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.
Human rating impacts to flight-proven existing EELVare 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)
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 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!
Quote from: sdsds on 06/23/2012 12:33 amI 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
When was the last time the Centaur was launched exposed?Would be good to look up.
Quote from: Prober on 06/23/2012 01:36 pmWhen was the last time the Centaur was launched exposed?Would be good to look up.3 days ago. Shakes head.
Quote from: Chris Bergin on 06/22/2012 10:57 pmMoreover, 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.
Thanks. Good article. I have one question about this paragraph:QuoteEven 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? QuoteHuman rating impacts to flight-proven existing EELVare understood– Separate VIF/MLP or pad with crew ingress/egresshttp://www.nasa.gov/pdf/361835main_08%20-%20ULA%20%201.0_Augustine_Public_6_17_09_final_R1.pdfSee also p. 5 of this ULA document:http://www.ulalaunch.com/site/docs/publications/AtlasDeltaCrewLaunch2010.pdf
Human rating impacts to flight-proven existing EELVare understood– Separate VIF/MLP or pad with crew ingress/egresshttp://www.nasa.gov/pdf/361835main_08%20-%20ULA%20%201.0_Augustine_Public_6_17_09_final_R1.pdfSee also p. 5 of this ULA document:http://www.ulalaunch.com/site/docs/publications/AtlasDeltaCrewLaunch2010.pdf
Quote from: sdsds on 06/23/2012 12:33 amI'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!
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!
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.
I read another article that said the Dream Chaser was going to have thousands of tiles. It doesn't seem like it is going to be very cost efficient totally replacing all damaged tiles, even if only scratched.
And it doesn't seem like it will have early abort capability.
QuoteQuote from: sdsds on 06/23/2012 12:33 amI'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.
Atlas 4xx has a limit of about 20,000 lbs for payload. Does the DreamChaser really have such a low weight?
I read another article that said the Dream Chaser was going to have thousands of tiles. It doesn't seem like it is going to be very cost efficient totally replacing all damaged tiles, even if only scratched. Plus the docking adapter is only one time use?...
The entire booster is only used one time, why worry about the docking adapter? Consider it part of the booster. Seriously, if it's cheaper to make a new one than to refurbish the old, what's the problem?
Quote from: ChrisGebhardt on 06/23/2012 02:56 pmQuoteQuote from: sdsds on 06/23/2012 12:33 amI'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.What would the pad crew, who is assisting the astronauts, do, if they need to get away from the pad and the rocket in a hurry? (Or the astronauts, when they are not settled in yet.)
Quote from: laszlo on 06/24/2012 12:36 pmThe entire booster is only used one time, why worry about the docking adapter? Consider it part of the booster. Seriously, if it's cheaper to make a new one than to refurbish the old, what's the problem?Because it is not part of the booster. It is a integral part of the spacecraft and its pressure vessel.
So much for using humorous rhetorical questions to make a point. It's still not a problem. It's the 21st Century and we have bolt & gasket technology. Don't confuse integral with permanent.
Quote from: laszlo on 06/24/2012 01:23 pmSo much for using humorous rhetorical questions to make a point. It's still not a problem. It's the 21st Century and we have bolt & gasket technology. Don't confuse integral with permanent.Your point and humor failed because it is wrong. Don't confuse technology as a fix for proper engineering.
Quote from: Jim on 06/24/2012 01:30 pmQuote from: laszlo on 06/24/2012 01:23 pmSo much for using humorous rhetorical questions to make a point. It's still not a problem. It's the 21st Century and we have bolt & gasket technology. Don't confuse integral with permanent.Your point and humor failed because it is wrong. Don't confuse technology as a fix for proper engineering.Doesn't SpaceX jettison Dragon's docking adapter before entry?
From what I'm hearing, a two month turnaround at best for Dreamchaser. So what is being advertised to the public as a quick turnaround vehicle is just not so.
Quote from: Danderman on 06/23/2012 03:11 pmAtlas 4xx has a limit of about 20,000 lbs for payload. Does the DreamChaser really have such a low weight?The DC might not actually have such a low weight. There are several factors that could benefit the (required) performance. - No payload faring, reducing weight on the Atlas.- Altlas 402 (x02?), not the 401 we are used to. Better performance to LEO because of the dual engine Centaur.- DC might do an OMS-2 or even an OMS-1 style burn, lowering the dV requirement on the Atlas.
For that matter, how is replacing the docking adapter after the flight different from swapping out any other component?
Proper engineering? Is it not proper engineering when a spacecraft temporarily modifies its pressure vessel by attaching a space station or another spacecraft to it?
Quote from: laszlo on 06/24/2012 03:57 pmProper engineering? Is it not proper engineering when a spacecraft temporarily modifies its pressure vessel by attaching a space station or another spacecraft to it?The basic vessel integrity is not changed.
LIDS is a doorway. How often do doors get thrown away after a single use?
Quote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Every Soyuz and Progress launch?
Quote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Most doorways don't have to be protected from hash enviroments. If dreamchaser had a cargo bay like the shuttle it would make sense to reuse, but hanging outside like that, it maybe better to discard.
Quote from: pathfinder_01 on 06/24/2012 11:57 pmQuote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Most doorways don't have to be protected from hash enviroments. If dreamchaser had a cargo bay like the shuttle it would make sense to reuse, but hanging outside like that, it maybe better to discard.Isn't that essentially what Elon said? That it was less expensive to replace than refurbish?
Quote from: Lee Jay on 06/24/2012 11:48 pmQuote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Every Soyuz and Progress launch?Thank you Lee Jay.How did the Shuttle connection work, did the refurbishment require extensive re-build or did USA build new connectors for every launch?
Quote from: clongton on 06/25/2012 12:02 amQuote from: pathfinder_01 on 06/24/2012 11:57 pmQuote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Most doorways don't have to be protected from hash enviroments. If dreamchaser had a cargo bay like the shuttle it would make sense to reuse, but hanging outside like that, it maybe better to discard.Isn't that essentially what Elon said? That it was less expensive to replace than refurbish?I thought so too, but I can't find the post that quotes Elon as saying that, Is there a post or statement from Boeing on how they intend to deal with LIDS on the CST-100?
Quote from: BrightLight on 06/24/2012 11:56 pmQuote from: Lee Jay on 06/24/2012 11:48 pmQuote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Every Soyuz and Progress launch?Thank you Lee Jay.How did the Shuttle connection work, did the refurbishment require extensive re-build or did USA build new connectors for every launch?I don't know about how much refurb got done, but I'm reasonably confident that the ODS wasn't replaced after each flight.
Quote from: BrightLight on 06/25/2012 12:06 amQuote from: clongton on 06/25/2012 12:02 amQuote from: pathfinder_01 on 06/24/2012 11:57 pmQuote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Most doorways don't have to be protected from hash enviroments. If dreamchaser had a cargo bay like the shuttle it would make sense to reuse, but hanging outside like that, it maybe better to discard.Isn't that essentially what Elon said? That it was less expensive to replace than refurbish?I thought so too, but I can't find the post that quotes Elon as saying that, Is there a post or statement from Boeing on how they intend to deal with LIDS on the CST-100?CST-100 uses careful arrangement and a forward heat shield.
Quote from: Dappa on 06/24/2012 11:59 amQuote from: Danderman on 06/23/2012 03:11 pmAtlas 4xx has a limit of about 20,000 lbs for payload. Does the DreamChaser really have such a low weight?The DC might not actually have such a low weight. There are several factors that could benefit the (required) performance. - No payload faring, reducing weight on the Atlas.- Altlas 402 (x02?), not the 401 we are used to. Better performance to LEO because of the dual engine Centaur.- DC might do an OMS-2 or even an OMS-1 style burn, lowering the dV requirement on the Atlas.Its a structural loads issue, not a payload performance issue. Atlas 4xx actually can orbit more mass than it can lift with 2 RL-10s in the Centaur.
Quote from: erioladastra on 06/25/2012 01:28 amQuote from: BrightLight on 06/25/2012 12:06 amQuote from: clongton on 06/25/2012 12:02 amQuote from: pathfinder_01 on 06/24/2012 11:57 pmQuote from: A_M_Swallow on 06/24/2012 11:23 pmLIDS is a doorway. How often do doors get thrown away after a single use?Most doorways don't have to be protected from hash enviroments. If dreamchaser had a cargo bay like the shuttle it would make sense to reuse, but hanging outside like that, it maybe better to discard.Isn't that essentially what Elon said? That it was less expensive to replace than refurbish?I thought so too, but I can't find the post that quotes Elon as saying that, Is there a post or statement from Boeing on how they intend to deal with LIDS on the CST-100?CST-100 uses careful arrangement and a forward heat shield.CST-100 was baselined as APAS, with possible replacement with NDS (NASA docking system) depending on development schedules. The fwd heat shield protects the Navigation and Rendezvous sensors. CST does not plan on major refurbishment of the APAS between flights.
Quote from: dbooker on 06/23/2012 03:28 pmI read another article that said the Dream Chaser was going to have thousands of tiles. It doesn't seem like it is going to be very cost efficient totally replacing all damaged tiles, even if only scratched. Remember DC is many times smaller than Shuttle (as my visit yesterday to Udvar Hazy drove home in abundance)....
Quite a good point. Even with identical tiles, servicing the TPS on Dreamchaser should be at least an order of magnitude easier. And because Dream Chaser is much smaller and just getting started now, they can improve the techniques, perhaps build a better version of Dream Chaser later on (with larger tiles for less servicing? even a totally different TPS concept?) with improved turnaround capability.I don't really buy a lot of the advantages of Dream Chaser, but its reusable TPS is potentially a significant advantage.
Quote from: Robotbeat on 06/25/2012 06:08 pmQuite a good point. Even with identical tiles, servicing the TPS on Dreamchaser should be at least an order of magnitude easier. And because Dream Chaser is much smaller and just getting started now, they can improve the techniques, perhaps build a better version of Dream Chaser later on (with larger tiles for less servicing? even a totally different TPS concept?) with improved turnaround capability.I don't really buy a lot of the advantages of Dream Chaser, but its reusable TPS is potentially a significant advantage.I was under the impression that Dreamchaser used a heat shield "shoe" that uses an ablative substance:
I was under the impression that it largely used reusable tiles. Certainly the hottest parts (if not ablative) would be RCC pieces (really expensive, but can be in single large pieces and should be reusable...).I must admit the impression was formed quite a while ago and things may have changed.
Great header for Chris's next DC article!
Mach 5, just another 12 or so to go
Neat Schlieren photography image of Dream Chaser on the stack in the Marshall wind tunnel...http://www.nasa.gov/centers/marshall/about/star/star120516.html
Quote from: Rocket Science on 07/06/2012 01:46 pmNeat Schlieren photography image of Dream Chaser on the stack in the Marshall wind tunnel...http://www.nasa.gov/centers/marshall/about/star/star120516.htmlI thought the tail fins would make a larger wake in the airflow, but it appears that blends into the wake caused by the inter-stage adapter / top of the centaur fairly well.I see another wake caused by the transition from the centaur to the first stage, and then another wake caused by a protusion at the bottom of the first stage. Is that a problem with the CCB model, or are they looking at airflow with an SRB attached in a Atlas 412 configuration ?
I think that is a prop line.
Quote from: Rocket Science on 07/06/2012 01:46 pmNeat Schlieren photography image of Dream Chaser on the stack in the Marshall wind tunnel...http://www.nasa.gov/centers/marshall/about/star/star120516.htmlI love the Schlieren... I've done it several times, and it always looks so cool!
Neat Schlieren photography image of Dream Chaser on the stack in the Marshall wind tunnel...
Does anyone know the anticipated gross weight, lift-to-drag ratio, and airspeed at touchdown? Crosswind tolerance? CG range? It would be interesting to compare the DC with the X-37 given their different configuratoins, though of course data on the latter is not very accessible.