Author Topic: CRS-2: Dream Chaser Cargo System  (Read 118824 times)

Offline MattMason

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Re: CRS-2: Dream Chaser Cargo System
« Reply #60 on: 03/19/2015 12:53 pm »
I appreciate the concept that SNC offers, but, like some of you, it's the use of the IDA port and the extra service module that makes DC Cargo a strange beast to challenge SpaceX, Boeing, Orbital and Lockheed combined.

Using the Common Berthing Mechanism simply makes large cargo easy to manage. To mix crew apples with cargo oranges by occupying one of the IDAs, especially if a crew vehicle arrives and finds a technical problem that prohibits the use of the remaining IDA, is a serious challenge. A redesign of the service module to become an CBM port would fix this.

The DC certainly has the best recovery option in terms of speed. You can practically unload this ship moments after safeing it. But, speed of off-loading isn't a mission issue, is it? After all, there's no crew, and this isn't carrying luggage that needs to meet a connecting flight. So SNC's video creates a rather misleading notion that cargo transfer is important once back on Earth.

I think that DC Cargo has a slight edge over Lockheed's Jupiter in terms of cargo return. But with CST-100 Cargo also offering this, Boeing's clout shadow hangs once again over SNC's effort, I fear.

DC Cargo offer more upmass than Dragon and way more than CST-100 Cargo based on my checks, but Expanded Cygnus and Jupiter easily trump this. Downmass, it would be comparable to Dragon. The folding wing thing doesn't bother me any more than solar panels but it's an added technical step.

If so, that's their one saving grace--IF they can get past the use of the IDA. There's also the matter of SNC's one Achilles's Heel: They are the only competitor reliant on an LV from one of their other competitors. It would more beneficial, IMO, for them to lean to working with SpaceX and buying reused boosters once they start populating. I don't think SpaceX would have an axe to grind since they also have Commercial Crew and a lot of things going on.
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Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #61 on: 03/19/2015 12:59 pm »
« Last Edit: 03/19/2015 01:02 pm by Rocket Science »
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Offline MattMason

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Re: CRS-2: Dream Chaser Cargo System
« Reply #62 on: 03/19/2015 01:12 pm »
Sorry for the extra posting (I prefer to make one post and wait for thoughts, if any) but I just recalled that CST-100 Cargo would also use the IDA, too, so this is a balancing offset to DC-C's use of it, as well. As I said, I just think that every competitor owning their own LV generates a stronger advantage overall to SNCs offering.

But some could argue of Orbital's "reliability" with the ORB-3 failure, SpaceX's youth and ever-growing manifest, development time for Jupiter, and so on. If SNC could also promise a very fast development time, the LV issue might be less of a problem. Alliances within competitors might be advantageous. Just watch an episode of "Survivor," or read the ULA newsletter.
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Offline Comga

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Re: CRS-2: Dream Chaser Cargo System
« Reply #63 on: 03/19/2015 02:00 pm »
The wing hinges fold so that the mechanisms have to hold them against the drag.  Sounds difficult.
The fairing simplifies the aerodynamics but adds cost and mass, which could mean extra solids on Atlas and even more cost.
The X-38 was to have folding wings so the idea is not "too off the wall"...
Aircraft carrier fighter airplanes have been using them for decades. It ain't rocket science.

Yeah, but the carrier airplane wings are folded by ground crews.  They don't have to be folded autonomously in space.

Nobody is arguing that it's impossible, just that it adds mass and complexity and cost.  None of those things helps Dream Chaser cargo compete against the other proposals, none of which have to deal with folding wings.

You have to love NSF.  A small point gets such a response.  The videos of folding and unfolding aircraft are terrific.

People are correct: Automatic folding wings have been done.  Others like Jim are also right: These don't involve hypersonic flight. But the basic point was that this is an additional development task and additional complexity.

Beyond folding wings there are so many other additional development tasks for DCC vs. its DC predecessor that take additional time and money.  (Note that the $2.6B is not a relevant number, as it included (6?) crew carrying flights.)  It seems so much more complex than Jupiter/Exo-liner, and so far behind Dragon and CST-100.  (I have a friend working DCC who has commented on the enourmous expected workload if they win.) 

And it starts with the same Atlas V with DEC as CST-100 and Jupiter/Exoliner. 
I just don't see this as being competitive. 
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #64 on: 03/19/2015 02:06 pm »
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #65 on: 03/19/2015 02:18 pm »
ESA was to build components for the X-38. Perhaps this model is what SNC is planning to get their involvement in DC.

http://www.spaceref.ca/news/viewnews.html?id=353
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Offline baldusi

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Re: CRS-2: Dream Chaser Cargo System
« Reply #66 on: 03/19/2015 02:39 pm »
I've been giving some thought to the use of IDA for cargo delivery within the context of the CRS-2. And while CBM has capabilities that IDA obviously lack, it also sucks a lot of crew time. So, within the context of CRS-2, and considering that they already have the HTV, if they chose one additional CBM vehicle to make bulk transfers, they could use another IDA capable craft for increasing the visit opportunities without incurring in such a high crew time cost.
Besides, there will be two IDA ports, and since they appear to keep the crewed vehicle interleaved with Soyuz, they could simply launch the IDA capable cargo once the Commercial Crew is already docked, use the second port, and leave before the crew leaves. So, for each dock and undock of the crew, there would be two IDA's available, but they could use the secondary in the mean times (free use of five months in each six month period).
If they chose a third Cargo contractor, then they might even desire that the third contractor uses IDA.

Offline adrianwyard

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Re: CRS-2: Dream Chaser Cargo System
« Reply #67 on: 03/19/2015 02:56 pm »
Yes, it is interesting that SNC chose IDA when it looks as though their service module is just about wide enough to accommodate a CBM.

While the CRS-2 RFP talks about docking (IDA) and berthing (CBM) being options, it also says that they need a CBM solution in the mix because of its width. See Answer 20 here: https://prod.nais.nasa.gov/eps/eps_data/160022-OTHER-003-001.pdf so that implies that at least SpaceX or Orbital ATK will get chosen.
_________
In prior threads it's been noted that the Cargo Dragon doesn't have enough internal volume to accommodate a full size ISS rack, but that's not seen as a major detriment.

Offline A_M_Swallow

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Re: CRS-2: Dream Chaser Cargo System
« Reply #68 on: 03/19/2015 07:03 pm »
The is video on web showing the thrusters, 3 small ones on each side.

Can't compete with Dragons trunk for bulky unpressurized cargo.

Hmmm, if you ask me it looks like those thrusters are aimed at the solar panels...

To use the tail thrusters to slow down I would expect the Dream Chaser to be flying backwards. It would turn around after the burn.

Boosting the station! How? The thrusters point to wards to station. Unless there is an additional set of thrusters somewhere that point towards the nose of the spacecraft.

I'm not following. The solar panels are in the way of the thrusters regardless of whether you're flying forwards or backwards WRT the ISS. Also, you need the ability to brake/abort the approach in the last few moments before docking, i.e. you need these station-facing thrusters to be available. I think the obvious answer is the graphics are just wrong; in reality the panels would be hinged at a different location, and can be folded out of the way of the thruster plume during docking.

I was not worried about docking, that is easy just fit tiny RCS thrusters.

I was worried about (a) re-entry and (b) boasting the ISS. The video shows the Dream Chaser using its main engines to slow down for re-entry but firing in the same direction it is flying.

The tiny RCS thrusters could be used to boast the ISS but it will be a very long burn, certainly several minutes possibly hours.

Offline rayleighscatter

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Re: CRS-2: Dream Chaser Cargo System
« Reply #69 on: 03/19/2015 07:40 pm »
Dreamchaser was already going to have aerosurfaces for maneuvering that would have to move properly. Shuttle had elevons, a body flap, and a rudder that had moving surfaces under load with tps. Folding the whole stablizier isn't really breaking much new ground.

Offline ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #70 on: 03/19/2015 08:18 pm »
If they chose a third Cargo contractor, then they might even desire that the third contractor uses IDA.

They might select a cargo contractor in spite of them using IDA, but I don't think they'd prefer it.  They have two of each kind of port and a third cargo contractor would mean two crew and two other cargo vehicles.  Do they really need three cargo vehicles at the same time?  Probably not.  And redundancy is probably more important for crew than for cargo, so they'd probably rather keep the IDAs clear for crew vehicles so if one is down they still have the other for another crew vehicle.

Offline ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #71 on: 03/19/2015 08:22 pm »
I can't see why they would build a carrier aircraft with wings that can be folded by the pilot from the cockpit.  It would be like designing a car that lets you remove the wheels from the driver's seat.  It seems obvious to me it's better to require someone to physically go up to the wheel with a lug wrench and unbolt the wheel, both because it prevents accidental, catastrophic removal of the wheel while driving and because it would be a bunch of extra complexity that's not needed because there's no reason to remove the wheel except when the vehicle is stopped and you can physically access it.
While I might have supposed something similar...

We don't need suppositions when we have facts.  Ladies and gentlemen, the E-2C, the EA-6B, the V-22, and the F/A-18.  The last one is now the base platform for the vast majority of USAF carrier aircraft.

That's interesting!

As always, evidence trumps what we suppose would be the case. :-)

I'm really curious now why they chose to do it that way.

Offline ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #72 on: 03/19/2015 08:26 pm »
Dreamchaser was already going to have aerosurfaces for maneuvering that would have to move properly. Shuttle had elevons, a body flap, and a rudder that had moving surfaces under load with tps. Folding the whole stablizier isn't really breaking much new ground.

Even if there are already similar things, it's still complexity and mass.  Also, the loads on the stabilizers may be a lot greater than the loads on those control surfaces.

Offline arachnitect

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Re: CRS-2: Dream Chaser Cargo System
« Reply #73 on: 03/19/2015 08:50 pm »
I can't see why they would build a carrier aircraft with wings that can be folded by the pilot from the cockpit.  It would be like designing a car that lets you remove the wheels from the driver's seat.  It seems obvious to me it's better to require someone to physically go up to the wheel with a lug wrench and unbolt the wheel, both because it prevents accidental, catastrophic removal of the wheel while driving and because it would be a bunch of extra complexity that's not needed because there's no reason to remove the wheel except when the vehicle is stopped and you can physically access it.
While I might have supposed something similar...

We don't need suppositions when we have facts.  Ladies and gentlemen, the E-2C, the EA-6B, the V-22, and the F/A-18.  The last one is now the base platform for the vast majority of USAF carrier aircraft.

That's interesting!

As always, evidence trumps what we suppose would be the case. :-)

I'm really curious now why they chose to do it that way.


Protects sailors. Fewer people running around the flight deck handling aircraft is better.

Offline baldusi

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Re: CRS-2: Dream Chaser Cargo System
« Reply #74 on: 03/19/2015 09:28 pm »
If they chose a third Cargo contractor, then they might even desire that the third contractor uses IDA.

They might select a cargo contractor in spite of them using IDA, but I don't think they'd prefer it.  They have two of each kind of port and a third cargo contractor would mean two crew and two other cargo vehicles.  Do they really need three cargo vehicles at the same time?  Probably not.  And redundancy is probably more important for crew than for cargo, so they'd probably rather keep the IDAs clear for crew vehicles so if one is down they still have the other for another crew vehicle.
I specifically said that I was speculating that IDA has lower crew time requirements. The arm positioning and the crew practice plus actual operation takes a couple of days of crew time. IDA vehicles would need only final approach attention. That's the advantage over CBM. Thus, if they cover their bulk cargo needs (let's say by keeping Dragon and Super Cygnus) on five launches, an additional launch would add cargo but take away crew time. An IDA, would not. And if it is a CST-100, they earn one extra downmass opportunity, plus unpressurized and (if Boeing was aggressive enough on price) synergies with he crewed launcher. Under Commercial Crew, they might get as little as two flights. With this, they would get at least eight total (minimum of 2 crewed and 6 cargo). That's a plus on capabilities and demonstrated performance.

Offline Lars-J

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Re: CRS-2: Dream Chaser Cargo System
« Reply #75 on: 03/20/2015 01:20 am »
There is a reason why ISS will have two CBM and two IDA ports. NASA would clearly *prefer* that the cargo supply vessels use the earth-facing CBM ports, to leave the IDA ports for commercial crew. The CBM earth facing locations also have the advantage of the approaching craft naturally drifting apart if there is a problem.

So while IDA is not forbidden, I would find it VERY implausible that two IDA cargo providers would be chosen. And the only one with a real chance is IMO CST-100, due to the overlap with the crew version.

Offline Jim

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Re: CRS-2: Dream Chaser Cargo System
« Reply #76 on: 03/20/2015 01:26 am »
Dreamchaser was already going to have aerosurfaces for maneuvering that would have to move properly. Shuttle had elevons, a body flap, and a rudder that had moving surfaces under load with tps. Folding the whole stablizier isn't really breaking much new ground.


Not true.  All those aerosurfaces had hinge lines perpendicular to the air flow and not parallel as in a folding wing.

Offline joek

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Re: CRS-2: Dream Chaser Cargo System
« Reply #77 on: 03/20/2015 02:41 am »
While the CRS-2 RFP talks about docking (IDA) and berthing (CBM) being options, it also says that they need a CBM solution in the mix because of its width. See Answer 20 here: https://prod.nais.nasa.gov/eps/eps_data/160022-OTHER-003-001.pdf so that implies that at least SpaceX or Orbital ATK will get chosen.

CRS-2 RFP calls for (among other things) pressurized cargo up/down per-flight range of: M01 bag 0-10; M02 bag 10-TBP; M03 bag 0-6. How those bags fit with respect to NDS, Cygnus mini-CBM and CBM is shown in the attached figure below.

edit: add ISPR; edit: add NDS 120cm; add NDS petals; add possible M03 bag fit through NDS with one set of petals removed (not sure if that is possible).
« Last Edit: 03/21/2015 01:50 pm by joek »

Offline Burninate

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Re: CRS-2: Dream Chaser Cargo System
« Reply #78 on: 03/20/2015 03:07 am »
While the CRS-2 RFP talks about docking (IDA) and berthing (CBM) being options, it also says that they need a CBM solution in the mix because of its width. See Answer 20 here: https://prod.nais.nasa.gov/eps/eps_data/160022-OTHER-003-001.pdf so that implies that at least SpaceX or Orbital ATK will get chosen.

CRS-2 RFP calls for (among other things) pressurized cargo up/down per-flight range of: M01 bag 0-10; M02 bag 10-TBP; M03 bag 0-6. How those bags fit with respect to NDS, Cygnus mini-CBM and CBM is shown in the attached figure below.
This is excellent.  Could you add external dimensions of a monolithic ISPR rack though?
« Last Edit: 03/20/2015 03:10 am by Burninate »

Offline manboy

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Re: CRS-2: Dream Chaser Cargo System
« Reply #79 on: 03/20/2015 06:54 am »
Is a CBM even an option, or is NDS implicitly mandated?

LM's proposal seems to use the CBM.

Besides, the ISS will only have 2 NDS ports. At least one will have a commercial crew vehicle attached to it at all times. The other has to remain available for contingency and crew rotations.

I don't see how an NDS-equipped commercial cargo vehicle can fit into that scheme.
Isn't in-direct crew handover still the plan?
"Cheese has been sent into space before. But the same cheese has never been sent into space twice." - StephenB

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