vehicle.

Do you consult, if not, you may want to consider it!

The code using Titan Data was applied to Ares I.   Could it also be applied to Atlas?

A20 destruct at MET=40s, so we all look forward to understanding how the teams have address the steps to certification with a 4x2 configuration that last flew when?

Quote from: USAF45thSpaceWingStudy
Conclusions a) Re-Confirm Codes. Re-confirm predictive codes & values for solid propellant motor fragmentation, comparing results of the late-1980's joint NASA/DOE/INSRP Explosion Working Group (and related) analyses of solid propellant rocket debris (particularly applied to the Titan and NASA SRB's), and verifying that code accuracy continues into the later 1998 Titan A20 destruct at MET=40s.

Offline Jim

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The code using Titan Data was applied to Ares I.   Could it also be applied to Atlas?


No, not the same size solids.

Offline rayleighscatter

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Why did the US adopt a space policy to prevent Atlas/Delta from launching crew?  Besides being a convenient way to maintain excess, expensive launch capacity, did anyone think that solids and crew would not be mixed in the future rockets? Since Earth departure is a very small part of LOC....perhaps yes.
I left the linked portion of that quote because it is relevant as seen below.

Quote
NASA will development Crew LV derived from Space Shuttle solid boosters  20 to 30 mT class

So no, there appeared to be no intent to separate crew and solids.
« Last Edit: 10/15/2016 02:49 PM by rayleighscatter »

Offline muomega0

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Why did the US adopt a space policy to prevent Atlas/Delta from launching crew?  Besides being a convenient way to maintain excess, expensive launch capacity, did anyone think that solids and crew would not be mixed in the future rockets? Since Earth departure is a very small part of LOC....perhaps yes.

USAF 45th Space Wing Study released in 2009 concluded that the Ares I capsule will not survive an abort between MET's of ~30 and 60 seconds.  Another conclusion is that it re-affirmed the predictive codes of the 1980s, where, to increase performance, solids were added to Titan.   Days after ESAS, and confirmed here, for example, about a year later Ares could not do the job because of LAS mass.  What are the range of times being studied for the destruct button in this 422 configuration?

That is why when Musk revisted Titan I with only one engine type, those who, even serendipitously, knew history, understood its merits.
I left the linked portion of that quote because it is relevant as seen below.

Quote
NASA will development Crew LV derived from Space Shuttle solid boosters  20 to 30 mT class

So no, there appeared to be no intent to separate crew and solids.
An how did that work out..LAS mass crew larger than the capsule!

You also left out a very import part of the policy: 

Quote from: 2004SpacePolicy
Recognizing the schedule burdens placed on unmanned payloads launched using human rated systems, we understand that the DOD and NASA believe that separating human rated space exploration from unmanned payload launch will best achieve reliable and affordable assured access to space while maintaining our industrial base in both liquid and solid propulsion launch systems.

2. NASA will development Crew LV derived from Space Shuttle solid boosters  20 to 30 mT class

a)  each LV would all have their "separate" task-  e.g. keep everything separate to retain excess capacity
     Ares I for LEO crew, HLV for BEO, Atlas Delta for DOD, sats.....very very convenient indeed....

b) Separating human rated space exploration from unmanned payload launch will achieve reliable and affordable space access  (e.g. no crew on Atlas/Delta in 2004...Falcon did not exist)
        - Falcon likely will show that common configurations without 3 engine product lines and no solids is one affordable and reliable way to fly Class A cargo and Crew...
        - 10 flights to reach $100M/flight with Vulcan...
   
c)  Ares I could not loft crew safely, so much for Crew LV with shuttle solids.. so how about that 422/CST-100?

Yes less energy in the Atlas solids creates a smaller debris field volume but really the same physics (F=ma include drag, etc) ....at what time can they explode wrt chute deployment?  Why even bother with all of this?  Oops i forgot, the USG cannot tell the private sector what to do (too many regulations and all) with taxpayer funds.
« Last Edit: 10/15/2016 04:18 PM by muomega0 »

Offline Jim

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2004SpacePolicy

No need to keep quoting this.  It has been outdated longer ( 8 years) than it was in affect (4years) That was under the previous administration and and no longer relevant.   


        - Falcon likely will show that common configurations without 3 engine product lines and no solids is one affordable and reliable way to fly Class A cargo and Crew...
       

No, it is hasn't


   
c)  Ares I could not loft crew safely, so much for Crew LV with shuttle solids.. so how about that 422/CST-100?

Yes less energy in the Atlas solids creates a smaller debris field volume but really the same physics (F=ma include drag, etc) ....at what time can they explode wrt chute deployment? 

Not even close to the same thing.
« Last Edit: 10/15/2016 04:25 PM by Jim »

Offline vapour_nudge

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Why is the addition of the skirt such a problem. Heck, it's not much and is short. I'd call it a mini-skirt myself. They're just making a safe, reliable launch system safer. Wouldn't you feel safer going up on an Atlas than any other rocket?
What I meant here was there's a big deal being made of this yet if I were an astronaut heading to space and the engineers said we need to add a skirt, I'd take it as a positive. They found something of concern and dealt with it, even though it adds cost, mass and maybe delay.
Full credit to them please
As for making the LV safer, the mini skirt reduces loads on the Centaur making the LV safer when this particular payload is launched.  You must expect changed conditions if you do away with the fairing. What would you expect?
The various kinds of Atlas vehicles haven't had an outright failure causing total loss of a payload since 93. That's got to count for something. Right now I myself wouldn't trust the F9 or Antares with the cheapest of payloads. With time, I expect I'll change my mind about that if they begin to show some reliability. I would have felt the same about Atlas back in 93. 23 years helps to allay my fears
I hope none of them suffer another launch failure

Offline edkyle99

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As for making the LV safer, the mini skirt reduces loads on the Centaur making the LV safer when this particular payload is launched.  You must expect changed conditions if you do away with the fairing. What would you expect?
In my view, a better solution would have been to properly position the payload to begin with, allowing a longer tapered fairing (or whatever solution solved the problem) that would have prevented the aero-loading in the first place.  This aeroskirt is a tacked-on fix to save schedule (re-positioning the payload would have meant rebuilding the service tower and redesigning umbilicals) for a problem that shouldn't even exist.

 - Ed Kyle
« Last Edit: 10/16/2016 02:37 PM by edkyle99 »

Online sewebster

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Is there an extra separation event for the skirt, or was there going to be something similar anyway for some other fairing/adapter?

Offline woods170

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As for making the LV safer, the mini skirt reduces loads on the Centaur making the LV safer when this particular payload is launched.  You must expect changed conditions if you do away with the fairing. What would you expect?
In my view, a better solution would have been to properly position the payload to begin with, allowing a longer tapered fairing (or whatever solution solved the problem) that would have prevented the aero-loading in the first place.  This aeroskirt is a tacked-on fix to save schedule (re-positioning the payload would have meant rebuilding the service tower and redesigning umbilicals) for a problem that shouldn't even exist.

 - Ed Kyle
Pardon me? Should not exist? This little problem with CST-100 is not the first time (and IMO it will not be the last either) that a given stack-design turns out to have aero-acoustic trouble identified late in the game.

Offline edkyle99

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Is there an extra separation event for the skirt, or was there going to be something similar anyway for some other fairing/adapter?
They've added a separation event for this skirt.  It likely will occur around the time that most Atlas 5 payload fairings separate, I'm supposing.

 - Ed Kyle

Offline edkyle99

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In my view, a better solution would have been to properly position the payload to begin with, allowing a longer tapered fairing (or whatever solution solved the problem) that would have prevented the aero-loading in the first place.  This aeroskirt is a tacked-on fix to save schedule (re-positioning the payload would have meant rebuilding the service tower and redesigning umbilicals) for a problem that shouldn't even exist.

 - Ed Kyle
Pardon me? Should not exist? This little problem with CST-100 is not the first time (and IMO it will not be the last either) that a given stack-design turns out to have aero-acoustic trouble identified late in the game.
I can't think of an example from any past vehicle that required such a substantial, and atypical, add-on to the design.

 - Ed Kyle

Offline Jim

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there are some with Orion

Offline edkyle99

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there are some with Orion
Orion itself, with the SM fairings, changes in SM design, etc, but I don't think that SLS itself has seen substantial changes - at least not visible hardware changes.

 - Ed Kyle

Offline sdsds

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If the skirt is being built by ULA does that make it part of the launch vehicle rather than part of the spacecraft?
-- sdsds --

Offline GWH

Quote from Tory Bruno on reddit regarding skirt:
"The capsule is optimized for its in space mission. The skirt is not really there to make a smooth aerodynamic profile. Its primary job is to move the reattachment of the shock further down the rocket so it will not overload Centaur's soda can thin skin"

https://www.reddit.com/r/ula/comments/57a382/united_launch_alliance_and_the_boeing_company/d8sh6qy?context=3
« Last Edit: 10/17/2016 04:29 PM by GWH »

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there are some with Orion
Orion itself, with the SM fairings, changes in SM design, etc, but I don't think that SLS itself has seen substantial changes - at least not visible hardware changes.

 - Ed Kyle
You're looking at the difference between designing a spacecraft to go on top of a pre-existing launch vehicle design that is outside of the original use concept vs contemporaneous spacecraft and launch vehicle design.

Offline edkyle99

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You're looking at the difference between designing a spacecraft to go on top of a pre-existing launch vehicle design that is outside of the original use concept vs contemporaneous spacecraft and launch vehicle design.
My question is, why did the original design of CST-100 with the stumpy adapter pass muster?  They wind tunnel tested it some time back and it was made the baseline design.  What changed, and why?

 - Ed Kyle

Offline Jim

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You're looking at the difference between designing a spacecraft to go on top of a pre-existing launch vehicle design that is outside of the original use concept vs contemporaneous spacecraft and launch vehicle design.
My question is, why did the original design of CST-100 with the stumpy adapter pass muster?  They wind tunnel tested it some time back and it was made the baseline design.  What changed, and why?

 - Ed Kyle

We don't know if it passed muster.  Nothing could have changed, just more testing was done

Offline JasonAW3

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USAF 45th Space Wing Study released in 2009 concluded that the Ares I capsule will not survive an abort between MET's of ~30 and 60 seconds.  Another conclusion is that it re-affirmed the predictive codes of the 1980s, where, to increase performance, solids were added to Titan.   Days after ESAS, and confirmed here, for example, about a year later Ares could not do the job because of LAS mass.  What are the range of times being studied for the destruct button in this 422 configuration?

That is why when Musk revisted Titan I with only one engine type, those who, even serendipitously, knew history, understood its merits.



More mumble jumble nonsense and linking to your own posts

The Ares I study has nothing do with this vehicle.

Jim, correct me if I'm wrong, but wasn't the CST-100 supposed to be designed as a sort of "Orion Lite"?

      Primarily for "shuttle" use to and from the ISS or any other manned facilities or craft that was put in orbit.  While it shared many of the basic lines of the Orion, but never really intended to be used beyond LEO

      Also, my impression was that it was supposed to be a sort of proof of principle craft, mostly to confirm the Orion design and be upgraded as it went.  Sort of a Block I, II, and then III evolution into an Orion-like craft.
My God!  It's full of universes!

Offline sdsds

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My question is, why did the original design of CST-100 with the stumpy adapter pass muster?  They wind tunnel tested it some time back and it was made the baseline design.  What changed, and why?

Maybe the use of the 422 configuration gives them plenty of performance margin, so ULA was free to address a concern they had about Centaur (even though it involved a low probability failure mode) in a way that -- by their calculations -- increased the overall likelihood of mission success.

In that context the first questions to ask might be:

- When was the concern raised?
- Who raised the concern and what response did it get initially?
- Was a decision to proceed without the skirt ever made, and then reversed?
-- sdsds --

Offline SWGlassPit

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Pure speculation:

Perhaps the trajectory design changed after the original OML was baselined, which would have resulted in a different velocity/altitude profile, meaning different shock wave behavior.  If the issue involved is shock wave reattachment, then we're not talking a simple analysis, and I'm not surprised that something like this would show up later in the game.

Wind tunnel testing is helpful, but scaling factors mean that you can't test everything exactly like it will be on the full size vehicle.  Ultimately, some things are different.  To fill in the gaps, you have to do CFD analyses, which are labor intensive and take time.

Offline woods170

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You're looking at the difference between designing a spacecraft to go on top of a pre-existing launch vehicle design that is outside of the original use concept vs contemporaneous spacecraft and launch vehicle design.
My question is, why did the original design of CST-100 with the stumpy adapter pass muster?  They wind tunnel tested it some time back and it was made the baseline design.  What changed, and why?

 - Ed Kyle

We don't know if it passed muster.  Nothing could have changed, just more testing was done
We know that multiple configurations of the stack have been tested in the wind-tunnel. The one shown in the image up-thread was the original configuration with no solids on the stack. That quickly changed to a configuration with one solid on the stack followed by two solids on the stack. Somewhere in-between CST-100 gained a perforated ring around the SM circumference for aerodynamic stability and finally the skirt was added to have the shockwave re-attach to the stack well below Centaur.
So yeah, likely much more testing done once the first couple of rounds were complete.

I'm not so much troubled by the found aerodynamic stability and aero-acoustic issues, but by the overweight issue. How did Boeing manage to get the spacecraft so much heavier that it required not one but two additional solids on Atlas 5? Haven't heard much details about that.
« Last Edit: 10/18/2016 07:21 AM by woods170 »

Offline SWGlassPit

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Mass issues are common in aerospace.  Even Shuttle had them.  When you design a new vehicle from the ground up, you estimate as best you can, and you include a growth allowance to account for things you haven't designed yet.  You design a big-picture concept, you do some analysis, you refine details, you do more analysis, you add more detailed design, lather, rinse, repeat.

The problem is that every little screw, every little threaded insert, every inch of wire, every wire clip, every thousandth of an inch of wall thickness has mass, and it all adds up.  Now, were your estimates three years ago good enough?  Was your mass growth allowance enough?  What if you identified a problem late in the game that required a redesign?  Is it mass neutral?

Don't forget also that you have to make design trades throughout the development life cycle.  A big one fighting against mass is cost.  Lighter weight components are more expensive to design.  They are more expensive to analyze.  They are more expensive to manufacture.  Decisions have to be made based on these mass-cost trades, but the information you have early in the design stage is different from the information you have later on, so which fixed budget do you blow, your fiscal budget or your mass budget?

Offline SgtPoivre

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Mass issues are common in aerospace.  Even Shuttle had them.  When you design a new vehicle from the ground up, you estimate as best you can, and you include a growth allowance to account for things you haven't designed yet.  You design a big-picture concept, you do some analysis, you refine details, you do more analysis, you add more detailed design, lather, rinse, repeat.

The problem is that every little screw, every little threaded insert, every inch of wire, every wire clip, every thousandth of an inch of wall thickness has mass, and it all adds up.  Now, were your estimates three years ago good enough?  Was your mass growth allowance enough?  What if you identified a problem late in the game that required a redesign?  Is it mass neutral?

Don't forget also that you have to make design trades throughout the development life cycle.  A big one fighting against mass is cost.  Lighter weight components are more expensive to design.  They are more expensive to analyze.  They are more expensive to manufacture.  Decisions have to be made based on these mass-cost trades, but the information you have early in the design stage is different from the information you have later on, so which fixed budget do you blow, your fiscal budget or your mass budget?
Also in these early design phases there is a huge pressure to "sell" your concepts and consequently to take optimistic assumptions and minimize your mass margins.
As most conceptual design remain only paper this is usually not an issue!
« Last Edit: 10/18/2016 05:39 PM by SgtPoivre »

Online Lars-J

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Mass issues are common in aerospace.  Even Shuttle had them.  When you design a new vehicle from the ground up, you estimate as best you can, and you include a growth allowance to account for things you haven't designed yet.  You design a big-picture concept, you do some analysis, you refine details, you do more analysis, you add more detailed design, lather, rinse, repeat.

The problem is that every little screw, every little threaded insert, every inch of wire, every wire clip, every thousandth of an inch of wall thickness has mass, and it all adds up.  Now, were your estimates three years ago good enough?  Was your mass growth allowance enough?  What if you identified a problem late in the game that required a redesign?  Is it mass neutral?

We all know this (or most of us do) - but this is why you always design with mass margins. Clearly something out of the ordinary must have happened here to require *two* solid boosters instead of zero.

And those added booster's aren't "free", they do add to the launch cost and decrease the safety by some amount. Boeing seems happy with the tradeoffs, it seems.
« Last Edit: 10/18/2016 06:44 PM by Lars-J »

Offline SWGlassPit

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We all know this (or most of us do) - but this is why you always design with mass margins. Clearly something out of the ordinary must have happened here to require *two* solid boosters instead of zero.

And those added booster's aren't "free", they do add to the launch cost and decrease the safety by some amount. Boeing seems happy with the tradeoffs, it seems.

Ultimately, you have to decide what the mass growth allowance is at the beginning of your project.  You have to pick a number, and in the aerospace world, that number unfortunately can't be very big.  In a perfect world, that number is enough.  Things happen during design/analysis cycles.  Surprises show up.  Engineers aren't clairvoyant.

Offline arachnitect

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I can't remember CST ever being "officially" on Atlas 401/402. When those concepts were going around, they were also circulating artwork with CST on Delta IV M+ and Falcon 9.

I think CST was on 412 when the ULA/Boeing partnership was formalized, and the switch to 422 came not long afterwards.

Offline vapour_nudge

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I can't remember CST ever being "officially" on Atlas 401/402. When those concepts were going around, they were also circulating artwork with CST on Delta IV M+ and Falcon 9.

I think CST was on 412 when the ULA/Boeing partnership was formalized, and the switch to 422 came not long afterwards.
From the complete opposite perspective, perhaps that played a big part in the choice of the Atlas. If they went with the F9, they can't increase mass past a point. You can add an extra solid or even two to a 412 & get a 422 or 432. Delta would need two or four. The Atlas can be tailored somewhat if mass increases. A bonus over the other LVs
IIRC the Atlas OSIRIS-REx mission started with a 401 & grew to a 411
« Last Edit: 10/19/2016 02:08 AM by vapour_nudge »

Online Lars-J

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I can't remember CST ever being "officially" on Atlas 401/402. When those concepts were going around, they were also circulating artwork with CST on Delta IV M+ and Falcon 9.

I think CST was on 412 when the ULA/Boeing partnership was formalized, and the switch to 422 came not long afterwards.
From the complete opposite perspective, perhaps that played a big part in the choice of the Atlas. If they went with the F9, they can't increase mass past a point. You can add an extra solid or even two to a 412 & get a 422 or 432.

Little did they know at the time that F9 v1.1 and then v1.2 (and soon v1.3?) would appear...  ;D But yes, you do have a point, "dial-a-rocket" buys you flexibility.

Offline muomega0

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I can't remember CST ever being "officially" on Atlas 401/402. When those concepts were going around, they were also circulating artwork with CST on Delta IV M+ and Falcon 9.

I think CST was on 412 when the ULA/Boeing partnership was formalized, and the switch to 422 came not long afterwards.
it was unlikely that the 0 SRB version would fly a capsule because of launch capacity, TMK.

Atlas Generic Lift Capacity              the Apollo CM was 5,557kg       
401    411   421    431                    Wiki list Orion at 10,387
4750 5950 6890 7700 (kg)

Edit:  The wiki page is wrong.  The two engine Atlas V has *not* flown.  NROL-35 -->541

Centaur_(rocket_stage)
Quote from: centaurwiki
The Atlas V rocket currently uses the Common Centaur variant.[10] In 2014, on the NROL-35 mission, Atlas V's Common Centaur first flew in a reengined configuration with an RL10-C-1 replacing its previous RL10-A-4-2. This engine is meant to be common between Centaur and the Delta Cryogenic Second Stage to reduce costs.[11][12] RL10-A-4-2 will continue to be used on some future flights. Atlas V launches using the Dual Engine Centaur configuration must use RL10-A-4-2 because the new engine is too wide to accommodate two side-by-side.[12] To date, all Atlas V launches have used the Single Engine Centaur variant, however CST-100 Starliner and Dream Chaser missions will require the dual engine variant, because it allows a "flatter" trajectory safer for aborts.
As on Titan-Centaur, Atlas V 500 launches encapsulate the upper stage inside the payload fairing, to reduce aerodynamic loads. Atlas V 400 flights carry the fairing on top of Centaur, exposing it to the air.

Adding margin(SRBs) helps to obtain future 'market' share. 

"The baseline, at least for NASA missions, is two flights a year for crew,"
said John Mulholland, vice president and program manager of commercial programs at Boeing Space Exploration. "So augmenting that plan with some cargo missions, or extending crew missions beyond NASA, will be important for us and will help drive the overall price down to get that efficiency of scale.

Inside the crew cabin, though, the displays, seats and life support system will be removed and replaced with a cargo pallet able to handle at least 2,500 kg (5,500 lb.) of food, clothing and hardware for the orbiting outpost."

Solids are common with Vulcan v0, so the efforts are more aligned with the current and future LVs, not to mention Cislunar1000.   NASA gets shuttle derived SLS and the to be retired Atlas....
« Last Edit: 10/19/2016 06:58 PM by muomega0 »

Offline Welsh Dragon

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The two engine Centaur first flew in 2014.  All previous launches were the single engine variant.
Incorrect. The majority of Centaurs were two engine flights, starting all the way back in the 60s. The single engine model first flew on Atlas III, in 2000 (?). If you are talking about Atlas V Centaurs, all have been single engine.

Offline muomega0

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The two engine Centaur first flew in 2014.  All previous launches were the single engine variant.
Incorrect. The majority of Centaurs were two engine flights, starting all the way back in the 60s. The single engine model first flew on Atlas III, in 2000 (?). If you are talking about Atlas V Centaurs, all have been single engine.
Yes, many two engine Centaurs!  Sorry for the confusion.  The wiki page incorrectly states two engine Atlas V flew.   Thanks.
needed to add Atlas V....typed too quick...


The two engine {Atlas V reengined} Centaur first flew in 2014.  All previous {Atlas V }launches were the single engine variant.
Quote from: centaurwiki
The Atlas V rocket currently uses the Common Centaur variant.[10] In 2014, on the NROL-35 mission, Atlas V's Common Centaur first flew in a reengined configuration with an RL10-C-1 replacing its previous RL10-A-4-2. This engine is meant to be common between Centaur and the Delta Cryogenic Second Stage to reduce costs.[11][12] RL10-A-4-2 will continue to be used on some future flights. Atlas V launches using the Dual Engine Centaur configuration must use RL10-A-4-2 because the new engine is too wide to accommodate two side-by-side.[12] To date, all Atlas V launches have used the Single Engine Centaur variant, however CST-100 Starliner and Dream Chaser missions will require the dual engine variant, because it allows a "flatter" trajectory safer for aborts.
As on Titan-Centaur, Atlas V 500 launches encapsulate the upper stage inside the payload fairing, to reduce aerodynamic loads. Atlas V 400 flights carry the fairing on top of Centaur, exposing it to the air.

NASA gets shuttle derived SLS and the to be retired Atlas....

Wrong like most of your posts
Atlas V has yet to fly dual engines. The  Common Centaur variant is a single engine.  All Atlas Centaurs, Atlas I's and Atlas II's had dual engines.  The single engine Centaurs were introduced during Atlas III flights and all Atlas V's are single engine to this point.

And NASA does not get Atlas
Atlas V has yet to fly dual engines.   Got it.    That's not a good thing, right?
When was the last time any dual engine Atlas flew?

True..NASA does not *get* Atlas (nor Vulcan) mixing solids and crew....The reason is that it would require a substantial number of flights to test all the possible flight conditions and its not worth the effort given that LOC is so small during ascent *and* the LV will be retired.   Simply redesign Vulcan v0 without solids and start on the path towards reuse, and only certify Vulcan, not Atlas.   My guess is that ULA would jump at the chance.., no?  Oh..I see now...Vulcan has to have solids so it 'looks like'  Atlas.  Bravo. 

BTW.  Corrections always welcome....

Offline Jim

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Atlas V has yet to fly dual engines.   Got it.    That's not a good thing, right?
When was the last time any dual engine Atlas flew?

True..NASA does not *get* Atlas (nor Vulcan) mixing solids and crew....The reason is that it would require a substantial number of flights to test all the possible flight conditions and its not worth the effort given that LOC is so small during ascent *and* the LV will be retired.   Simply redesign Vulcan v0 without solids and start on the path towards reuse, and only certify Vulcan, not Atlas.   My guess is that ULA would jump at the chance.., no?  Oh..I see now...Vulcan has to have solids so it 'looks like'  Atlas.  Bravo. 

BTW.  Corrections always welcome....

Again, all wrong. and what is your point?

Flying dual engines is not a big deal.  2004 was the last time they flew
There is no need to test all possible flight conditions.  It has never been done for any vehicle, manned or unmanned.
There is no issue with mixing crew and solids
There is no sense in only certifying Vulcan, not Atlas since Atlas will be flying crew for many years before Vulcan is available
and finally, Vulcan doesn't need solids for CST-100
« Last Edit: 10/19/2016 08:04 PM by Jim »

Online Lar

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let's all be excellent to each other.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline FutureSpaceTourist

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Quote
Hardware!  Structural test article for #Starliner #Atlas LV adapter

https://twitter.com/torybruno/status/861615045729439744

Offline FutureSpaceTourist

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Hardware!  Structural test article for #Starliner #Atlas LV adapter

https://twitter.com/torybruno/status/861615045729439744

Quote
Great hardware designed by @ulalaunch engineer Ed Walton and built by our excellent Decatur facility!
CC: @barbegan13

https://twitter.com/tylerrogers82/status/861625539114618880

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