Pros and Cons, Dragon V2, CST-100 and Dream Chaser

[Lar]

Guys, this is supposed to be about the spacecraft, not the launch vehicles or their engines. There are other threads dedicated to those subjects. Can we get back on topic and discuss the pros and cons of the spacecraft please?

What he said, but with the codicil that in my view, how easy/hard it is to adapt to other launchers is a pro/con. (one we probably have little visiblity to anyway though)

[rcoppola]

Sorry, still sounds like misdirection.  THe air force may care about a shortage of russian engines for their satellites, sure. That is the point. The russian threat was to stop engines for military launches, not commercial crew.  My question stands: is there a real basis for concern that atlas for commercial crew would be grounded due to a boycott of sales to ULA for commercial crew. The answer provided SEEMS to muddy the water, thus my continuing frustration with trying to find a factual basis for the whole issue of the rd-180 "issue."   Is there a real threat to current timelines and Is a domestic substitute able to be found in time, if needed? Inquiring minds (really) want to know, because they would like to assess this situation factually instead of from the self-serving spin by spaceX advocates, who after all are ADVOCATES, and considering the conpany's credibility is stretched a bit tight to begin with.

Yes it's frustrating but illustrative of the carnival of incompetence that runs rampant in both Executive and Congressional  circles.

1. Is there a real basis for concern? Yes. But as of right now, it's status-quo. Business is business...until it's not.

2. A threat to current timelines?  If you mean the ability to provide CC services from 2017-2020 or 2024...nobody knows.

3. A domestic substitute in time?  In time to be used for crew services in 2017-2020? ULA will report in September concerning Atlas domestic re-engine possibilities. How much it will actually cost, how long it will actually take and who will actually pay for it? Nobody knows.

1 & 2 are simply beyond anyone's control to factually predict. It's too interdependent on both international and domestic politics. Both of which are not currently being practiced at their apex.

#3 is fully within our means of self-determination. Except...well, who's going to pay for those means? Nobody knows.

I'm not trying to be flippant or humorous. The fact is that for today, right now, everything continues as it has. Until it doesn't. When will it not?...Yep, you guessed it...Nobody knows.

[edkyle99]

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

Dragon V2 cons:
   - ...
   - powered landing reduces usable mass to orbit
   - ...

Back to the original topic.

I'm surprised that nobody picked up on this. Powered landing does *not* reduce usable mass to orbit because the propellant for the landing is the abort propellant.

How about compared to use of a traditional parachute system?  In that case, the landing propellant mass would not have to be orbited.

 - Ed Kyle

[Mader Levap]

You mean Dmitry Rogozin Deputy Prime Minister of Russian Government in charge of defense and space industry?  (the guy who suggested US use a trampoline to get to the ISS)

maybe he joked. or not.. sounds a high profile treat to me

Why everyone thinks that laws (including sanctions) in Russia are done by Twitter posts? Good grief.

[docmordrid]

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

Dragon V2 cons:
   - ...
   - powered landing reduces usable mass to orbit
   - ...

Back to the original topic.

I'm surprised that nobody picked up on this. Powered landing does *not* reduce usable mass to orbit because the propellant for the landing is the abort propellant.

How about compared to use of a traditional parachute system?  In that case, the landing propellant mass would not have to be orbited.

 - Ed Kyle

But it's onboard anyhow for RCS and lunch abort. Gonna leave those behind?

[edkyle99]

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

Dragon V2 cons:
   - ...
   - powered landing reduces usable mass to orbit
   - ...

Back to the original topic.

I'm surprised that nobody picked up on this. Powered landing does *not* reduce usable mass to orbit because the propellant for the landing is the abort propellant.

How about compared to use of a traditional parachute system?  In that case, the landing propellant mass would not have to be orbited.

 - Ed Kyle

But it's onboard anyhow for RCS and lunch abort. Gonna leave those behind?

The launch abort mass, the largest percentage, doesn't go to orbit (it jettisons well before most of the velocity has been attained) and thus most of it would be mass able to be replaced by usable payload.

 - Ed Kyle

[docmordrid]

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

Dragon V2 cons:
   - ...
   - powered landing reduces usable mass to orbit
   - ...

Back to the original topic.

I'm surprised that nobody picked up on this. Powered landing does *not* reduce usable mass to orbit because the propellant for the landing is the abort propellant.

How about compared to use of a traditional parachute system?  In that case, the landing propellant mass would not have to be orbited.

 - Ed Kyle

But it's onboard anyhow for RCS and lunch abort. Gonna leave those behind?

The launch abort mass, the largest percentage, doesn't go to orbit and thus would be mass able to be replaced by usable payload.

 - Ed Kyle

Yes it does go to orbit. Same prop stores. In Dragon V2 it's used for RCS and landing.

[clongton]

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

Dragon V2 cons:
   - ...
   - powered landing reduces usable mass to orbit
   - ...

Back to the original topic.

I'm surprised that nobody picked up on this. Powered landing does *not* reduce usable mass to orbit because the propellant for the landing is the abort propellant.

How about compared to use of a traditional parachute system?  In that case, the landing propellant mass would not have to be orbited.

 - Ed Kyle

Except that *all 3* contenders carry their abort propellant all the way to orbit, and then actually "use" it for some part of the mission, making the abort propellant mass a mute point for all 3. In terms of this metric they are all more or less equal. So the abort propellant on any of the 3 is neither a Pro nor a Con. Therefore it shouldn't even be in the list - that was my point.

Now CST-100 does return by parachute, but to a shock-absorbing bag landing. CST-100 carries BOTH abort propellant *and* absorption bag, making the landing mechanism for CST-100 a "Con" for it because the mass of the bag and deployment hardware is extra mass that neither Dream Chaser nor Dragon have to carry. That does negatively impact the CST-100 IMLEO. A definite Con - from a mass perspective.

[Ike17055]

Self-confirming is self-serving. If It serves one's purposes to "confirm" that you are "right," by focusing just on repeating the questions, while choosing to ignore the subsequent answers, It is self-serving.  Quibbling over this is even more misdirection. It is Changing the topic, which was the extent to which issues are (mis) used to establish a slanted set of "facts." 

[TrevorMonty]

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

Dragon V2 cons:
   - ...
   - powered landing reduces usable mass to orbit
   - ...

Back to the original topic.

I'm surprised that nobody picked up on this. Powered landing does *not* reduce usable mass to orbit because the propellant for the landing is the abort propellant.

How about compared to use of a traditional parachute system?  In that case, the landing propellant mass would not have to be orbited.

 - Ed Kyle

Except that *all 3* contenders carry their abort propellant all the way to orbit, and then actually "use" it for some part of the mission, making the abort propellant mass a mute point for all 3. In terms of this metric they are all more or less equal. So the abort propellant on any of the 3 is neither a Pro nor a Con. Therefore it shouldn't even be in the list - that was my point.

Now CST-100 does return by parachute, but to a shock-absorbing bag landing. CST-100 carries BOTH abort propellant *and* absorption bag, making the landing mechanism for CST-100 a "Con" for it because the mass of the bag and deployment hardware is extra mass that neither Dream Chaser nor Dragon have to carry. That does negatively impact the CST-100 IMLEO. A definite Con - from a mass perspective.

I'm not sure the DC uses its main engines for a ISS mission. Mark Sinangelo stated they could use the  main engines for going to a higher orbit and do additional work after departing the ISS.
This may also apply to CST100 and Dragon. In Dragon case it would have to forgo a powered landing.

If DC doesn't need to use its main engines for a ISS mission, that is quite a cost saving. It also gives them emergency thrust for landings.

[edkyle99]

The launch abort mass, the largest percentage, doesn't go to orbit and thus would be mass able to be replaced by usable payload.
 - Ed Kyle

Yes it does go to orbit. Same prop stores. In Dragon V2 it's used for RCS and landing.

On Dragon V2 and the other entrants it would, yes, but what I'm asking is how this would compare to flying a traditional throwaway escape rocket that would jettison and thus eliminate the need to carry that substantial mass all the way to orbit and back.  Essentially my question boils down to this:  does a parachute weigh more than the propellant and engines needed for landing in addition to the propellant needed to boost them both into and out of orbit?

 - Ed Kyle

[A_M_Swallow]

Sorry, still sounds like misdirection.  THe air force may care about a shortage of russian engines for their satellites, sure. That is the point. The russian threat was to stop engines for military launches, not commercial crew.  My question stands: is there a real basis for concern that atlas for commercial crew would be grounded due to a boycott of sales to ULA for commercial crew. The answer provided SEEMS to muddy the water, thus my continuing frustration with trying to find a factual basis for the whole issue of the rd-180 "issue."   Is there a real threat to current timelines and Is a domestic substitute able to be found in time, if needed? Inquiring minds (really) want to know, because they would like to assess this situation factually instead of from the self-serving spin by spaceX advocates, who after all are ADVOCATES, and considering the conpany's credibility is stretched a bit tight to begin with.

You are asking a badly framed question.  Old rule, silly questions get silly answers.

Try - We have evidence that the Russians are thinking about cutting off supplies of RD-180 engines.  The Rd-180 forms part of the Atlas V launch vehicle.  Is the probability that the Atlas V will be available for DoD flights over the next 10 years High, Medium or Low?

Or if you want a Yes or No answer.  Can NASA be 100% certain that engines will be available every year for the next 10 years?

[A_M_Swallow]

For pro and con answers.

The Falcon 9 has a payload adaptor for the Dragon V1.0.
The Falcon 9 will have a payload adaptor for the Dragon V2.0
Can a Falcon 9 payload adaptor be developed for the DreamChaser?
Can a Falcon 9 payload adaptor be developed for the CST-100?
Can a Falcon 9 payload adaptor be developed for the New Shepard?

The Atlas V will have a payload adaptor for the CST-100.
The Atlas V will have a payload adaptor for the Dreamchaser.
Can an Atlas V payload adaptor be developed for the Dragon V2.0?
Can an Atlas V payload adaptor be developed for the New Shepard?

The Blue Origin's launch vehicle has a payload adaptor for the New Shepard.
Can a Blue Origin payload adaptor be developed for the Dragon V2.0?
Can a Blue Origin payload adaptor be developed for the CST-100?
Can a Blue Origin payload adaptor be developed for the DreamChaser?

A practical system may require modifications to both the payload adaptor and the spacecraft.

[su27k]

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

Dragon V2 cons:
   - ...
   - powered landing reduces usable mass to orbit
   - ...

Back to the original topic.

I'm surprised that nobody picked up on this. Powered landing does *not* reduce usable mass to orbit because the propellant for the landing is the abort propellant.

How about compared to use of a traditional parachute system?  In that case, the landing propellant mass would not have to be orbited.

 - Ed Kyle

Except that *all 3* contenders carry their abort propellant all the way to orbit, and then actually "use" it for some part of the mission, making the abort propellant mass a mute point for all 3. In terms of this metric they are all more or less equal. So the abort propellant on any of the 3 is neither a Pro nor a Con. Therefore it shouldn't even be in the list - that was my point.

Now CST-100 does return by parachute, but to a shock-absorbing bag landing. CST-100 carries BOTH abort propellant *and* absorption bag, making the landing mechanism for CST-100 a "Con" for it because the mass of the bag and deployment hardware is extra mass that neither Dream Chaser nor Dragon have to carry. That does negatively impact the CST-100 IMLEO. A definite Con - from a mass perspective.

I'm not sure the DC uses its main engines for a ISS mission. Mark Sinangelo stated they could use the  main engines for going to a higher orbit and do additional work after departing the ISS.
This may also apply to CST100 and Dragon. In Dragon case it would have to forgo a powered landing.

If DC doesn't need to use its main engines for a ISS mission, that is quite a cost saving. It also gives them emergency thrust for landings.

I thought Mark Sinangelo said on the spaceshow recording they will dump the fuel before returning, not sure if it's done in orbit or just before landing.

[clongton]

Sorry, still sounds like misdirection.  THe air force may care about a shortage of russian engines for their satellites, sure. That is the point. The russian threat was to stop engines for military launches, not commercial crew.  My question stands: is there a real basis for concern that atlas for commercial crew would be grounded due to a boycott of sales to ULA for commercial crew. The answer provided SEEMS to muddy the water, thus my continuing frustration with trying to find a factual basis for the whole issue of the rd-180 "issue."   Is there a real threat to current timelines and Is a domestic substitute able to be found in time, if needed? Inquiring minds (really) want to know, because they would like to assess this situation factually instead of from the self-serving spin by spaceX advocates, who after all are ADVOCATES, and considering the conpany's credibility is stretched a bit tight to begin with.

You are asking a badly framed question.  Old rule, silly questions get silly answers.

Try - We have evidence that the Russians are thinking about cutting off supplies of RD-180 engines.  The Rd-180 forms part of the Atlas V launch vehicle.  Is the probability that the Atlas V will be available for DoD flights over the next 10 years High, Medium or Low?

Or if you want a Yes or No answer.  Can NASA be 100% certain that engines will be available every year for the next 10 years?

Off Topic! There are other threads dedicated to that topic. Please go there.

[clongton]

Ed, there are all kinds of trades that were made to determine the mode of return of the three CC contenders. SpaceX chose powered landing with parachute only as a backup. DreamChaser, like Shuttle, glides to a runway and has no backup. Only CST-100 chose to stick with parachutes as the landing method, and added landing bags to enable solid ground landing. I understand your question, but istm that you're getting into territory of "what if" DC and Dv2 used parachutes, like CST-100. It's an interesting question, except that this thread is about the Pros and Cons of the three spacecraft as they are currently designed, not what they might have been.

With regard to parachute as the main landing mode, I would say that it is a Con for CST-100 v.s. the other two because powered landing (Dv2) and runway landing (DC) can be considered pinpoint landing, something that will have to become normal if commercial spaceflight is to become commonplace. Dropping under a parachute can never get better than "close", providing the winds cooperate. Parachute landings can never be commonplace to a healthy commercial spaceflight industry.

[clongton]

For pro and con answers.

The Blue Origin's launch vehicle has a payload adaptor for the New Shepard.
Can a Blue Origin payload adaptor be developed for the Dragon V2.0?
Can a Blue Origin payload adaptor be developed for the CST-100?
Can a Blue Origin payload adaptor be developed for the DreamChaser?

A practical system may require modifications to both the payload adaptor and the spacecraft.

Good questions but you should ask aero, who started this thread, if it's ok to include the New Shephard spacecraft in the discussion. For example he specifically excluded Orion because it is not one of the three contenders for commercial crew, and AIUI, neither is Blue Origin's New Shepard. It was my understanding that aero intended the discussion to remain focused on just CST-100, Dragon and DreamChaser. No other spacecraft under development, and there are several, are contenders for NASA's Commercial Crew contract.

[muomega0]

Ed, there are all kinds of trades that were made to determine the mode of return of the three CC contenders. SpaceX chose powered landing with parachute only as a backup. DreamChaser, like Shuttle, glides to a runway and has no backup. Only CST-100 chose to stick with parachutes as the landing method, and added landing bags to enable solid ground landing. I understand your question, but istm that you're getting into territory of "what if" DC and Dv2 used parachutes, like CST-100. It's an interesting question, except that this thread is about the Pros and Cons of the three spacecraft as they are currently designed, not what they might have been.

With regard to parachute as the main landing mode, I would say that it is a Con for CST-100 v.s. the other two because powered landing (Dv2) and runway landing (DC) can be considered pinpoint landing, something that will have to become normal if commercial spaceflight is to become commonplace. Dropping under a parachute can never get better than "close", providing the winds cooperate. Parachute landings can never be commonplace to a healthy commercial spaceflight industry.

NASA is paying the vendors to economically send crew safely to LEO and back.  It does not specify the location of return, nor departure.   IOW: "close" is good enough since since a large number of missions is not required prior to ISS splashdown in 20152020--its a limited use vehicle.  OTOH:  if this thread considered any possibility of being included in BEO, then many other pros/cons arise, and "what ifs" would be considered as part of the flexible path forward.  For example, does XXX have a payload adapter for Dragon V4 or SLS v1,234,567.25?

[Coastal Ron]

With regard to parachute as the main landing mode, I would say that it is a Con for CST-100 v.s. the other two because powered landing (Dv2) and runway landing (DC) can be considered pinpoint landing, something that will have to become normal if commercial spaceflight is to become commonplace. Dropping under a parachute can never get better than "close", providing the winds cooperate. Parachute landings can never be commonplace to a healthy commercial spaceflight industry.

It has been mentioned that with it's cross-range capabilities the Dream Chaser can avoid bad weather because it has a large landing area to choose from (up to 1,000 mi).  Capsules have to come down closer to the track they descend from space on, so they have to plan for rougher weather landings than the Dream Chaser.

Speaking of bad weather at the landing site for the two capsules, wouldn't the Dragon's powered landing system provide them with better control in windy conditions?  And if they don't pop their chute they have less chance of being dragged around in high winds after landing.  No doubt there is a limit to how windy they could land in, but I would think powered landings could be more safe from that aspect.

[Rocket Science]

21st century LEO ops should not include a return to Earth that looks like a SAR operation. We live on a planetary body that has an atmosphere so why not use it for landing. It’s free and always there and DC’s lifting body maximizes it utilization to the greatest effect...