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

[arachnitect]

Dragon V2 will have two launch vehicles. F9 and FH. Having the extra lift of FH will offer an operational advantage.

What do you propose to do with the extra performance?

Don't need FH to get 4 people to ISS.

No but you could get a lot of junk in the trunk with all that extra performance.
 Speaking of trunks, how do CST100 and DC stack up against Dragon with respect to cargo in addition to crew?

Biggest issue is docking collar inner diameter. CST-100 might get adapted to CBM. But then they will have to change the approx ops. I've not seen a single reference that CBM could be fit to the DC aft. Apparently it's simply too small.
DC has the "softer" entry advantage. And until Dv2 it was able to offer shorter times from landing to payload deliveries (L+1 vs L+8, I think). But if Dv2 propulsive landing is implemented, Spx can offer that service, too.
Now, an HL42 on a FH could make for an amazing LEO transport. But that's just for a whole different discussion.

When Dragon aborts, does it take the trunk with it or not? If it does, that probably constrains trunk cargo more than LV performance. Is Canadarm access an issue if they're docked at Node 2 fwd?

CST and DC have no capacity for external cargo. All the vehicles have room for some cargo along with passengers. Both Boeing and SNC have announced their intention to offer dedicated cargo versions for the CRS Follow On contract, ">1100 kg" and "~1350 kg" respectively. Adding a CBM to either is impossible without essentially building an entirely new vehicle.

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

The empty area of the CST-100 SM will be occupied/obscured by the solar panel mission kit they will be using.

[QuantumG]

What happens to the vehicles that are not selected?. I've not read anything stating what a manufacturer will do if their vehicle is not selected.

SpaceX has Mars as along term goal, plus there was an arrangement with Bigelow which I've not heard much about recently.

Boeing has an arrangement with Bigelow plus Space Adventures  http://spaceflightnow.com/news/n1406/15lunarsoyuz/#.U59XkGf7Jgg

SNC have stated a few different uses for DC but not sure if they have any firm customers.

Yeah, but I think the reality is that two will die on the vine. If Bigelow is serious about demanding two providers for crew transport before putting up his first station, then I think he'll never fly. It's a shame, but the reality is that human spaceflight in the US is still strongly dependent upon NASA's budget. The idea of independent financing for human spaceflight coming in and changing this is great, and many people would welcome it, but so far that's not even on the horizon.

[baldusi]

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

The crewed version has the LAS engines on the Service Module, which sort of precludes an unpressurized thunk. Unless they do something like the ATK proposal, where the thunk is embedded between the capsule and the SM. This might be an interesting solution since it might enable the use of the SM propulsion for station reboost.
Alternatively, a different SM might be developed. Let's remember that the CST is wider than Dragon and thus could have a hollow SM. But it will require some design effort.

Would Dream Chaser have any capacity for vacuum cargo?

They have shown some pictures with DC having a harness with an attached satellite in the aft. I believe it would be more difficult to carry unpressurized cargo. Specially because the docking mechanism is on the aft.

Vacuum cargo capacity may not be required that frequently but it is important.

To say the truth, even Cygnus could do unpressurized. And if HTV is continued, then they most certainly could go with it. The wild card here is that the longer they push the contract to allow third parties to mature technologies the more OSCATK and SpaceX will accrue their systems. And with the Dragon v2 and F9R combo, they have the potential to reduce costs a lot.

[docmordrid]

Speaking of the DV2,trunk, in the concept video it looks a lot longer than DV1's in some views. Hinting the extended 34 m3 trunk?

[DGH]

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

Would Dream Chaser have any capacity for vacuum cargo?

Vacuum cargo capacity may not be required that frequently but it is important.

The retiring ATV does not really transport vacuum cargo.
More than half of what it has transported has been fuel.
With another large percentage being water and air.
This seems to favor the CST-100 with its large service module.

[guckyfan]

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

Would Dream Chaser have any capacity for vacuum cargo?

Vacuum cargo capacity may not be required that frequently but it is important.

The retiring ATV does not really transport vacuum cargo.
More than half of what it has transported has been fuel.
With another large percentage being water and air.
This seems to favor the CST-100 with its large service module.

Do the docking ports support transfer of liquids? I don't think so.

But if they do there are those two pipes we saw in Dragon V2 going straight from the bottom of Dragon up to the top where the docking adapter is placed. Someone asked what those pipes are for but there was no answer. We do know there are liquids connections from Dragon to the trunk.

It seems there is not any one vehicle that can supply all the ISS needs.

[moralec]

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

Would Dream Chaser have any capacity for vacuum cargo?

Vacuum cargo capacity may not be required that frequently but it is important.

The retiring ATV does not really transport vacuum cargo.
More than half of what it has transported has been fuel.
With another large percentage being water and air.
This seems to favor the CST-100 with its large service module.

Do the docking ports support transfer of liquids? I don't think so.

But if they do there are those two pipes we saw in Dragon V2 going straight from the bottom of Dragon up to the top where the docking adapter is placed. Someone asked what those pipes are for but there was no answer. We do know there are liquids connections from Dragon to the trunk.

It seems there is not any one vehicle that can supply all the ISS needs.

How are liquids currently transferred to the ISS. According to this http://blogs.esa.int/atv/2013/08/27/update-on-todays-final-water-transfer-to-the-iss/ is done manually by astronauts. Maybe a similar system could be implemented for other liquids?

[guckyfan]

How are liquids currently transferred to the ISS. According to this http://blogs.esa.int/atv/2013/08/27/update-on-todays-final-water-transfer-to-the-iss/ is done manually by astronauts. Maybe a similar system could be implemented for other liquids?

Yes  water. But not fuel as mentioned in the case of ATV.

[douglas100]

...When Dragon aborts, does it take the trunk with it or not? If it does, that probably constrains trunk cargo more than LV performance...

I think it does take the trunk (not everyone agrees.) But I don't think cargo in the trunk would significantly affect the abort margins when you have eight SD's firing at full throttle producing in the order of 60 tons of thrust.

EDIT: added "significantly."

[Zed_Noir]

Dragon V2 will have two launch vehicles. F9 and FH. Having the extra lift of FH will offer an operational advantage.

What do you propose to do with the extra performance?

Don't need FH to get 4 people to ISS.

I think he has flights beyond LEO in mind...

I think if needed, a Dragon V2 on a FH can go to the ISS from either VAFB or South Texas.

Guess you can launch 3 Dragons to the same LEO orbit more or less simultaneously. Of course what good is that fact to anyone is not apparent.

[Darren_Hensley]

Having studied CBMs and APAS, adapters on the US side, and the Probe and Drogue adapters on the Russian side over the past 5 years... No, there is no one visiting vehicle(VV) that can service all of the ISSs Gas and Liquid transfer needs.

This is all the more reason the next generation Docking and Birthing adapters need to be studied further for this serious lack of imagination. Up to 14 independant lines would be needed, some gas, some liquid, some fuel, some electrical, some optical data. I've yet to get any real feedback on my designs and configurations.

I propose that a vehicle as large as the HTV could have a Birthing interface that accomodates all of the transfer needs of a space station. Using the plenum, and vestibule, multiple redundant loop connections can be installed for all needs except AIR circulation systems. The duct takes up valuable space needed for lines and wires.

IMO Air circulation systems need no be installed if the station is properly designed for air flow through the open hatches of the CBMs. Yes I know this requires some kind of race track configuration without dead end modules. No design I've come up with is perfect, but the dead end modules can be the source for fresh air, if the connected interim modules, all have a circulation system installed. But that's another subject.

Liquids transfer from VVs as large as the HTV would be a great asset. The ONLY downside I've been able to see is that the Astronauts aboard the station must make all the hose and wire connections in the vestibule mannualy. However the controls can be either VV or station mounted to manage the transfer once the lines have been purged and certified for transfer, or uplink is established and talkback is working.

We've proven this ideal on a limited basis mostly on Soyuz, and ATV's. To me the birthing interface the Russian side uses is inadequate. It physically cannot accomodate an ISPRs external dimensions, and has no vestibule connections like CBMs.

My Two Cents...

[A_M_Swallow]

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

Would Dream Chaser have any capacity for vacuum cargo?

Vacuum cargo capacity may not be required that frequently but it is important.

Instead of using the docking port the Dream Chaser could connect to a cargo module using its undercarriage.

If Jeeps can be locked into trays via their wheels when carried by aircraft then catches for the Dream Chaser's wheels and slide can be devised for a cargo module.

The Dream Chaser would have to remain airtight when the wheels are down in vacuum.  The pilot would have to 'land' the vehicle on the back of the cargo module.  To maintain control authority the cargo module may need an RCS controlled from the Dream Chaser.

[kerlc]

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

Would Dream Chaser have any capacity for vacuum cargo?

Vacuum cargo capacity may not be required that frequently but it is important.

Instead of using the docking port the Dream Chaser could connect to a cargo module using its undercarriage.

If Jeeps can be locked into trays via their wheels when carried by aircraft then catches for the Dream Chaser's wheels and slide can be devised for a cargo module.

The Dream Chaser would have to remain airtight when the wheels are down in vacuum.  The pilot would have to 'land' the vehicle on the back of the cargo module.  To maintain control authority the cargo module may need an RCS controlled from the Dream Chaser.

The dream chaser already uses its main engines to get to orbit, I don't think adding mass to it would be of much help.

However, if a different, more powerful launcher were used, it might work. Except that tacking on a reusable cargo module like that would mess with the aerodynamics quite a bit.

What about making a disposable cargo module? I know, it costs some of the reusability, but you could always make it optional.

On the subject of adding things to the DC, what about adding a disposable orbital module, like the Kliper concept had? It might give the DC the ability to do solo missions and give the crew a bit more leg room.

[Darren_Hensley]

Would the service module of CST-100 allow similar size and weight of vacuum cargo as the Dragon trunk? I think not but may be wrong.

Would Dream Chaser have any capacity for vacuum cargo?

Vacuum cargo capacity may not be required that frequently but it is important.

Instead of using the docking port the Dream Chaser could connect to a cargo module using its undercarriage.

If Jeeps can be locked into trays via their wheels when carried by aircraft then catches for the Dream Chaser's wheels and slide can be devised for a cargo module.

The Dream Chaser would have to remain airtight when the wheels are down in vacuum.  The pilot would have to 'land' the vehicle on the back of the cargo module.  To maintain control authority the cargo module may need an RCS controlled from the Dream Chaser.

The dream chaser already uses its main engines to get to orbit, I don't think adding mass to it would be of much help.

However, if a different, more powerful launcher were used, it might work. Except that tacking on a reusable cargo module like that would mess with the aerodynamics quite a bit.

What about making a disposable cargo module? I know, it costs some of the reusability, but you could always make it optional.

On the subject of adding things to the DC, what about adding a disposable orbital module, like the Kliper concept had? It might give the DC the ability to do solo missions and give the crew a bit more leg room.

I see that both arguments add complexity to a system, Using ILIDS restricts transfer through the docking port, I don't think the DC should have such complexity added to it. It may be best suited for transfer of personnel and small cargo as designed. Adding a cargo unit apollo style(like a LM was added to the CM) could have advantages, but IMO we should be thinking about a universal cargo deck concept that will adapt to all the transports using the same interface. And that is the ILIDS system. So a tunnel through a cargo module is needed. An empty tunnel is wasted space, and can be filled with, again, small cargo bags. So far none of this is vacuum cargo.

I'm thinking a dedicated cargo system is best for cargo transfers. The Dragon v2 is designed for personnel as it's primary cargo, Dragon Cargo we know it does it's job well. Both will use a trunk, ergo vacuum cargo is a built in feature.

CST-100 would need some kind of SM with real storage built in. Don't know of any design with this in mind. Not that it's impossible, just not observed.

I see that the Dragon has diameter sufficient to install a full size CBM in leiu of a ILIDS, I can't say if that's a Pro or Con. but CST and DC would be interesting case studies for adoption, but without a clear reason for such mods, why bother to study it?. Dragon docked or birthed uses the trunk for it's vacuum cargo, making attachment methods a choice, not a mandate, and vacuum cargo transfer by external arm a mandate, not a choice.

Dragon cargo needs an arm to birth, Dragon v2 docks without the aid of an arm. Both have a trunk. I do see that as a Pro.

[A_M_Swallow]

Interesting ideas but we have a major constraint.  With spacecraft the cargo has to be in front of the nozzles.  (Or away from them.)

Like most spacecraft the Dream Chaser has the nozzles for its main engines at the back.  Unfortunately it also has the docking port at the back.  So if anything is attached via the NDS/ILIDS the spacecraft cannot fire its main engines without destroying the 'thing'.

The Orion, Dragon and CST-100 have their docking port at the front and the main engines towards the back and sides.

By attaching the cargo module to Dream Chaser using the undercarriage there is no destructive flame impairment.  This also uses the existing strong points on the spacecraft.

[Jim]

Like most spacecraft the Dream Chaser has the nozzles for its main engines at the back.  Unfortunately it also has the docking port at the back.  So if anything is attached via the NDS/ILIDS the spacecraft cannot fire its main engines without destroying the 'thing'.

Meaningless.  NDS/ILIDS is not an interface that can support a object during launch. 

[Burninate]

I see that the Dragon has diameter sufficient to install a full size CBM in leiu of a ILIDS, I can't say if that's a Pro or Con. but CST and DC would be interesting case studies for adoption, but without a clear reason for such mods, why bother to study it?.

So you're looking for a reason to mount a CBM to another reusable capsule with a comfortable ride down -  how about downmass?  Returning a full, intact ISPR rack is something we could do with MPLM aboard the Shuttle, but which I think we now lack the capability to do.  Dragon Cargo's interior is right at the edge of feasibility to hold an object this size, but perhaps it's more practical for DC or CST?

[Prober]

Interesting ideas but we have a major constraint.  With spacecraft the cargo has to be in front of the nozzles.  (Or away from them.)

Like most spacecraft the Dream Chaser has the nozzles for its main engines at the back.  Unfortunately it also has the docking port at the back.  So if anything is attached via the NDS/ILIDS the spacecraft cannot fire its main engines without destroying the 'thing'.

The Orion, Dragon and CST-100 have their docking port at the front and the main engines towards the back and sides.

By attaching the cargo module to Dream Chaser using the undercarriage there is no destructive flame impairment.  This also uses the existing strong points on the spacecraft.

that's a good looking pic to brighten this day.

[Zed_Noir]

Interesting ideas but we have a major constraint.  With spacecraft the cargo has to be in front of the nozzles.  (Or away from them.)

Like most spacecraft the Dream Chaser has the nozzles for its main engines at the back.  Unfortunately it also has the docking port at the back.  So if anything is attached via the NDS/ILIDS the spacecraft cannot fire its main engines without destroying the 'thing'.

The Orion, Dragon and CST-100 have their docking port at the front and the main engines towards the back and sides.

By attaching the cargo module to Dream Chaser using the undercarriage there is no destructive flame impairment.  This also uses the existing strong points on the spacecraft.

1. Can the landing gear doors be open and close in vacuum without compromising the TPS? Also can the tires on the landing gear and the landing gears themselves be exposed to external vacuum environment?

2. Attitude control would be interesting with your suggested stack configuration.

3. The landing gears are not design to take the loads in your stack configuration. Never mind there is no nose landing gear (the skid is not something you can attached things to).


IMO if you want to move cargo through a CBM port with something like the DC, build a bigger unmanned DC with a CBM port for berthing.

[A_M_Swallow]

Interesting ideas but we have a major constraint.  With spacecraft the cargo has to be in front of the nozzles.  (Or away from them.)

Like most spacecraft the Dream Chaser has the nozzles for its main engines at the back.  Unfortunately it also has the docking port at the back.  So if anything is attached via the NDS/ILIDS the spacecraft cannot fire its main engines without destroying the 'thing'.

The Orion, Dragon and CST-100 have their docking port at the front and the main engines towards the back and sides.

By attaching the cargo module to Dream Chaser using the undercarriage there is no destructive flame impairment.  This also uses the existing strong points on the spacecraft.

1. Can the landing gear doors be open and close in vacuum without compromising the TPS? Also can the tires on the landing gear and the landing gears themselves be exposed to external vacuum environment?

2. Attitude control would be interesting with your suggested stack configuration.

3. The landing gears are not design to take the loads in your stack configuration. Never mind there is no nose landing gear (the skid is not something you can attached things to).


IMO if you want to move cargo through a CBM port with something like the DC, build a bigger unmanned DC with a CBM port for berthing.

1.  On the current Dream Chaser or the mark 2?  New wheels that can handle vacuum and air tight seals can be added.

2.  The cargo module will need its own RCS controlled from the Dream Chaser.

3.  The spacecraft touches down at over 100 miles per hour.  So the skid can take strong forces.  A metal hand for instance may be able to grab the skid from the side.

The Dream Chaser is a manned return vehicle.  If it is being used to tractor the cargo then the mission probably needs the skills of the pilot.  The EELV, SLS and COTS LV can launch automated cargo modules.

There will have to be some sort of expendable interstage between the cargo and Dream Chaser during launch.

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