Author Topic: Pros and Cons, Dragon V2, CST-100 and Dream Chaser  (Read 128890 times)

Offline aero

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I left Orion out because it is not commercial crew. The following post is a good start I think.

I think the question should be: Is there anything that CST-100 has over Dragon v2?

Abort propellant that's less toxic than hypergolics. The ability to use unused abort propellant in gimbaled thrusters for ISS reboost. More experience with in-space ECLSS. Willingness to use whatever launcher is most promising rather than only the one made by the company that made the spacecraft.

The first two are reasonable points for CST-100.

The third isn't about CST-100, it's about the organization building CST-100, and there's no evidence it will give CST-100 anything Dragon V2 doesn't.  We could make all sorts of statements about Boeing and SpaceX as companies, but the question was about actual design features of CST-100 versus those of Dragon V2.

The final item also doesn't translate to anything concrete for CST-100.  "Willingness" is vague.  What's actually planned is for it to have one launch vehicle, Atlas V.  Falcon 9 has been mentioned as a possibility if plans change, but it would clearly be a lot of work and would require SpaceX to agree to it.  It wouldn't be any technically harder or easier to switch Dragon V2 from F9 to Atlas V than to switch CST-100 from Atlas V to F9.  The only reason nobody has talked about that is that F9 is so much cheaper than Atlas V and doesn't have engines made in Russia, so there's no reason to switch.  In fact, the talk of possibly switching CST-100 from Atlas V to Falcon 9 just highlights the fact that Dragon V2's plan-of-record launch vehicle is pretty compelling.

I point out that Dream Chaser also has shown some flexibility in its launch vehicle choice, considering Ariane 5 in place of Atlas V. Both CST-100 and DC have Atlas V as the plan-of-record launch vehicle.
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Offline dkovacic

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #1 on: 06/03/2014 07:53 AM »
My try:

Here is my try, I am sure many will have diverging opinions:

Dragon V2 pros:
   - key components already flight proven (Draco, PICA-X, pressure shell, GN&C, water/parachute landing)
   - full vertical integration of the whole stack in the same company
   - redundant landing options (powered vs. parachute)
   - Elon Musk aura 8)
   - reusable
   - significantly lower retrieval cost (in powered landing)
   - classic (proven) capsule design
   - lowest cost per mission (estimated up to 140 million)

Dragon V2 cons:
   - toxic hypergolics used
   - powered landing reduces usable mass to orbit
   - powered landing not proven

CST-100 pros:
  - conservative, low risk capsule design
  - Boeing as a proven provider
  - could switch launch vehicles (although not likely)

CST-100 cons:
  - higher (or even highest) cost per flight
  - boring :-[

DC pros:
  - lifting body design, horizontal landing
  - reusable from the start
  - inspirational, airplane like
  - lowest G forces during EDL
  - can switch launch vehicles
  - cost effective for larger number of flights?

DC cons:
 - least proven design/highest risk
 - producer with least spaceflight heritage
 - might be locked to Atlas V
 - more expensive than Dragon?

Costwise I would predict the following:
  - Dragon V2 + F9R - 140mil per mission
  - CST-100 + Atlas V 401 - 250mil per mission
  - DC + Atlas V 401 - 200mil per mission

Online MP99

Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #2 on: 06/03/2014 07:59 AM »
DC pros:
  - lifting body design, horizontal landing
  - can switch launch vehicles

I believe the lifting body makes this more complicated to integrate with a new vehicle than a capsule.

Cheers, Martin

Offline darkenfast

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #3 on: 06/03/2014 09:44 AM »
One comment IRT the often-stated lower G-force on DC during re-entry: it seems to me that this is only of value if you can move the seats to a reclining position.  This was done on the Shuttle on the mid-deck for long-duration astronauts returning from the station.  I don't know if long-duration returnees ever flew sitting up, perhaps someone can help with that.  Are there plans to lower some or all of the seats on DC?

Offline Roy_H

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #4 on: 06/15/2014 03:05 AM »
I like the Dream Chaser for its capability to land at any major airport. I also has the largest cross-range capability on re-entry. Somehow I just like wings, because it seems safer than depending on rockets or parachutes to operate correctly, wings are just there, they do not have to be deployed.

The seating arrangement in the DC would seem to favor horizontal integration. Climb in while oriented as a normal aircraft then the rocket is raised to upright position with crew already aboard. OTOH getting into those seats, all lined up behind each other in vertical orientation on top of the rocket looks rather awkward.
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Offline darkenfast

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #5 on: 06/15/2014 03:29 AM »
That won't happen because the rocket is fueled while vertical. Climbing into the seats is a much smaller issue.

Offline vt_hokie

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #6 on: 06/15/2014 03:58 AM »
Somehow I just like wings, because it seems safer than depending on rockets or parachutes to operate correctly, wings are just there, they do not have to be deployed.

I'm a spaceplane fan to be sure, but the movable aero surfaces and all of their associated hardware and software have to work properly, as well as the landing gear of course! 

Offline arachnitect

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #7 on: 06/15/2014 05:15 AM »
Commercial Crew section: http://forum.nasaspaceflight.com/index.php?board=56.0 Thank you mods

CST and Dragon use the same hypergolic propellant.

Dreamchaser is advertising their "non-toxic" hybrid motors. Don't know what their RCS uses.


  - Dragon V2 + F9R - 140mil per mission
  - CST-100 + Atlas V 401 - 250mil per mission
  - DC + Atlas V 401 - 200mil per mission


CST uses AV 422. DC is probably AV 412
« Last Edit: 06/16/2014 03:10 AM by arachnitect »

Offline QuantumG

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #8 on: 06/15/2014 07:06 AM »
Don't know what their RCS uses.

Cold gas, nitrogen.
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Offline CuddlyRocket

Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #9 on: 06/15/2014 08:03 AM »
DC pros:
  - lifting body design, horizontal landing
  - ....

Those are only a pro if they enable something that is not achievable as readily with an alternative design.

As for cons, add: Not developable to BLEO.

Offline Hauerg

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #10 on: 06/15/2014 08:06 AM »
Both DC and CST100 have the Atlas V issue to cope with. They might switch from being at the mercy of the Russians to being at the mercy of Elon. Tough choice. Also the delays caused by the launcher switch. OK, Delta 4, but still would take years.

Offline Jim

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #11 on: 06/15/2014 11:47 AM »
Both DC and CST100 have the Atlas V issue to cope with.

Not an issue for commercial and NASA missions

Offline yg1968

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #12 on: 06/15/2014 12:58 PM »
DC cons:
 - might be locked to Atlas V
 

SNC has said that DC might eventually fly on a F9.
« Last Edit: 06/15/2014 01:00 PM by yg1968 »

Offline deruch

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #13 on: 06/15/2014 01:25 PM »
Both DC and CST100 have the Atlas V issue to cope with.

Not an issue for commercial and NASA missions

We hope.  Certainly, all the bluster so far has only included threats to military launches.  But with continued worsening in relations vis a vis Russia, that could change (personally, fingers crossed,  I don't think any of this is more than rhetoric as they need the money too much).  The best way to defuse the threat though would be to quickly certify the F9 (and FH ASAP).  If losing access to the RD-180 has no impact on US launch capability there's even less reason to block their sale.  Blocking them would gain Russia nothing and would lose them badly needed money.  Anyways, the point being that Putin is nuts (US perspective) and who knows how bad things might get in the future, so....We hope.
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Offline Llian Rhydderch

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #14 on: 06/15/2014 01:41 PM »
Both DC and CST100 have the Atlas V issue to cope with.

Not an issue for commercial and NASA missions

Sure, it's an "issue."  Since the entire future of the Atlas V is an "issue", given the current situation with the Russian government having announced it won't honor the former RD-180 engine contracts it had formerly signed.

So while the (current) offficial announcement is that they will hold off only on "military" uses of the RD-180s, that announcement, and the whole US/Russia geopolitical brouhaha, makes sourcing of Atlas V engines in the future an open question.  Moreover, there is the whole US Congress debate/action of funding an alternative hydrocarbon-based government-funded engine.

So, ya, sure it's an issue.
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Offline AncientU

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #15 on: 06/15/2014 03:07 PM »
CST-100 pros:
  - conservative, low risk capsule design
  - Boeing as a proven provider
  - could switch launch vehicles (although not likely)

CST-100 cons:
  - higher (or even highest) cost per flight
  - boring :-[


As stated in the OP, the highlighted pro is not about the CST-100 design; a con in the same vein is that Boeing has the least skin in the game according to NASA.  Being a proven provider when someone else is always paying the tab might make it difficult to make a business case for divvying-up.
« Last Edit: 06/15/2014 03:08 PM by AncientU »
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Offline Prober

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #16 on: 06/15/2014 04:21 PM »
Both DC and CST100 have the Atlas V issue to cope with.

Not an issue for commercial and NASA missions

Sure, it's an "issue."  Since the entire future of the Atlas V is an "issue", given the current situation with the Russian government having announced it won't honor the former RD-180 engine contracts it had formerly signed.


No, again the RD-180 Was Made an issue by an orchestrated program.   Will say it until i'm blue in the face, correctly manufacturing the RD-180 is a purely political decision.   The decision is not one of manufacturing know how or ability.  :)
« Last Edit: 06/15/2014 04:23 PM by Prober »
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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #17 on: 06/15/2014 04:48 PM »
No, again the RD-180 Was Made an issue by an orchestrated program.   Will say it until i'm blue in the face, correctly manufacturing the RD-180 is a purely political decision.   The decision is not one of manufacturing know how or ability.  :)

No at this point it's a purely commercial decision.  At the start of the program it was political but now it's 100% commercial. ULA will keep buying the RD-180 from the Russians as long as they can both get them and make a profit at it.
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Offline kerlc

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #18 on: 06/15/2014 05:42 PM »
I left Orion out because it is not commercial crew. The following post is a good start I think.
One should also consider these options and consider if there is a realized advantage vs Soyuz and the cost savings...

Soyuz:
Pros:  Proven, safe, operational, affordable (... in other words <<< $1B/year)
Cons:  Requires astronaut training in another country.  Flight services may be ending by 2020 (could be continued).
I wouldn't call $70 million per seat affordable.
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Offline WmThomas

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Re: Pros and Cons, Dragon V2, CST-100 and Dream Chaser
« Reply #19 on: 06/15/2014 06:05 PM »
Has anyone mentioned that Dream Chaser's wings are not guaranteed to work all the time. Space Shuttle had wings too, and when Columbia's failed, the crew died.

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