Author Topic: Sierra Nevada’s 5-year partnership with NASA - Progress on Dream Chaser  (Read 27937 times)

Online Chris Bergin

Another Dream Chaser article! :) This time Chris Gebhardt has written up some of the latest and some of our content via Lee Jay's visit to SNC:

http://www.nasaspaceflight.com/2012/06/sierra-nevadas-5-year-partnership-nasa-progress-dream-chaser/

Offline AndrewSTS

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Awesome! This site's really covering this vehicle really well! :)

Offline yg1968

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Thanks. Good article.

I have one question about this paragraph:

Quote
Even more impressive is the seeming lack of modifications needed to the Atlas V’s ground equipment currently in use by United Launch Alliance. In fact, Sierra Nevada indicates that only an adaptor to the current launch tower would be needed for vehicle access – both for the crews of Dream Chaser and support personnel who would assist astronauts with entry into the vehicle and final preparations for launch.

Wouldn't you need a pad with crew ingress/egress as explained by Gass on page 8 of the ULA presentation at the Augustine Committee?   

Quote
Human rating impacts to flight-proven existing EELV
are understood
– Addition of an Emergency Detection System (EDS)
– Separate VIF/MLP or pad with crew ingress/egress
 Low non-recurring ($400M) and recurring costs
($130M/launch)

http://www.nasa.gov/pdf/361835main_08%20-%20ULA%20%201.0_Augustine_Public_6_17_09_final_R1.pdf

See also p. 5 of this ULA document:
http://www.ulalaunch.com/site/docs/publications/AtlasDeltaCrewLaunch2010.pdf
« Last Edit: 06/23/2012 12:12 AM by yg1968 »

Offline ginahoy

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Moreover, the vehicle’s docking adapter will be removed and replaced after each mission instead of being reused.

According to Mark Sirangelo, “The economics work out that it’s not really advantageous to reuse it.”  This goes toward an explanation for why there is no body flap on the back of Dream Chaser, like there was on Shuttle, to protect Dream Chaser’s docking adaptor.

I thought the purpose of the Shuttle body flap was to protect the SME's and for pitch control during aerodynamic reentry.

Offline Prober

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2017 - Everything Old is New Again.
I have not failed. I've just found 10,000 ways that won't work. ~ by Thomas Alva Edison

Offline Rocket Science

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Nice comprehensive article Chris G and thanks again to Lee Jay! The excitement continues to build… ;)
"The laws of physics are unforgiving"
~Rob, Physics instructor, aviator, vintage auto racer

Offline sdsds

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I really like the focus the article puts on the launch vehicle configuration. It's an Atlas 4xx because it flies with the Centaur exposed rather than enclosed; it has no fairing. This recent buffet testing should lay to rest most concerns about that, the weirdness of the "Z511" image (http://www.nasaspaceflight.com/wp-content/uploads/2012/06/Z511.jpg)  notwithstanding. The article also makes the point that during an abort with zero solids the range wouldn't need to destroy the vehicle while the crew were still getting away.

I'm a bit confused though about emergency egress. I get the bit shown in the photo where a gangplank from the existing mobile launch platform gets the crew into the vehicle. But what if they need to get down in a hurry? (I'm hoping the answer involves a zip-line! :))
-- sdsds --

Offline Alpha Control

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Fine article, Chris G! My optimism remains cautious, but I am hopeful that the "baby orbiter" will indeed have her day in the sun, and that we will once again see a spaceplane descend from space and land on a runway.
Space launches attended:
Antares/Cygnus ORB-D1 Wallops Island, VA Sept 2013 | STS-123 KSC, FL March 2008 | SpaceShipOne Mojave, CA June 2004

Offline Alpha Control

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I really like the focus the article puts on the launch vehicle configuration. It's an Atlas 4xx because it flies with the Centaur exposed rather than enclosed; it has no fairing. This recent buffet testing should lay to rest most concerns about that, the weirdness of the "Z511" image (http://www.nasaspaceflight.com/wp-content/uploads/2012/06/Z511.jpg)  notwithstanding. The article also makes the point that during an abort with zero solids the range wouldn't need to destroy the vehicle while the crew were still getting away.

I'm a bit confused though about emergency egress. I get the bit shown in the photo where a gangplank from the existing mobile launch platform gets the crew into the vehicle. But what if they need to get down in a hurry? (I'm hoping the answer involves a zip-line! :))

Sdsds, I'm not clear on your reference to the "exposed Centaur". Are you referring to the fact that a fairing would provide a uniform airflow for the Centaur behind it, whereas the Dream Chaser will not?
Thanks,
David
Space launches attended:
Antares/Cygnus ORB-D1 Wallops Island, VA Sept 2013 | STS-123 KSC, FL March 2008 | SpaceShipOne Mojave, CA June 2004

Offline Downix

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I really like the focus the article puts on the launch vehicle configuration. It's an Atlas 4xx because it flies with the Centaur exposed rather than enclosed; it has no fairing. This recent buffet testing should lay to rest most concerns about that, the weirdness of the "Z511" image (http://www.nasaspaceflight.com/wp-content/uploads/2012/06/Z511.jpg)  notwithstanding. The article also makes the point that during an abort with zero solids the range wouldn't need to destroy the vehicle while the crew were still getting away.

I'm a bit confused though about emergency egress. I get the bit shown in the photo where a gangplank from the existing mobile launch platform gets the crew into the vehicle. But what if they need to get down in a hurry? (I'm hoping the answer involves a zip-line! :))

Sdsds, I'm not clear on your reference to the "exposed Centaur". Are you referring to the fact that a fairing would provide a uniform airflow for the Centaur behind it, whereas the Dream Chaser will not?
Thanks,
David
No, it literally means as it says, the Centaur is exposed.  The 5xx series Atlas' have the Centaur enshrouded.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline Lars_J

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Alpha Control,
Atlas V 4XX on the left, 5XX on the right. The 5XX flights have both the Centaur and payload inside the fairing.
« Last Edit: 06/23/2012 01:11 AM by Lars_J »

Offline Alpha Control

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Thanks Lars and Downix. Appreciate the clarification. I didn't realize that the entire Centaur was enclosed within the fairing for the 5 series.
Space launches attended:
Antares/Cygnus ORB-D1 Wallops Island, VA Sept 2013 | STS-123 KSC, FL March 2008 | SpaceShipOne Mojave, CA June 2004

Online BrightLight

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This site is wonderful,
where else can we get such deep and accurate reporting about such exciting developments. Being a fan of lifting bodies and the HL-20/DC is specific - there is no other place to see the development of this long awaited space plane.
Thanks Chris!!

Offline manboy

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Do we know what kind of TPS it will use (TUFROC?)?
"Cheese has been sent into space before. But the same cheese has never been sent into space twice." - StephenB

Offline Prober

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When was the last time the Centaur was launched exposed?

Would be good to look up.
2017 - Everything Old is New Again.
I have not failed. I've just found 10,000 ways that won't work. ~ by Thomas Alva Edison

Offline Jim

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When was the last time the Centaur was launched exposed?

Would be good to look up.


3 days ago. 

Shakes head.
« Last Edit: 06/23/2012 01:41 PM by Jim »

Offline Prober

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When was the last time the Centaur was launched exposed?

Would be good to look up.


3 days ago. 

Shakes head.


Not close to the fine details like you folk.

2017 - Everything Old is New Again.
I have not failed. I've just found 10,000 ways that won't work. ~ by Thomas Alva Edison

Offline ChrisGebhardt

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Moreover, the vehicle’s docking adapter will be removed and replaced after each mission instead of being reused.

According to Mark Sirangelo, “The economics work out that it’s not really advantageous to reuse it.”  This goes toward an explanation for why there is no body flap on the back of Dream Chaser, like there was on Shuttle, to protect Dream Chaser’s docking adaptor.

I thought the purpose of the Shuttle body flap was to protect the SME's and for pitch control during aerodynamic reentry.

Yes, it was (for Shuttle). As the article says, Shuttle had the body for protection. Since there's nothing worth protecting on Dream Chaser's aft (i.e., the docking adapter), there will be no body flap.

Offline clongton

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My personally preferred commercial crew stack - Atlas-V/DC.
Thank you Chris(s). Nicely done!
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline ChrisGebhardt

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Thanks. Good article.

I have one question about this paragraph:

Quote
Even more impressive is the seeming lack of modifications needed to the Atlas V’s ground equipment currently in use by United Launch Alliance. In fact, Sierra Nevada indicates that only an adaptor to the current launch tower would be needed for vehicle access – both for the crews of Dream Chaser and support personnel who would assist astronauts with entry into the vehicle and final preparations for launch.

Wouldn't you need a pad with crew ingress/egress as explained by Gass on page 8 of the ULA presentation at the Augustine Committee?   

Quote
Human rating impacts to flight-proven existing EELV
are understood
– Separate VIF/MLP or pad with crew ingress/egress

http://www.nasa.gov/pdf/361835main_08%20-%20ULA%20%201.0_Augustine_Public_6_17_09_final_R1.pdf

See also p. 5 of this ULA document:
http://www.ulalaunch.com/site/docs/publications/AtlasDeltaCrewLaunch2010.pdf

OK. Let's actually look at what those documents say.

The Augustine Committee made a blanket, without in-depth analysis assumption that ULA would need a completely new VIF and ML for the Atlas V 402 manned launch vehicle.

This assumption is now proven incorrect by ULA based on the Dream Chaser's narrowing design and capabilities. Thus, a new VIF and MLP are unnecessary.

For the ULA doc, it quite literally says, "launch site modifications to accommodate crew ingress and emergency egress" (pg. 5).

It says nothing about a VIF of MLP being needed, only that a modification to provide crew access and egress is necessary.

Let us also remember here that egress does not necessarily mean "There's an emergency. Everyone out!" It means, "we scrubbed for the day because of xxxxxx."

Quote

I'm a bit confused though about emergency egress. I get the bit shown in the photo where a gangplank from the existing mobile launch platform gets the crew into the vehicle. But what if they need to get down in a hurry? (I'm hoping the answer involves a zip-line! :))

For a launch pad abort, SNC is looking at a separation of Dream Chaser from the Atlas V 402 stack and subsequent landing on a nearby runway, thereby eliminating the need for an emergency egress system for the crew at the pad. How that Pad Abort going to happen? I'm not sure. But that's what Mark Sirangelo noted in his interview with Lee Jay.
« Last Edit: 06/23/2012 02:58 PM by ChrisGebhardt »

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