Author Topic: Commercial Crew - Discussion Thread 1  (Read 640898 times)

Offline Oli

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #880 on: 01/21/2017 05:17 pm »
I doubt the LAS can rely on the engines being properly shut down, solid or liquid. The Saturn V did not have solids anyway.

Why?  Per the argument in this post, it appears to me that engine shut-down was envisioned for Apollo-Saturn aborts.  Though I can't find it now, there is also a paper from circa 1968 suggesting that on of the Saturn V's engines might need to be kept running during an abort, because shutting down all engines could lead to break-up of the stack.

I'm sure it was envisioned, but did the LAS rely on it? The question is, what is the worst case scenario the LAS is designed for?

As I said, it's ~17g for the Apollo LAS despite the lack of solids.

Offline Robotbeat

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #881 on: 01/21/2017 05:26 pm »
With small solids, it's easy to get very high acceleration, so you might as well do it. And yes, it is reasonable to rely on cutting the engines, though 5-6 gees is still enough without that.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Proponent

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #882 on: 01/22/2017 07:09 pm »
I doubt the LAS can rely on the engines being properly shut down, solid or liquid. The Saturn V did not have solids anyway.

Why?  Per the argument in this post, it appears to me that engine shut-down was envisioned for Apollo-Saturn aborts.  Though I can't find it now, there is also a paper from circa 1968 suggesting that on of the Saturn V's engines might need to be kept running during an abort, because shutting down all engines could lead to break-up of the stack.

I'm sure it was envisioned, but did the LAS rely on it? The question is, what is the worst case scenario the LAS is designed for?

As I said, it's ~17g for the Apollo LAS despite the lack of solids.

The analysis I refer to identifies the assumption that the launch vehicle flies on at constant velocity after the abort is triggered as a conservative assumption.  The assumption would not be conservative if the launch vehicle were expected to remain under power.  Shutting the engines down requires only closing a valve.  If that can't be taken for granted, then other aspects of the abort procedure are highly questionable.

Offline Space Ghost 1962

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #883 on: 01/22/2017 09:07 pm »
In practical terms the rocket is not that different for aborts from a non solid augmented one.
Presuming FTS works on the solids too BEFORE crew escape. Duh.

A liquid only vehicle does not have that critical dependency. And remember ... 2x for each solid (e.g. multiplicative not additive).

Offline baldusi

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #884 on: 01/22/2017 10:09 pm »
In practical terms the rocket is not that different for aborts from a non solid augmented one.
Presuming FTS works on the solids too BEFORE crew escape. Duh.

A liquid only vehicle does not have that critical dependency. And remember ... 2x for each solid (e.g. multiplicative not additive).
I don't think they would activate the FTS until the LAS activates and the capsule clears the conic volume of possible debris. In fact, the safest place for the solids to be until the capsule is safely away, it's probably to still be attached to the Atlas V stack.

Offline Space Ghost 1962

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #885 on: 01/23/2017 12:35 am »
In practical terms the rocket is not that different for aborts from a non solid augmented one.
Presuming FTS works on the solids too BEFORE crew escape. Duh.

A liquid only vehicle does not have that critical dependency. And remember ... 2x for each solid (e.g. multiplicative not additive).
I don't think they would activate the FTS until the LAS activates and the capsule clears the conic volume of possible debris. In fact, the safest place for the solids to be until the capsule is safely away, it's probably to still be attached to the Atlas V stack.
Agreed. However ...

If your LRE detonates and fractures the thrust structure, the solids rip free and become potential IP's of the capsule ...

Offline woods170

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #886 on: 01/23/2017 06:42 am »
In practical terms the rocket is not that different for aborts from a non solid augmented one.
Presuming FTS works on the solids too BEFORE crew escape. Duh.

A liquid only vehicle does not have that critical dependency. And remember ... 2x for each solid (e.g. multiplicative not additive).
Carefull there please.
Even the slightest suggestion that FTS would possibly not work will invoke the wrath of favourite concise-answer-man.

Offline russianhalo117

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #887 on: 01/23/2017 05:16 pm »
In practical terms the rocket is not that different for aborts from a non solid augmented one.
Presuming FTS works on the solids too BEFORE crew escape. Duh.

A liquid only vehicle does not have that critical dependency. And remember ... 2x for each solid (e.g. multiplicative not additive).
Carefull there please.
Even the slightest suggestion that FTS would possibly not work will invoke the wrath of favourite concise-answer-man.
That is a Jim reference right??

Offline Oli

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #888 on: 01/23/2017 06:23 pm »
I doubt the LAS can rely on the engines being properly shut down, solid or liquid. The Saturn V did not have solids anyway.

Why?  Per the argument in this post, it appears to me that engine shut-down was envisioned for Apollo-Saturn aborts.  Though I can't find it now, there is also a paper from circa 1968 suggesting that on of the Saturn V's engines might need to be kept running during an abort, because shutting down all engines could lead to break-up of the stack.

I'm sure it was envisioned, but did the LAS rely on it? The question is, what is the worst case scenario the LAS is designed for?

As I said, it's ~17g for the Apollo LAS despite the lack of solids.

The analysis I refer to identifies the assumption that the launch vehicle flies on at constant velocity after the abort is triggered as a conservative assumption.  The assumption would not be conservative if the launch vehicle were expected to remain under power.  Shutting the engines down requires only closing a valve.  If that can't be taken for granted, then other aspects of the abort procedure are highly questionable.

Thanks, I did not notice the link in your previous post.

Still, does it matter? The time until the shockwave of the explosion hits the CM, which is the relevant parameter in the document you refer to, should be the same time regardless of whether the rocket behind it continues to accelerate.
« Last Edit: 01/23/2017 06:24 pm by Oli »

Offline Space Ghost 1962

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #889 on: 01/23/2017 07:29 pm »
In practical terms the rocket is not that different for aborts from a non solid augmented one.
Presuming FTS works on the solids too BEFORE crew escape. Duh.

A liquid only vehicle does not have that critical dependency. And remember ... 2x for each solid (e.g. multiplicative not additive).
Carefull there please.
Even the slightest suggestion that FTS would possibly not work will invoke the wrath of favourite concise-answer-man.
That is a Jim reference right??
Of course it is.

But he's also as wary as anyone of any propulsion system that can't be shutdown. As anyone wise would be.

The two best things about Atlas solids are 1)limited burn time and 2)monolithic construction. So your risk is contained, but not eliminated.

My issue with the post that triggered this exchange was specifically the reference to "as a non solid augmented one". That was clearly going too far.

And before a red herring starts, yes you can thrust terminate a solid with ports, but that is not the same thing as a LRE - an LRE you have to work to keep running, withdraw that work and it'll stop (hopefully w/o additional surprise), while a solid will always "burn" regardless. That fact makes them endemically risky where the tender flesh of the H in HSF is concerned.

Online gongora

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #890 on: 02/02/2017 08:25 pm »
Wall Street Journal: Congressional Investigators Warn of SpaceX Rocket Defects
Quote
The Government Accountability Office’s preliminary findings reveal a pattern of problems with turbine blades that pump fuel into rocket engines, these officials said. The final GAO report, scheduled to be released in coming weeks, is slated to be the first public identification of one of the most serious defects affecting Falcon 9 rockets.
...
cracks continued to be found during tests as recently as September 2016, Robert Lightfoot, NASA’s acting administrator, confirmed in an interview with The Wall Street Journal earlier this week.

The article also mentions a few other red flags for the commercial crew schedule, such as frequent Falcon 9 changes and Boeing parachute testing.  Will be interesting to read the GAO report when it comes out.

Offline yg1968

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #891 on: 02/08/2017 02:44 am »
From these numbers, you then get to $1.1B for SpaceX's 6 post-certification missions (excluding cargo) by adding $58M x 12 missions x 4 seats x $2.6B/$6.8B = $1.1B. So for SpaceX you would get a price of approximately $46M per seat ($1.1B /6 missions / 4 seats =$44M). An easier way to get to that price per seat number is through this equation: $58M x 2 seats (one for each of the providers) x $2.6B/$6.8B=$44M.

For Boeing, you would get $1.7B for six post-certification missions ($58M x 12 missions x 4 seats x $4.2B/$6.8B = $1.7B). You would then divide that $1.7B by 6 missions and by 4 seats which gives you approximately $72M per seat. An easier way to get to that price per seat number is through this equation: $58M x 2 seats x $4.2B/$6.8B=$72M.

P.S. These numbers assume that the ratio of the price of the post-certifications missions (without cargo) over the total value of the CCtCap contract is similar for both SpaceX and Boeing. This may not be the case.

It occured to me that we can figure out the price of the 4 optional post certification missions by subtracting the total value of the contract by the base value of the contract which was mentionned by the GAO in the context of the SNC protest:

http://www.gao.gov/press/pr_statement_sierra_nevada_bid_protest.htm

Quote from: GAO
Sierra Nevada’s price was $2.55 billion. [...]

Boeing’s price was $3.01 billion. [...]

SpaceX’s price was $1.75 billion.

Based on these numbers, SpaceX' post certification missions were ($2.6B less $1.75B) / 4 missions = $212.5M per mission.

Based on these numbers, Boeing's post certification missions were ($4.2B less $3.01B) / 4 missions = $297.5M per mission.
« Last Edit: 02/08/2017 02:48 am by yg1968 »

Offline Sesquipedalian

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #892 on: 02/08/2017 07:22 pm »
Based on these numbers, SpaceX' post certification missions were ($2.6B less $1.75B) / 4 missions = $212.5M per mission.

Based on these numbers, Boeing's post certification missions were ($4.2B less $3.01B) / 4 missions = $297.5M per mission.

If each flight carries 4 passengers, that is $53.1M per person for SpaceX and $74.4M per person for Boeing.

If each flight carries 5 passengers (direct rotation + short-term experimenter or "spaceflight participant"), that is $42.5M per person for SpaceX and $59.5M per person for Boeing.  (This could explain why Boeing takes every opportunity to mention its ability to carry five people.)

Online gongora

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #893 on: 02/23/2017 06:50 pm »
Tweet from Stephen Clark
Quote
ASAP’s Frost: SpaceX agrees there will be seven flights in “frozen” configuration of the Block 5 version of Falcon 9 before crew flights.

edit: A couple other tweets phrased it as 7 flights before putting crew on rocket, so I think they could do DM-1 as part of the seven flights.
« Last Edit: 02/23/2017 06:52 pm by gongora »

Online FutureSpaceTourist

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #894 on: 02/24/2017 06:17 am »
Quote
Crusan: looking at add’l Soyuz seats or Orion missions to ISS as contingency options only. Want comm’l crew to be successful.

https://twitter.com/jeff_foust/status/834927503043067904

Offline abaddon

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #895 on: 02/24/2017 01:39 pm »
Quote
Crusan: looking at add’l Soyuz seats or Orion missions to ISS as contingency options only. Want comm’l crew to be successful.
::)

Offline yg1968

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #896 on: 02/27/2017 02:53 pm »
NASA quitely announced that it bought Soyuz seats for 2017 and 2018 from Boeing last week:

https://www.nasa.gov/feature/additional-crew-flights-boost-space-station-science-and-research/
« Last Edit: 02/27/2017 02:57 pm by yg1968 »

Online gongora

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #897 on: 02/27/2017 03:16 pm »
NASA quitely announced that it bought Soyuz seats for 2017 and 2018 from Boeing last week:

https://www.nasa.gov/feature/additional-crew-flights-boost-space-station-science-and-research/

Quote
The agreement is a contract action that modifies the space station's Vehicle Sustaining Engineering Contract, originally awarded in January 1995, and most recently extended in 2015. The modification provides crew transportation services for two U.S. crew members to and from the International Space Station (ISS) on the Russian Soyuz spacecraft – one each in the fall of 2017 and spring of 2018. The modification total value including the option is $373.5 million.

So this would be for 5 seats with the option?  Around $75 million per seat?

Offline yg1968

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #898 on: 02/27/2017 03:38 pm »
That sounds right based on the RFP which you previously linked. See below:

Ars Technica: As leadership departs, NASA quietly moves to buy more Soyuz seats
Eric Berger wrote an article about NASA planning to buy more Soyuz seats for early 2019, as well as extra seats available in 2017 and 2018. 

He provides a link to the solicitation: PROCUREMENT OF CREW TRANSPORTATION AND RESCUE SERVICES FROM BOEING.  Apparently Boeing bought the rights to the available Soyuz seats and is going to resell them to NASA.

Here are some excerpts from the solicitation:
Quote
NASA is considering contracting with The Boeing Company (Boeing) for crew transportation services to and from the International Space Station (ISS) on the Russian Soyuz vehicle. This transportation would be for one crewmember in the Fall of 2017 and one crewmember in the Spring of 2018. NASA is considering purchasing these services from Boeing, without competition, because no other vehicles are currently capable of providing these services in Fall 2017 or Spring 2018. NASA has contracts with two U.S. commercial companies for crew transportation to the ISS. However, these vehicles are still in the developmental stage, and not expected to begin fully operational flights to the ISS until 2019. NASA also is considering an option to acquire crew transportation from Boeing for three crewmembers on the Soyuz in 2019, to ensure the availability of back-up transportation capability in the event the U.S. commercial contractor vehicles are delayed or to augment future ISS operations and research.
...
An agreement was recently reached between the Boeing Company and S.P. Korolev Rocket and Space Public Corporation, Energia ("RSC Energia"), who is the manufacturer of the Soyuz spacecraft and has the legal rights to sell the seats and associated services. As a part of this agreement, Energia agreed to provide to Boeing two specifically identified seats on the Soyuz spacecraft for long-duration travel to and from the ISS, one on a flight to occur in the Fall 2017 timeframe and another on a flight to occur in the Spring 2018 timeframe. Additionally, Energia provided Boeing three additional specifically identified seats in the Spring 2019 timeframe on two Soyuz spacecraft. Finally, Boeing and RSC Energia agreed that each of these five seats will include a launch of an individual to and from the ISS, including all services normally provided during launches to ISS. Boeing and RSC Energia have represented that Boeing has the full rights to these seats and can sell them to any third party.

Online AnalogMan

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #899 on: 03/03/2017 10:39 pm »
A Justification for Other than Full and Open Competition (JOFOC) for the purchase of Soyuz seats from Boeing was posted today:

https://www.fbo.gov/utils/view?id=1907d288ae46bb83bfe83f192adef5ed

[OCR'd copy attached]

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