Author Topic: CRS-2: Dream Chaser Cargo System  (Read 57664 times)

Offline adrianwyard

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Re: CRS-2: Dream Chaser Cargo System
« Reply #40 on: 03/18/2015 11:01 PM »
Assuming Boeing delivers on its CST-100 commercial crew contract, then requiring Dual Engine Centaur for CRS-2 seems reasonable.

Offline TrevorMonty

Re: CRS-2: Dream Chaser Cargo System
« Reply #41 on: 03/18/2015 11:35 PM »
It looks to me like the Dream Chaser Cargo has a much higher development cost and schedule risk than any of the other known CRS2 proposals.  Not only do they have to do a huge amount of development on Dream Chaser itself, but they also have to develop a service module.  The service module probably won't be developed entirely from scratch since SNC has some experience in the area, but I think they're a lot farther away from a service module than LM is from Jupiter.

The service module is also going to add to their per-mission costs.  Being compatible with a variety of launch vehicles is definitely a step in the right direction on cost, but for CRS-2 they will have had to propose missions with a specific launch vehicle partner.  Launching on Ariane isn't allowed by the CRS-2 rules, as I understand them, so unless SpaceX signed onto their bid (which I highly doubt for competive reasons), they're still stuck with Atlas V.  With both LM and Boeing submitting competing CRS-2 bids, ULA probably didn't offer SNC a particularly special deal on Atlas V for DC for CRS-2.

So I don't think they can compete with SpaceX on price for downmass.  And OrbitalATK and LM proposals have much more cargo per trip, so I don't think they can compete with either of those bids.

I think it's not impossible Dream Chaser could pick up something from CRS-2, but it's a long shot.

I agree on the development costs and the long shot.
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.
Does Cargo Dream Chaser still include the Dual Engine Centaur?
(Does the LM's proposal use a single or dual engine Centaur?)
Isn't that another element to be developed?
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.

Offline GreenShrike

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Re: CRS-2: Dream Chaser Cargo System
« Reply #42 on: 03/19/2015 12:12 AM »
I feel there is very little chance now especially that LM has thrown their hat into the ring. DCSS looks like it would take a lot of time & effort to get to where it needs to be & I just don't see that happening.

And Jupiter/ExoLiner won't take a lot of time and effort?

A full, autonomous space tug versus a pressurized tin can with a docking adapter on the end? A cargo version of Dream Chaser is likely simpler and easier than a crewed version -- what with not having to ensure astronaut safety and all, so no abort engines, no ECLSS -- and the crew version was only a couple of years from flying. Folding wings and a fairing simplifies things, and folding wings have been used for decades on military aircraft pulling higher Gs than DC will returning from orbit.

In the long run Jupiter is likely a better investment and would be very cool to see fly, but for the purposes of CRS2 -- which is all NASA is concerned with -- I'm not at all certain that DCCS wouldn't be a better choice.
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Offline Mike Harris-Stone

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Re: CRS-2: Dream Chaser Cargo System
« Reply #43 on: 03/19/2015 01:43 AM »
It looks to me like the Dream Chaser Cargo has a much higher development cost and schedule risk than any of the other known CRS2 proposals.  Not only do they have to do a huge amount of development on Dream Chaser itself, but they also have to develop a service module.  The service module probably won't be developed entirely from scratch since SNC has some experience in the area, but I think they're a lot farther away from a service module than LM is from Jupiter.

The service module is also going to add to their per-mission costs.  Being compatible with a variety of launch vehicles is definitely a step in the right direction on cost, but for CRS-2 they will have had to propose missions with a specific launch vehicle partner.  Launching on Ariane isn't allowed by the CRS-2 rules, as I understand them, so unless SpaceX signed onto their bid (which I highly doubt for competive reasons), they're still stuck with Atlas V.  With both LM and Boeing submitting competing CRS-2 bids, ULA probably didn't offer SNC a particularly special deal on Atlas V for DC for CRS-2.

So I don't think they can compete with SpaceX on price for downmass.  And OrbitalATK and LM proposals have much more cargo per trip, so I don't think they can compete with either of those bids.

I think it's not impossible Dream Chaser could pick up something from CRS-2, but it's a long shot.

I agree on the development costs and the long shot.
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.
Does Cargo Dream Chaser still include the Dual Engine Centaur?
(Does the LM's proposal use a single or dual engine Centaur?)
Isn't that another element to be developed?
The X-38 was to have folding wings so the idea is not "too off the wall"...

Actually, the HL-20 itself was possibly going to have folding wings so it could meet the requirement of fitting in an orbiter's payload bay.

Online ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #44 on: 03/19/2015 05:11 AM »
NASA has a tough choice ahead, but DCSS could squeak in.

If SpaceX and Orbital get the primary CRS2 contracts as they did with CRS1, they'll again provide dissimilar services. SpaceX has its modest upmass thanks to the cramped capsule but also includes unpressurized upmass and extremely important return downmass capability. Orbital has much larger upmass due to the large volume of Cygnus and soon Enhanced Cygnus, and disposes of ISS's trash when it burns up after mission end.

DCSS can backstop both craft: SpaceX's unpressurized upmass and return downmass, as well as Cygnus' large volume (with both DC's internal space and the pressurized external pod) and trash disposal (when the pod detaches and burns up during reentry). And if DCSS flies on Atlas V, then that's a third rocket providing services to the ISS, after SpaceX's Falcon 9 and Orbital's Antares (well, Antares II, I guess).

With those three flying CRS2 missions, if any provider is forced to stand down launches, NASA won't lose any capability.

I sure hope not.

The way to reduce costs is with more scale.  Dividing the work among more vehicles just means each one has less scale and costs more.

NASA shouldn't choose more than two providers for CRS-2.  That gives redundancy for getting cargo to the station, which is the most important thing.  In the CRS-2 timeframe, some additional downmass will be provided by the two commercial crew vehicles.  They don't need two different CRS-2 providers to both provide downmass.

Even if there is a failure of one of the CRS-2 systems, the downtime is unlikely to be very long, especially if it's one of the systems that is already in use for CRS-1.  It doesn't carry crew, so they don't have to be so paranoid after a failure.  It's OK to launch again if needed even before they are certain of the root cause.  And if it's one of the CRS-1 systems, a fundamental flaw that makes the system very likely to fail, such as the one Orbital is dealing with now, just isn't going to happen because the systems will already have flown to ISS so many times that any such fundamental flaws already would have been found.  Even if they find a flaw that makes it only 95% reliable, it's still OK to keep launching commercial cargo missions before they fix the flaw.

Online ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #45 on: 03/19/2015 05:21 AM »
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.

Online ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #46 on: 03/19/2015 05:28 AM »
I feel there is very little chance now especially that LM has thrown their hat into the ring. DCSS looks like it would take a lot of time & effort to get to where it needs to be & I just don't see that happening.

And Jupiter/ExoLiner won't take a lot of time and effort?

Not nearly as much as Dream Chaser.

A full, autonomous space tug versus a pressurized tin can with a docking adapter on the end?

That autonomous space tug is put together from existing, proven pieces.  The core of it is the same as MAVEN, which is in orbit around Mars right now.  SNC is starting with much less on their service module, and that doesn't even count Dream Chaser itself.

Remember, SNC's bid for Crew Dream Chaser was $2.4 billion.  Even if they can cut some of that for the crew version, that's a lot of money.

A cargo version of Dream Chaser is likely simpler and easier than a crewed version -- what with not having to ensure astronaut safety and all, so no abort engines, no ECLSS -- and the crew version was only a couple of years from flying.

And $2.4 billion away from flying.

Folding wings and a fairing simplifies things, and folding wings have been used for decades on military aircraft pulling higher Gs than DC will returning from orbit.

Folding wings may simplify some things, but it makes other things more complex.  There are no aircraft carrier crew members to fold/unfold and lock/unlock the wings.  They'll need to have actuators and locking mechanisms.

Offline adrianwyard

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Re: CRS-2: Dream Chaser Cargo System
« Reply #47 on: 03/19/2015 06:04 AM »
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.

What makes you think the wings on carrier aircraft are folded by ground crew? Not that this small point makes any difference to the bigger argument, but there's no harm in being factually correct.

Online ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #48 on: 03/19/2015 06:24 AM »
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.

What makes you think the wings on carrier aircraft are folded by ground crew? Not that this small point makes any difference to the bigger argument, but there's no harm in being factually correct.

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.

Offline adrianwyard

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Re: CRS-2: Dream Chaser Cargo System
« Reply #49 on: 03/19/2015 06:43 AM »
Well you need to tell the Navy they're doing it wrong then! See F/A-18 and others.

The (very small) point for this discussion is that you are incorrect when you say SNC will be doing something new with a folding wing. It can still be a bad idea, just not a new one. Perhaps we can get back to bigger scale issues now?
« Last Edit: 03/19/2015 06:44 AM by adrianwyard »

Offline Burninate

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Re: CRS-2: Dream Chaser Cargo System
« Reply #50 on: 03/19/2015 06:44 AM »
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.

What makes you think the wings on carrier aircraft are folded by ground crew? Not that this small point makes any difference to the bigger argument, but there's no harm in being factually correct.

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.


« Last Edit: 03/19/2015 06:48 AM by Burninate »

Offline Burninate

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Re: CRS-2: Dream Chaser Cargo System
« Reply #51 on: 03/19/2015 06:54 AM »
Lest you think this is new or expensive technology, the F-4U Corsair from 1944:


Offline Nibb31

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Re: CRS-2: Dream Chaser Cargo System
« Reply #52 on: 03/19/2015 07:28 AM »
The old Russian BOR-4 had folding wings too.

Offline Jim

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Re: CRS-2: Dream Chaser Cargo System
« Reply #53 on: 03/19/2015 10:03 AM »

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.


Not relevant.  None of those perform reentry,  have TPS on them or deal with high velocity hot gas.
« Last Edit: 03/19/2015 10:04 AM by Jim »

Offline Baranquilla

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Re: CRS-2: Dream Chaser Cargo System
« Reply #54 on: 03/19/2015 10:56 AM »

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.


Not relevant.  None of those perform reentry,  have TPS on them or deal with high velocity hot gas.

At least some of these aircraft are/were fighter jets (being able to take some serious g forces). Maybe we can conclude that making such a folding system (as far as structural integrity is concerned)  has been done BUT that combining that with a heatshield, etc is novel. This will indeed make for a higher risk factor and a higher price.

Personally I don't think it will get selected. That Trunk looks like it was conceived 5 minutes before the deadline.
PS: Maybe this should become a discussion thread.
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Online jsgirald

Re: CRS-2: Dream Chaser Cargo System
« Reply #55 on: 03/19/2015 11:12 AM »
Just a crackpot idea.

That SM somehow reminds me of the Jupiter tug. Pairing the tug with the spaceplane might make a fully reusable orbital system.  8)
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Offline jak Kennedy

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Re: CRS-2: Dream Chaser Cargo System
« Reply #56 on: 03/19/2015 11:23 AM »
I must have missed it but why would the cargo Dream Chaser need to be inside a fairing?

Offline Baranquilla

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Re: CRS-2: Dream Chaser Cargo System
« Reply #57 on: 03/19/2015 11:27 AM »
I must have missed it but why would the cargo Dream Chaser need to be inside a fairing?

Aerodynamics, IMHO. Stresses on the launch vehicle are less in a payload fairing I think, plus hasn't SNC always said they want to be able to launch on several vehicles?
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Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #58 on: 03/19/2015 11:29 AM »
I must have missed it but why would the cargo Dream Chaser need to be inside a fairing?
It simplifies the aerodynamics for the launch vehicle and the avionics/guidance system with little modification from standard.
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Offline Nibb31

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Re: CRS-2: Dream Chaser Cargo System
« Reply #59 on: 03/19/2015 12:47 PM »
Yes, but except for the new aft module with unpressurized bits and solar panels sticking out, the aerodynamics haven't changed since the CCDev proposal and the avionics should be the same.

Surely it would have been much lighter to just put a fairing around the aft module or make it fit inside the adapter.

Why does DC all of a sudden need a fairing and solar panels when the manned version didn't? Or was the original CCDev proposal too optimistic about the aero loads and avionics?

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