Author Topic: SNC Dream Chaser DISCUSSION Thread  (Read 532265 times)

Offline adrianwyard

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1780 on: 02/13/2017 08:12 PM »
Right. There was speculation that SNC would switch over to Orbitec abort motors after they acquired the company in 2014. Propane-NOx IIRC. But then they lost the crew contract, and cargo DC was spec'd without them.

Orbitec are reportedly providing the thrusters for cargo DC, so it's possible they could develop large motors for abort at some point.

Side note: info on the cargo DC thrusters is still surprisingly hard to find, i.e. which propellants will be used, spark ignition? Anyone heard anything of late?
« Last Edit: 02/13/2017 08:13 PM by adrianwyard »

Offline Rocket Science

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1781 on: 02/13/2017 08:20 PM »
Right. There was speculation that SNC would switch over to Orbitec abort motors after they acquired the company in 2014. Propane-NOx IIRC. But then they lost the crew contract, and cargo DC was spec'd without them.

Orbitec are reportedly providing the thrusters for cargo DC, so it's possible they could develop large motors for abort at some point.

Side note: info on the cargo DC thrusters is still surprisingly hard to find, i.e. which propellants will be used, spark ignition? Anyone heard anything of late?
All I know is that it will still be non-toxic which is one of their selling points...
http://www.sncspace.com/Mediakit/FAQ
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Online Lars-J

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1782 on: 02/13/2017 11:55 PM »
I will try to post a few quotes from the article tonight. I have access to it through my phone's Twitter account for some reason. Essentially, SNC suggested this Hubble servicing mission with a crewed DC (twice) to the transition team. The transition team said that this is the kind of decision that would have to be made by the NASA Administrator but that the Trump administration is open to private-public partnerships especially if a mission can be done prior to 2020.

That's .. interesting ... but seems more like wishful thinking than anything else.
« Last Edit: 02/13/2017 11:59 PM by Lars-J »

Offline TrevorMonty

Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1783 on: 02/14/2017 03:22 AM »
May be possible with cargo version plus a crew dragon or star liner. Have crew rendezvous with DC at Hubble, transfer to DC. Use its robotic arm and airlock for repair mission, then transfer back to crew vehicle for return.

NB developing a crew DC by 2020 maybe big ask especially if NASA is not helping fund it.


Offline brickmack

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1784 on: 02/14/2017 06:32 PM »
The old plans for HL-20 did include a 'towed package' stored in the stage adapter, so you could resurrect that idea, but it seems less useful than the DC cargo module or Dragon trunk.

DC Crew was also proposed to support such a thing, was shown able to carry modules about the size of DC Cargos expendable module.

Online Lars-J

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1785 on: 03/28/2017 06:40 AM »
From the update thread:
The problem with the crewed version is that it has to be launched inside a payload shroud with wings folded which vastly complicates the abort system.

The reason it has to be launched in a shroud is that otherwise the booster is highly unstable in pitch due to the lifting surface at the nose. Dyna-Soar tried to fix this problem with big tail fins on the boosters but wind tunnel tests revealed unpredictable interactions between the spacecraft wing and the booster fins.

Also, I think NASA would be scared stiff by the wing folding joints. The landing gear doors were a lot of trouble on Shuttle but the long wing joints on the "navalized" Dream Chaser are just asking for a burn-through.

DC does not have to be in launched in a shroud. That's just the development shortcut taken the cargo version, to reduce the amount of work needed to counteract/handle the lifting surfaces. The crewed DC was going to be launched without a shroud. It is not an unsolvable problem, but it is one big hurdle that will have to be cleared if they are going to ever fly a crewed version.

Apparently they thought having foldable wings was easier than solving the aero loads during launch issue.
« Last Edit: 03/28/2017 06:42 AM by Lars-J »

Offline adrianwyard

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1786 on: 03/28/2017 02:58 PM »
SNC's Sirangelo is on record several times saying launching without a fairing was found not to be a problem; it was extensively tested in wind-tunnels. I suppose it's possible he spoke prematurely, and problems were discovered late in wind tunnel testing, but the reason cargo DC *has* to launch in a fairing is it is attached to the cargo module with exposed payloads.

In order to fit in a fairing the wings have to fold, but a happy side effect is transporting DC becomes easier as it will now fit inside smaller cargo aircraft.

Offline psloss

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1787 on: 03/28/2017 07:41 PM »

Offline john smith 19

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1788 on: 03/28/2017 08:03 PM »

A full sized  crew rated CFC structure lifting body, with low maintenance TPS and flush mount air data system.

These are just some of the reason why DC remains the most advanced design of the COTS programme.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Jester

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1789 on: 04/03/2017 09:51 AM »
@psloss

Wait, its assembled and ready for captive ? Shouldnt this be in the update thread ? source of that capture ?
« Last Edit: 04/03/2017 09:54 AM by Jester »

Offline shuttle_buff

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1790 on: 04/17/2017 12:33 AM »
Let's hope the next drop test is soon. The development of this spacecraft is taking FOREVER! Started in 2005? It's 2017!

I know they lost out to Boeing and SpaceX a few years ago but by the time they get this ship operational the ISS will be retiring and I'll be dead!

Really I think it's great system and want to see it work but it can't land on the Moon or Mars. It's a low earth orbit and back access system. SNC really needs some sense of urgency. Things are moving way to slow in my opinion.

Offline yg1968

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1791 on: 04/17/2017 03:37 PM »
The cargo DC should be ready in late 2019 or 2020.

For crewed DC, I wouldn't hold my breath. My guess is that it is kept alive in case that a new contract opportunity arises but that's about it. 

Offline rockets4life97

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1792 on: 04/18/2017 04:53 PM »
From the update thread:

This French article from March 21st 2017 says that SNC has not yet decided on a LV for cargo DC except for its first flight (which will be on an Atlas V). In the running are the following LVs:

Ariane 6 with 4 boosters
Blue Origin's New Glenn
ULA's Vulcan
SpaceX's Falcon 9


http://www.futura-sciences.com/sciences/actualites/dream-chaser-ariane-6-lancera-t-elle-mini-navette-dream-chaser-66745/

I have a hard time believing Falcon 9 is really in the running. I don't think SpaceX will be launching anything other than Dragon to the ISS. I can't see how it is their interest to help out a direct competitor.

Offline RonM

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1793 on: 04/18/2017 04:57 PM »
From the update thread:

This French article from March 21st 2017 says that SNC has not yet decided on a LV for cargo DC except for its first flight (which will be on an Atlas V). In the running are the following LVs:

Ariane 6 with 4 boosters
Blue Origin's New Glenn
ULA's Vulcan
SpaceX's Falcon 9


http://www.futura-sciences.com/sciences/actualites/dream-chaser-ariane-6-lancera-t-elle-mini-navette-dream-chaser-66745/

I have a hard time believing Falcon 9 is really in the running. I don't think SpaceX will be launching anything other than Dragon to the ISS. I can't see how it is their interest to help out a direct competitor.

Money is money.

Offline brickmack

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1794 on: 04/18/2017 07:59 PM »
I have a hard time believing Falcon 9 is really in the running. I don't think SpaceX will be launching anything other than Dragon to the ISS. I can't see how it is their interest to help out a direct competitor.

SNC is no longer a direct competitor to SpaceX, they only compete prior to the contract initially being awarded. They're still going to buy flights from someone, its in SpaceX's interest to get as many launch contracts as they can and prevent their actual competitors from getting launches.

Plus, ULA has already sold flights to SNC and OATK even though they're partially owned by Boeing, and Boeing has looked into non-ULA launch options as well

Offline yg1968

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1795 on: 04/19/2017 01:36 PM »
From the update thread:

This French article from March 21st 2017 says that SNC has not yet decided on a LV for cargo DC except for its first flight (which will be on an Atlas V). In the running are the following LVs:

Ariane 6 with 4 boosters
Blue Origin's New Glenn
ULA's Vulcan
SpaceX's Falcon 9

The article says that SNC will make a decision this spring on its LV for DC.

http://www.futura-sciences.com/sciences/actualites/dream-chaser-ariane-6-lancera-t-elle-mini-navette-dream-chaser-66745/

I have a hard time believing Falcon 9 is really in the running. I don't think SpaceX will be launching anything other than Dragon to the ISS. I can't see how it is their interest to help out a direct competitor.

I have trouble believing that too. I was under the impression that the F9 fairing wasn't tall enough for cargo DC. In certain presentations, SNC has indicated that FH (presumably with a taller fairing) would be required.
« Last Edit: 04/19/2017 01:46 PM by yg1968 »

Offline RonM

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1796 on: 04/19/2017 03:24 PM »
From the update thread:

This French article from March 21st 2017 says that SNC has not yet decided on a LV for cargo DC except for its first flight (which will be on an Atlas V). In the running are the following LVs:

Ariane 6 with 4 boosters
Blue Origin's New Glenn
ULA's Vulcan
SpaceX's Falcon 9

The article says that SNC will make a decision this spring on its LV for DC.

http://www.futura-sciences.com/sciences/actualites/dream-chaser-ariane-6-lancera-t-elle-mini-navette-dream-chaser-66745/

I have a hard time believing Falcon 9 is really in the running. I don't think SpaceX will be launching anything other than Dragon to the ISS. I can't see how it is their interest to help out a direct competitor.

I have trouble believing that too. I was under the impression that the F9 fairing wasn't tall enough for cargo DC. In certain presentations, SNC has indicated that FH (presumably with a taller fairing) would be required.

If F9 and a custom fairing is still competitive, then F9 is still in the running. Sure, the custom fairing will be more expensive, but the overall cost could be lower than the competition.

Offline Rocket Science

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1797 on: 04/19/2017 03:26 PM »
From the update thread:

This French article from March 21st 2017 says that SNC has not yet decided on a LV for cargo DC except for its first flight (which will be on an Atlas V). In the running are the following LVs:

Ariane 6 with 4 boosters
Blue Origin's New Glenn
ULA's Vulcan
SpaceX's Falcon 9

The article says that SNC will make a decision this spring on its LV for DC.

http://www.futura-sciences.com/sciences/actualites/dream-chaser-ariane-6-lancera-t-elle-mini-navette-dream-chaser-66745/

I have a hard time believing Falcon 9 is really in the running. I don't think SpaceX will be launching anything other than Dragon to the ISS. I can't see how it is their interest to help out a direct competitor.

I have trouble believing that too. I was under the impression that the F9 fairing wasn't tall enough for cargo DC. In certain presentations, SNC has indicated that FH (presumably with a taller fairing) would be required.

If F9 and a custom fairing is still competitive, then F9 is still in the running. Sure, the custom fairing will be more expensive, but the overall cost could be lower than the competition.
Especially if they recover the fairings! ;)
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Offline baldusi

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1798 on: 04/19/2017 09:39 PM »
Please remember that DreamChaser is expected to use a 552 Atlas V. It should be able to do around 21 tonnes to LEO. Which is around what SpaceX claims Falcon 9 to do in expendable mode (22 tonnes). So it would either need a fully expendable Falcon 9 or a RTLS Falcon Heavy. An Atlas V 552 should cost quite a penny, probably in the 110~120M range. How much would SpaceX charge for a Falcon Heavy? Which would be the expected reliability and schedule margins? I wouldn't count Atlas V nor Vulcan out, yet.

Offline Flying Beaver

Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1799 on: 04/19/2017 10:02 PM »
Dream Chaser Cargo should weight in at about 14.5tons (9ton ship, 5.5ton cargo).

14.5tons is in the Falcon 9's range for LEO orbit, with a GTO style S1 landing profile. Remember a Iridium mission is a little over 10tons, and the first stage is still about to do a major divert, downrange ASDS landing.

For FH though, $90M for a land-able mission. http://www.spacex.com/about/capabilities

Saw OG-2 Booster Land in person 21/12/2015.

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